Inputs Of As Research Articles

Heavy metal residues, releases and food health risks between the two main crayfish culturing models: Rice-crayfish coculture system versus crayfish intensive culture system

High-density culturing with excessive feeding of commercial feed has caused heavy metals pollution to agricultural production system. In this study, the dynamic changes and transfer of heavy metals in rice-crayfish coculture system (RCCS) and crayfish intensive culture system (CICS) within a completed culture cycle were systematically quantified. Our results showed that Cd in feed represented more than 50% of the total Cd input, and the inputs of As and Cr were mainly from irrigation. The residues of As and Pb in RCCS were slightly higher than those in CICS, while the residues of Cd and Cr in RCCS were far fewer than those in CICS. Moreover, the metal pollution index in CICS was 0.781, while it was 0.543 in the RCCS. Furthermore, a large proportion of the Cd and Pb in CICS was released into the external environment through drainage. Notably, the absorption and solidification of heavy metals by straw did not increase the residues of As and Pb in the major components of RCCS in the second year. Compared to CICS, RCCS did not produce many heavy metal residues or cause heavy metal discharge pressure on the external environment, and its food product had a low risk of heavy metal contamination.

Spatiotemporal variations, sources, water quality and health risk assessment of trace elements in the Fen River

As the largest river in Shanxi Province, the Fen River is the main water source for regional economic and ecological development. Water deficiency and industrialization have led to serious water pollution in the Fen River. The major and trace elements of seasonal river waters were measured to determine the spatiotemporal variations and assess the water quality as well as its controlling factors in the Fen River. Trace elements are divided into high abundance elements (B, Ba, Li, and Mn) and low abundance elements (As, Cu, Fe, Ni, Rb, Se, U, and V). The spatial variation of trace elements is obvious, with low values upstream, intermediate values downstream, and very high values midstream. The average values of the trace elements showed different seasonal variations, with high values of As, B, Ba, Mn, and Rb in the wet season, high Cu, V, and Li values in the dry season, and minor seasonal variations of Fe, Ni, Se, and U concentrations. Principal component analysis (PCA) and correlation analysis (CA) showed natural origins of Ba, Mn, Ni, and U, anthropogenic input of As, B, Cu, Li, Rb, Se, and V. According to the results of absolute principal component sore-multivariate linear regression (APCS-MLR), the major pollution sources in the Fen River basin were related to human activities. The land use type significantly influenced the concentrations of trace elements, with high values in the cropland and low values in the forest. The water quality index (WQI) values were higher in the midstream and wet season. In comparison with other rivers in the world, the pollution of the Fen River is at a moderate level. Health risk assessment showed that As, Ba, Mn, Ni, V, and Se were the potential pollutants damaging in the Fen River, especially for children. This study highlights the importance of seasonal sample analysis and can provide vital data for water quality conservation in the Fen River basin.

Anthropocene footprint in the Nalón estuarine sediments (northern Spain)

Four boreholes drilled at depths ranging from 9 to 27 m and retrieved from the Nalón estuary (Asturias, northern Spain) were investigated to assess the impact of the historical human footprint on the sedimentary sequence. Analytical measurements of grain size, geochemical composition (major and trace elements), and stable Pb isotopic ratios were performed. Two different sections of the sedimentary profile were identified throughout the sedimentary sequence using Pb isotopic ratios and then corroborated with grain size characteristics and As, Hg, Pb and Zn concentrations. The upper sediment layer of the boreholes (variable depth ranging between 3 and 9 m) exhibited an increase in 208Pb/206Pb ratios and a decrease in 206Pb/207Pb ratios, whereas, in the deepest layers, these ratios remained unchanged. These variations reflected the anthropogenic input of Pb into estuarine sediments, which can be attributed to mining activities when compared to Pb isotopic ratios from coal mined in the region. The anthropogenic input can be also noted on the basis of the variability of the trace element concentrations with depth. The enrichment factors of As (max 7.5), Hg (max 45.4), Pb (max 10.3), and Zn (max 8.6), calculated using local geochemical background values helped distinguish the impact of intense anthropogenic activities, which can be attributed to mining exploitation in the Nalón River drainage basin. Despite the closure of several of these mines during the second half of the 20th century, geochemical characteristics have revealed the ongoing input of As, Hg, Pb, and Zn into the coastal zone. Thus, the legacy of contamination from these elements, mainly from leaching slags and tailing dams, is still being recorded in estuarine sediments and requires careful scrutiny on the part of local authorities in terms of its possible effects on the aquatic biota.

