Spatial and seasonal variation in heavy metals in interstitial water of salt marsh soils

The composition of interstitial water collected from a salt marsh in NW Spain showed clear seasonal and spatial variations associated with redox cycles of Fe and S. In the summer, salinity increased in all soils as a consequence of the increase in evapotranspiration. The pH and concentrations of heavy metals also differed with season, but not all environments showed the same variations. Soils not colonized by plants had the highest pH and lowest heavy metal concentrations in the summer. These results support the idea that higher temperatures lead to an increase in the activity of sulfate-reducing bacteria, which in turn leads to an increase in alkalinity and concentration of sulfides in the water. Trace metals tend to precipitate with sulfides under these conditions and are removed from the interstitial water. In contrast, in the soils colonized by Spartina maritima, the oxidation of metal sulfides during the summer led to a decrease in pH and an increase in the metal concentrations in the interstitial water. The results obtained concur with those found for seasonal variations in metal sulfides in soils from the same salt marsh.     

Effects of heavy metal exposure on the condition and health of nestlings of the great tit (Parus major), a small songbird species

In this study we examined the possible effects of heavy metal exposure on the condition and health of great tit nestlings (Parus major) at four study sites along a pollution gradient near a large non-ferrous smelter in Belgium during three consecutive breeding seasons. Our results showed that nestlings were indeed exposed to large amounts of heavy metals. Excrements contained significantly higher concentrations of several heavy metals (silver, arsenic, cadmium, mercury, lead) near the pollution source than at study sites farther away. When taking into account the number of young in the nest at the time of sampling, nestling body mass and condition were significantly reduced at the most polluted site. Nestlings at the two most polluted sites fledged significantly later than at the least polluted site. We also observed growth abnormalities of the legs near the pollution source. Tarsus length, wing length and haematocrit values did not differ significantly among study sites.     

Heavy metal in sediments of Ziya River in northern China: distribution,potential risks,and source apportionment

The concentration partitioning between the sediment particle and the interstitial water phase plays an important role in controlling the toxicity of heavy metals in aquatic systems. The aim of this study was to assess the sediment quality in a polluted area of the Ziya River, Northern China. The contamination potential and bioavailability of six metals were determined from the concentrations of total metals and the bioavailable fractions. The results showed that the concentrations of Cr, Cu, Ni, Zn, and Pb exceeded the probable effect concentration at several sites. The high geoaccumulation indices showed that the sediments were seriously contaminated by Cd. The ratio of acid-volatile sulfide (AVS) to simultaneously extracted metal (SEM) was higher than 1, which indicated that the availability of metals in sediments was low. The risk assessment of interstitial waters confirmed that there was little chance of release of metals associated with acid-volatile sulfide into the water column. Values of the interstitial water criteria toxicity unit indicated that none of the concentrations of the studied metals exceeded the corresponding water quality thresholds of the US Environmental Protection Agency. Positive matrix factorization showed that the major sources of metals were related to anthropogenic activities. Further, if assessments are based on total heavy metal concentrations, the toxicity of heavy metals in sediment may be overestimated.     

Metal uptake capability of <Emphasis Type="Italic">Cyperus articulatus</Emphasis> L. and its role in mitigating heavy metals from contaminated wetlands

Wetland plants are biological filters that play an important role in maintaining aquatic ecosystem and can take up toxic metals from sediments and water. The present study investigated the seasonal variation in the accumulation potential of heavy metals by Cyperus articulatus in contaminated watercourses. Forty quadrats, distributed equally in 8 sites (six contaminated sites along Ismailia canal and two uncontaminated sites along the River Nile), were selected seasonally for sediment, water, and plant investigations. Autumn was the flourishing season of C. articulatus with the highest shoot density, length, and diameter as well as aboveground biomass, while summer showed the least growth performance. The photosynthetic pigments were markedly reduced under contamination stress. C. articulatus plants accumulated concentrations of most heavy metals, except Pb, in their roots higher than the shoots. The plant tissues accumulated the highest concentrations of Fe, Cd, Ni, and Zn during autumn, while Cu and Mn during spring, and Cr and Co during winter. It was found that Cd, Cu, Ni, Zn, Pb, and Co had seasonal bioaccumulation factor (BF) > 1 with the highest BF for Cd, Ni, and Zn during autumn, Co, Cu, and Pb in winter, spring, and summer, respectively. The translocation factor of most heavy metals, except Pb in spring, was <1 indicating potential phytostabilization of these metals. In conclusion, autumn is an ideal season for harvesting C. articulatus in order to monitor pollution in contaminated wetlands.     

