Showing papers in "Environmental Science & Technology in 2013"
TL;DR: It is shown that microplastics are ingested by, and may impact upon, zooplankton, and imply that marine microplastic debris can negatively impact upon zoopLankton function and health.
Abstract: Small plastic detritus, termed “microplastics”, are a widespread and ubiquitous contaminant of marine ecosystems across the globe. Ingestion of microplastics by marine biota, including mussels, worms, fish, and seabirds, has been widely reported, but despite their vital ecological role in marine food-webs, the impact of microplastics on zooplankton remains under-researched. Here, we show that microplastics are ingested by, and may impact upon, zooplankton. We used bioimaging techniques to document ingestion, egestion, and adherence of microplastics in a range of zooplankton common to the northeast Atlantic, and employed feeding rate studies to determine the impact of plastic detritus on algal ingestion rates in copepods. Using fluorescence and coherent anti-Stokes Raman scattering (CARS) microscopy we identified that thirteen zooplankton taxa had the capacity to ingest 1.7–30.6 μm polystyrene beads, with uptake varying by taxa, life-stage and bead-size. Post-ingestion, copepods egested faecal pellets lade...
1,832 citations
TL;DR: Pits visualized in the PMD surface conformed to bacterial shapes suggesting active hydrolysis of the hydrocarbon polymer, implying that plastic serves as a novel ecological habitat in the open ocean.
Abstract: Plastics are the most abundant form of marine debris, with global production rising and documented impacts in some marine environments, but the influence of plastic on open ocean ecosystems is poorly understood, particularly for microbial communities. Plastic marine debris (PMD) collected at multiple locations in the North Atlantic was analyzed with scanning electron microscopy (SEM) and next-generation sequencing to characterize the attached microbial communities. We unveiled a diverse microbial community of heterotrophs, autotrophs, predators, and symbionts, a community we refer to as the “Plastisphere”. Pits visualized in the PMD surface conformed to bacterial shapes suggesting active hydrolysis of the hydrocarbon polymer. Small-subunit rRNA gene surveys identified several hydrocarbon-degrading bacteria, supporting the possibility that microbes play a role in degrading PMD. Some Plastisphere members may be opportunistic pathogens (the authors, unpublished data) such as specific members of the genus Vib...
1,789 citations
TL;DR: Understanding of sources, atmosphere-land-ocean Hg dynamics and health effects are synthesized, and integration of Hg science with national and international policy efforts is needed to target efforts and evaluate efficacy.
Abstract: Mercury (Hg) is a global pollutant that affects human and ecosystem health. We synthesize understanding of sources, atmosphere-land-ocean Hg dynamics and health effects, and consider the implications of Hg-control policies. Primary anthropogenic Hg emissions greatly exceed natural geogenic sources, resulting in increases in Hg reservoirs and subsequent secondary Hg emissions that facilitate its global distribution. The ultimate fate of emitted Hg is primarily recalcitrant soil pools and deep ocean waters and sediments. Transfers of Hg emissions to largely unavailable reservoirs occur over the time scale of centuries, and are primarily mediated through atmospheric exchanges of wet/dry deposition and evasion from vegetation, soil organic matter and ocean surfaces. A key link between inorganic Hg inputs and exposure of humans and wildlife is the net production of methylmercury, which occurs mainly in reducing zones in freshwater, terrestrial, and coastal environments, and the subsurface ocean. Elevated human exposure to methylmercury primarily results from consumption of estuarine and marine fish. Developing fetuses are most at risk from this neurotoxin but health effects of highly exposed populations and wildlife are also a concern. Integration of Hg science with national and international policy efforts is needed to target efforts and evaluate efficacy.
1,631 citations
TL;DR: It is emphasized that the facile synthesis of a GO membrane exploiting the ideal properties of inexpensive GO materials offers a myriad of opportunities to modify its physicochemical properties, potentially making the GO membrane a next-generation, cost-effective, and sustainable alternative to the long-existing thin-film composite polyamide membranes for water separation applications.
Abstract: We report a novel procedure to synthesize a new type of water separation membrane using graphene oxide (GO) nanosheets such that water can flow through the nanochannels between GO layers while unwanted solutes are rejected by size exclusion and charge effects. The GO membrane was made via layer-by-layer deposition of GO nanosheets, which were cross-linked by 1,3,5-benzenetricarbonyl trichloride, on a polydopamine-coated polysulfone support. The cross-linking not only provided the stacked GO nanosheets with the necessary stability to overcome their inherent dispensability in water environment but also fine-tuned the charges, functionality, and spacing of the GO nanosheets. We then tested the membranes synthesized with different numbers of GO layers to demonstrate their interesting water separation performance. It was found that the GO membrane flux ranged between 80 and 276 LMH/MPa, roughly 4–10 times higher than that of most commercial nanofiltration membranes. Although the GO membrane in the present deve...