Current inventory and changes of the input/output balance of trace elements in farmland across China.

The inventory and input/output balance of trace elements in farmland play an important role in risk assessment and soil management, but there is little information about nationwide changes of the input/output balance of trace elements in farmland in China. In the present study, the inventory of trace element inputs to farmland was updated based on the dataset from the literature published during 2006–2015, and changes of the input/output balance were investigated. Compared with 1999–2006, net inputs of Cr, Ni, and Zn increased by 52.9%, 59.7%, and 20.6%, respectively. The increases in fossil fuel derived energy consumption, industrial manufacture, municipal solid waste incineration, and transportation were the predominant contributors to these increases. Net inputs of Cd, Cu, and Hg decreased dramatically by 46.7%, 25.2%, and 50.4%, respectively. The decreases are due to the strict management of feed additives, fertilizers, and emissions of atmospheric pollutants. Net inputs of As and Pb still remained relatively stable. These results demonstrated that better achievements have been gained by administration of air, water and soil in China. Regulation of atmospheric emission for Cr, Ni, and Zn was recommended as atmospheric deposition was the predominant source for increases of Cr, Ni, and Zn inputs to farmland across China.

Quantitative analyzing for As’s transferring process in coastal waters in Jiaozhou Bay

This paper quantified the horizontal and vertical transferring processes of As in coastal waters in the southwest and the bay mouth of Jiaozhou Bay using investigation data in July and October 1982. Results showed that the horizontal absolute loss amounts of As contents in surface waters were 0.20-2.44 μg L-1, and the horizontal relative loss amounts in surface waters were 19.23%-87.14%, respectively. The horizontal absolute loss amounts of As contents in bottom waters were 0.27-2.44 μg L-1, and the horizontal relative loss amounts in bottom waters were 25.00%-54.46%, respectively. The vertical absolute dilution amounts of As contents were 0.02-0.28 μg L-1, and the vertical relative dilution amounts were 1.78-16.66%. The vertical absolute accumulation amounts of Pb contents were 0.10-0.86 μg L-1, and the vertical relative accumulation amounts were 7.35%-35.83%. The vertical absolute dilution amount and vertical relative dilution amount of As’s contents were 0.20-0.76 μg L-1 and 19.23%-27.14%, respectively. The vertical absolute accumulation amount and vertical relative accumulation amount of As’s contents were 0.28-4.12 μg L-1 and 25.00%-91.96%, respectively. The changes of As contents in surface and bottom waters were determined by the source inputs of As and the transferring distance of As from the terrisgenous sources.

The consistency of Arsenic’s high value regions in surface and bottom waters in Jiaozhou Bay

This paper analyzed the contents and distributions of As in Jiaozhou Bay in 1982. Results showed that As’s contents in bottom waters in coastal waters in the southwest of the bay and the bay mouth in Jiaozhou Bay in July and October 1982 were 0.88-4.48 μg L-1 and 0.84-1.16 μg L-1, respectively. As’s contents were much lower than the guide line of Grade I, and the pollution level of As in bottom waters in Jiaozhou Bay in 1982 was still very slight. There was high value region in coastal waters in the southwest of the bay in July 1982 (4.48 μg L-1), while in October 1982 high value region was in the bay mouth (1.16 μg L-1). The source input of As from overland runoff in the southwest was strong in July, resulted in relative high value region in surface waters in coastal waters in the southwest of the bay, and therefore resulted in high value region in bottom waters in same region by means of rapid sedimentation of As. October was wet season and there was little As input to the bay, resulted in low As’s contents in surface waters, as well as bottom waters. At any time, the terrigenous As was foremost transported to surface waters, and was subsided to sea bottom through water body by vertical water’s effect. Hence, the high value regions of As’s contents in surface and bottom waters had characteristic of consistency in Jiaozhou Bay.

Phytoextraction of arsenic-contaminated soil with Pteris vittata in Henan Province, China: comprehensive evaluation of remediation efficiency correcting for atmospheric depositions.