Heavy metal pollution in China: Origin,pattern and control

GOAL, SCOPE AND BACKGROUND: Heavy metal is among one of the pollutants, which cause severe threats to humans and the environment in China. The aim of the present review is to make information on the source of heavy metal pollution, distribution of heavy metals in the environment, and measures of pollution control accessible internationally, which are mostly published in Chinese. METHODS: Information from scientific journals, university journals and governmental releases are compiled focusing mainly on Cd, Cu, Pb and Zn. Partly Al, As, Cr, Fe, Hg, Mn and Ni a included also in part as well. RESULTS AND DISCUSSION: In soil, the average contents of Cd, Cu, Pb and Zn are 0.097, 22.6, 26.0 and 74.2 mg/kg, respectively. In the water of the Yangtze River Basin, the concentrations of Cd, Cu, Pb and Zn are 0.080, 7.91, 15.7 and 18.7 microg/L, respectively. In reference to human activities, the heavy metal pollution comes from three sources: industrial emission, wastewater and solid waste. The environment such as soil, water and air were polluted by heavy metals in some cases. The contents of Cd, Cu, Pb and Zn even reach 3.16, 99.3, 84.1 and 147 mg/kg, respectively, in the soils of a wastewater irrigation zone. These contaminants pollute drinking water and food, and threaten human health. Some diseases resulting from pollution of geological and environmental origin, were observed with long-term and non-reversible effects. CONCLUSIONS: In China, the geological background level of heavy metal is low, but with the activity of humans, soil, water, air, and plants are polluted by heavy metals in some cases and even affect human health through the food chain. RECOMMENDATIONS AND OUTLOOK: To remediate and improve environmental quality is a long strategy for the polluted area to keep humans and animals healthy. Phytoremediation would be an effective technique to remediate the heavy metal pollutions.     

Toxic heavy metal contamination and risk assessment of street dust in small towns of Shanghai suburban area, China

The aims of this paper were to quantify the heavy metal concentrations in street dust of small towns in Shanghai suburban area compared with those in urban area, and examine their seasonal and spatial variations, and to assess their risks to water environment and local populations. Street dust samples were collected from three small towns and urban area in Shanghai in different seasons. Levels of heavy metals were determined by atomic adsorption spectrophotometer analyzer. The method of potential ecological risk index and the health risk assessment model were used to evaluate the potential risks to water bodies and local residents, respectively. The mean metal concentrations in street dust of small towns were far above soil background values but still lower than those in the urban area. No significant seasonal change was observed except for Cr, Ni, and Zn concentrations. Higher metal concentrations tended to be located in central area of towns and township roads. The integrated metal contamination was high and posed a strong potential ecological risk. Children had greater health risk than adults. The carcinogenic risk probabilities were under the acceptable level. The hazard index values to children were close to the safe level. Street dust from the studied area has been contaminated by heavy metals. The contamination of these elements is related more to the pollution source than seasonal change. The combination of the six metals may threaten the water environment and has non-cancer health risk to children, but not to adults.     

