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Spatial and temporal dynamics of heavy metal pollution and source identification in sediment cores from the short-term flooding riparian wetlands in a Chinese delta
2016
Bai, Junhong | Jia, Jia | Zhang, Guangliang | Zhao, Qingqing | Lu, Qiongqiong | Cui, Baoshan | Liu, Xinhui
Sediment samples were collected to a depth of 60 cm along a 350-m sampling belt in a short-term-flooding riparian wetland in the Yellow River Delta of China in three sampling seasons. Contents of heavy metals were determined to investigate their spatial and temporal distributions, sources and ecotoxities. Our results showed that As contents in the top 20 cm sediments increased before decreasing along the sampling belt in summer, whereas they kept stable before increasing in fall and spring. Cd contents increased along the sampling belt in three sampling seasons, whereas Ni and Cr generally exhibited a decreasing tendency. Comparatively, Cu, Pb and Zn consistently increased at the first 50 m distance and then decreased before increasing from the distance of 150 m in summer and fall and increased to the maximum at the distance of 250 m and then showed a decrease in spring. Two “hotspots” of heavy metal accumulation in sediment cores along the belt were observed at the distance from 50 to 100 m in summer and at the distance from 200 to 300 m in spring. Most of sediment samples contained higher heavy metals in excess of threshold effect levels except for Zn and Pb in three sampling seasons and the values of toxic units in more than 30% of sediment samples exceeded 4 in summer. As, Ni and Cr had relatively higher contribution to the values of toxic units compared with other heavy metals in three sampling seasons. Multivariance analysis showed that As and Cd might originate from the same source and Cu, Zn, Cr, Pb and Ni might derive from another similar source. Cd was significantly correlated with salinity (p < 0.01) and pH (p < 0.05). Meanwhile, these heavy metals were also significantly correlated with other properties such as S, Al, TP, SOM and Silt + Clay.
اظهر المزيد [+] اقل [-]Anthropogenic impact on mangrove sediments triggers differential responses in the heavy metals and antibiotic resistomes of microbial communities
2016
Cabral, Lucélia | Júnior, Gileno Vieira Lacerda | Pereira de Sousa, Sanderson Tarciso | Dias, Armando Cavalcante Franco | Lira Cadete, Luana | Andreote, Fernando Dini | Hess, Matthias | de Oliveira, Valéria Maia
Mangroves are complex and dynamic ecosystems highly dependent on diverse microbial activities. In the last decades, these ecosystems have been exposed to and affected by diverse human activities, such as waste disposal and accidental oil spills. Complex microbial communities inhabiting the soil and sediment of mangroves comprise microorganisms that have developed mechanisms to adapt to organic and inorganic contaminants. The resistance of these microbes to contaminants is an attractive property and also the reason why soil and sediment living microorganisms and their enzymes have been considered promising for environmental detoxification. The aim of the present study was to identify active microbial genes in heavy metals, i.e., Cu, Zn, Cd, Pb and Hg, and antibiotic resistomes of polluted and pristine mangrove sediments through the comparative analysis of metatranscriptome data. The concentration of the heavy metals Zn, Cr, Pb, Cu, Ni, Cd, and Hg and abundance of genes and transcripts involved in resistance to toxic compounds (the cobalt-zinc-cadmium resistance protein complex; the cobalt-zinc-cadmium resistance protein CzcA and the cation efflux system protein CusA) have been closely associated with sites impacted with petroleum, sludge and other urban waste. The taxonomic profiling of metatranscriptome sequences suggests that members of Gammaproteobacteria and Deltaproteobacteria classes contribute to the detoxification of the polluted soil. Desulfobacterium autotrophicum was the most abundant microorganism in the oil-impacted site and displayed specific functions related to heavy metal resistance, potentially playing a key role in the successful persistence of the microbial community of this site.
