Bioaccumulation of trace metals in aquatic food web. A case study, Liaodong Bay, NE China

The recently developed modelling tool MERLIN-Expo was applied to support the exposure assessment of an aquatic food web to trace metals in a coastal environment. The exposure scenario, built on the data from Daliao River estuary in the Liaodong Bay (Bohai Sea, China), affected by long-term and large-scale industrial activities as well as rapid urbanization in Liao River watershed, represents an interesting case-study for ecological exposure modelling due to the availability of local data on metal concentrations in water and sediment. The bioaccumulation of selected trace metals in aquatic organisms was modelled and compared with field data from local aquatic organisms. Both model results and experimental data demonstrated that As, Cd, Cu, Ni, Pb and Zn, out of examined metals, were accumulated most abundantly by invertebrates and less by higher trophic level species. The body parts of the sampled animals with the highest measured concentration of metals were predominantly muscles, intestine and liver and fish skin in the case of Cr.The Morris and extended Fourier Analysis (EFAST) were used to account for variability in selected parameters of the bioaccumulation model. Food assimilation efficiency and slopes and intercepts of two sub-models for calculating metal specific BCFs (BCFmetarexposure concentration) and fish weight (Weightiuh-Lengthfish) were identified as the most influential parameters on ecological exposure to selected metals

Peroxymonosulfate assisted mechanochemical method for the degradation of phenanthrene in contaminated soils

In recent years, mechanochemical method has received attention in the field of degrading pollutants, especially for persistent organic pollutants. In this study, peroxymonosulfate (PMS) as a co-grinding reagent, coupled with contaminated soil were placed in a ball mill for mechanochemical reaction. Through investigating the influences of ball-milling parameters on the degradation efficiency, the reaction conditions were optimized. Under the optimal condition (mass ratio of soil to oxidant is 10:1, mass ratio of ball to material is 30:1, rotation speed of ball mill is 400 rpm), more than 98% phenanthrene (PHE) in contaminated soil could be degraded within 4 h. Meanwhile, the effects of soil organic matter content and soil type on the degradation efficiency were investigated. The results showed that the organic matter content was negatively correlated with the degradation efficiency. XPS analysis provided evidence for the breakage of the CC bond and confirmed that Fe in soil was an important factor in activating PMS. XRD further verified the destruction of PHE structure. GC-MS analysis was performed to identify the intermediates and possible pathways were proposed. Keywords: Mechanochemical method, PMS, PHE, Degradation, Soi

Tungsten distribution in soil and rice in the vicinity of the world's largest and longest-operating tungsten mine in China.

The objective of this study is to investigate tungsten (W) contamination in soil and its enrichment in rice in the area of the world's largest and longest-operating W mines in China. Root zone soil and rice plants were sampled at 15 sites in the agricultural field adjacent to W mines and analyzed for Al, Fe, Mn, Sc, and W contents and W chemical forms in the soil samples and W contents in the rice root, stem, leaf, and grain samples. Results showed that W content in the soil ranged from 3.99 to 43.7 mg kg(-1), with more than 90% of W in the residual fraction, showing its low mobility and bioavailability. Average W contents in the rice root, stem, leaf, and grain were 7.06, 2.34, 4.76, 0.17 mg kg(-1), respectively. In addition, they were linearly independent of W content and chemical forms in the soil. Average enrichment factor values were 0.39, 0.13, 0.28, and 0.01 for the root, stem, leaf, and grain, respectively. In can be concluded that W mining activity in the Dayu county contaminated the nearby agricultural soil and led to W bioaccumulation in the rice. This may pose a health risk to residents via food and soil ingestion, which should be a focus of scrutiny

Contamination and human health risk of lead in soils around lead/zinc smelting areas in China