1,224 citations
TL;DR: In situ characterization of the oxide surface with ATR-FTIR and Raman during the PMS decomposition suggested that surface Cu(II)- Cu(III)-Cu(II) redox cycle was responsible for the efficient sulfate radical generation from PMS.
Abstract: A simple, nonhazardous, efficient and low energy-consuming process is desirable to generate powerful radicals from peroxymonosulfate (PMS) for recalcitrant pollutant removal. In this work, the production of radical species from PMS induced by a magnetic CuFe2O4 spinel was studied. Iopromide, a recalcitrant model pollutant, was used to investigate the efficiency of this process. CuFe2O4 showed higher activity and 30 times lower Cu2+ leaching (1.5 μg L–1 per 100 mg L–1) than a well-crystallized CuO at the same dosage. CuFe2O4 maintained its activity and crystallinity during repeated batch experiments. In comparison, the activity of CuO declined significantly, which was ascribed to the deterioration in its degree of crystallinity. The efficiency of the PMS/CuFe2O4 was highest at neutral pH and decreased at acidic and alkaline pHs. Sulfate radical was the primary radical species responsible for the iopromide degradation. On the basis of the stoichiometry of oxalate degradation in the PMS/CuFe2O4, the radical ...
892 citations
TL;DR: Polystyrene microplastic had statistically significant effects on the organisms' fitness and bioaccumulation, but the magnitude of the effects was not high, and may be different for sites with different plastic concentrations, or plastics with a higher affinity for POPs.
Abstract: It has been speculated that marine microplastics may cause negative effects on benthic marine organisms and increase bioaccumulation of persistent organic pollutants (POPs). Here, we provide the first controlled study of plastic effects on benthic organisms including transfer of POPs. The effects of polystyrene (PS) microplastic on survival, activity, and bodyweight, as well as the transfer of 19 polychlorinated biphenyls (PCBs), were assessed in bioassays with Arenicola marina (L.). PS was pre-equilibrated in natively contaminated sediment. A positive relation was observed between microplastic concentration in the sediment and both uptake of plastic particles and weight loss by A. marina. Furthermore, a reduction in feeding activity was observed at a PS dose of 7.4% dry weight. A low PS dose of 0.074% increased bioaccumulation of PCBs by a factor of 1.1–3.6, an effect that was significant for ΣPCBs and several individual congeners. At higher doses, bioaccumulation decreased compared to the low dose, whic...
811 citations
TL;DR: To quantify the occurrence of ingested plastic in fish species caught at different geographical positions in the North Sea, and to test whether the fish condition is affected by ingestion of plastics, 1203 individual fish of seven common North Sea species were investigated.
Abstract: To quantify the occurrence of ingested plastic in fish species caught at different geographical positions in the North Sea, and to test whether the fish condition is affected by ingestion of plastics, 1203 individual fish of seven common North Sea species were investigated: herring, gray gurnard, whiting, horse mackerel, haddock, atlantic mackerel, and cod. Plastic particles were found in 2.6% of the examined fish and in five of the seven species. No plastics were found in gray gurnard and mackerel. In most cases, only one particle was found per fish, ranging in size from 0.04 to 4.8 mm. Only particles larger than 0.2 mm, being the diameter of the sieve used, were considered for the data analyses, resulting in a median particle size of 0.8 mm. The frequency of fish with plastic was significantly higher (5.4%) in the southern North Sea, than in the northern North Sea above 55°N (1.2%). The highest frequency (>33%) was found in cod from the English Channel. In addition, small fibers were initially detected in most of the samples, but their abundance sharply decreased when working under special clean air conditions. Therefore, these fibers were considered to be artifacts related to air born contamination and were excluded from the analyses. No relationship was found between the condition factor (size–weight relationship) of the fish and the presence of ingested plastic particles.
741 citations
TL;DR: The results suggest that microplastics such as micro- or nanosized PS beads may have negative impacts on marine copepods.
Abstract: We investigated the effects of three sizes of polystyrene (PS) microbeads (0.05, 0.5, and 6-μm diameter) on the survival, development, and fecundity of the copepod Tigriopus japonicus using acute and chronic toxicity tests. T. japonicus ingested and egested all three sizes of PS beads used and exhibited no selective feeding when phytoplankton were added. The copepods (nauplius and adult females) survived all sizes of PS beads and the various concentrations tested in the acute toxicity test for 96 h. In the two-generation chronic toxicity test, 0.05-μm PS beads at a concentration greater than 12.5 μg/mL caused the mortality of nauplii and copepodites in the F0 generation and even triggered mortality at a concentration of 1.25 μg/mL in the next generation. In the 0.5-μm PS bead treatment, despite there being no significant effect on the F0 generation, the highest concentration (25 μg/mL) induced a significant decrease in survival compared with the control population in the F1 generation. The 6-μm PS beads d...