Informal e-waste recycling: environmental risk assessment of heavy metal contamination in Mandoli industrial area,Delhi, India

Nowadays, e-waste is a major source of environmental problems and opportunities due to presence of hazardous elements and precious metals. This study was aimed to evaluate the pollution risk of heavy metal contamination by informal recycling of e-waste. Environmental risk assessment was determined using multivariate statistical analysis, index of geoaccumulation, enrichment factor, contamination factor, degree of contamination and pollution load index by analysing heavy metals in surface soils, plants and groundwater samples collected from and around informal recycling workshops in Mandoli industrial area, Delhi, India. Concentrations of heavy metals like As (17.08 mg/kg), Cd (1.29 mg/kg), Cu (115.50 mg/kg), Pb (2,645.31 mg/kg), Se (12.67 mg/kg) and Zn (776.84 mg/kg) were higher in surface soils of e-waste recycling areas compared to those in reference site. Level exceeded the values suggested by the US Environmental Protection Agency (EPA). High accumulations of heavy metals were also observed in the native plant samples (Cynodon dactylon) of e-waste recycling areas. The groundwater samples collected form recycling area had high heavy metal concentrations as compared to permissible limit of Indian Standards and maximum allowable limit of WHO guidelines for drinking water. Multivariate analysis and risk assessment studies based on total metal content explains the clear-cut differences among sampling sites and a strong evidence of heavy metal pollution because of informal recycling of e-waste. This study put forward that prolonged informal recycling of e-waste may accumulate high concentration of heavy metals in surface soils, plants and groundwater, which will be a matter of concern for both environmental and occupational hazards. This warrants an immediate need of remedial measures to reduce the heavy metal contamination of e-waste recycling sites.     

Ecological risk assessment of heavy metals in sediment and human health risk assessment of heavy metals in fishes in the middle and lower reaches of the Yangtze River basin

The concentrations of heavy metals (Cr, Cd, Hg, Cu, Zn, Pb and As) in the water, sediment, and fish were investigated in the middle and lower reaches of the Yangtze River, China. Potential ecological risk analysis of sediment heavy metal concentrations indicated that six sites in the middle reach, half of the sites in the lower reach, and two sites in lakes, posed moderate or considerable ecological risk. Health risk analysis of individual heavy metals in fish tissue indicated safe levels for the general population and for fisherman but, in combination, there was a possible risk in terms of total target hazard quotients. Correlation analysis and PCA found that heavy metals (Hg, Cd, Pb, Cr, Cu, and Zn) may be mainly derived from metal processing, electroplating industries, industrial wastewater, and domestic sewage. Hg may also originate from coal combustion. Significant positive correlations between TN and As were observed.     

Dissolved heavy metal concentrations of the Kralkızı, Dicle and Batman dam reservoirs in the Tigris River basin,Turkey

Water samples were collected at monthly intervals during 1 year of monitoring from Kralk?z?, Dicle and Batman dam reservoirs in the Tigris River basin to assess the concentrations of dissolved heavy metals and to determine their spatial and seasonal variations. The results indicated that dissolved heavy metal concentrations in the reservoirs were very low, reflecting the natural background levels. The lowest total metal concentrations in the three dam reservoirs were detected at sampling sites close to the dam wall. However, the highest total concentrations were observed at sites, which are located at the entrance of the streams to the reservoirs. Fe, Cr and Ni were the most abundant elements in the reservoirs, whereas Cd and As were the less abundant. The mean concentrations of dissolved metals in the dam reservoirs never exceeded the maximum permitted concentrations established by EC (European Community), WHO and USEPA drinking water quality guidelines. All heavy metals showed significant seasonal variations. As, Cd, Cr, Cu, Fe, Ni and Pb displayed higher values in the dry season, while higher values for Zn in the wet season. Cluster analysis grouped all ten sampling sites into three clusters. Clusters 1 and 2, and cluster 3 corresponded to relatively low polluted and moderate polluted regions, respectively. PCA/FA demonstrated the dissolved metals in the dam reservoirs controlled by natural sources.     