Research on the appropriate method for evaluating phytoremediation efficiency is limited. A 2-year field experiment was conducted to investigate phytoremediation efficiency using the hyperaccumulator Pteris vittata on an arsenic (As)-contaminated site. The remediation efficiency was evaluated through the removal rate of As in soils and extraction rate of heavy metals in plants. After 2years of remediation, the concentration of total As in soils decreased from 16.27mgkg-1 in 2012 to 14.58mgkg-1 in 2014. The total remediation efficiency of As was 10.39% in terms of the removal rate of heavy metals calculated for soils, whereas the remediation efficiency calculated from As uptake by P. vittata was 16.09%. Such a discrepancy aroused further consideration on the potential input of As. A large amount of As was brought in by atmospheric emissions, which possibly biased the calculation of remediation efficiency. In fact, considering also the atmospheric depositions of As, the corrected removal rate of As from soil was 16.57%. Therefore, the results of this work suggest that (i) when evaluating the phytoextraction efficiency, the whole input and output cycle of the element of interest in the targeted ecosystem must be considered, and (ii) P. vittata has the potential to be used to remediate As-contaminated soils in Henan Province, China.

Peat Bogs as Hotspots for Organoarsenical Formation and Persistence.

Peatlands have received significant atmospheric inputs of As and S since the onset of the Industrial Revolution, but the effect of S deposition on the fate of As is largely unknown. It may encompass the formation of As sulfides and organosulfur-bound As, or the indirect stimulation of As biotransformation processes, which are presently not considered as important As immobilization pathways in wetlands. To investigate the immobilization mechanisms of anthropogenically derived As in peatlands subjected to long-term atmospheric pollution, we explored the solid-phase speciation of As, Fe, and S in English peat bogs by X-ray absorption spectroscopy. Additionally, we analyzed the speciation of As in pore- and streamwaters. Linear combination fits of extended X-ray absorption fine structure (EXAFS) data imply that 62-100% (average: 82%) of solid-phase As (Astot: 9-92 mg/kg) was present as organic As(V) and As(III). In agreement with appreciable concentrations of organoarsenicals in surface waters (pH: 4.0-4.4, Eh: 165-190 mV, average Astot: 1.5-129 μg/L), our findings reveal extensive biotransformation of atmospheric As and the enrichment of organoarsenicals in the peat, suggesting that the importance of organometal(loid)s in wetlands subjected to prolonged air pollution is higher than previously assumed.

Arsenite modifies structure of soil microbial communities and arsenite oxidization potential

The influence of arsenite [As(III)] on natural microbial communities and the capacity of exposed communities to oxidize As(III) has not been well explored. In this study, we conducted soil column experiments with a natural microbial community exposed to different carbon conditions and a continuous flow of As(III). We measured the oxidation rates of As(III) to As(V), and the composition of the bacterial community was monitored by 454 pyrosequencing of 16S rRNA genes. The diversity of As(III)-oxidizing bacteria was examined with the aox gene, which encodes the enzyme involved in As(III) oxidation. Arsenite oxidation was high in the live soil regardless of the carbon source and below detection in sterilized soil. In columns amended with 200 μmol kg(-1) of As (III), As(V) concentrations reached 158 μmol kg(-1) in the column effluent, while As(III) decreased to unmeasurable levels. Although the number of bacterial taxa decreased by as much as twofold in treatments amended with As(III), some As(III)-oxidizing bacterial groups increased up to 20-fold. Collectively, the data show the large effect of As(III) on bacterial diversity, and the capacity of natural communities from a soil with low initial As contamination to oxidize large inputs of As(III).