698 citations
TL;DR: It is found that desalination for reuse of produced water is technically feasible and can be economically relevant, however, because produced water management is primarily an economic decision, expanding desalinated for reuse is dependent on process and material improvements to reduce capital and operating costs.
Abstract: In the rapidly developing shale gas industry, managing produced water is a major challenge for maintaining the profitability of shale gas extraction while protecting public health and the environment. We review the current state of practice for produced water management across the United States and discuss the interrelated regulatory, infrastructure, and economic drivers for produced water reuse. Within this framework, we examine the Marcellus shale play, a region in the eastern United States where produced water is currently reused without desalination. In the Marcellus region, and in other shale plays worldwide with similar constraints, contraction of current reuse opportunities within the shale gas industry and growing restrictions on produced water disposal will provide strong incentives for produced water desalination for reuse outside the industry. The most challenging scenarios for the selection of desalination for reuse over other management strategies will be those involving high-salinity produced water, which must be desalinated with thermal separation processes. We explore desalination technologies for treatment of high-salinity shale gas produced water, and we critically review mechanical vapor compression (MVC), membrane distillation (MD), and forward osmosis (FO) as the technologies best suited for desalination of high-salinity produced water for reuse outside the shale gas industry. The advantages and challenges of applying MVC, MD, and FO technologies to produced water desalination are discussed, and directions for future research and development are identified. We find that desalination for reuse of produced water is technically feasible and can be economically relevant. However, because produced water management is primarily an economic decision, expanding desalination for reuse is dependent on process and material improvements to reduce capital and operating costs.
676 citations
TL;DR: Air pollution monitoring paradigm is rapidly changing due to recent advances in the development of portable, lower-cost air pollution sensors reporting data in near-real time at a high-time resolution, increased computational and visualization capabilities, and wireless communication/infrastructure.
Abstract: The air pollution monitoring paradigm is rapidly changing due to recent advances in (1) the development of portable, lower-cost air pollution sensors reporting data in near-real time at a high-time...
653 citations
TL;DR: Simulation of PAH emissions in developed and developing countries would decrease by 46-71% and 48-64%, respectively, based on the six IPCC SRES scenarios, resulting in a new estimate ofPAH emission factor variation among different countries and over time.
Abstract: Global atmospheric emissions of 16 polycyclic aromatic hydrocarbons (PAHs) from 69 major sources were estimated for a period from 1960 to 2030. Regression models and a technology split method were used to estimate country and time specific emission factors, resulting in a new estimate of PAH emission factor variation among different countries and over time. PAH emissions in 2007 were spatially resolved to 0.1° × 0.1° grids based on a newly developed global high-resolution fuel combustion inventory (PKU-FUEL-2007). The global total annual atmospheric emission of 16 PAHs in 2007 was 504 Gg (331-818 Gg, as interquartile range), with residential/commercial biomass burning (60.5%), open-field biomass burning (agricultural waste burning, deforestation, and wildfire, 13.6%), and petroleum consumption by on-road motor vehicles (12.8%) as the major sources. South (87 Gg), East (111 Gg), and Southeast Asia (52 Gg) were the regions with the highest PAH emission densities, contributing half of the global total PAH emissions. Among the global total PAH emissions, 6.19% of the emissions were in the form of high molecular weight carcinogenic compounds and the percentage of the carcinogenic PAHs was higher in developing countries (6.22%) than in developed countries (5.73%), due to the differences in energy structures and the disparities of technology. The potential health impact of the PAH emissions was greatest in the parts of the world with high anthropogenic PAH emissions, because of the overlap of the high emissions and high population densities. Global total PAH emissions peaked at 592 Gg in 1995 and declined gradually to 499 Gg in 2008. Total PAH emissions from developed countries peaked at 122 Gg in the early 1970s and decreased to 38 Gg in 2008. Simulation of PAH emissions from 2009 to 2030 revealed that PAH emissions in developed and developing countries would decrease by 46-71% and 48-64%, respectively, based on the six IPCC SRES scenarios.
TL;DR: In this article, a simple linear regression between log10 transformed mercury (Hg) concentration and stable nitrogen isotope values (δ15N), hereafter called trophic magnification slope (TMS), was used to represent the overall degree of Hg biomagnification.
