Showing papers in "Journal of Soils and Sediments in 2017"

Biochar for crop production: potential benefits and risks

Abstract: Biochar, the by-product of thermal decomposition of organic materials in an oxygen-limited environment, is increasingly being investigated due to its potential benefits for soil health, crop yield, carbon (C) sequestration, and greenhouse gas (GHG) mitigation. In this review, we discuss the potential role of biochar for improving crop yields and decreasing the emission of greenhouse gases, along with the potential risks involved with biochar application and strategies to avoid these risks. Biochar soil amendment improves crop productivity mainly by increasing nutrient use efficiency and water holding capacity. However, improvements to crop production are often recorded in highly degraded and nutrient-poor soils, while its application to fertile and healthy soils does not always increase crop yield. Since biochars are produced from a variety of feedstocks, certain contaminants can be present. Heavy metals in biochar may affect plant growth as well as rhizosphere microbial and faunal communities and functions. Biochar manufacturers should get certification that their products meet International Biochar Initiative (IBI) quality standards (basic utility properties, toxicant assessment, advanced analysis, and soil enhancement properties). The long-term effects of biochar on soil functions and its fate in different soil types require immediate attention. Biochar may change the soil biological community composition and abundance and retain the pesticides applied. As a consequence, weed control in biochar-amended soils may be difficult as preemergence herbicides may become less effective.

Biochar-induced changes in soil properties affected immobilization/mobilization of metals/metalloids in contaminated soils

Abstract: Remediation of metal contaminated soil with biochar is attracting extensive interest in recent years. Understanding the significance of variable biochar properties and soil types helps elucidating the meticulous roles of biochar in immobilizing/mobilizing metals/metalloids in contaminated soils. Six biochars were produced from widely available agricultural wastes (i.e., soybean stover, peanut shells and pine needles) at two pyrolysis temperatures of 300 and 700 °C, respectively. The Pb-, Cu-, and Sb-contaminated shooting range soils and Pb-, Zn-, and As-contaminated agricultural soils were amended with the produced biochars. The mobility of metals/metalloids was assessed by the standard batch leaching test, principal component analysis and speciation modeling. The changes in soil properties were correlated to feedstock types and pyrolysis temperatures of biochars based on the principal component analysis. Biochars produced at 300 °C were more efficient in decreasing Pb and Cu mobility (>93 %) in alkaline shooting range soil via surface complexation with carboxyl groups and Fe-/Al-minerals of biochars as well as metal-phosphates precipitation. By contrast, biochars produced at 700 °C outperformed their counterparts in decreasing Pb and Zn mobility (100 %) in acidic agricultural soil by metal-hydroxides precipitation due to biochar-induced pH increase. However, Sb and As mobility in both soils was unfavorably increased by biochar amendment, possibly due to the enhanced electrostatic repulsion and competition with phosphate. It is noteworthy that the application of biochars is not equally effective in immobilizing metals or mobilizing metalloids in different soils. We should apply biochar to multi-metal contaminated soil with great caution and tailor biochar production for achieving desired outcome and avoiding adverse impact on soil ecosystem.

Use of biochar-compost to improve properties and productivity of the degraded coastal soil in the Yellow River Delta, China

Abstract: Nutrient deficiency and salt stress (sodium, Na+) strongly limited the productivity of the degraded coastal soils in the Yellow River Delta. Biochar-based functional materials have been considered as a promising amendment to solving the problem of global soil security (e.g., erosion, fertility loss, acidification, and salinization). Therefore, this study aimed to explore the potential of using a biochar-compost amendment (BCA) to improve the coastal soil properties and productivity. The BCA was produced from composting of biochar and additives including seafood shell powder, peanut shell, commercial humate, and inorganic nutrients. Two halophytes, sesbania (Sesbania canabina (Retz.) Pers) and seashore mallow (Kosteletzkya virginica), were chosen as the tested plants in a 52-day pot experiment. BCA was added as the rates of 0, 1.5, 5, and 10 % (w/w). At the end of the incubation, the shoot height, biomass, and root morphological parameters including length, tips, and surface area were measured, as well as the properties (e.g., soil organic matter (SOM) content and cation exchange capacity (CEC)) of the rhizosphere and non-rhizosphere soils. The BCA application at 1.5 % enhanced the growth of sesbania and seashore mallow and increased their total biomass by 309 and 70.8 %, respectively, while significantly inhibited both the halophyte growths at 10 %. Similarly, both the halophyte root morphologies (e.g., length and tips) significantly increased by BCA addition at 1.5 %. The promoting growth of the both halophytes could be resulted from the improvement of soil properties such as the increased SOM and CEC, the decreased amount of the exchangeable sodium (Ex-Na) and exchangeable sodium percentage (ESP), and the rhizosphere effect (e.g., decreased soil pH). The higher rate of BCA addition (e.g., 10 %) sharply increased soil salinity, responsible for the inhibition of both the halophyte growths. Although BCA addition may directly supply much nitrogen (N) for the soils, N bioavailability for both halophytes was not largely improved. The short-term laboratory pot experiments revealed that producing the biochar-compost with desired properties (e.g., BCA) could be a feasible alternative to remediate the degraded coastal soil in the Yellow River Delta. Moreover, the addition of BCA should be kept at an optimal level, which may produce expected positive results. Our results will be helpful for supporting the strategy of designing right biochar-compost for the right soil.

Comammox—a newly discovered nitrification process in the terrestrial nitrogen cycle

Abstract: Nitrification, the microbial oxidation of ammonia to nitrate via nitrite, is a pivotal component of the biogeochemical nitrogen cycle. Nitrification was conventionally assumed as a two-step process in which ammonia oxidation was thought to be catalyzed by ammonia-oxidizing archaea (AOA) and bacteria (AOB), as well as nitrite oxidation by nitrite-oxidizing bacteria (NOB). This long-held assumption of labour division between the two functional groups, however, was challenged by the recent unexpected discovery of complete ammonia oxidizers within the Nitrospira genus that are capable of converting ammonia to nitrate in a single organism (comammox). This breakthrough raised fundamental questions on the niche specialization and differentiation of comammox organisms with other canonical nitrifying prokaryotes in terrestrial ecosystems. This article provides an overview of the recent insights into the genomic analysis, physiological characterization and environmental investigation of the comammox organisms, which have dramatically changed our perspective on the aerobic nitrification process. By using quantitative PCR analysis, we also compared the abundances of comammox Nitrospira clade A and clade B, AOA, AOB and NOB in 300 forest soil samples from China spanning a wide range of soil pH. Comammox Nitrospira are environmentally widespread and numerically abundant in natural and engineered habitats. Physiological data, including ammonia oxidation kinetics and metabolic versatility, and comparative genomic analysis revealed that comammox organisms might functionally outcompete other canonical nitrifiers under highly oligotrophic conditions. These findings highlight the necessity in future studies to re-evaluate the niche differentiation between ammonia oxidizers and their relative contribution to nitrification in various terrestrial ecosystems by including comammox Nitrospira in such comparisons. The discovery of comammox and their broad environmental distribution added a new dimension to our knowledge of the biochemistry and physiology of nitrification and has far-reaching implications for refined strategies to manipulate nitrification in terrestrial ecosystems and to maximize agricultural productivity and sustainability.