Natural and anthropogenic influences on heavy metals in airborne particles over the Korean Peninsula

Six monitoring stations were selected to characterize the variations in airborne concentrations of heavy metals in South Korea between 1999 and 2012. Three stations represented higher concentrations, and three represented lower concentrations. The heavy metals monitored at these stations include cadmium, chromium, copper, iron (Fe), lead, manganese (Mn), and nickel. During the study period, concentrations of heavy metals at many stations, including those around the Seoul metropolitan area, showed a decreasing trend. However, concentrations of Mn and Fe that are primarily of crustal origin increased at four of the six stations. Some stations were significantly affected by emissions from the local industrial complex (IC), and heavy metal concentrations at those stations were relatively high even in summer. Many heavy metal concentrations were higher in spring than in winter, but wintertime concentrations of Cr and Pb were higher at the stations representing lower concentrations due to the dominant influence of combustion emissions. At stations less affected by emissions from the IC, concentrations of Fe and Mn that are predominantly crustal in origin were higher in spring, when Asian dust (AD) events are most frequent. Although Mn concentrations were also high at stations within the steelmaking IC during AD periods, they were much higher during non-AD periods due to local emissions. Variations in heavy metal concentrations, which are heavily influenced by emissions from the IC, warrant individual analysis because their emission characteristics differ from those of typical cases.     

Heavy metal (Cd, Cr, Cu, Hg, Pb, Zn) concentrations in seven fish species in relation to fish size and location along the Yangtze River

Purpose

The objective of this paper is to assess the regulation of the accumulation of heavy metals in the aquatic environment and different fish species.

Methods

Water and fish samples were collected from upper to lower reaches of the Yangtze River. The heavy metal (Cd, Cr, Cu, Hg, Pb, Zn) concentrations in the muscle tissue of seven fishes were measured. Additionally, the relationships between heavy metal concentrations in fish tissue and fish size (length and weight), condition factor, water layer distribution, and trophic level were investigated.

Results

Metal concentrations (milligrams per kilogram wet weight) were found to be distributed differently among different fish species. The highest concentrations of Cu (1.22?mg/kg) and Zn (7.55?mg/kg) were measured in Pelteobagrus fulvidraco, the highest concentrations of Cd (0.115?mg/kg) and Hg (0.0304?mg/kg) were measured in Silurus asotus, and the highest concentrations of Pb (0.811?mg/kg) and Cr (0.239?mg/kg) were measured in Carassius auratus and Cyprinus carpio. A positive relationship was found between fish size and metal level in most cases. The variance of the relationships may be the result of differences in habitat, swimming behavior, and metabolic activity. In this study, fishes living in the lower water layer and river bottom had higher metals concentrations than in upper and middle layers. Benthic carnivorous and euryphagous fish had higher metals concentrations than phytoplankton and herbivorous fish. Generally, fish caught from the lower reach had higher metals concentrations than those from the upper reach.

Conclusions

Cadmium and lead concentrations in several fishes exceeded the permissible food consumption limits, this should be considered to be an important warning signal.     

Estimation of atmospheric trace metal emissions in Vilnius City, Lithuania, using vertical concentration gradient and road tunnel measurement data

A new approach for the estimation of trace metal emissions in Vilnius city was implemented, using vertical concentration profiles in the urban boundary layer and road tunnel measurement data. Heavy metal concentrations were examined in fine and coarse particle fractions using a virtual impactor (cut-off size diameter 2.5 μm). Negative vertical concentration gradients were obtained for all metals (Ba, Pb, V, Sb, Zn) and both fractions. It was estimated that the vertical concentration gradient was formed due to emissions from an area of about 12 km². Road tunnel measurements indicated that trace metal concentrations on fine particles were lower than those on coarse particles, which suggested that re-emitted road dust was highly enriched in trace metal due to historic emissions within the tunnel. Emission rates of different pollutants in the road tunnel were calculated using pollutant concentration differences at the tunnel entrance and exit and traffic flow data. Heavy metal emission rates from the area of Vilnius city were estimated using the vertical gradient of heavy metal concentrations and the coefficient of turbulent mixing, as derived from meteorological measurement data. The emission values calculated by the two different methods coincided reasonably well, which indicated that the main source of airborne trace metals in Vilnius city is traffic. The potential of the vertical concentration gradient method for the direct estimation of urban heavy metal emissions was demonstrated.     