Abstract: The slope of the simple linear regression between log10 transformed mercury (Hg) concentration and stable nitrogen isotope values (δ15N), hereafter called trophic magnification slope (TMS), from several trophic levels in a food web can represent the overall degree of Hg biomagnification. We compiled data from 69 studies that determined total Hg (THg) or methyl Hg (MeHg) TMS values in 205 aquatic food webs worldwide. Hg TMS values were compared against physicochemical and biological factors hypothesized to affect Hg biomagnification in aquatic systems. Food webs ranged across 1.7 ± 0.7 (mean ± SD) and 1.8 ± 0.8 trophic levels (calculated using δ15N from baseline to top predator) for THg and MeHg, respectively. The average trophic level (based on δ15N) of the upper-trophic-level organisms in the food web was 3.7 ± 0.8 and 3.8 ± 0.8 for THg and MeHg food webs, respectively. For MeHg, the mean TMS value was 0.24 ± 0.08 but varied from 0.08 to 0.53 and was, on average, 1.5 times higher than that for THg with a...
TL;DR: The findings of this study elucidated a new pathway of persulfate activation, which could degrade environmental contaminants efficiently and provide useful information for the remediation of contaminated soil and water by Persulfate.
Abstract: There has been considerable interest in the use of persulfate for in situ chemical oxidation of organic contaminants in soils, sediments, and groundwater. Since humic acid (HA) exists ubiquitously in these environmental compartments, its redox active functional moieties, such as quinones, may play an important role in the oxidation processes of persulfate treatments. Understanding the effects of HA, especially the quinone functional groups on the degradation of pollutants by persulfate and the production of sulfate radicals (SO4(•-)) from persulfate, is beneficial for devising effective and economically feasible remediation strategies. In this study, the effects of model quinone compounds and HA on the degradation of 2,4,4'-trichlorobiphenyl (PCB28) by persulfate and the production of SO4(•-) from persulfate were investigated. It was found that quinones and HA can efficiently activate persulfate for the degradation of PCB28. The mechanism of persulfate activation was elucidated by quenching and electron paramagnetic resonance (EPR) studies. The results indicated that production of SO4(•-) from persulfate and quinones was semiquinone radical-dependent. The effects of quinone concentrations were also studied. The findings of this study elucidated a new pathway of persulfate activation, which could degrade environmental contaminants efficiently and provide useful information for the remediation of contaminated soil and water by persulfate.
TL;DR: A global-scale analysis of the presence of 203 pharmaceuticals across 41 countries is presented and it is shown that contamination is extensive due to widespread consumption and subsequent disposal to rivers.
Abstract: Pharmaceuticals have emerged as a major group of environmental contaminants over the past decade but relatively little is known about their occurrence in freshwaters compared to other pollutants. We present a global-scale analysis of the presence of 203 pharmaceuticals across 41 countries and show that contamination is extensive due to widespread consumption and subsequent disposal to rivers. There are clear regional biases in current understanding with little work outside North America, Europe, and China, and no work within Africa. Within individual countries, research is biased around a small number of populated provinces/states and the majority of research effort has focused upon just 14 compounds. Most research has adopted sampling techniques that are unlikely to provide reliable and representative data. This analysis highlights locations where concentrations of antibiotics, cardiovascular drugs, painkillers, contrast media, and antiepileptic drugs have been recorded well above thresholds known to cause toxic effects in aquatic biota. Studies of pharmaceutical occurrence and effects need to be seen as a global research priority due to increasing consumption, particularly among societies with aging populations. Researchers in all fields of environmental management need to work together more effectively to identify high risk compounds, improve the reliability and coverage of future monitoring studies, and develop new mitigation measures.
TL;DR: Concerns regarding marine plastic pollution and its affinity for chemical pollutants led us to quantify relationships between different types of mass-produced plastic and organic contaminants in an urban bay and suggest that for PAHs and PCBs, PET and PVC reach equilibrium in the marine environment much faster than HDPE, LDPE, and PP.
Abstract: Concerns regarding marine plastic pollution and its affinity for chemical pollutants led us to quantify relationships between different types of mass-produced plastic and organic contaminants in an urban bay. At five locations in San Diego Bay, CA, we measured sorption of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) throughout a 12-month period to the five most common types of mass-produced plastic: polyethylene terephthalate (PET), high-density polyethylene (HDPE), polyvinyl chloride (PVC), low-density polyethylene (LDPE), and polypropylene (PP). During this long-term field experiment, sorption rates and concentrations of PCBs and PAHs varied significantly among plastic types and among locations. Our data suggest that for PAHs and PCBs, PET and PVC reach equilibrium in the marine environment much faster than HDPE, LDPE, and PP. Most importantly, concentrations of PAHs and PCBs sorbed to HDPE, LDPE, and PP were consistently much greater than concentrations sorbed to PET and...