Bioavailability of Cd and Zn in soils treated with biochars derived from tobacco stalk and dead pigs

Abstract: Previous studies show that application of biochar can reduce the bioavailability of heavy metals in soil. A plant growth experiment was carried out to evaluate the effect of tobacco stalk- and dead pig-derived biochars on the extractability and redistribution of cadmium (Cd) and zinc (Zn) in contaminated soil, and the impact on tobacco (Nicotiana tabacum L.) plant growth. The top 20 cm of a soil contaminated with Cd and Zn was used in this study. Biochars derived from tobacco stalk and dead pig were applied to the soil at four application rates (0, 1, 2.5, and 5 %), and tobacco plants were grown. After 80-days growth, the pH, electrical conductivity (EC), CaCl2-extractable heavy metals and fractions of heavy metals in soil samples, as well as the plant biomass and the concentrations of heavy metals in the plant were determined. The plant growth experiment demonstrated that tobacco stalk biochar and dead pig biochar significantly (P < 0.05) increased the pH, but had no significant effect on the electrical conductivity (EC) of the soil. The CaCl2-extractable Cd and Zn content decreased as the application rates increased. The concentration of extractable Cd and Zn decreased by 64.2 and 94.9 %, respectively, for the tobacco stalk biochar treatment, and 45.8 and 61.8 %, respectively, for the dead pig biochar treatment at 5 % application rate. After biochar addition, the exchangeable Cd was mainly transformed to fractions bound to carbonates and Fe-Mn oxides, while the Zn was immobilized mainly in the fraction bound to Fe-Mn oxides. Tobacco stalk biochar increased the tobacco plant biomass by 30.3 and 36.2 % for shoot and root, respectively at the 5 % application rate. Dead pig biochar increased the tobacco plant biomass by 43.5 and 40.9 % for shoot and root, respectively, at the 2.5 % application rate. Both biochars significantly (P < 0.05) decreased the Cd and Zn accumulation by tobacco plant. As a soil amendment, tobacco stalk biochar was more effective at removing Cd, whereas dead pig biochar was more effective at removing Zn, and a higher application rate was more effective than a lower application rate. Overall, biochar derived from tobacco stalk was more effective, than dead pig biochar, at remediating soil contaminated with Cd and Zn, as well as promoting tobacco growth.

Phytoremediation of a multi contaminated soil: mercury and arsenic phytoextraction assisted by mobilizing agent and plant growth promoting bacteria

Abstract: The possibility of using chemical and microbial additives to enhance the phytoextraction of mercury (Hg) and arsenic (As) from a multi-contaminated soil could be very effective, leading to a significant saving in terms of time and costs of the reclamation. The aim of this study was to evaluate the efficacy of the addition of (i) thiosulfate and (ii) metal-tolerant bacteria isolated from the polluted soil having plant growth promotion (PGP) potential to perform As and Hg phytoextraction by Brassica juncea and Lupinus albus. A collection of 13 bacterial isolates able to tolerate As and Hg was obtained from the contaminated soil, identified by partial 16S rRNA gene sequencing and tested in vitro for PGP activities. The most promising strains were further tested in vivo for the evaluation of plant growth ability and rhizocompetence on model plants. Pot experiments were conducted in microcosms, with polluted soil vegetated with B. juncea and L. albus. Ammonium thiosulfate and potassium dihydrogen phosphate were used as mobilizing agents, together with a bacterial consortium composed by the most promising PGP isolates. Thirteen indigenous metal-tolerant bacterial strains were isolated, and their in vitro characterization highlighted their great potential in assisting the phytoremediation process; most of them tolerated both trace elements and showed, at the same time, multiple PGP traits. The results were confirmed in vivo on model plants and lead to the selection of the most promising PGP strains to be applied in microcosm-scale phytoextraction experiments. Thiosulfate addition significantly increased the mobilization of both elements, promoting bioavailability and phytoextraction. When a selected bacterial consortium was supplemented in addition to thiosulfate, the efficacy of the phytoaccumulation was increased up to 85 % for As and up to 45 % for Hg. The use of the common fertilizer thiosulfate appeared to have great potential in phytoextraction practices since it was able to facilitate the uptake by plants of both Hg and As. Moreover, the application of a consortium of indigenous PGP bacteria (PGPB) produced a further positive effect on the plant biomass, supporting and enhancing the phytoextraction strategy, thus demonstrating their potential in a microbe-assisted phytoremediation intervention.

Soil-water retention behavior of compacted biochar-amended clay: a novel landfill final cover material

Abstract: Biochar has long been proposed for amending agricultural soils to increase soil-water retention capacity and therefore promotes crop growth. Recent studies revealed the potential use of biochar-amended soil in landfill final covers to promote methane oxidation and odor reduction. However, the effects of biochar application ratio, compaction water content (CWC), and degree of compaction (DOC) on soil-water retention characteristics of biochar-amended clay (BAC) at high soil suction (dry condition) are not well understood. The present study aims to overcome this knowledge gap. Soil suction was induced using vapor equilibrium technique by a temperature- and humidity-controlled chamber, and the water desorption (drying) and adsorption (wetting) water retention curves (WRCs) of compacted pure kaolin clay and peanut shell BAC with different biochar application ratios (0, 5, and 20 %, w/w), DOCs (80, 90, and 100 %), and CWCs (30 and 35 %) were measured. The correlations between these factors and the gravimetric water content were analyzed by three-way ANOVA followed by the Tukey HSD test. The soil micro-structure was studied by scanning electronic microscope with energy-dispersive X-ray spectroscopy. Measured WRCs of BAC suggest that the soil-water retention capacity at high suction range (48.49–124.56 MPa) was in general increased, upon biochar application. The BAC compacted with CWC of 35 % at low (80 %) and high (100 %) DOCs for the 5 % BAC were increased by 7.30 and 9.77 %, when compared with clay, while the increases of 20 % BAC were 39.89 and 59.20 %, respectively. This is attributed to the embedded effects of clay particles in biochar pores, which reduce the total pore space of BAC. The soil-water retention capacity of BAC was also increased with CWC and decreased with DOC. The results of three-way ANOVA analysis show that the effects of DOC and biochar ratio on soil gravimetric water content was significant (p < 0.05) only at 48.49 MPa on drying path. For other induced suctions, only effects of CWC were significant (p < 0.05). Biochar application increases soil-water retention capacity of the BAC at high soil suction (48.49–124.56 MPa) (dry condition) at both low (80 %) and high DOC (100 %). The soil-water retention capacity of 20 % BAC was much higher than that of 5 % BAC. BAC is a potential alternative landfill final cover soil with a higher soil-water retention capacity to be used in dry areas or regions with a long period of evaporation event.

