Mercury speciation, bioavailability, and biomagnification in contaminated streams on the Savannah River Site (SC, USA)

Xu, Xiaoyu; Bryan, A. Lawrence; Mills, Gary L.; Korotasz, Alexis M.

doi:10.1016/j.scitotenv.2019.02.301

Cited by 20 publications

(54 citation statements)

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“…As part of an ongoing study, soil samples were obtained from the SRS Mills Branch (area 101) which is found cocontaminated with total Hg concentrations in the range of 300-700 ng/g dry weight (Xu et al, 2019) as well as U. To isolate heavy metal resistant bacteria, soils were serially diluted and plated onto Lysogeny Broth agar (LBA) containing 5 µg/ml of mercuric chloride; the resulting colonies were picked and further isolated based on their distinct morphologies and pigmentation (Chauhan et al, 2018;Agarwal et al, 2019Agarwal et al, , 2020a.…”

Section: Experimental Section Isolation and Identification Of Strain mentioning

confidence: 99%

Is Long-Term Heavy Metal Exposure Driving Carriage of Antibiotic Resistance in Environmental Opportunistic Pathogens: A Comprehensive Phenomic and Genomic Assessment Using Serratia sp. SRS-8-S-2018

et al. 2020

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The carriage of both, heavy metal and antibiotic resistance appears to be a common trait in bacterial communities native to long-term contaminated habitats, including the Savannah River Site (SRS). There is widespread soil contamination at the SRS; a United States Department of Energy (DOE) facility with long-term contamination from past industrial and nuclear weapons production activities. To further evaluate the genomic and metabolic traits that underpin metal and antibiotic resistance, a robust mercury (Hg) and uranium (U)-resistant strain-SRS-8-S-2018, was isolated. Minimum inhibitory concentration of this strain revealed resistance to Hg (10 µg/ml) and U (5 mM), the two main heavy metal contaminants at the SRS. Metabolic assessment of strain SRS-8-S-2018 using Biolog metabolic fingerprinting analysis revealed preference for carbohydrate utilization followed by polymers, amino acids, carboxy acids, and esters; this physiological activity diminished when Hg stress was provided at 1 and 3 µg/ml and completely ceased at 5 µg/ml Hg, indicating that continued release of Hg will have negative metabolic impacts to even those microorganisms that possess high resistance ability. Development of antibiotic resistance in strain SRS-8-S-2018 was evaluated at a functional level using phenomics, which confirmed broad resistance against 70.8% of the 48 antibiotics tested. Evolutionary and adaptive traits of strain SRS-8-S-2018 were further assessed using genomics, which revealed the strain to taxonomically affiliate with Serratia marcescens species, possessing a genome size of 5,323,630 bp, 5,261 proteins (CDS), 55 genes for transfer RNA (tRNA), and an average G + C content of 59.48. Comparative genomics with closest taxonomic relatives revealed 360 distinct genes in SRS-8-S-2018, with multiple functions related to both, antibiotic and heavy metal resistance, which likely facilitates the strain's survival in a metalliferous soil habitat.

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Section: Experimental Section Isolation and Identification Of Strain mentioning

confidence: 99%

Is Long-Term Heavy Metal Exposure Driving Carriage of Antibiotic Resistance in Environmental Opportunistic Pathogens: A Comprehensive Phenomic and Genomic Assessment Using Serratia sp. SRS-8-S-2018

et al. 2020

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“…Methylmercury (MeHg) is the most toxic mercury compound, exerting neurotoxic effects, and it is easily released by sediments and bioaccumulated in food webs [ 2 , 6 , 7 ]. Moreover, MeHg shows a strong biomagnification potential, significantly increasing both as concentration and as a percentage to total mercury (THg) with increasing trophic level, posing the risk of secondary poisoning to top predators [ 8 , 9 , 10 ].…”

Section: Introductionmentioning

confidence: 99%

“…They serve as food for many fish species in the aquatic habitat, while adult insects are also prey for terrestrial animals such as insects, birds, and bats [ 16 ]. However, studies on mercury bioaccumulation in freshwater invertebrates are limited (e.g., [ 10 , 11 , 17 , 18 , 19 ]). Aquatic invertebrates can be characterized by relevant concentrations of MeHg, mostly ranging between 10% and 90% of THg, determining significant transfer to predators [ 10 , 20 ].…”

Section: Introductionmentioning

confidence: 99%

“…However, studies on mercury bioaccumulation in freshwater invertebrates are limited (e.g., [ 10 , 11 , 17 , 18 , 19 ]). Aquatic invertebrates can be characterized by relevant concentrations of MeHg, mostly ranging between 10% and 90% of THg, determining significant transfer to predators [ 10 , 20 ]. Thus, they are important sentinels for mercury exposure for a wide range of higher organisms.…”