Arsenic concentration in topsoil of central Chile is associated with aberrant methylation of P53 gene in human blood cells: a cross-sectional study

Gene expression can be modified in people who are chronically exposed to high concentrations of heavy metals. The soil surrounding the Ventanas Industrial Complex, located on the coastal zone of Puchuncaví and Quintero townships (Chile), contain heavy metal concentrations (As, Cu, Pb, Zn, among others) that far exceed international standards. The aim of this study was to determine the potential association of the heavy metals in soils, especially arsenic, with the status of methylation of four tumor suppressor genes in permanent residents in those townships. To study the methylation status in genes p53, p16, APC, and RASSF1A, we took blood samples from adults living in areas near the industrial complex for at least 5 years and compared it to blood samples from adults living in areas with normal heavy metal concentrations of soils. Results indicated that inhabitants of an area with high levels of heavy metals in soil have a significantly higher proportion of methylation in the promoter region of the p53 tumor suppressor gene compared with control areas (p-value: 0.0035). This is the first study to consider associations between heavy metal exposure in humans and aberrant DNA methylation in Chile. Our results suggest more research to support consistent decision-making on processes of environmental remediation or prevention of exposure.

     

北运河沉积物/水界面上重金属迁移转化规律

分析测定了6种元素(Cr、Co、Mn、Cu、Pb、Zn)在北运河水系10个采样点水体和表层沉积物中的含量和形态分布,利用SPSS 19.0统计软件对重金属在不同形态中的含量进行相关性分析。结果显示,北运河下游重金属污染程度高于上游;Cr、Cu、Pb、Zn在底泥可提取态中所占比例相当高,多数采样点都超过10.0%。所研究的重金属多数在底泥Fe-Mn结合态与悬浮物、可交换态、硫化物和有机质结合态均存在相关性;Mn是北运河地化循环中最为活跃的元素。     

Relation between heavy metal concentrations in salt marsh plants and soil

The aim of the research reported here was to investigate the relation between heavy metal concentrations in salt marsh plants, extractability of the metals from soil and some soil characteristics. In April 1987, Spartina anglica and Aster tripolium plants and soil were collected from four salt marshes along the Dutch coast. The redox potential of the soil between the roots of the plants and at bare sites was measured. Soil samples were oven-dried and analyzed for chloride concentration, pH, fraction of soil particles smaller than 63 microm (f < 63 microm), loss on ignition (LOI) and ammonium acetate and hydrochloric acid extractable Cd, Cu and Zn concentrations. The roots and shoots of the plants were analyzed for Cd, Cu and Zn. Because drying of the soil prior to chemical analysis might have changed the chemical speciation of the metals, and therefore the outcome of the ammonium acetate extraction, a second survey was performed in October 1990. In this survey A. tripolium plants and soil were collected from two salt marshes. Fresh and matched oven-dried soil samples were analyzed for water, ammonium acetate and diethylene triaminepentaacetic acid (DTPA) extractable Cd, Cu and Zn concentrations. The soil samples were also analyzed for f < 63 microm, LOI and total (HNO(3)/HCl digestion) metal concentrations. Soil metal concentrations were correlated with LOI. Drying prior to analysis of the soil had a significant effect on the extractability of the metals with water, ammonium acetate or DTPA. Plant metal concentrations significantly correlated only with some extractable metal concentrations determined in dried soil samples. However, these correlations were not consistently better than with total metal concentrations in the soil. It was concluded that extractions of metals from soil with water, ammonium acetate or DTPA are not better predictors for metal concentrations in salt marsh plants than total metal concentrations, and that a major part of the variation in metal concentrations in the plants cannot be explained by variation in soil composition.     