Biochar addition drives soil aggregation and carbon sequestration in aggregate fractions from an intensive agricultural system

Abstract: Biochar application is deemed to modify soil properties, but current research has been mostly conducted on the degraded land in tropical regions. Using six consecutive years of biochar field trial, we investigated effects of biochar on soil aggregates, structural stability, and soil organic carbon (SOC) and black C (BC) concentrations in aggregate fractions. The findings have important implications in managing soil structure and SOC sequestration in high fertility soils of the temperate areas. The study had four treatments: control; biochar rate at 4.5 (B4.5) and biochar rate at 9.0 t ha−1 year−1 (B9.0); and straw return (SR). Soil samples were collected from 0–10-cm layer, and aggregate size distribution was determined with the wet-sieving method. Then, the mean weight diameter (MWD) of aggregates and the aggregate ratio (AR), i.e., the ratio of the >250 μm to the 53–250 μm size were calculated to assess the structural stability. Total SOC and BC concentrations in bulk soil ( 2000, 250–2000, 53–250, and 2000, 250–2000, and 53–250 μm) and BC in extracted fractions under biochar soils were observed. These results implied that biochar addition enhanced both native SOC and BC physical protection by aggregation. Biochar application is effective in mediating soil aggregation, and thus improves both native SOC and BC stabilization in an intensive cropping system of North China.

Soil loss in an olive grove in Central Spain under cover crops and tillage treatments, and farmer perceptions

Abstract: Soil erosion is a threat for the sustainability of the grove production all over the world, and olive groves are where the highest erosion is achieved. This study aimed to (1) evaluate soil loss from water erosion in microplots (1 m2) under natural rainfall events in an olive grove managed with tillage and three different cover crops; (2) determine the main climatic factors on soil loss and selective transportation; and (3) survey the willingness of local farmers to adopt cover crops. Over four hydrological years (2010 to 2014), tillage and three cover crop treatments have been assessed in a sloping olive grove in the Mediterranean area, in a semiarid climate and gypsiferous soil. The treatments were tillage (once a year), two annual covers (barley and legumes) and a permanent cover (Brachypodium distachyon). Soil loss was collected after each rainfall event, dried and weighted. Rainfall data was recorded and soil cover (%) was determined. Organic carbon (% OC) and texture were measured for sediments of tillage treatment to study their selective transportation. Local farmers were polled regarding their knowledge of the biophysical factors that affect soil conservation, their management practices and their willingness to adopt sustainable land management practices as cover crops. The tillage treatment exhibited the highest soil loss (6.8 t ha−1 year−1). Cover crops significantly reduced soil loss: 40 % for legumes, 60 % for barley and permanent cover led to an 80 % decrease (1.4 t ha−1 year−1). The soil loss depends mainly on the soil cover and kinetic energy of rainfall events. Vegetation cover higher than 40 % in autumn and spring was essential to limiting soil loss, even under heavy events. Mobilised sediments were enriched 2.4 times in OC and 1.6 in the clay fraction. In spite of the well-known benefits of cover crops in soil conservation, local farmers do not use them. A lack of environmental education and awareness has been detected. Tillage in olive groves produced unsustainable rates of soil loss, while permanent cover demonstrated high efficiency. Gypsiferous soils are vulnerable to water erosion processes if they are not protected by vegetation. Farmers should adopt tailored soil cover practices during spring and autumn, when the soil loss is higher. A few farmers use sustainable soil management techniques, and therefore cover crops in olive groves are rare in Central Spain because farmers are reluctant to change.

Role of woody biochar and fungal-bacterial co-inoculation on enzyme activity and metal immobilization in serpentine soil

Abstract: In this study, we investigated the effect of biochar (BC) and fungal bacterial co-inoculation (FB) on soil enzymatic activity and immobilization of heavy metals in serpentine soil in Sri Lanka. A pot experiment was conducted with tomatoes (Lycopersicon esculentum L.) at 1, 2.5, and 5 % (w/w) BC ratios. Polyphenol oxidase, catalase and dehydrogenase activities were determined by idometric, potassium permanganate oxidisable, and spectrophotometric methods, respectively. Heavy metal concentrations were assessed by 0.01 M CaCl2 and sequential extraction methods. An increase in BC application reduced polyphenol oxidase, dehydrogenase, and catalase activity. The application of FB increased soil dehydrogenase activity, with the maximum activity found in 1 % BC700 + FB treatment. Moreover, the CaCl2 extractable metals (Ni, Mn, and Cr) in 5 % BC700 amended soil decreased by 92, 94, and 100 %, respectively, compared to the control. Sequential extraction showed that the exchangeable concentrations of Ni, Mn, and Cr decreased by 55, 70, and 80 % in 5 % BC700, respectively. Results suggest that the addition of BC to serpentine soil immobilizes heavy metals and decreases soil enzymatic activities. The addition of FB to serpentine soil improves plant growth by mitigating heavy metal toxicity and enhancing soil enzymatic activities.

Soil organic matter and nutrient accumulation in areas under intensive management and swine manure application.