اظهر المزيد [+] اقل [-]Integrated multi-biomarker responses in two dreissenid species following metal and thermal cross-stress
2016
Potet, Marine | Devin, Simon | Pain-Devin, Sandrine | Rousselle, Philippe | Giambérini, Laure
With current global changes, the combination of several stressors such as temperature and contaminants may impact species distribution and ecosystem functioning. In this study, we evaluated the combined impact of two metals (Ni and Cr) with a thermal stress (from 12 to 17 °C) on biomarker responses in two bivalves, Dreissena rostriformis bugensis and Dreissena polymorpha. Biomarkers are informative tools to evaluate exposure and effects of stressors on organisms. The set of 14 biomarkers measured here was representative of both physiologic (filtration activity) and cellular antioxidant and detoxification mechanisms. Our aim was to study the response pattern of both species, and its meaning in terms of invasive potential. The implications for the use of these mussels in environmental monitoring are also discussed. Results evidenced that the two species do not respond to multiple stressors in the same way. Indeed, the effects of contamination on biomarker responses were more marked for D. polymorpha, especially under nickel exposure. While we cannot conclude as to the effect of temperature, invasiveness could be influenced by species sensitivity to contaminants. The physiological and cellular differences between D. polymorpha and D. r. bugensis might also be of concern for environmental risk assessment. The two species present differential bioaccumulation patterns, filtration activity and cellular biomarker responses. If D. polymorpha populations decline, their substitution by D. r. bugensis for biomonitoring or laboratory studies will not be possible without a deeper understanding of biomarker responses of the new invasive.
اظهر المزيد [+] اقل [-]Heavy metals in PM2.5 and in blood, and children's respiratory symptoms and asthma from an e-waste recycling area
2016
Zeng, Xiang | Xu, Xijin | Zheng, Xiangbin | Reponen, Tiina | Chen, Aimin | Huo, Xia
This study was to investigate the levels of heavy metals in PM2.5 and in blood, the prevalence of respiratory symptoms and asthma, and the related factors to them. Lead and cadmium in both PM2.5 and blood were significant higher in Guiyu (exposed area) than Haojiang (reference area) (p < 0.05), however, no significant difference was found for chromium and manganese in PM2.5 and in blood. The prevalence of cough, phlegm, dyspnea, and wheeze of children was higher in Guiyu compared to Haojiang (p < 0.05). No significant difference was found for the prevalence of asthma in children between Guiyu and Haojiang. Living in Guiyu was positively associated with blood lead (B = 0.196, p < 0.001), blood cadmium (B = 0.148, p < 0.05) and cough (OR, 2.37; 95% CI, 1.30–4.32; p < 0.01). Blood lead>5 μg/dL was significantly associated with asthma (OR, 9.50; 95% CI, 1.16–77.49). Higher blood chromium and blood manganese were associated with more cough and wheeze, respectively. Our data suggest that living in e-waste exposed area may lead to increased levels of heavy metals, and accelerated prevalence of respiratory symptoms and asthma.
اظهر المزيد [+] اقل [-]Comparison of pollution indices for the assessment of heavy metal in Brisbane River sediment
2016
Duodu, Godfred Odame | Goonetilleke, Ashantha | Ayoko, G. A. (Godwin A.)
Estuarine environment is complex and receives different contaminants from numerous sources that are persistent, bioaccumulative and toxic. The distribution, source, contamination and ecological risk status of heavy metals in sediment of Brisbane River, Australia were investigated. Sediment samples were analysed for major and minor elements using LA-ICP-MS. Principal component analysis and cluster analysis identified three main sources of metals in the samples: marine sand intrusion, mixed lithogenic and sand intrusion as well as transport related. To overcome inherent deficiencies in using a single index, a range of sediment quality indices, including contamination factor, enrichment factor, index of geo-accumulation, modified degree of contamination, pollution index and modified pollution index were utilised to ascertain the sediment quality. Generally, the sediment is deemed to be “slightly” to “heavily” polluted. A further comparison with the Australian Sediment Quality Guidelines indicated that Ag, Cr, Cu, Ni, Pb and Zn had the potential to rarely cause biological effects while Hg could frequently cause biological effects. Application of potential ecological risk index (RI) revealed that the sediment poses moderate to considerable ecological risk. However, RI could not account for the complex sediment behaviour because it uses a simple contamination factor. Consequently, a modified ecological risk index (MRI) employing enrichment factor is proposed. This provides a more reliable understanding of whole sediment behaviour and classified the ecological risk of the sediment as moderate to very high. The results demonstrate the need for further investigation into heavy metal speciation and bioavailability in the sediment to ascertain the degree of toxicity.
