Variations In Heavy Metal Concentrations Research Articles

Heavy metal concentrations in tissues of marine fish and crab collected from the middle coast of Zhejiang Province, China.

Concentrations of the heavy metals As, Cd, Cu, Hg, Pb, and Zn in various tissues of five marine fish species and one crab species collected from the middle coast of Zhejiang Province of China were investigated in this study. The results indicated considerable variation in heavy metal concentrations in different tissues and species. Elevated concentrations of most heavy metals were identified in fish gills and crab gills and hepatopancreas, with some differences by heavy metal type. In addition, carnivorous and benthivorous fish species generally contained relatively high concentrations of heavy metals due to feeding habits and habitats. Geographical variations of heavy metal concentrations in muscle may be attributable to species-dependent differences and terrigenous contamination. The potential health risk assessment suggested that exposure doses of most heavy metals were safe for human consumption, with the exception of As.

Ecosystem (Dis)benefits Arising from Formal and Informal Land-Use in Manchester (UK); a Case Study of Urban Soil Characteristics Associated with Local Green Space Management

Urban soils are subject to anthropogenic influences and, reciprocally, provide benefits and disbenefits to human wellbeing; for example carbon storage, nutrient cycling and the regulation trace element and contaminant mobility. Collective stewardship of urban green commons provides contemporary examples of the diversity of uses and management of green space in cities and represents a growing movement in user participation in, and awareness of, the importance of urban ecological health. Exploring the range of social-ecological benefits exemplified in the urban environment has generally focused on above-ground processes, with few studies examining the potential for (dis)benefits arising from edaphic characteristics of collectively-managed spaces. An investigation into the influence of formal and informal green space management on carbon fluxes and heavy metal concentrations in urban soils was carried out in Manchester (UK) finding that carbon storage in soils of collectively managed urban green commons (7.15 ± 1.42 kg C m−2) was significantly greater than at formally managed sites (for example city parks: 5.08 ± 0.69 kg C m−2), though the latter exhibited reduced losses through CO2 emission. Variation in heavy metal concentrations and mobility were likewise observed, exemplified by the acidification of surface soils by leaf litter at orchard sites, and the resultant increase in the mobility of lead (Pb) and zinc (Zn). The results of this study indicate the importance of small-scale contemporary urban green space management on selected ecosystem services provided by the limited soil resource of cities. Thus, a greater consideration of the effects of horticultural and amenity activities with regards to soil quality/functionality is required to ensure available urban green commons retain or increase their ecological quality over time.

Heavy Metal Contaminations at Two Iranian Copper Mining Areas and the Remediation by Indigenous Plants

Background: High concentrations of various heavy metals of mine tailings can easily contaminate the environment. Such materials need monitoring and remediation to prevent them from polluting the environment and food chain. Methods: The concentrations of certain metals were evaluated in the soil samples at Sorkheh and Mazraeh copper mining areas in northwestern Iran, using three reliable pollution indices. We assessed the ability of three plants, Alhaji maurorum and Stachys inflata at Sorkheh mines, and Cirsium vulgare at Mazraeh mines, the dominant plants grown in those areas, in taking up the metals from the associated soils. The plant and soil samples were analyzed inductively by coupled plasma-mass spectrometry (ICP-MS). Results: The results revealed that the soil samples at Sorkheh and Mazraeh mining areas were highly contaminated with As at CF values of 16.9 and 4.6, respectively. The soil samples from the two mining areas were moderately contaminated with Pb and Zn. The data confirmed that A. maurorum and S. inflata had a good ability to accumulate Cd, Mo and Sc from the soils in Sorkheh area. The other plant, C. vulgare, accumulated Zn and Pb at 1891 mg/kg and 18.6 mg/kg, respectively. The studied plants were good indicators of heavy metals contaminating the soils in these mining areas. Conclusion: This study provided geochemical evidence about the heavy metals that contaminated the soils in the mining areas, and contributed new information about these toxic metals and their concentrations in the three plants and the soil samples.

Seasonal Variation of Heavy Metal Concentrations in Farm Soils of Sreepur Industrial Area of Gazipur, Bangladesh: Pollution Level Assessment

A study was conducted to measure the seasonal variation of different heavy metal contents in farm soils of Sreepur Upazila of Gazipur district and to assess their pollution level. Industrial affected and non-affected soil samples were collected from 5 locations in three seasons viz. pre-monsoon (April), monsoon (August), and dry season (January), thus a total of 30 soil samples were analyzed for this study. Concentrations of different heavy metals (Cd, Pb, Cr, Ni, Cu, and Zn) in soil samples were determined by an Atomic Absorption Spectrophotometer (AAS). The mean total concentration of Cd, Pb, Cr, Ni, Cu and Zn in industrial affected soils were trace, 12.05, 101.10, 51.32, 20.79 and 55.40 mg kg-1, respectively in the pre-monsoon, trace, 28.54, 40.96, 22.70, 2.46 and 7.72 mg kg-1, respectively in the monsoon and 0.27, 10.49, 39.45, 20.69, 1.85 and 4.11 mg kg-1, respectively in the dry season. All heavy metal concentrations in industrial affected soil samples were higher than the corresponding non-affected sites. The study results revealed that Cd contents in the dry season and Pb contents in the monsoon season for industrial affected soils were higher compared to the average earth’s crust abundance value. The geoaccumulation index (Igeo) values for Pb of industrial affected soils ranged from 0.30-0.85 in the monsoon that means Igeo class 1, indicating unpolluted/moderately polluted soil quality. Furthermore, the calculated Igeo value for one industrial affected location revealed moderate soil pollution by Cr in the pre-monsoon season and unpolluted/moderately polluted soil quality by Ni and Cd in the pre-monsoon and the dry season, respectively. The measured pollution load index (PLI) values were also higher in all industrially polluted sites than corresponding non-polluted sites in three seasons, which indicates pollution load due to anthropogenic sources.