Abstract: Land use change and soil management are frequently associated to land degradation and soil organic matter (SOM) losses in tropical regions. In Brazil, in order to avoid this process, different management strategies have been applied, such as no-tillage and agricultural disposal of swine manure (SM). This study was carried out to evaluate the quantity and quality of SOM, as well as the occurrence of nutrient accumulation in soils of areas under contrasting management systems that have received consecutive applications of SM over the last decades in Brazil. Five land uses were sampled: native vegetation (NV), pasture with SM application (PA + SM), no-tillage with SM application (NT + SM), no-tillage (NT), and conventional tillage with SM application (CT + SM). Soil organic carbon (SOC), N, labile C, C management index (CMI), P, Ca2+, Mg2+, K+, Al3+, Fe, Zn, Mn, Cu, and H + Al were quantified. Except for PA + SM, the agricultural land uses caused decreases in SOC contents comparing to NV. PA + SM showed the highest C stocks, 138.9 ± 3.4 Mg ha−1 down to 0.4 m. The application of SM can be associated to the greater C stocks in PA + SM, NT + SM, and CT + SM and to the higher N contents in all land uses under this practice. Land uses which receive higher rates of swine manure application (PA + SM and CT + SM) have shown CMI greater than 100. However, this practice is associated to the accumulation of P, Cu, Na, and Zn in these soils. The SM application is associated to improvement on C stocks and SOM quality in area under pasture, no-tillage, and conventional tillage in Parana State, Brazil. However, this practice is the main driver of nutrient accumulation in these areas.

Chicken-manure-derived biochar reduced bioavailability of copper in a contaminated soil

Abstract: Copper (Cu) contamination has been increasing in land ecosystems due to economic development activities. Excessive amount of Cu in soils is toxic to both plants and microorganisms. Biochar (BC) is known to immobilize soil Cu. The objectives of this research were to investigate the effects of chicken-manure-derived BC (CMB) on Cu immobilization, and growth of native metallophyte Oenothera picensis in a Cu-contaminated soil. A Cu-contaminated sandy soil (338 mg Cu kg−1) was spiked and equilibrated with additional Cu (0, 100, and 500 mg Cu kg−1). The spiked soil was then amended with CMB (0, 5, and 10 % w/w) and incubated for 2 weeks. The metallophyte was grown on these treatments under greenhouse conditions for 3 months. Pore water solutions were collected from the plant pots every 30 days. After the harvest, soil and pore water pH, soil Cu fractions, pore water Cu concentration, soil microbial activity, plant biomass weight, and Cu concentration in plant parts were determined. The CMB increased the pH of soils and soil pore water, and probably also soil major nutrients. It reduced the exchangeable fraction of Cu but increased its organic matter and residual fractions. At the same time, it decreased the Cu concentration in the soil pore water. The CMB increased basal respiration and dehydrogenase activity. The CMB application produced up to three and seven times more root and shoot biomass, respectively. In addition, shoots accumulated lesser Cu than control but roots did more. Plants survived in soil that was spiked with 500 mg Cu kg−1, only when CMB dose was 10 %. The CMB affected the Cu uptake in plant by altering the mobility, bioavailability, and spatial distribution of Cu in soils. The increase in available nutrients and decrease in Cu toxicity facilitated plant growth. The increased microbial activity probably also promoted the plant growth and reduced the Cu bioavailability. Therefore, CMB can be used to remediate Cu-contaminated soils.

Effects of biochar on copper immobilization and soil microbial communities in a metal-contaminated soil

Abstract: Copper (Cu) contamination has been increasing in land ecosystems. Biochars (BCs) and arbuscular mycorrhizal fungi (AMF) are known to bind metals, and metallophyte can remove metals from soils. Will BC in combination with AMF contain the Cu uptake by a metallophyte growing in a metal-contaminated soil? The objective of this study was to investigate the effects of BCs on the Cu immobilization and over soil microbial communities in a metal-contaminated soil in the presence of AMF and metallophyte. Two BCs were produced from chicken manure (CMB) and oat hull (OHB). A Cu-contaminated sandy soil (338 mg kg−1) was incubated with CMB and OHB (0, 1, and 5 % w/w) for 2 weeks. Metallophyte Oenothera picensis was grown in pots (500 mL) containing the incubated soils in a controlled greenhouse for 6 months. A number of analyses were conducted after the harvest. These include plant biomass weight, microbial basal respiration, and dehydrogenase activity (DHA), AMF root colonization, spore number, and glomalin production; changes in fungal and bacterial communities, Cu fractions in soil phases, and Cu uptake in plant tissues. The BCs increased the soil pH, decreased easily exchangeable fraction of Cu, and increased organic matter and residual fraction of Cu. The BCs provided favorable habitat for microorganisms, thereby increasing basal respiration. The CMB increased DHA by ∼62 and ∼574 %, respectively, for the low and high doses. Similarly, the OHB increased soil microbial activity by ∼68 and ∼72 %, respectively, for the low and high doses. AMF root colonization, spore number, and total glomalin-related soil protein (GRSP) production increased by ∼3, ∼2, and ∼3 times, respectively, in soils treated with 1 % OHB. Despite being a metalophyte, O. picensis could not uptake Cu efficiently. Root and shoot Cu concentrations decreased or changed insignificantly in most BC treatments. The results show that the BCs decreased bioavailable Cu, decreased Cu uptake by O. picensis, improved habitat for microorganisms, and enhanced plant growth in Cu-contaminated soil. This suggests that biochars may be utilized to remediate Cu-contaminated soils.

Phytoremediation of soils contaminated by organic compounds: hype, hope and facts

Abstract: The present opinion paper is focused on the phytoremediation of organic pollutants and is based on the lectures given by the author during the International Congress of Phytoremediation of Polluted Soils, held at Vigo, Spain, 29–30 July 2014. The aim of this position paper is (1) to highlight some progress made within the last few years (after the end of COST Action 859 in October 2009) in the phytoremediation of selected organic pollutants and (2) to suggest new research and approaches, which seem important and promising in the opinion of the author to make this environmentally friendly remediation technique more attractive and more successful. Depending on the type of soil to be treated, as well as on the xenobiotic contaminants, their concentration and ageing, different approaches can be considered and are briefly presented with some recent and successful applications, but also highlighting their limitations and needs for future developments: phytoextraction of hydrophobic xenobiotic compounds like polychlorobiphenyls (PCBs), phytodegradation of xenobiotics and its possible impacts on primary and secondary metabolism of the plant and phytostimulation of rhizospheric microorganisms by root exudates for the rhizodegradation of petroleum hydrocarbons. Finally, some promising approaches are suggested for overcoming the bottlenecks and making phytoremediation a reliable, mature and sustainable technology: how to deal with mixed pollution; the potential of endophytic bacteria; possible improvements by soil amendments and co-cropping; validation of laboratory results by field experimentation; evolution of regulations from the total concentration of a pollutant to its bioavailable fraction; and the use of biomass for added-value products, fine chemicals and biofuels in biorefineries or the production of ornamental plants.