Size Distribution and Source Apportionment of Airborne Metallic Elements in Nanjing, China

In order to investigate the temporal and spatial variations and the size distribution of atmospheric particulate matter and associated airborne elements, atmospheric particulate matter (TSP, PM2.5 and size-segregated aerosol particles) were collected monthly for one year from the traditional central district and suburbs of Nanjing, China. Source identification of airborne elements in PM2.5 was carried out using multivariate statistical analysis. The annual mass concentrations ranged from 49.4 µg/m 3 to 391 µg/m 3 , with a mean of 135 µg/m 3 for TSP and from 20.4 µg/m 3 to 200 µg/m 3 with a mean of 80.5 µg/m 3 for PM2.5. The distribution of annual size-segregated aerosol particles showed a bimodal pattern of coarse and fine particle fractions. Spatial and seasonal variations of elemental composition in atmospheric particulates were observed. The major elements (A1, Ca, Fe, Mg, Na and Mn) were mainly distributed in coarse fractions, while toxic elements, such as As, Cd, Pb and Zn, were significantly enriched in the fine fractions. The enrichment factor indicated anthropogenic inputs of As, Cu, Ni, Pb and Zn in the TSP and PM2.5 examined in this work. Four potential sources for PM2.5 were identified by principal component analysis. The source contributions calculated using absolute principal component scores were 37.5% for the first component, 34.1% for the second, 9.0% for the third and 19.8% for the fourth. The Na/Cr/Cu component identified by principal component analysis was divided into Na/Cr and Cu groups using R-mode cluster analysis of PM2.5, and the Ti in the fourth component was assigned to Cluster 2, indicating a statistical difference in airborne metallic elements. The results of the investigation of element composition, size distribution, and source apportionment carried out in this work can help to better understand and manage the effects of these aerosols on health and air quality.

Arsenic in sediments, groundwater, and streamwater of a glauconitic Coastal Plain terrain, New Jersey, USA—Chemical “fingerprints” for geogenic and anthropogenic sources

Abstract Glauconite-bearing deposits are found worldwide, but As levels have been determined for relatively few. The As content of glauconites in sediments of the Inner Coastal Plain of New Jersey can exceed 100 mg/kg, and total As concentrations (up to 5.95 μg/L) found historically and recently in streamwaters exceed the State standard. In a major watershed of the Inner Coastal Plain, chemical “fingerprints” were developed for streambed sediments and groundwater to identify contributions of As to the watershed from geologic and anthropogenic sources. The fingerprint for streambed sediments, which included Be, Cr, Fe and V, indicated that As was predominantly of geologic origin. High concentrations of dissolved organic C, nutrients (and Cl−) in shallow groundwater indicated anthropogenic inputs that provided an environment where microbial activity released As from minerals to groundwater discharging to the stream. Particulates in streamwater during high flow constituted most of the As load; the chemical patterns for these particulates resembled the geologic fingerprint of the streambed sediments. The As/Cr ratio of these suspended particles likely indicates they derived not only from runoff, but from groundwater inputs, because As contributed by groundwater is sequestered on streambed sediments. Agricultural inputs of As were not clearly identified, although chemical characteristics of some sediments indicated vehicle-related inputs of metals. Sediment sampling during dry and wet years showed that, under differing hydrologic conditions, local anthropogenic fingerprints could be obscured but the geologic fingerprint, indicating glauconitic sediments as an As source, was robust.

Spatial distribution and mapping of risk elements pollution in agricultural soils of southern Tehran, Iran

In order to evaluate risk elements and their spatial distribution in agricultural fields south of Tehran, statistics, geostatistics and geographic information system (GIS) were used. The content of Hg, As, Pb, Mo, and Be were determined in 106 samples. The results showed that primary inputs of As and Hg were due to anthropogenic sources, while Pb, Mo and Be were associated with pedogenic and anthropogenic factors. Ordinary kriging was carried out to map the spatial patterns of risk elements and disjunctive kriging was used to quantify the probability of risk elements concentrations higher than their guide value. The results show that As, Hg, Mo and Be exhibit pollution risk in the study area. The high pollution sources evaluated were related with usage of urban and industrial wastewater for agricultural practice. The results of this study are helpful for risk assessment of environmental pollution for decision making for vegetable production and ecosystem improving.