Pb/Zn smelting, an important economic activity in China, has led to heavy environmental pollution. This research reviewed studies on soil Pb contamination at Pb/Zn smelting sites in China published during the period of 2000 to 2015 to clarify the total levels, spatial changes, and health risks for Pb contamination in soils at local and national scales. The results show that Pb contents in surface soils at 58 Pb/Zn smelting sites in China ranged from 7 to 312,452 mg kg−1 with an arithmetic average, geometric average, and median of 1982, 404, and 428 mg kg−1, respectively (n = 1011). Surface soil Pb content at these smelting sites decreased from an average of 2466 to 659 mg kg−1, then to 463 mg kg−1 as the distance from the smelters increased from 2000 m. With respect to variation with depth, the average soil Pb content at these sites gradually decreased from 986 mg kg−1 at 0- to 20-cm depth to 144 mg kg−1 at 80- to 100-cm depth. Approximately 78 % of the soil samples (n = 1011) at the 58 Pb/Zn smelting sites were classified as having high Pb pollution levels. Approximately 34.2 and 7.7 % of the soil samples (n = 1011) at the 58 Pb/Zn smelting sites might pose adverse health effects and high chronic risks to children, respectively. The Pb/Zn smelting sites in the southwest and southeast provinces of China, as well as Liaoning province, were most contaminated and thus should receive priority for remediation.Pb/Zn smelting, an important economic activity in China, has led to heavy environmental pollution. This research reviewed studies on soil Pb contamination at Pb/Zn smelting sites in China published during the period of 2000 to 2015 to clarify the total levels, spatial changes, and health risks for Pb contamination in soils at local and national scales. The results show that Pb contents in surface soils at 58 Pb/Zn smelting sites in China ranged from 7 to 312,452 mg kg−1 with an arithmetic average, geometric average, and median of 1982, 404, and 428 mg kg−1, respectively (n = 1011). Surface soil Pb content at these smelting sites decreased from an average of 2466 to 659 mg kg−1, then to 463 mg kg−1 as the distance from the smelters increased from 2000 m. With respect to variation with depth, the average soil Pb content at these sites gradually decreased from 986 mg kg−1 at 0- to 20-cm depth to 144 mg kg−1 at 80- to 100-cm depth. Approximately 78 % of the soil samples (n = 1011) at the 58 Pb/Zn smelting sites were classified as having high Pb pollution levels. Approximately 34.2 and 7.7 % of the soil samples (n=1011) at the 58 Pb/Zn smelting sites might pose adverse health effects and high chronic risks to children, respectively. The Pb/Zn smelting sites in the southwest and southeast provinces of China, as well as Liaoning province, were most contaminated and thus should receive priority for remediation

Typical pesticides diffuse loading and degradation pattern differences under the impacts of climate and land-use variations

Riverine sediment can reconstruct the history of organic pollution loads and can provide reliable temporal information for pesticide metabolite dynamics in watershed. Sediment core samples were collected from two riverine sections of a cold watershed base in the presence land use change under agricultural development, and the vertical concentrations of four pesticides (atrazine, prometryn, isoprothiolane, and oxadiazon) and two atrazine metabolites (deisopropyl-atrazine and deethyl-atrazine) were determined by gas chromatography-mass spectrometry. The presence of pesticides and metabolites was detected at different depths (11-17 cm) at 1-cm intervals along the two sediment cores, and the flux was calculated with a constant rate of supply model based on the observed concentrations and Pb-210 isotope radioactivity chronology. By comparing the concentrations and fluxes of pesticides between the two sediment sections, significant differences in accumulation under different land-use patterns were found. Redundancy analysis further indicated that temporal watershed farmland variance was the dominant factor for pesticide loading. The lower concentration of atrazine and the higher concentration of the other pesticides in the estuarine sediment was closely related to the decreasing upland in the upstream area and the increase in paddy fields in the downstream area. The analysis of atrazine and the metabolites indicated that atrazine is more likely degraded to deethyl-atrazine and the metabolites have similar migration processes in the sediments, which can easily migrate downward. Moreover, the ratio of metabolites to atrazine showed that atrazine degradation was intensive during the transport process, but the metabolites efficiency was lower in this area due to the cold temperature. The results provide insights for the management of pesticide pollution control in watersheds and the potential effects of low temperature on the degradation of pesticides

Vertical Distribution of Lead and Mercury in the Wetland Argialbolls of the Sanjiang Plain in Northeastern China

<div><p>The wetland Argialbolls pedon was chosen to investigate the effects of pedogenic processes and anthropogenic activities on the vertical distribution of lead and mercury concentration and to assess the potential use of soil as an archive of atmospheric Pb and Hg pollution. The soil was sampled from 5 cm from the surface to a depth of 90 cm at two locations in the Sanjiang Plain in northeastern China. The soil was analyzed for pH, soil organic matter (SOM), Fe, Mn, and Al. The results indicate that the SOM concentration gradually decreased with depth, while Fe and Mn were reductively leached from the upper horizons and accumulated significantly in the lower argillic horizons. Atmospheric Pb and Hg deposition and their redistribution during the pedogenic process led to a unique vertical distribution in the wetland Argialbolls. Overall, Pb was leached from the upper horizons and then accumulated in the lower argillic horizons. However, the Hg concentration decreased with depth, following the SOM distribution. The Pb concentration was significantly correlated to the Fe and Mn concentrations in the Argialbolls profiles, while the Hg concentration was significantly correlated with SOM. Post-depositional mobility along the wetland Argialbolls profile is higher for Pb and low for Hg. Therefore, the Argialbolls profile does not provide an accurate reconstruction of atmospheric Pb deposition, but might provide an accurate reconstruction of net atmospheric Hg deposition.</p></div