Effects of vermicompost amendment as a basal fertilizer on soil properties and cucumber yield and quality under continuous cropping conditions in a greenhouse

Abstract: We examined the effects of vermicompost application as a basal fertilizer on the properties of a sandy loam soil used for growing cucumbers under continuous cropping conditions when compared to inorganic or organic fertilizers. A commercial cucumber (Cucumis sativus L.) variety was grown on sandy loam soil under four soil amendment conditions: inorganic compound fertilizer (750 kg/ha,), replacement of 150 kg/ha of inorganic compound fertilizer with 3000 kg/ha of organic fertilizer or vermicompost, and untreated control. Experiments were conducted in a greenhouse for 4 years, and continuous planting resulted in seven cucumber crops. The yield and quality of cucumber fruits, basic physical and chemical properties of soil, soil nutrient characteristics, and the soil fungal community structure were measured and evaluated. Continuous cucumber cropping decreased soil pH and increased electrical conductivity. However, application of vermicompost significantly improved several soil characteristics and induced a significant change in the rhizosphere soil fungal community compared to the other treatments. Notably, the vermicompost amendments resulted in an increase in the relative abundance of Ascomycota, Chytridiomycota, Sordariomycetes, Eurotiomycetes, and Saccharomycetes, and a decrease in Glomeromycota, Zygomycota, Dothideomycetes, Agaricomycetes, and Incertae sedis. Compared to the organic fertilizer treatment, vermicompost amendment increased the relative abundance of beneficial fungi and decreased those of pathogenic fungi. Cucumber fruit yield decreased yearly under continuous cropping conditions, but both inorganic and organic fertilizer amendments increased yields. Vermicompost amendment maintained higher fruit yield and quality under continuous cropping conditions. Continuous cropping decreased cucumber yield in a greenhouse, but basic fertilizer amendment reduced this decline. Moreover, basal fertilizer amendment decreased beneficial and pathogenic fungi, and the use of vermicompost amendment in the basic fertilizer had a positive effect on the health of the soil fungal community.

Verrucomicrobial elevational distribution was strongly influenced by soil pH and carbon/nitrogen ratio

Abstract: The bacterial phylum Verrucomicrobia plays important roles in biogeochemical cycling processes, while the ecology of this phylum is still unclear. Previous elevational studies mainly focused on whole bacterial communities, while no study exclusively picked out Verrucomicrobia. Our objectives were to investigate the abundance, diversity and community composition of soil Verrucomicrobia across an elevation gradient on Changbai Mountain. In total, 24 soil samples representing six elevation gradients were collected. Primer set 515F/806R was used for PCR amplifications and sequencing was conducted on an Illumina HiSeq2000 platform. Data sets comprising of Verrucomicrobial phylum were culled from all quality sequences for the further analyses of Verrucomicrobial diversity and community composition. The relative abundance of Verrucomicrobia accounted for ~20% of the total bacterial communities, and Spartobacteria and DA101 were the most dominant class and genus, respectively. Verrucomicrobia community composition differed significantly among elevations, while the Verrucomicrobia diversity showed no apparent trend along elevation although the richness of some classes or genera significantly changed with elevation. The Verrucomicrobial community composition, diversity, and relative abundance of specific classes or genera were significantly correlated with soil pH and carbon/nitrogen ratio (C:N ratio). These results indicated that Verrucomicrobia were abundant in Changbai Mountain soils, and Verrucomicrobial elevational distribution was strongly influenced by soil pH and C:N ratio. Our results also provide potential evidence that the dominant genus DA101 occupies different ecological niches and performs oligotrophic life history strategy in soil environment.

Accumulation and phytoremediation of Pb, Zn, and Ag by plants growing on Koshk lead–zinc mining area, Iran

Abstract: This study investigated the extent of metal accumulation by plants colonizing a mining area in Yazd Province in Central Iran. It also investigated the suitability of these plants for phytoextraction and phytostabilization as two potential phytoremediation strategies. Plants with a high bioconcentration factor (BCF) and low translocation factor (TF) have the potential for phytostabilization, whereas plants with both BCFs and TFs >1 may be appropriate for phytoextraction. In this study, both shoots and roots of 40 plant species and associated soil samples were collected and analyzed for total concentrations of trace elements (Pb, Zn, and Ag). BCFs and TFs were calculated for each element. Nonnea persica, Achillea wilhelmsii, Erodium cicutarium, and Mentha longifolia were found to be the most suitable species for phytostabilization of Pb and Zn. Colchicum schimperi, Londesia eriantha, Lallemantia royleana, Bromus tectorum, Hordeum glaucum, and Thuspeinantha persica are the most promising species for element phytoextraction in sites slightly enriched by Ag. Ferula assa-foetida is the most suitable species for phytostabilization of the three studied metals. C. schimperi, L. eriantha, L. royleana, B. tectorum, M. longifolia, and T. persica accumulated Ag, albeit at low level. Our preliminary study shows that some native plant species growing on this contaminated site may have potential for phytoremediation.

Origin and spatial distribution of metals in urban soils

Abstract: This study assessed soils from 36 parks and gardens (Vigo City, NW of Spain) where there are different degrees of traffic intensity and activity. The soils were characterised, and the content of Ba, Ca, Cr, Cu, Fe, Mg, Mn, Na, Ni, Pb, Si, Sr and Zn was analysed. Further assessment determined the geoaccumulation index, enrichment factor and the contamination degree by metals with adverse effects on human health and environmental quality. The results reveal the existence of a moderate degree of contamination by Ba, Pb and Cu, which contribute the most to soil contamination due to the influence of industrial areas and main transport routes. Correlation and cluster analyses suggest that the metals included in the study have three possible origins: “natural” (Na and Si), “mixed” (two groups with different source intensity: Ca and Sr and Cr, Fe, Mg, Mn and Ni) and two possible “urban” sources: traffic (Cu, Pb, Zn) and mixed (Ba). None of the soils can be classified as strongly contaminated but more than 61 % of the moderate contamination degree determined in the studied soils is explained by the Ba, Cu and Pb contents.