Characterization of soil heavy metal contamination and potential health risk in metropolitan region of northern China

Soil in metropolitan region suffers great contamination risk due to the rapid urbanization especially in developing countries. Beijing and Tianjin, together with their surrounding regions, form a mega-metropolitan region in northern China. To assess the soil environmental quality, a total of 458 surface soil samples were collected from this area. Concentrations of Cr, Cu, Pb, Zn, As, Cd, and Hg were analyzed and compared to the Chinese environmental quality standards for soil. Multivariate analysis was carried out to identify the possible sources and Geographic Information Systems techniques were applied to visualize the spatial data. It was found that the primary inputs of As were due to pedogenic sources, whereas Hg was mainly of anthropogenic source. Other elements including Cr, Cu, Pb, Zn, and Cd were from both lithogenic and anthropogenic origins. Health risk assessment based on the maximum heavy metal concentration indicated that As derived from sewage irrigation area can result in carcinogenic lifetime risk due to ingestion and/or dermal contact of soil. The potential non-carcinogenic risk for children is significant for Pb and the cumulative effect of multiple metals is of concern for children in the vicinity of mining site. The results increased our knowledge for understanding natural and anthropogenic sources as well as health risk for metals in metropolitan soil.

Geochemical controls on distributions and speciation of As and Hg in sediments along the Gaoping (Kaoping) Estuary–Canyon system off southwestern Taiwan

Surface and box-cored sediments were collected along the Gaoping (formerly spelled Kaoping) Estuary–Canyon system and analyzed for As and Hg contents and speciation, 210Pb-based sedimentation rates and various geochemical parameters to elucidate the mechanisms that control natural and anthropogenic inputs of As and Hg from the Gaoping (Kaoping) River (KPR). The contents of As and Hg in surface sediments ranged from 1.84 to 20.7 mg kg − 1 and from 0.07 to 2.15 mg kg − 1 , respectively, in the estuary and canyon. The concentrations generally decreased from the lower river toward the mixing boundary and then increased toward the estuarine mouth, followed by a slight variation in the canyon. Both As and Hg concentrations correlated strongly with clay, total organic carbon (TOC), Al, Fe and Mn contents in estuarine sediments but not necessary the same cases for canyon surface sediments. The factor analysis of surface sediments shows that the first two factors, which account for 75.6% of the variance, may represent major roles of carriers (clay, Al and Fe–Mn oxides) and TOC in controlling As and Hg distributions, respectively. Accordingly, the spatial patterns of the enrichments of As (1.9–16.2) and Hg (1.8–30.8) with reference to the crust levels follow the individual element's distribution patterns, likely because of deposition variability following inputs from the river. The contents of mobile As and Hg correlated substantially with the contents of both metals that were extracted with 0.1 M HCl. In addition to the major pool in the residual fraction (65–87%), As was relatively abundant in Fe–Mn oxides/hydroxides, whereas Hg was abundant in the organic/sulfide fraction. The deposition and accumulation rates of As and Hg in the canyon clearly decreased as the depth of water increased. The depth distributions of both metals are likely controlled primarily by TOC and Fe–Mn oxides associated factors followed by a contribution from anthropogenic pollution. The metal pollution appears to have increased substantially around 1970, following the economic boom in Taiwan, suggesting that modern sediments in the Gaoping (Kaoping) Canyon were derived from the Gaoping (Kaoping) River (KPR).

Controls on Arsenic Speciation and Solid-Phase Partitioning in the Sediments of a Two-Basin Lake

Arsenic (As) regeneration from sediments of Spy Pond, a two-basin lake near Boston, MA, continues to result in seasonally elevated As levels despite the several decades that have elapsed since the pond's historical contamination by a pulse input of As. Solid-phase speciation and partitioning of As in the sediments appear to be primary determinants of both potential As regeneration rate and, conversely, the rate at which long-term burial of the pond's As burden will occur. Although iron (Fe) chemistry often controls As speciation in lakes, a higher rate of As regeneration in the south basin, accompanied by the absence of a correlation between regenerated As and Fe in this basin, suggest that additional factors operate to control As cycling in this lake. Solid-phase As speciation was remarkably similar between sediments of the two basins of this lake, about 40% of sedimentary As in upper sediments being in relatively labile (ionically bound and strongly adsorbed) fractions and a larger fraction of As being associated with recalcitrant minerals, likely sulfides. Extraction, X-ray fluorescence, and acid-volatile sulfide data collectively suggest that sedimentary As cycling in both basins is largely controlled by the formation of sulfide minerals. An accounting of the size of sulfur (S) pools supports this conclusion, showing that sufficient S exists in the north basin to control both Fe and As, while the south basin has lower S levels resulting in seasonal accumulation of Fe in the porewater.