TL;DR: The present study adds hydroxylamine (HA), a common reducing agent, into Fe(II)/PMS process to accelerate the transformation from Fe(III) to Fe( II) and generates reactive oxidants capable of degrading refractory organic contaminants in water treatment.
Abstract: The reaction between ferrous iron (Fe(II)) with peroxymonosulfate (PMS) generates reactive oxidants capable of degrading refractory organic contaminants. However, the slow transformation from ferric iron (Fe(III)) back to Fe(II) limits its widespread application. Here, we added hydroxylamine (HA), a common reducing agent, into Fe(II)/PMS process to accelerate the transformation from Fe(III) to Fe(II). With benzoic acid (BA) as probe compound, the addition of HA into Fe(II)/PMS process accelerated the degradation of BA rapidly in the pH range of 2.0-6.0 by accelerating the key reactions, including the redox cycle of Fe(III)/Fe(II) and the generation of reactive oxidants. Both sulfate radicals and hydroxyl radicals were considered as the primary reactive oxidants for the degradation of BA in HA/Fe(II)/PMS process with the experiments of electron spin resonance and alcohols quenching. Moreover, HA was gradually degraded to N2, N2O, NO2 (−), and NO3 (−), while the environmentally friendly gas of N2 was considered as its major end product in the process. The present study might provide a promising idea based on Fe(II)/PMS process for the rapid degradation of refractory organic contaminants in water treatment.
TL;DR: For the first time, Hg methylation is demonstrated in a number of species other than sulfate- (SRB) and iron- (FeRB) reducing bacteria, including methanogens, and syntrophic, acetogenic, and fermentative Firmicutes, which indicates organisms are much more phylogenetically and environmentally diverse than previously thought.
Abstract: Microbial mercury (Hg) methylation transforms a toxic trace metal into the highly bioaccumulated neurotoxin methylmercury (MeHg). The lack of a genetic marker for microbial MeHg production has prevented a clear understanding of Hg-methylating organism distribution in nature. Recently, a specific gene cluster (hgcAB) was linked to Hg methylation in two bacteria.1 Here we test if the presence of hgcAB orthologues is a reliable predictor of Hg methylation capability in microorganisms, a necessary confirmation for the development of molecular probes for Hg-methylation in nature. Although hgcAB orthologues are rare among all available microbial genomes, organisms are much more phylogenetically and environmentally diverse than previously thought. By directly measuring MeHg production in several bacterial and archaeal strains encoding hgcAB, we confirmed that possessing hgcAB predicts Hg methylation capability. For the first time, we demonstrated Hg methylation in a number of species other than sulfate- (SRB) an...
TL;DR: Results suggested the postsorption biochar can be cycled back directly to soils as an effective slow-release P-fertilizer.
Abstract: This work explored the potential application of an engineered biochar prepared from Mg-enriched tomato tissues to reclaim and reuse phosphate (P) from aqueous solution. Findings from batch sorption experiments suggested that, although sorption of P on the biochar was controlled by relatively slow kinetics, the maximum P sorption capacity of the biochar could reach >100 mg·g(-1). Mathematical modeling and postsorption characterization results indicated that the sorption was mainly controlled by two mechanisms: precipitation of P through chemical reaction with Mg particles and surface deposition of P on Mg crystals on biochar surfaces. Most of the P retained in the engineered biochar was bioavailable and could be released equally at multiple successive extractions. In addition, the P-laden biochar significantly stimulated grass seed germination and growth. These results suggested the postsorption biochar can be cycled back directly to soils as an effective slow-release P-fertilizer.
TL;DR: The fraction of PFASs consisting of perfluorinated carboxylates and sulfonates was greater in groundwater and solid samples than in any archived AFFF formulations, suggesting that much of the mass of precursors released at the site was converted to perfluOrinated car boxylate and sulf onates.
Abstract: Several classes of polyfluorinated chemicals that are potential precursors to the perfluorinated carboxylates and sulfonates are present in aqueous film-forming foams (AFFF). To assess the persistence of these AFFF-derived precursors, groundwater, soil, and aquifer solids were obtained in 2011 from an unlined firefighter training area at a U.S. Air Force Base where AFFF was regularly used between 1970 and 1990. To measure the total concentration of perfluorinated carboxylate and sulfonate precursors in archived AFFF formulations and AFFF-impacted environmental samples, a previously developed assay that uses hydroxyl radical to oxidize precursors to perfluorinated carboxylates was adapted for these media. This assay was employed along with direct measurement of 22 precursors found in AFFF and a suite of other poly- and perfluoroalkyl substances (PFASs). On a molar basis, precursors accounted for 41–100% of the total concentration of PFASs in archived AFFF formulations. In the training area, precursors meas...