Taxon-specific responses of soil microbial communities to different soil priming effects induced by addition of plant residues and their biochars

Abstract: This work investigated changes in priming effects and the taxonomy of soil microbial communities after being amended with plant feedstock and its corresponding biochar. A soil incubation was conducted for 180 days to monitor the mineralization and evolution of soil-primed C after addition of maize and its biochar pyrolysed at 450 °C. Responses of individual microbial taxa were identified and compared using the next-generation sequencing method. Cumulative CO2 showed similar trends but different magnitudes in soil supplied with feedstock and its biochar. Feedstock addition resulted in a positive priming effect of 1999 mg C kg−1 soil (+253.7 %) while biochar gave negative primed C of −872.1 mg C kg−1 soil (−254.3 %). Linear relationships between mineralized material and mineralized soil C were detected. Most priming occurred in the first 15 days, indicating co-metabolism. Differences in priming may be explained by differences in properties of plant material, especially the water-extractable organic C. Predominant phyla were affiliated to Acidobacteria, Actinobacteria, Chloroflexi, Gemmatimonadetes, Firmicutes, Planctomycetes, Proteobacteria, Verrucomicrobia, Ascomycota, Basidiomycota, Blastocladiomycota, Chytridiomycota, Zygomycota, Euryarchaeota, and Thaumarchaeota during decomposition. Cluster analysis resulted in separate phylogenetic grouping of feedstock and biochar. Bacteria (Acidobacteria, Firmicutes, Gemmatimonadetes, Planctomycetes), fungi (Ascomycota), and archaea (Euryarchaeota) were closely correlated to primed soil C (R 2 = −0.98, −0.99, 0.84, 0.81, 0.91, and 0.91, respectively). Quality of plant materials (especially labile C) shifted microbial community (specific microbial taxa) responses, resulting in a distinctive priming intensity, giving a better understanding of the functional role of soil microbial community as an important driver of priming effect.

A review of diffuse pollution modeling and associated implications for watershed management in China

Abstract: Diffuse pollution has been extensively studied in China from loading assessments to watershed management, which are important in international research. However, few studies that assess the advances of diffuse pollution modeling and studies of trace diffuse pollutants have been conducted. The adaption and development of imported model systems based on local observations and climatic features have improved study skills and presented unique characteristics. In addition to traditional diffuse pollutants (e.g., nitrogen and phosphorus), modeling trace heavy metals and pesticide also provides insights for watershed management. We reviewed existing literature on diffuse pollution model applications and developments in China, attempting to provide a better understanding of the advances of diffuse pollution and new research directions for pollution modeling. Diverse methods have been adopted to express diffuse pollution formation, transport and environmental impacts using modeling as an effective tool for developing management guidelines in China. Model applications at different temporal–spatial scales, development of diffuse pollution modeling for emerging pollutants, and impacts of diffuse pollution on water quality in China were analyzed. Pollution loading decreased from east to west, coinciding with farmland distributions, tillage intensity, and economic levels. The temporal patterns of pollution loading have increased in recent decades due to increased fertilizer additions and climate warming which has put more pressure on water quality. This analysis indicated that enhancing existing models, with more field observations, is key for future diffuse pollution studies of trace organic pollutants and heavy metals. Establishing national databases and validating standard model parameters are essential and currently weak points at the national scale with respect to diffuse pollution modeling. Diffuse pollution has become a challenging issue in watershed management, and agricultural diffuse pollution poses the greatest risk to watershed management in China. However, the mechanisms involved in trace pollutant transport and the environmental consequences of these pollutants are largely unknown in China, where complicated tillage methods are used and climatic conditions vary throughout the country. Accumulated field observations at diverse temporal–spatial scales are important to accurately model and perform water risk assessments.

Land preparation and vegetation type jointly determine soil conditions after long-term land stabilization measures in a typical hilly catchment, Loess Plateau of China

Abstract: Land preparation (e.g., leveled ditches, leveled benches, adversely graded tableland, and fish-scale pits) is one of the most effective ecological engineering practices to reduce water erosion in the Loess Plateau, China. Land preparation greatly affects soil physicochemical properties. This study investigated the influence of different land preparation techniques during vegetation restoration on soil conditions, which remained poorly understood to date. Soil samples were collected from depths of 0–10, 10–20, 20–40, 40–60, 60–80, and 80–100 cm, in the typical hilly watershed of Dingxi City, Loess Plateau. Soil bulk density (BD), soil organic matter (SOM), and total nitrogen (TN) were determined for different land preparations and vegetation type combinations. Fractal theory was used to analyze soil particle size distribution (PSD). (1) The effect of land preparation on soil properties and PSD varied with soil depth. For each land preparation category, SOM and TN values showed a significant difference between the top soil layer and the underlying soil depths. (2) The fractal dimension of PSD showed a significant positive correlation with clay and silt content, but a significant negative correlation with sand content. (3) The 20 cm soil layer was a boundary that distinguished the explanatory factors, with land preparation and vegetation type as the controlling factors in the 0–20- and 20–100-cm soil layers, respectively. Land preparation and vegetation type significantly influenced soil properties, with 20 cm soil depth being the boundary for these two factors. This study provided a foundation for developing techniques for vegetation restoration in water-limited ecosystems.

Sugarcane bagasse biochars impact respiration and greenhouse gas emissions from a latosol.

Abstract: A paucity in knowledge remains on the influence of biochar production temperature and the rate of application on greenhouse gas emissions from soil. The objective of this column experiment was to evaluate a biochar thermosequence by doses on CO2, N2O, and CH4 emissions from a latosol following nitrogen fertilizer application following a pre-incubation period. Biochar was produced from sugarcane bagasse pyrolyzed at 300, 500, and 700 °C (BC 300, BC 500, and BC 700, respectively). Biochars were added to air-dried latosol columns at rates of 0, 0.5, 1, 2, 5, 10, and 15 % (w/w), and the water content was brought to 95 % of water-filled pore space (WFPS). The emissions from columns were tested on days 1, 3, 7, 15, and 30 following a 30-day pre-incubation. All treatments showed a decrease in respiration across the study period. The higher doses of biochar of BC 300 and BC 700 resulted in significantly higher respiration than controls on days 15 and 30. Neither biochar dose nor temperature had a significant effect on CH4 emissions during the study period. Application of all biochars suppressed the emissions of N2O at all doses on days 1 and 3, compared to the control. N2O emissions from higher temperature biochar-amended soil at 2, 5, 10, and 15 % were greater than that from corresponding treatments of lower-temperature biochar-amended soil on days 15 and 30. Soil respiration and overall greenhouse gas emission from latosol increased with biochar dose and pyrolysis temperature in the 30-day study period due to increasing water retention facilitated by biochar. Careful consideration is needed when applying bagasse biochar as it changes N cycling and soil physical properties.

