Showing papers on "Trace metal published in 2020"

Hydrogeochemical Processes and Trace Metal Contamination in Groundwater: Impact on Human Health in the Maputaland Coastal Aquifer, South Africa

Abstract: The main objective of the study is to evaluate the hydrogeochemical processes and potential health risk assessment for humans in groundwater of Maputaland coastal aquifer, South Africa. In this study, 53 and 42 groundwater samples were collected from bore wells during 2018 and 2019 and were analysed for major ions, minor ions, nutrients and trace metals. Na–Cl water type was dominant in groundwater followed by Ca–HCO3. Cross plots revealed that ion exchange, reverse ion exchange, silicate weathering, seawater mixing and anthropogenic inputs from agricultural activities govern the groundwater chemistry. GIS methods were adopted to produce spatial distribution maps of major ions through which locations of groundwater contamination and the intensity of hydrogeochemical processes were identified. Mean concentration of trace metals were in the order: Zn > Li > Al > Fe > Mn > Cu > Pb > As > Co > Cd in 2018, Fe > Zn > Mn > Sr > B > Pb > Cu > Co > Cr > Cd > Ag > Al > Ni in 2019. Most of the trace metals were found to be within the WHO standards for drinking water except Cd, Zn, Pb, Mn, Al and Fe. Health risk assessment of trace metals in groundwater via ingestion and dermal absorption pathways were carried out. Hazard Quotients (HQs) and Hazard Index (HI) of all trace metals were below 1, except HQingestion and HI for Co and Pb which were greater than 1 in children. This suggests that these metals pose adverse risks to local people, and children were more sensitive to risks than adults. HI values for adults and children were medium indicating high risk. This is the first baseline study conducted in the study area which identifies the chemical characterization and the potential health risk due to trace metals contamination.

Trace Metal Substitution in Marine Phytoplankton

Abstract: The sinking of organic matter to the deep ocean leaves extremely low concentrations of major and trace nutrients for photosynthetic organisms at the sunlit surface. As a result, marine phytoplankto...

Contamination and oxidative stress biomarkers in estuarine fish following a mine tailing disaster.

Abstract: Background The Rio Doce estuary, in Brazil, was impacted by the deposition of iron mine tailings, caused by the collapse of a dam in 2015. Based on published baseline datasets, the estuary has been experiencing chronic trace metal contamination effects since 2017, with potential bioaccumulation in fishes and human health risks. As metal and metalloid concentrations in aquatic ecosystems pose severe threats to the aquatic biota, we hypothesized that the trace metals in estuarine sediments nearly two years after the disaster would lead to bioaccumulation in demersal fishes and result in the biosynthesis of metal-responsive proteins. Methods We measured As, Cd, Cr, Cu, Fe, Mn, Pb, Se and Zn concentrations in sediment samples in August 2017 and compared to published baseline levels. Also, trace metals (As, Cd, Cr, Cu, Fe, Hg, Mn, Pb, Se and Zn) and protein (metallothionein and reduced glutathione) concentrations were quantified in the liver and muscle tissues of five fish species (Cathorops spixii, Genidens genidens, Eugerres brasilianus, Diapterus rhombeus and Mugil sp.) from the estuary, commonly used as food sources by local populations. Results Our results revealed high trace metal concentrations in estuarine sediments, when compared to published baseline values for the same estuary. The demersal fish species C. spixii and G. genidens had the highest concentrations of As, Cr, Mn, Hg, and Se in both, hepatic and muscle, tissues. Trace metal bioaccumulation in fish was correlated with the biosynthesis of metallothionein and reduced glutathione in both, liver and muscle, tissues, suggesting active physiological responses to contamination sources. The trace metal concentrations determined in fish tissues were also present in the estuarine sediments at the time of this study. Some elements had concentrations above the maximum permissible limits for human consumption in fish muscles (e.g., As, Cr, Mn, Se and Zn), suggesting potential human health risks that require further studies. Our study supports the high biogeochemical mobility of toxic elements between sediments and the bottom-dwelling biota in estuarine ecosystems.