TL;DR: The application of PANI@GO composites as suitable materials for the preconcentration and removal of lanthanides and actinides from aqueous solutions in environmental pollution management in a wide range of acidic to alkaline conditions is focused on.
Abstract: Graphene oxide-supported polyaniline (PANI@GO) composites were synthesized by chemical oxidation and were characterized by SEM, Raman and FT-IR spectroscopy, TGA, potentiometric titrations, and XPS. The characterization indicated that PANI can be grafted onto the surface of GO nanosheets successfully. The sorption of U(VI), Eu(III), Sr(II), and Cs(I) from aqueous solutions as a function of pH and initial concentration on the PANI@GO composites was investigated. The maximum sorption capacities of U(VI), Eu(III), Sr(II), and Cs(I) on the PANI@GO composites at pH 3.0 and T = 298 K calculated from the Langmuir model were 1.03, 1.65, 1.68, and 1.39 mmol·g–1, respectively. According to the XPS analysis of the PANI@GO composites before and after Eu(III) desorption, nitrogen- and oxygen-containing functional groups on the surface of PANI@GO composites were responsible for radionuclide sorption, and that radionuclides can hardly be extracted from the nitrogen-containing functional groups. Therefore, the chemical a...
TL;DR: This Review evaluates the current state of knowledge regarding the mechanisms regulating microbial mercury methylation, including the speciation of mercury in environments where methylation occurs and the processes that control mercury bioavailability to these organisms.
Abstract: Mercury is a potent neurotoxin for humans, particularly if the metal is in the form of methylmercury. Mercury is widely distributed in aquatic ecosystems as a result of anthropogenic activities and natural earth processes. A first step toward bioaccumulation of methylmercury in aquatic food webs is the methylation of inorganic forms of the metal, a process that is primarily mediated by anaerobic bacteria. In this Review, we evaluate the current state of knowledge regarding the mechanisms regulating microbial mercury methylation, including the speciation of mercury in environments where methylation occurs and the processes that control mercury bioavailability to these organisms. Methylmercury production rates are generally related to the presence and productivity of methylating bacteria and also the uptake of inorganic mercury to these microorganisms. Our understanding of the mechanisms behind methylation is limited due to fundamental questions related to the geochemical forms of mercury that persist in an...
TL;DR: GO nanomaterials will be stable in the natural aquatic environment and that significant aqueous transport of GO is possible, according to time-resolved dynamic light scattering relevant to natural and engineered systems.
Abstract: While graphene oxide (GO) has been found to be the most toxic graphene-based nanomaterial, its environmental fate is still unexplored. In this study, the aggregation kinetics and stability of GO were investigated using time-resolved dynamic light scattering over a wide range of aquatic chemistries (pH, salt types (NaCl, MgCl2, CaCl2), ionic strength) relevant to natural and engineered systems. Although pH did not have a notable influence on GO stability from pH 4 to 10, salt type and ionic strength had significant effects on GO stability due to electrical double layer compression, similar to other colloidal particles. The critical coagulation concentration (CCC) values of GO were determined to be 44 mM NaCl, 0.9 mM CaCl2, and 1.3 mM MgCl2. Aggregation and stability of GO in the aquatic environment followed colloidal theory (DLVO and Schulze-Hardy rule), even though GO’s shape is not spherical. CCC values of GO were lower than reported fullerene CCC values and higher than reported carbon nanotube CCC value...
TL;DR: Elevated levels of chloride and bromide, combined with the strontium, radium, oxygen, and hydrogen isotopic compositions of the effluents reflect the composition of Marcellus Shale produced waters, posing potential environmental risks of radium bioaccumulation in localized areas of shale gas wastewater disposal.
Abstract: The safe disposal of liquid wastes associated with oil and gas production in the United States is a major challenge given their large volumes and typically high levels of contaminants. In Pennsylvania, oil and gas wastewater is sometimes treated at brine treatment facilities and discharged to local streams. This study examined the water quality and isotopic compositions of discharged effluents, surface waters, and stream sediments associated with a treatment facility site in western Pennsylvania. The elevated levels of chloride and bromide, combined with the strontium, radium, oxygen, and hydrogen isotopic compositions of the effluents reflect the composition of Marcellus Shale produced waters. The discharge of the effluent from the treatment facility increased downstream concentrations of chloride and bromide above background levels. Barium and radium were substantially (>90%) reduced in the treated effluents compared to concentrations in Marcellus Shale produced waters. Nonetheless, 226Ra levels in stre...
TL;DR: PCPs are an important source of human exposure to parabens; the contribution of PCPs to phthalate exposure is low, except for DEP.