Simultaneous immobilization of lead, cadmium, and arsenic in combined contaminated soil with iron hydroxyl phosphate

Abstract: Combined contamination of lead (Pb), cadmium (Cd), and arsenic (As) in soils especially wastewater-irrigated soil causes environmental concern. The aim of this study is to develop a soil amendment for simultaneous immobilization of Pb, Cd, and As in combinative contaminated soil. A soil amendment of iron hydroxyl phosphate (FeHP) was prepared and characterized, and its potential application in simultaneous immobilization of Pb, Cd, and As in combined contaminated soil from wastewater-irrigated area was evaluated. The effects of FeHP dosage, reaction time, and soil moisture on Pb, Cd, and As immobilization in the soil were examined. The immobilization efficiencies of Pb, Cd, and As generally increased with the increasing of FeHP dosage. With FeHP dosage of 10 %, the immobilization percentages of NaHCO3-extractable As and DTPA-extractable Pb and Cd reached 69, 59, and 44 %, respectively. The equilibrium time required for immobilization of these contaminants was in the following order: NaHCO3-extractable As (0.25 days) < DTPA-extractable Cd(3 days) < DTPA-extractable Pb (7 days). However, the immobilization efficiencies of Pb, Cd, and As have not changed much under soil moisture varied from 20 to 100 %. According to the results of the sequential extraction, the percentages of Pb, Cd, and As in residual fractions increased after the application of FeHP amendment, while their percentages in exchangeable fractions decreased, illustrating that FeHP can effectively decrease the mobilities and bioavailabilities of Pb, Cd, and As in the soil. Moreover, the application of FeHP will not have soil acidification and soil structure problem based on the soil pH measurements and soil morphology. FeHP can immobilize Pb, Cd, and As in the combinative contaminated soil from wastewater irrigation area simultaneously and effectively. Thus, it can be used as a potential soil amendment for the remediation of Pb, Cd, and As-combined contaminated soil.

Soil pH, organic matter, and nutrient content change with the continuous cropping of Cunninghamia lanceolata plantations in South China

Abstract: Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) is an important native tree species in China. Consecutive cropping traditionally occurs in Chinese fir plantations (CFPs), but this practice has resulted in productivity declines in subsequent rotations. This study was designed to better understand the change of soil properties in the continuous cropping CFPs. We investigated soil pH, soil organic matter (SOM), and nutrient contents in different soil layers and in rhizosphere soil (RS) and non-rhizosphere soil (NRS) under CFPs of different ages and in different rotations. In the upper (0–20 cm) soil layer, soil pH decreased, while SOM increased, beneath mature CFPs with consecutive rotations. Total nitrogen (TN), available potassium, and available phosphorus contents in the upper soil layers did not differ significantly with consecutive rotations. Soil pH in RS was significantly lower than in NRS under mature plantations of the third rotation. Soil organic matter, TN, and available nitrogen did not differ between RS and NRS. Available phosphorus in RS was consistently lower than in NRS, and was highly deficient in the third rotation. We conclude that no severe soil nutrient degradation occurred in the continuous cropping CFPs examined in this study, with soil acidification and phosphorus deficiency being two primary problems observed.

Effects of in-situ straw decomposition on composition of humus and structure of humic acid at different soil depths

Abstract: Returning straw to soil improved soil carbon sequestration capacity and increase soil organic matter. However, in different soil depth, especially in subsoil, there were few studies on the effects of straw decomposition on soil carbon sequestration and the properties of humic substances. Therefore, an in-situ incubation study, with six different straw rates and three different soil depths, was carried out to explore the effects of straw decomposition on soil organic carbon and humic substance composition at different soil depths. The experiment was composed of six straw rates: 0, 0.44, 0.88, 1.32, 2.64, and 5.28% of soil dry mass. The maize straw was proportionately mixed with soil and put into nylon bags. Then, the nylon bags were buried in soil at three depths (15, 30, and 45 cm) and the straw decomposition trial lasted for 17 consecutive months in-situ. Soil samples were collected after completion of the field trial. Humic substances were quantitatively and qualitatively analyzed using the modification method of humus composition and the methods specified by the International Humus Association. Fourier transform infrared spectroscopy and fluorescence spectroscopy were used in this study. Results indicated that CO2 concentration increased with increase in soil depth. Compared with the “zero” straw control, soil organic carbon contents in the treatments amended with 1.32, 2.64, and 5.28% maize straw increased significantly, and most accumulations were at 30–45 cm depths. FTIR and fluorescence emission spectra analyses indicated that the addition of straw enhanced the aliphatic structure and decreased the aromaticity of humic acid (HA), that was to say that HA molecular structure approaches to the development of simplification and younger. The maximum change in HA molecular structure was under the 5.28% treatment in the 30–45 cm depth. Returning maize straw to the subsoil layers is more conducive to the accumulation of soil organic carbon and improvement of the quality and activity of HA and the organic carbon in the subsoil can be renewed.

Straw amendment to paddy soil stimulates denitrification but biochar amendment promotes anaerobic ammonia oxidation

Abstract: Organic matter amendment is usually used to improve soil physicochemical properties and to sequester carbon for counteracting climate change. There is no doubt that such amendment will change microbial activity and soil nitrogen transformation processes. However, the effects of straw and biochar amendment on anammox and denitrification activity and on community structure in paddy soil are unclear. We conducted a 30-day pot experiment using rice straw and rice straw biochar to deepen our understanding about the activity, microbial abundance, and community structure associated with soil nitrogen cycling during rice growth. Regarding activity, anammox contributed 3.1–8.1% of N2 production and denitrification contributed 91.9–96.9% of N2 production; straw amendment resulted in the highest denitrification rate (38.9 nmol N g−1 h−1), while biochar amendment resulted in the highest anammox rate (1.60 nmol N g−1 h−1). Both straw and biochar amendments significantly increased the hzsB and nosZ gene abundance (p < 0.05). Straw amendment showed the highest nosZ gene abundance, while biochar amendment showed the highest hzsB gene abundance. Phylogenetic analysis of the anammox bacteria 16S rRNA genes indicated that Candidatus Brocadia and Kuenenia were the dominant genera detected in all treatments. Straw and biochar amendments have different influences on anaerobic ammonia oxidation and denitrification within paddy soil. Our results suggested that the changes in denitrification and anammox rates in the biochar and straw treatments were mainly linked to functional gene abundance rather than microbial community structure and that denitrification played the more major role in N2 production in paddy soil.