Early atmospheric contamination on the top of the Himalayas since the onset of the European Industrial Revolution.

Abstract: Because few ice core records from the Himalayas exist, understanding of the onset and timing of the human impact on the atmosphere of the "roof of the world" remains poorly constrained. We report a continuous 500-y trace metal ice core record from the Dasuopu glacier (7,200 m, central Himalayas), the highest drilling site on Earth. We show that an early contamination from toxic trace metals, particularly Cd, Cr, Mo, Ni, Sb, and Zn, emerged at high elevation in the Himalayas at the onset of the European Industrial Revolution (∼1780 AD). This was amplified by the intensification of the snow accumulation (+50% at Dasuopu) likely linked to the meridional displacement of the winter westerlies from 1810 until 1880 AD. During this period, the flux and crustal enrichment factors of the toxic trace metals were augmented by factors of 2 to 4 and 2 to 6, respectively. We suggest this contamination was the consequence of the long-range transport and wet deposition of fly ash from the combustion of coal (likely from Western Europe where it was almost entirely produced and used during the 19th century) with a possible contribution from the synchronous increase in biomass burning emissions from deforestation in the Northern Hemisphere. The snow accumulation decreased and dry winters were reestablished in Dasuopu after 1880 AD when lower than expected toxic metal levels were recorded. This indicates that contamination on the top of the Himalayas depended primarily on multidecadal changes in atmospheric circulation and secondarily on variations in emission sources during the last 200 y.

Effect of Organic Manure and Mineral Fertilizers on Bioaccumulation and Translocation of Trace Metals in Maize.

Abstract: Mineral fertilizers and organic manure are used as soil amender to enhance the mineral status of the soil. These fertilizers contain trace metals besides providing macro and micronutrients. The present study was performed to observe the effect of mineral fertilizers, poultry manure and cow manure on trace metal content of soil and various parts (root, shoot, and grains) of maize plant (Zea mays L.). The analysis of metals was performed by atomic absorption spectrophotometer (AA-6300 Shimadzu Japan). The highest level of Pb, Fe, Ni and Cu was observed in the root as 0.36–0.55, 70.41–83.03, 4.98–7.44 and 2.94–4.43 mg kg− 1, respectively. The highest level of Cd, Zn and Mn was determined in grains as 0.44–1.59, 28.05–46.39 and 26.24–46.57 mg kg− 1, respectively. The values of all metals were found within their permissible limit given by FAO/WHO except for the Cd. The interactive use of mineral and organic fertilizers enhanced the level of trace metals in maize as compared to their sole application. In the present findings, the health risk index for all metals was less than 1 in all treatments. So, it was concluded that the level of metals in poultry manure, cow manure and mineral fertilizer treated maize did not pose any potential threat to the consumers.

Endosymbiotic dinoflagellates pump iron: differences in iron and other trace metal needs among the Symbiodiniaceae

Abstract: Iron (Fe) is essential to the physiology and growth of marine phytoplankton. It remains unclear how important iron is to the functional ecology of symbiotic dinoflagellates in the family Symbiodiniaceae, and whether limitations in iron ultimately affect the health and productivity of coral hosts, especially during episodes of ocean warming. Five Symbiodiniaceae species (spanning three genera) were used to investigate the effects of reduced iron availability on cell growth and the acquisition of other trace metals. When grown under iron replete conditions, intracellular iron quotas (content) reflected a large biochemical demand and ranged from 7.8 to 23.1 mmol Fe mol Phosphorus−1. Symbiodinium necroappetens was the only species that acclimated and maintained high growth rates while subjected to the lowest iron treatment (250 pM Fe′). Cultures surviving under low iron concentrations experienced changes in cellular concentrations (and presumably their use as cofactors) of other trace metals (e.g., zinc, copper, cobalt, manganese, nickel, molybdenum, vanadium), in ways that were species-specific, and possibly related to the natural ecology of each species. These changes in trace metal contents may have cascading effects on vital biochemical functions such as metalloenzyme activities, photosynthetic performance, and macronutrient assimilation. Furthermore, these species-specific responses to iron limitation provide a basis for investigations on how iron availability effects cellular processes among species and genera of Symbiodiniaceae, and ultimately how metal shortages modulate the response of coral–algal mutualisms to physiological stressors.