Abstract: Despite the widespread usage of phthalates and parabens in personal care products (PCPs), little is known about concentrations and profiles as well as human exposure to these compounds through the use of PCPs. In this study, nine phthalates and six parabens were determined in 170 PCPs (41 rinse-off and 109 leave-on), including 20 baby care products collected from Albany, New York. Phthalates were less frequently found in rinse-off PCPs but were more frequently found in perfumes (detection frequency of 100% for diethyl phthalate [DEP], 67% for dibutyl phthalate [DBP]), skin toners (90% for DEP), and nail polishes (90% for DBP). Parabens were found in ∼40% of rinse-off products and ∼60% of leave-on products. The highest concentrations of DEP, DBP, methyl- (MeP), ethyl- (EtP), propyl- (PrP), and butyl parabens (BuP) were on the order of 1000 μg per gram of the product. On the basis of amount and frequency of use of PCPs and the measured median concentrations of target analytes, the total dermal intake doses (sum of all phthalates or parabens) were calculated to be 0.37 and 31.0 μg/kg-bw/day for phthalates and parabens, respectively, for adult females. The calculated dermal intake of phthalates from PCPs was lower for infants and toddlers than for adult females. In contrast, dermal intake of parabens from PCPs by infants and toddlers was higher than that for adult females. The calculated maximum daily exposure dose of MeP, EtP, and PrP from PCPs ranged between 58.6 and 766 μg/kg-bw/day for infants and toddlers, which was 3 times higher than that calculated for adult females. PCPs are an important source of human exposure to parabens; the contribution of PCPs to phthalate exposure is low, except for DEP.
TL;DR: The QSAR can well predict the developmental toxicity of most of the DBPs tested and involved two physical-chemical property descriptors and two electronic descriptors to indicate the transport, biouptake, and biointeraction of these DBPs.
Abstract: Using seawater for toilet flushing may introduce high levels of bromide and iodide into a city’s sewage treatment works, and result in the formation of brominated and iodinated disinfection byproducts (DBPs) during chlorination to disinfect sewage effluents. In a previous study, the authors’ group has detected the presence of many brominated DBPs and identified five new aromatic brominated DBPs in chlorinated saline sewage effluents. The presence of brominated DBPs in chlorinated saline effluents may pose adverse implications for marine ecology. In this study, besides the detection and identification of another seven new aromatic halogenated DBPs in a chlorinated saline sewage effluent, their developmental toxicity was evaluated using the marine polychaete Platynereis dumerilii. For comparison, the developmental toxicity of some commonly known halogenated DBPs was also examined. The rank order of the developmental toxicity of 20 halogenated DBPs was 2,5-dibromohydroquinone > 2,6-diiodo-4-nitrophenol ≥ 2,4...
TL;DR: Three one-dimensional MnO2 nanoparticles with different crystallographic phases, α, β, and γ-MnO2, showed varying activities in activation of Oxone to generate sulfate radicals for phenol degradation depending on surface area and crystalline structure and exhibited high stability in recycled tests without losing activity.
Abstract: Three one-dimensional MnO2 nanoparticles with different crystallographic phases, α-, β-, and γ-MnO2, were synthesized, characterized, and tested in heterogeneous activation of Oxone for phenol degradation in aqueous solution. The α-, β-, and γ-MnO2 nanostructured materials presented in morphologies of nanowires, nanorods, and nanofibers, respectively. They showed varying activities in activation of Oxone to generate sulfate radicals for phenol degradation depending on surface area and crystalline structure. α-MnO2 nanowires exhibited the highest activity and could degrade phenol in 60 min at phenol concentrations ranging in 25-100 mg/L. It was found that phenol degradation on α-MnO2 followed first order kinetics with an activation energy of 21.9 kJ/mol. The operational parameters, such as MnO2 and Oxone loading, phenol concentration and temperature, were found to influence phenol degradation efficiency. It was also found that α-MnO2 exhibited high stability in recycled tests without losing activity, demonstrating itself to be a superior heterogeneous catalyst to the toxic Co3O4 and Co(2+).
TL;DR: A conceptual model that simulates the effects of plastic on bioaccumulation of POPs is developed and analyzed, showing that plastic with low affinity for POPs such as polystyrene will have a marginal decreasing effect on bio Accumulation, governed by dilution.