Influence of sorption processes by iron oxides and algae fixation on arsenic and phosphate cycle in an acidic estuary (Tinto river, Spain)

Inorganic arsenic and phosphate distributions have been studied in the acidic mixing zone of the Tinto river in November 1996, June 1997, and April 1998. This mixing zone receives high inputs of As, PO 3− 4 and Fe in relation with acid mine drainage and run-off from phosphogypsum waste. In the early stage of mixing the dissolution of detritic Fe phases (pyrite and oxides) releases Fe and As to water. This process is counterbalanced by removal due to precipitation of Fe-oxides and Fe-organic complexes and algae fixation. In autumn, the amount of algae is negligible and a release of As, Fe and PO 3− 4 to the dissolved phase was observed. As a consequence, high As and PO 3− 4 concentrations are registered in the water (up to 43 nM for As and 330 μM for PO 3− 4). In spring, the removal dominates in relation with high algae productivity. As a result As and PO 3− 4 are depleted in the dissolved phase in spring compared to autumn and high concentrations of As (up to 1530 μg g −1 and 700 μg g −1 in June and in April, respectively) were observed in the suspended particulate matter. In autumn dissolved As is correlated with Fe whilst in spring As behaves in a similar way as PO 3− 4.

Arsenic concentrations in successive needle age classes of Norway spruce ( Picea abies [L.] Karst.).

Arsenic has been determined in needles of Norway spruce by neutron activation analysis. Trees from 8 sites grown under different soil and environmental situations have been sampled. Trees and needle age classes have been treated individually. Endogenous As concentrations in needles <100 ng/g have been detected. Concentrations increased linearly with the needle age class. This biodynamic behaviour is attributed tentatively to a predominant foliar uptake. Concentrations at the various sites differed by a factor of 7. No connection could be found between As concentrations in needles and total As in the soil or pH of the soil. However, the strong correlation between the endogenous and the exogenous concentrations, and differences of As concentrations in needles between different sites are thought to be due mainly to different inputs of As from the atmosphere.

Accumulation and Trace-Metal Variability of Estuarine Sediments, Barataria Basin, Louisiana: ABSTRACT

ABSTRACT Bottom sediments of the upper Barataria Basin estuarine complex consist predominantly of silty clays and clayey silts derived from the erosion of the Lafourche and St. Bernard lobes of the Mississippi River delta and sediments associated with historic crevasses along the Mississippi River. The acid-leachable concentrations of 14 trace metals were determined for 136 bottom sediment samples and 40 core interval samples by plasma emission analysis. The areal distribution of the trace metals is controlled predominantly by the texture and mineralogy of the sediments. Near the centers of the Barataria Basin lakes, elevated trace-metal concentrations reflect the significant correlations that exist with smaller grain-size sediments. Sediment accumulation rates were determined from five cores within the study area using 210Pb geochronology. Rates varied from 0.21 to 0.37 cm/yr. Within the 2-cm core intervals, trace-metal concentrations of Ba, Cr, Cd, Pb, and Zn increased by 10 to 30% in sediments accumulated within the last 75 yr. Little variation in trace-metal content was noted from sediments accumulated during the 1800's with those of the last 25 yr. Trace-metal contents were plotted against aluminum, iron, clay, and total carbon. The most significant correlations occur between trace-metal concentrations and the aluminum and iron content of the sediment samples. Of the 14 trace metals analyzed, Ba, Cd, Pb, and Zn are the least correlatable and show the greatest anthropogenic influence. Natural trace-metal variability was determined by the use of an aluminum-normalization model based on Florida and Louisiana estuarine sediments, basinwide and Gulf Coast trace-metal comparisons, sediment geochronology, and grain-size corrected data. Trace-metal concentrations from sediments of the study area have greater mean concentrations han Florida estuarine sediments due to their finer grain size, lack of CaCO3, and higher clay and carbon content. Anthropogenic trace-metal inputs of As, Ba, Cd, Pb, V, and Zn were detected in sediments associated with oil and gas drilling and production, sandblasting and shipbuilding, dredging, and stormwater, municipal, and industrial discharges. Although evidence of trace-metal contributions within the study area exists, comparisons of average trace-metal concentrations with those of other Gulf Coast estuaries, and with the average shale concentration, reveal that only isolated industrialized areas within the upper Barataria Basin have been impacted.