Analysis of trace metal distribution in plants with lab-based microscopic X-ray fluorescence imaging.

Abstract: Many metals are essential for plants and humans. Knowledge of metal distribution in plant tissues in vivo contributes to the understanding of physiological mechanisms of metal uptake, accumulation and sequestration. For those studies, X-rays are a non-destructive tool, especially suited to study metals in plants. We present microfluorescence imaging of trace elements in living plants using a customized benchtop X-ray fluorescence machine. The system was optimized by additional detector shielding to minimize stray counts, and by a custom-made measuring chamber to ensure sample integrity. Protocols of data recording and analysis were optimised to minimise artefacts. We show that Zn distribution maps of whole leaves in high resolution are easily attainable in the hyperaccumulator Noccaea caerulescens. The sensitivity of the method was further shown by analysis of micro- (Cu, Ni, Fe, Zn) and macronutrients (Ca, K) in non-hyperaccumulating crop plants (soybean roots and pepper leaves), which could be obtained in high resolution for scan areas of several millimetres. This allows to study trace metal distribution in shoots and roots with a wide overview of the object, and thus avoids making conclusions based on singular features of tiny spots. The custom-made measuring chamber with continuous humidity and air supply coupled to devices for imaging chlorophyll fluorescence kinetic measurements enabled direct correlation of element distribution with photosynthesis. Leaf samples remained vital even after 20 h of X-ray measurements. Subtle changes in some of photosynthetic parameters in response to the X-ray radiation are discussed. We show that using an optimized benchtop machine, with protocols for measurement and quantification tailored for plant analyses, trace metal distribution can be investigated in a reliable manner in intact, living plant leaves and roots. Zinc distribution maps showed higher accumulation in the tips and the veins of young leaves compared to the mesophyll tissue, while in the older leaves the distribution was more homogeneous.

Characterizing the surface microlayer in the Mediterranean Sea: trace metal concentrations and microbial plankton abundance

Abstract: . The Sea Surface Microlayer (SML) is known to be enriched by trace metals relative to the underlying water and harbor diverse microbial communities (i.e., neuston). However, the processes linking metals and biota in the SML are not yet fully understood. The metal (Cd, Co, Cu, Fe, Ni, Mo, V, Zn and Pb) concentrations in aerosol samples in the SML (dissolved and total fractions) and in subsurface waters (SSWs; dissolved fraction at ∼1 m depth) from the western Mediterranean Sea were analyzed in this study during a cruise in May–June 2017. The composition and abundance of the bacterial community in the SML and SSW, the primary production, and Chl a in the SSW were measured simultaneously at all stations during the cruise. Residence times in the SML of metals derived from aerosol depositions were highly variable and ranged from minutes for Fe ( 3.6±6.0 min) to a few hours for Cu ( 5.8±6.2 h). Concentrations of most of the dissolved metals in both the SML and SSW were positively correlated with the salinity gradient and showed the characteristic eastward increase in the surface waters of the Mediterranean Sea (MS). In contrast, the total fraction of some reactive metals in the SML (i.e., Cu, Fe, Pb and Zn) showed a negative correlation with salinity and a positive correlation with microbial abundance, which might be associated with microbial uptake. Our results show a strong negative correlation between the dissolved and total Ni concentration and heterotrophic bacterial abundance in the SML and SSW, but we cannot ascertain whether this correlation reflects a toxicity effect or is the result of some other process.