Abstract: It has been hypothesized that persistent organic pollutants (POPs) in microplastic may pose a risk to aquatic organisms. Here we develop and analyze a conceptual model that simulates the effects of plastic on bioaccumulation of POPs. The model accounts for dilution of exposure concentration by sorption of POPs to plastic (POP “dilution”), increased bioaccumulation by ingestion of plastic-containing POPs (“carrier”), and decreased bioaccumulation by ingestion of clean plastic (“cleaning”). The model is parametrized for the lugworm Arenicola marina and evaluated against recently published bioaccumulation data for this species from laboratory bioassays with polystyrene microplastic. Further scenarios include polyethylene microplastic, nanosized plastic, and open marine systems. Model analysis shows that plastic with low affinity for POPs such as polystyrene will have a marginal decreasing effect on bioaccumulation, governed by dilution. For stronger sorbents such as polyethylene, the dilution, carrier, and c...
TL;DR: SSBC can be beneficial in rice paddy soil but the actual associated benefits will depend on site-specific conditions and source of SS; long-term effects remain a further unknown.
Abstract: Biochar addition to soil has been proposed to improve plant growth by increasing soil fertility, minimizing bioaccumulation of toxic metal(liod)s and mitigating climate change. Sewage sludge (SS) is an attractive, though potentially problematic, feedstock of biochar. It is attractive because of its large abundance; however, it contains elevated concentrations of metal(loid)s and other contaminants. The pyrolysis of SS to biochar (SSBC) may be a way to reduce the availability of these contaminants to the soil and plants. Using rice plant pot experiments, we investigated the influence of SSBC upon biomass yield, bioaccumulation of nutrients, and metal(loid)s, and green housegas (GHG) emissions. SSBC amendments increased soil pH, total nitrogen, soil organic carbon and available nutrients and decreased bioavailable As, Cr, Co, Ni, and Pb (but not Cd, Cu, and Zn). Regarding rice plant properties, SSBC amendments significantly (P ≤ 0.01) increased shoot biomass (71.3-92.2%), grain yield (148.8-175.1%), and the bioaccumulation of phosphorus and sodium, though decreased the bioaccumulation of nitrogen (except in grain) and potassium. Amendments of SSBC significantly (P ≤ 0.05) reduced the bioaccumulation of As, Cr, Co, Cu, Ni, and Pb, but increased that of Cd and Zn, though not above limits set by Chinese regulations. Finally regarding GHG emissions, SSBC significantly (P < 0.01) reduced N2O emissions and stimulated the uptake/oxidation of CH4 enough to make both the cultivated and uncultivated paddy soil a CH4 sink. SSBC can be beneficial in rice paddy soil but the actual associated benefits will depend on site-specific conditions and source of SS; long-term effects remain a further unknown.
TL;DR: The profiles of PFAS in groundwater differ from those found in fluorotelomer- and electrofluorination-based AFFF formulations, which potentially indicates environmental transformation ofPFAS.
Abstract: A new analytical method was developed to quantify 26 newly-identified and 21 legacy (e.g. perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and fluorotelomer sulfonates) per and polyfluorinated alkyl substances (PFAS) in groundwater and aqueous film forming foam (AFFF) formulations. Prior to analysis, AFFF formulations were diluted into methanol and PFAS in groundwater were micro liquid-liquid extracted. Methanolic dilutions of AFFF formulations and groundwater extracts were analyzed by large-volume injection (900 μL) high-performance liquid chromatography tandem mass spectrometry. Orthogonal chromatography was performed using cation exchange (silica) and anion exchange (propylamine) guard columns connected in series to a reverse-phase (C18) analytical column. Method detection limits for PFAS in groundwater ranged from 0.71 ng/L to 67 ng/L, and whole-method accuracy ranged from 96% to 106% for analytes for which matched authentic analytical standards were available. For analytes without authentic an...
TL;DR: It is suggested that even partial sulfidation of AgNP will decrease the toxicity of AgNPs relative to their pristine counterparts, and the presence of chloride in the exposure media strongly affects the toxicity results by affecting Ag speciation.
Abstract: Nanomaterials are highly dynamic in biological and environmental media. A critical need for advancing environmental health and safety research for nanomaterials is to identify physical and chemical transformations that affect the nanomaterial properties and their toxicity. Silver nanoparticles, one of the most toxic and well-studied nanomaterials, readily react with sulfide to form Ag(0)/Ag2S core–shell particles. Here, we show that sulfidation decreased silver nanoparticle toxicity to four diverse types of aquatic and terrestrial eukaryotic organisms (Danio rerio (zebrafish), Fundulus heteroclitus (killifish), Caenorhabditis elegans (nematode worm), and the aquatic plant Lemna minuta (least duckweed)). Toxicity reduction, which was dramatic in killifish and duckweed even for low extents of sulfidation (about 2 mol % S), is primarily associated with a decrease in Ag+ concentration after sulfidation due to the lower solubility of Ag2S relative to elemental Ag (Ag0). These results suggest that even partial ...