Spatial and temporal organic and heavy metal pollution at Mai Po Marshes Nature Reserve,Hong Kong

An intensive monthly sampling of water and sediments from 12 sites over 8 months covering wet and dry seasons at Mai Po Marshes Nature Reserve was conducted during June 1997-February 1998. Major organic (C, N and P) and heavy metal pollutants (Cd, Cr, Cu, Ni, Pb, Zn) water and sediment samples were examined. The results showed that Mai Po Marshes were severely polluted by organic matter and heavy metals, and the water from Deep Bay appeared to be the source of pollution. Up to 13-55% chance that the sediments of Mai Po Marshes were classified as moderately to seriously metal contaminated materials, according to the guideline set by Hong Kong Government. Empirical models describing organic matter and heavy metal spatial and seasonal dynamics in the water and sediments were formulated, based on data analysis. During wet season (June-October), more than 58% variations of total P can be explained by ortho-P in water, while ammonia-N explained up to 90% variations of total Kjeldahl nitrogen in water. Throughout the whole sampling period (June-February), there were significant correlations (p<0.01) between total organic C in water. pH in the sediments and salinity in water appeared to be important factors determining heavy metal mobility in sediments, while potential metal release from the sediments is a concern when any oxidizing processes such as flooding or dredging are imposed on sediments.     

Aquatic macrophytes potential for the simultaneous removal of heavy metals (Buenos Aires, Argentina)

Heavy metal removal from water has been approached by using different technologies. Phytotechnologies, with an increasing development during the last two decades, involve using plants for metal removal. Three autochthonous floating macrophytes, common in pampean shallow lakes (Argentina), Pista stratiotes, Spirodela intermedia and Lemna minor were used in laboratory experiences for the simultaneously removal of several heavy metals (Fe, Cu, Zn, Mn, Cr and Pb) resulting from anthropogenic activity, in order to simulate a naturally polluted environment. The experiences were performed for different concentrations of metals along 15 days. High metal removal percentages were obtained for the 3 species and metals. L. minor did not survive the conditions of the experiment. High correlation between the final water and the macrophytes metal concentration was obtained, deviations were due to PbCrO(4) precipitation. The rate of metal uptake was dependent on the metal concentration for the 3 species studied.     

Analyzing trophic transfer of heavy metals for food webs in the newly-formed wetlands of the Yellow River Delta, China

Nine heavy metals sampled from water, sediments, and aquatic organisms in the newly-formed wetlands of the Yellow River Delta (YRD) of China were analyzed to evaluate their concentrations and trophic transfer in food webs. The stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopes were used to investigate trophic interactions. Results show that most of heavy metals detected in water and sediments are lower than that in Yangtze River Delta and Pearl River Delta. The longest food web is approximately 4 with the highest trophic level of birds. The difference of heavy metal concentrations between endangered Saunders’s Gull and other three kinds of protected birds is not obvious. Cd, Zn, and Hg were identified to have an increase with the trophic level (TL), while As, Cr, Cu, Mn, Ni and Pb show an opposite trend, however, the biomagnification of the selected nine heavy metals in the food webs is not significant.     

Sources of variation in concentrations of nickel and copper in mountain birch foliage near a nickel-copper smelter at Monchegorsk, north-western Russia: results of long-term monitoring

Concentrations of nickel and copper, two principal metal pollutants of the 'Severonikel' smelter at Monchegorsk, NW Russia, were measured in unwashed leaves of mountain birch, Betula pubescens subsp. czerepanovii, collected in eight study sites along the pollution gradient during 1991-2003. In spite of significant decline in metal emissions, concentrations of foliar metals in most of the study sites did not decrease, indicating that soil contamination remains extremely high. Multiyear mean values peaked at 6.6 km S of the smelter, where they were 20-25 times higher than in the most distant study site. Concentrations of both metals demonstrated pronounced annual variation, which was explained by the meteorological conditions of early summer: higher precipitation in May increased foliar concentrations of both metals, whereas higher precipitation in June resulted in lower foliar concentrations of nickel. These data suggest that ecotoxicological situation in metal-contaminated areas can be modified by the expected climate change. In heavily polluted sites individual birch trees generally retained their ranks in terms of metal contamination during 1995-2003, demonstrating that the use of the same set of trees can significantly increase the accuracy of the monitoring data.