Section: Introductionmentioning

confidence: 99%

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Mercury Bioaccumulation in Benthic Invertebrates: From Riverine Sediments to Higher Trophic Levels

Marziali

Roscioli

Valsecchi

2021

Toxics

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Riverine sediments are important sites of mercury methylation and benthic invertebrates may be indicators of Hg exposure to higher organisms. From 2014 to 2018, sediments and invertebrates were collected along a mercury gradient in the Toce River (Northern Italy) and analyzed for THg and MeHg. Concentrations in invertebrates, separated according to taxon and to Functional Feeding Group, ranged from 20 to 253 µg kg−1 dry weight (d.w.) for THg, increasing from grazers (Leuctra, Baetis, Serratella) to predators (Perla). MeHg ranged from 3 to 88 µg kg−1 d.w. in biota, representing 6–53% of THg, while in sediments it was mostly below LOD (0.7 µg kg−1), accounting for ≤3.8% of THg. The Biota-Sediment Accumulation Factor (BSAF, ranging 0.2–4.6) showed an inverse relation to exposure concentrations (THg in sediments, ranging 0.014–0.403 µg kg−1 d.w.) and to organic carbon. THg in invertebrates (up to 73 µg kg−1 wet weight), i.e., at the basal levels of the aquatic trophic chain, exceeded the European Environmental Quality Standard for biota (20 µg kg−1 w.w.), posing potential risks for top predators. Concentrations in adult insects were close to those in aquatic stages, proving active mercury transfer even to terrestrial food chains.

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“…A range of methods has been developed for assessing metal bioavailability. Biomonitoring is the most direct approach to show the accumulative effect of combined factors in an environment, but it can be expensive for the sampling and processing procedures and may pose limitations on collecting a normal population (Zhou et al 2008; Cai and Wang 2019; Xu et al 2019a; Zhao and Wang 2019). Geochemical modeling is an alternative approach; it can exclude influences of complicated biotic factors by using metal complexation parameters to predict metal speciation and biotic membrane binding (Di Toro et al 2001; Bourgeault et al 2013; Philipps et al 2018a).…”

Section: Introductionmentioning

confidence: 99%

Limitations of Applying Diffusive Gradients in Thin Films to Predict Bioavailability of Metal Mixtures in Aquatic Systems with Unstable Water Chemistries

Peck

Fletcher

et al. 2020

Enviro Toxic and Chemistry

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The present study accessed the use of diffusive gradients in thin film (DGT) as a surrogate for estimating the bioavailability and bioaccumulation of copper (Cu) and zinc (Zn) in a freshwater mussel. We coupled DGTs with mussels and deployed them in a constructed wetland. Water quality parameters were measured for a 4-d period on 3 continuous occasions during 12-d trials in the summer and winter; metal speciation was modeled for each occasion. Higher cumulative rainfall and water turbidity during the summer trial resulted in higher particulate metal concentrations compared to the winter trial. Mussel accumulated metals did not correlate with DGT-measured metals but positively correlated with particulate metals in the summer because filtering particulate food mainly contributed to the bioaccumulation. In contrast, the winter trial suggested a positive correlation between metal bioaccumulation and DGT-measured metals because uptake of dissolved organic matter (DOM) from water mainly contributed to the bioaccumulation, and the labile metal species complexed with DOM generally overlapped with DGT-targeted metals. Though Cu has a higher affinity for organic ligands than Zn, the interactions between Cu and Zn in the mixture did not impede their uptake and bioaccumulation. The deployment duration when DGTs and mussels are coupled to compare metal bioavailability should be no less than 12 d so that mussels have enough time to accumulate contaminants from the environmental media. In summary, DGT is a convenient surrogate for biomonitoring, but it may not fit the real environment such as the aquatic system with unstable water chemistries. Geochemical modeling is good at calculating metal speciation but inferior to DGT in predicting bioavailability and mimicking bioaccumulation.

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Mercury speciation, bioavailability, and biomagnification in contaminated streams on the Savannah River Site (SC, USA)

Cited by 20 publications

References 67 publications

Is Long-Term Heavy Metal Exposure Driving Carriage of Antibiotic Resistance in Environmental Opportunistic Pathogens: A Comprehensive Phenomic and Genomic Assessment Using Serratia sp. SRS-8-S-2018

Is Long-Term Heavy Metal Exposure Driving Carriage of Antibiotic Resistance in Environmental Opportunistic Pathogens: A Comprehensive Phenomic and Genomic Assessment Using Serratia sp. SRS-8-S-2018

Mercury Bioaccumulation in Benthic Invertebrates: From Riverine Sediments to Higher Trophic Levels

Limitations of Applying Diffusive Gradients in Thin Films to Predict Bioavailability of Metal Mixtures in Aquatic Systems with Unstable Water Chemistries

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