اظهر المزيد [+] اقل [-]Metal measurement in aquatic environments by passive sampling methods: Lessons learning from an in situ intercomparison exercise
2016
Dabrin, A. | Ghestem, J.-P. | Uher, E. | Gonzalez, J.-L. | Allan, I.J. | Schintu, M. | Montero, N. | Balaam, J. | Peinerud, E. | Miège, C. | Coquery, M.
Passive sampling devices (PS) are widely used for pollutant monitoring in water, but estimation of measurement uncertainties by PS has seldom been undertaken. The aim of this work was to identify key parameters governing PS measurements of metals and their dispersion. We report the results of an in situ intercomparison exercise on diffusive gradient in thin films (DGT) in surface waters. Interlaboratory uncertainties of time-weighted average (TWA) concentrations were satisfactory (from 28% to 112%) given the number of participating laboratories (10) and ultra-trace metal concentrations involved. Data dispersion of TWA concentrations was mainly explained by uncertainties generated during DGT handling and analytical procedure steps. We highlight that DGT handling is critical for metals such as Cd, Cr and Zn, implying that DGT assembly/dismantling should be performed in very clean conditions. Using a unique dataset, we demonstrated that DGT markedly lowered the LOQ in comparison to spot sampling and stressed the need for accurate data calculation.
اظهر المزيد [+] اقل [-]Occurrence of antibiotic resistance genes in landfill leachate treatment plant and its effluent-receiving soil and surface water
2016
Zhang, Xiao-Hua | Xu, Yan-Bin | He, Xiao-Lin | Huang, Lu | Ling, Jia-Yin | Zheng, Li | Du, Qing-Ping
The antibiotic resistance genes (ARGs) from urban waste may spread to the environment with the discharge of leachate. Fifteen types of ARGs, including tetracycline, sulfonamides, AmpC β-lactamase and the class 1 integron gene were detected in the samples from the largest leachate treatment plant (LTP) in Guangzhou and its effluent receiving bodies (soil and surface water). The results showed that ARGs in leachates were in high levels and varied with seasons. The abundance of ARGs in the influent from high to low was in the turn of summer, winter, spring. About 2 to 4 orders of magnitude of ARGs were eliminated by the whole leachate treatment process. The predominant ARGs in the receiving soil were intI1, tetB, sul2, tetA and tetX, while those in the receiving surface water were sul2, intI1 and sul1, and the concentrations of ARGs in the receiving bodies were higher than those in the other natural bodies by 1 to 2 orders of magnitude. In addition, the results of bivariate correlation analysis showed that the abundances of ARGs (tetC, tetW, sul1, sul2, intI1 and FOX) were in significant correlation with the concentrations of heavy metals (Cu, Zn, Ni and Cr) (p < 0.05). LTPs are more likely to be sources of ARGs than wastewater treatment plant (WWTP) and need to be focused on.