Effect of the size of variable charge soil particles on cadmium accumulation and adsorption

Abstract: The size of soil particles strongly affects the accumulation and adsorption of heavy metals which partly controls the co-transport of heavy metals by soil colloids. However, the effect of the size of soil particles on the accumulation and adsorption of heavy metals in the colloidal dimension has seldom been studied. In this study, variable charge soils were selected and separated into five size fractions to elucidate the effect of the size of soil particles on Cd accumulation and adsorption. Five soil particle size fractions (>10, 10–1, 1–0.45, 0.45–0.2 and <0.2 μm) were obtained from Cd-contaminated soil by natural sedimentation and fractional centrifugation. The concentrations and species of Cd were measured in various sized soil particles. Batch adsorption experiments of Cd on the obtained soil particles were conducted under different pH values and concentrations of NaCl. Generally, the concentration of Cd increased with decreasing soil particle sizes, and the Cd proportion of exchangeable and carbonate fraction decreased from 43.84 to 17.75% with decreasing particle size. The soil particles with a size of 10–1 and <0.2 μm possessed a stronger adsorption ability than the other fractions in most cases. Moreover, the Cd adsorption capacities of the soil particles increased with increasing pH values and decreasing concentrations of NaCl, especially for soil particles containing more organic matter (OM) and variable charge minerals. Smaller soil particles are more capable of accumulating Cd and make Cd more stable. The adsorption capability of Cd is negatively related to the particle size and NaCl concentration and is positively related to the pH. The effects of the size of variable charge soil particles on Cd accumulation and adsorption are attributed to the differences in the physicochemical properties among various soil particle size fractions. This study contributes to the understanding of the co-transport of heavy metals in soil by soil colloids.

Methodological perspectives on the application of compound-specific stable isotope fingerprinting for sediment source apportionment

Abstract: Compound-specific stable isotope (CSSI) fingerprinting of sediment sources is a recently introduced tool to overcome some limitations of conventional approaches for sediment source apportionment. The technique uses the 13C CSSI signature of plant-derived fatty acids (δ13C-fatty acids) associated with soil minerals as a tracer. This paper provides methodological perspectives to advance the use of CSSI fingerprinting in combination with stable isotope mixing models (SIMMs) to apportion the relative contributions of different sediment sources (i.e. land uses) to sediments. CSSI fingerprinting allows quantitative estimation of the relative contribution of sediment sources within a catchment at a spatio-temporal resolution, taking into account the following approaches. First, application of CSSI fingerprinting techniques to complex catchments presents particular challenges and calls for well-designed sampling strategies and data handling. Hereby, it is essential to balance the effort required for representative sample collection and analyses against the need to accurately quantify the variability within the system. Second, robustness of the CSSI approach depends on the specificity and conservativeness of the δ13C-FA fingerprint. Therefore, saturated long-chain (>20 carbon atoms) FAs, which are biosynthesised exclusively by higher plants and are more stable than the more commonly used short-chain FAs, should be used. Third, given that FA concentrations can vary largely between sources, concentration-dependent SIMMs that are also able to incorporate δ13C-FA variability should be standard operation procedures to correctly assess the contribution of sediment sources via SIMMs. This paper reflects on the use of δ13C-FAs in erosion studies and provides recommendations for its application. We strongly advise the use of saturated long-chain (>20 carbon atoms) FAs as tracers and concentration-dependent Bayesian SIMMs. We anticipate progress in CSSI sediment fingerprinting from two current developments: (i) development of hierarchical Bayesian SIMMs to better address catchment complexity and (ii) incorporation of dual isotope approaches (δ 13C- and δ 2H-FA) to improve estimates of sediment sources.

Alpine meadow restorations by non-dominant species increased soil nitrogen transformation rates but decreased their sensitivity to warming

Abstract: Alpine meadow soils are large carbon (C) and nitrogen (N) pools correlated significantly with global C and N cycling. Soil N transformations, including nitrification and N mineralization, are key processes controlling N availability. Alpine meadow degradations are common worldwide, and vegetation restorations have been widely implemented. However, grass species used for restorations may alter soil N transformations or their response to warming and N deposition due to divergent plant traits and their different effects on soil characteristic. To understand the effects of meadow restorations by non-historically dominant species on N transformations, we measured N transformation rates in restored soils and control soils under the context of warming and N deposition. We collected soils from plots restored by dominant (Miscanthus floridulus) and non-dominant species (including Carex chinensis and Fimbristylis dichotoma) and non-restored plots in alpine meadows of Wugong Mountain, China. We measured nitrification and N mineralization rates when soils were incubated at different temperature (15 or 25 °C) and N additions (control vs. 4 g m−2) to examine their responses to restoration species, warming, and N. Vegetation restored soils differed substantially from non-restored bare soils. Total N, total organic C, pH, and dissolved organic C contributed the most to the separation. Restoration altered soil N transformations substantially, even though the effects varied among restoration species. Specifically, non-historically dominant species accelerated N transformations, while the originally dominant species decreased N transformations. In addition, sensitivity of nitrification to warming in restored soils was decreased by restorations. Soils restored by originally dominant species were higher in sensitivity of N transformations to warming than those restored by the other two species. Warming increased nitrification rates by 45.5 and 17.4 % in bare soils and restored soils, respectively. Meanwhile, N mineralization rates were increased by 52.8 and 21.9 %, respectively. Vegetation restoration of the degraded meadows impacted N transformations and their sensitivity to warming. The effects varied with identity of the restoration species, suggesting that grass species should be considered in future restorations of degraded meadows in terms of their divergent effects on N transformations and sensitivity to warming.

Sorption and transport of sulfonamides in soils amended with wheat straw-derived biochar: effects of water pH, coexistence copper ion, and dissolved organic matter

Abstract: Sulfonamides are widely used for the prevention and treatment of bacterial infections, hard-degraded contaminants distributed in the environment if they are discharged into the soil and water. Biochar could probably influence the geochemical behavior of ionized antibiotics in the soils. To determine the sorption/desorption of three representative sulfonamides (SAs) in soils amended with biochar, we investigated the effects of water pH, Cu2+, and dissolved humic acid on the sorption of sulfamethoxazole (SMX), sulfamethazine (SMZ), and sulfadiazine (SD) onto two different soil samples (S1 pH = 5.13 and S2 pH = 7.33) amended with wheat straw-derived biochar (size 0.5∼0.6 mm). Batch experiments showed that the sorption/desorption isotherms of SAs on soil with/without biochar followed the Freundlich model. The biochar had a strong adsorption potential for SMX, SMZ, and SD both in S1 and S2 at low water pH. Except for SMX, the presence of Cu2+ inhibited the sorption of SMZ and SD through competing hydrophobic adsorption region in soils. HA suppressed the sorption of three sulfonamides in soil S2 by electrostatic repulsion under alkaline condition. The soil leaching column experiments showed the SA transport in soils, and S1 and S2 amended with biochar (0.5 and 1.0 wt%) brought about 12–20 % increase in SMX, SMZ, and SD retention compared to the untreated soil. The results indicated that the presence of biochar effectively mitigated the mobility of ionized antibiotics such as SMX, SMZ, and SD in soils, which helps us reconsider the potential risk of antibiotics in the environment.