Trace metal fractional solubility in size-segregated aerosols from the tropical eastern Atlantic Ocean

Abstract: Soluble and total trace metals were measured in four size fractionated aerosol samples collected over the tropical eastern Atlantic Ocean. In samples that were dominated by Saharan dust, the size distributions of total iron, aluminum, titanium, manganese, cobalt, and thorium were very similar to one another and to the size distributions of soluble manganese, cobalt, and thorium. Finer particle sizes (< ~3 μm) showed enhanced soluble concentrations of iron, aluminum, and titanium, possibly as a result of interactions with acidic sulfate aerosol during atmospheric transport. The difference in fine particle solubility between these two groups of elements might be related to the hyperbolic increase in the fractional solubility of iron, and a number of other elements, during the atmospheric transport of Saharan dust, which is not observed for manganese and its associated elements. In comparison to elements whose solubility varies during atmospheric transport, the stability of thorium fractional solubility should reduce uncertainties in the use of dissolved concentrations of this element in seawater as a proxy for dust deposition, although this topic requires further work.

From canals to the coast: dissolved organic matter and trace metal composition in rivers draining degraded tropical peatlands in Indonesia

Abstract: . Worldwide, peatlands are important sources of dissolved organic matter (DOM) and trace metals (TMs) to surface waters, and these fluxes may increase with peatland degradation. In Southeast Asia, tropical peatlands are being rapidly deforested and drained. The blackwater rivers draining these peatland areas have high concentrations of DOM and the potential to be hotspots for CO2 release. However, the fate of this fluvial carbon export is uncertain, and its role as a trace metal carrier has never been investigated. This work aims to address these gaps in our understanding of tropical peatland DOM and associated elements in the context of degraded tropical peatlands in Indonesian Borneo. We quantified dissolved organic carbon and trace metal concentrations in the dissolved and fine colloidal ( µ m) and coarse colloidal (0.22–2.7 µ m) fractions and determined the characteristics ( δ13 C, absorbance, fluorescence: excitation-emission matrix and parallel factor – PARAFAC – analysis) of the peatland-derived DOM as it drains from peatland canals, flows along the Ambawang River (blackwater river) and eventually mixes with the Kapuas Kecil River (whitewater river) before meeting the ocean near the city of Pontianak in West Kalimantan, Indonesia. We observe downstream shifts in indicators of in-stream processing. An increase in the δ13 C of dissolved organic carbon (DOC), along with an increase in the C1∕C2 ratio of PARAFAC fluorophores, and a decrease in SUVA (specific UV absorbance) along the continuum suggest the predominance of photo-oxidation. However, very low dissolved oxygen concentrations also suggest that oxygen is quickly consumed by microbial degradation of DOM in the shallow layers of water. Blackwater rivers draining degraded peatlands show significantly higher concentrations of Al, Fe, Pb, As, Ni and Cd compared to the whitewater river. A strong association is observed between DOM, Fe, As, Cd and Zn in the dissolved and fine colloid fraction, while Al is associated with Pb and Ni and present in a higher proportion in the coarse colloidal fraction. We additionally measured the isotopic composition of lead released from degraded tropical peatlands for the first time and show that Pb originates from anthropogenic atmospheric deposition. Degraded tropical peatlands are important sources of DOM and trace metals to rivers and a secondary source of atmospherically deposited contaminants.

Trace metal concentration in planted cucumber (Cucumis sativus L.) from contaminated soils and its associated health risks

Abstract: The concentration of trace metals (TMs) in soils and cucumber plants in contaminated and reference sites and their health risk for children and adults were investigated. Plant and soil were sampled through 30 squares distributed equally in six cucumber fields in the two sites. The pollution load index, which is the ratio of the concentration of TMs in contaminated and reference soils, showed extensive accumulation of TMs in contaminated soils. The dry and fresh biomass, and fruit production of cucumbers was significantly reduced under pollution stress. The bioaccumulation factor was > 1 for all investigated TMs, except Cd in the reference and Cd, Cr, Zn and Co in the contaminated site indicating the uptake of the investigated TMs from the soil by the root. In addition, the translocation factor to the stem and leaves was 1 for Fe in adults, and Pb and Fe in children, indicating a health risk for humans by ingestion of cucumbers, while in reference site it was 1, indicating a high potential of health hazard to consumers. It is necessary to regularly monitor toxic TMs to prevent their accumulation in the food chain.