اظهر المزيد [+] اقل [-]Efficient arsenate removal by magnetite-modified water hyacinth biochar
2016
Zhang, Feng | Wang, Xin | Xionghui, Ji | Ma, Lijuan
Magnetic biochars (MW) prepared by chemical co-precipitation of Fe2+/Fe3+ on water hyacinth biomass followed by pyrolysis exhibited important potential in aqueous As(V) elimination. In comparison, MW2501 outperformed other MWs and exhibited the highest As(V) sorption capacity which was estimated to be 7.4 mg g−1 based on Langmuir-Freundlic model. With solution pH ranging from 3 to 10, As(V) removal efficiency by MW2501 kept stable and consistently higher than 90%. Besides, ∼100% removal of 0.5 mM As(V) can be obtained in the presence of P ≤ 0.1 mM or Cr/Sb ≤ 0.5 mM, indicating a wide applicability of MW2501 for treatment of As-containing water. The predominance of Fe3O4 on MW2501 surface was evidenced by XRD. Ligand exchange between As(V) anion and the hydroxylated surface of Fe3O4 as well as H bond was largely responsible for As(V) sorption as suggested by FTIR. XPS analysis further revealed the dominance of As(V) in the sorbed As on MW2501 surface with co-occurrence of a minor proportion of As(III) (11.45%). In parallel, oxidative transformation of Fe3O4 to Fe2O3 was also suggested by XPS. By a lab-scale column test, the potential and suitability of MW2501 in As-containing water treatment was further confirmed, which could also provide an alternative way to manage and utilize this highly problematic invasive species.
اظهر المزيد [+] اقل [-]Presence of trace metals in aquaculture marine ecosystems of the northwestern Mediterranean Sea (Italy)
2016
Squadrone, S. | Brizio, P. | Stella, C. | Prearo, M. | Pastorino, P. | Serracca, L. | Ercolini, C. | Abete, M.C.
Information regarding chemical pollutant levels in farmed fish and shellfish, along with the risks associated with their consumption is still scarce. This study was designed to assess levels of exposure to 21 trace elements in fish (Dicentrarchus labrax), mussels (Mytilus galloprovincialis) and oysters (Crassostrea gigas) collected from aquaculture marine ecosystems of the northwestern Mediterranean Sea. Metal concentrations showed great variability in the three species; the highest values of the nonessential elements As and Cd were found in oysters while the highest levels of Al, Pb and V were found in mussels. The essential elements Cu, Mn and Zn were highest in oysters, but Fe, Cr, Ni, Se, Co and Mo levels were highest in mussels. Fish had the lowest concentrations for all trace elements, which were at least one order of magnitude lower than in bivalves. The rare earth elements cerium and lanthanum were found at higher levels in mussels than in oysters, but undetectable in fish. The maximum values set by European regulations for Hg, Cd and Pb were never exceeded in the examined samples. However, comparing the estimated human daily intakes (EHDIs) with the suggested tolerable copper and zinc intakes suggested a potential risk for frequent consumers of oysters. Similarly, people who consume high quantities of mussels could be exposed to concentrations of Al that exceed the proposed TWI (tolerable weekly intake).
اظهر المزيد [+] اقل [-]The impact of sediment bioturbation by secondary organisms on metal bioavailability, bioaccumulation and toxicity to target organisms in benthic bioassays: Implications for sediment quality assessment
2016
Remaili, Timothy M. | Simpson, Stuart L. | Amato, Elvio D. | Spadaro, David A. | Jarolimek, Chad V. | Jolley, Dianne F.
Bioturbation alters the properties of sediments and modifies contaminant bioavailability to benthic organisms. These naturally occurring disturbances are seldom considered during the assessment of sediment quality. We investigated how the presence (High bioturbation) and absence (Low bioturbation) of a strongly bioturbating amphipod within three different sediments influenced metal bioavailability, survival and bioaccumulation of metals to the bivalve Tellina deltoidalis. The concentrations of dissolved copper decreased and manganese increased with increased bioturbation. For copper a strong correlation was observed between increased bivalve survival (53–100%) and dissolved concentrations in the overlying water. Increased bioturbation intensity resulted in greater tissue concentrations for chromium and zinc in some test sediments. Overall, the results highlight the strong influence that the natural bioturbation activities from one organism may have on the risk contaminants pose to other organisms within the local environment. The characterisation of field-based exposure conditions concerning the biotic or abiotic resuspension of sediments and the rate of attenuation of released contaminants through dilution or readsorption may enable laboratory-based bioassay designs to be adapted to better match those of the assessed environment.
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