Multivariate interactions of natural and anthropogenic factors on Cd behavior in arable soil

Multivariate interactions are far more complex between natural factors and pollutants resulting from anthropogenic practices than between pollutants themselves. But little attention has been focused on the complex interpretation of multivariate interactions. To bridge this research gap, this study aimed to identify the interactive effect of multiple affecting factors including freeze-thaw cycles (FT), soil water (SW) content, and chlorpyrifos (CP) on soil Cd behavior in arable soil, based on the analysis of changes in Cd fractionations and Cd availability. Moreover, the significant effect was computed via design of experiments. The content of Cd fractions and the evaluated index of Cd availability were obtained by employing the modified six-step sequential extraction method. The results showed that the main effect of FT, SW and CP on Cd fractionation and availability was significant. The binary interactions weakened the main effect of FT or SW, but enhanced the main effect of CP on Cd fractionation. The ternary interactions further weakened the binary interactions, whereas CP enhanced the interaction between SW and FT. The interaction between SW and CP had a negative effect on residual Cd, but positively affected water-soluble and organic matter-bound Cd. The binary interaction between CP and FT had a positive effect on residual Cd (21.0%), but negatively affected water-soluble and Fe-Mn-oxide-associated Cd (25.9% and 21.1%). These results covered more innovative information on the multivariate interactions between natural and anthropogenic factors on Cd behavior in arable soil. A possible new way to quantify the significant impact of multivariate factors also was provided

Health Risk Assessment of Metals via Multi-Source Oral Exposure for Children Living in Areas with Intense Electronic Manufacturing Activities

Oral ingestion is the predominant pathway of metal(loid)s exposure. In this study, the health risks of typical metal(loid)s (including Mn, As, Cr, Cd, and Pb) via multi-source, oral pathways for children aged 3–12 years, living in an area of China dominated by the electronic manufacturing industry, were studied based on the field sampling of duplicated diet, soil, and drinking water. Child-specific ingestion parameters were measured (except the soil ingestion rates, which were from a previous study of the same population), and a Monte Carlo method was applied to determine the uncertainty of the risk assessment. It was observed that children living in such environments were at risk of metal(loid)s exposure, with the accumulative carcinogenic risk exceeding the maximum acceptable level. Food intake was identified to be the primary exposure pathway. Moreover, Pb and Cr were the major risk elements to local children’s health. Compared with primary school students, kindergarten children experienced a higher risk. This study highlights that high attention should be paid to children living in suburban areas dominated by the electronic manufacturing industry, and that priority should be given to studies on metal(loid)s exposure deriving from different types of food and their corresponding bioavailability, in order to further discern the precise risk sources to protect children’s health

Toxicity and bioavailability of antimony to the earthworm (Eisenia fetida) in different agricultural soils

Laboratory experiments in which earthworms were exposed to four different Sb spiked agricultural soils (acidic, neutral, alkaline and calcareous alkaline soil) were conducted in a climate-controlled room. The study surveyed the toxicity of Sb to the Eisenia fetida at the individual (mortality, growth inhibition, Sb accumulation), physiological (enzymatic activities), subcellular and tissue levels (histological damage), and for the induction of an avoidance response of Sb. The results showed that earthworms clearly avoided Sb spiked soil, and the avoidance response tended to be correlated to the exposure dose. The EC50 values of the net avoidance response in the four soils were as followed: S1 (acidic soil, 135 +/- 37 mg kg(-1)) < S3 (alkaline soil, 430 +/- 114 mg kg(-1)) < S4 (calcareous alkaline soil, 455 +/- 29 mg kg(-1)) < S2 (neutral soil, 946 +/- 151 mg kg(-1)). Different toxic effects of Sb to earthworms cultivated in the four types of soils were observed. Antimony was more toxic in a sandy alkaline soil than that in the other three soils tested. The LC50 of the 28 d mortality ranged as follows: S3 (22.2 +/- 0.1 mg kg(-1)) < S2 (372 +/- 177 mg kg(-1)) < S4 (491 +/- 140 mg kg(-1)) < S1 (497 +/- 29 mg kg(-1)). Changes in oxidative stress and the subcellular distribution of Sb in earthworms induced by Sb exposure differed between soil types. Additionally, histological damage in earthworm's epidermis and intestine were observed under Sb stress. Mortality, growth inhibition and Sb accumulation in the earthworms tended to increase with Sb exposure regardless of soil type and were all significantly correlated with the exposure dose. The growth inhibition and Sb concentration in tissues of earthworms were sensitive indicators of Sb bioavailability. The relatively comprehensive toxicological data provided herein can contribute to the toxicity threshold and assessment of bioavailability of Sb contaminated agricultural soil, and then to the ecological risk assessments