Comparison of copper adsorption effectivity in acid mine drainage using natural zeolite and synthesized zeolite

Acid mine drainage (AMD) contains a high concentration of various heavy metals and have low pH levels. In this study, the comparison between the use of natural zeolite and synthesized zeolite for Cu2+ removal in AMD was conducted. The adsorbent of natural zeolite was prepared through a chemical activating method by adding NaOH. While, synthesized zeolite was made from coal fly ash using a two-step method, fusion, and hydrothermal process. The AMD used in this study was artificially designed with the concentration of Cu2+ 100 ppm and pH ± 3. The adsorption experiment was carried out using a batch method to observe the influential parameters such as adsorbent dosage, contact time, adsorbent isotherms, and kinetics. The result show that the removal efficiency of Cu2+ for natural zeolite and synthesized zeolite was 98,16% and 93,98 % with optimum adsorbent dose 1,5 g/l and 21 g/l, respectively. The optimum contact time for both adsorbents was 120 minutes. The Langmuir isotherm model fitted the adsorption for synthesized zeolite and natural zeolite, with the maximum sorption capacity of 23,8 mg/g and 30,03 mg/g, and the kinetics model of pseudo-second-order and pseudo-first-order. The result of this study that the good adsorption effectivity synthesized zeolite. Furthermore, both natural zeolite and synthesized zeolite have great potential as a sustainable and economical material for heavy metal removal ion Cu2+ in wastewater.

Toxic metal pollution and ecological risk assessment in superficial soils of “rural-agricultural and coastal-urban” of Monastir region, Eastern Tunisia

Spatial variability of heavy metal concentrations namely Fe, Pb, Cu, Cd, Ni and Zn, in surface soils of Monastir region showed almost similar trends (an exception made for Fe). The spatial distribution of calculated enrichment factors showed moderate enrichment of superficial soils collected from sites located in both western (rural-agricultural) and eastern (coastal-urban) parts of the region. Contrary, superficial soils collected from sites located in the central part were characterized by a minor enrichment. Adopted chemometric approaches based on principal component analysis and hierarchical cluster analysis highlighted the significant impact of local man-made sources (Traffic road in the costal-urban area and the motorway and railway crossing its western rural-agricultural area). Calculated geoaccumulation index values revealed that mobile source’s influence presumed by a moderate contamination in terms of Pb, Zn, Cu, Cd, and Ni. Referring to the coastal-urban area, a significant horizontal extension of contaminated sites in the western part of the region was recognized. Spatial distribution of the integrated pollution index revealed that only site neighboring the busy railway and motorway (≈0.6 km), indicated a high pollution level. Furthermore, it showed a moderate potential ecological risk for all selected metals.

Heavy metal concentrations in the outdoor and indoor air of high-traffic areas in Tehran, Iran

Tehran is a polluted metropolitan and the capital of Iran, where heavy traffic and excessive energy consumption (especially gasoline) are the major sources of heavy metal emissions. This study aimed to investigate the variations in heavy metal concentrations on the aerosols of the outdoor and indoor environments in the high-traffic regions of Tehran. This was a descriptive, applied research in terms of methodology. Six internal-external stations were specified in three high-traffic regions. Sampling was performed in six replications for each station during fall 2018(n=36). After the extraction of the heavy metals from the fiberglass filters using acidic digestion based on the ASTM method, their concentrations were measured via ICP-OES. Data analysis was performed in SPSS using MANOVA. According to the results, regions 2, 3, and 15 had the highest traffic in Tehran during the study, with the traffic rate estimated at 25-27% hours per day on average. A significant difference was observed between the outdoor and indoor regions in terms of heavy metal concentrations (P Fe>Pb>Mn>Cu>Zn>Cr>As>Ni>Cd. Aluminum and cadmium had the highest and lowest concentrations, respectively. In addition, the high concentration of lead and heavy traffic was alarming in Afsariyeh Street (region 15). Considering the adverse effects of pollution on the health of citizens, serious measures should be taken to control traffic in Tehran. Keywords: Heavy metals, Traffic volume, Tehran metropolitan, Indoor and outdoor environment

Health risks of heavy metal exposure and microbial contamination through consumption of vegetables irrigated with treated wastewater at Dubai, UAE.

The shortage of fresh water is a major problem throughout the world, but the situation is worst in the arid and semiarid regions. Therefore, reuse of nonconventional water resources such as treated wastewater (TWW) is a common practice to irrigate field crops, vegetables, and forestry sectors. The present study was conducted to evaluate the significant impact of different heavy metals such as copper (Cu), iron (Fe), chromium (Cr), and zinc (Zn) on the soil and leafy, root, and fruit vegetables following irrigation with TWW through subsurface drip irrigation. Our results indicate that iron (Fe) was highest in lettuce followed by spinach, and Zn and Cr were second and third most abundant element in the different vegetables. Eggplant and radish showed the lowest concentrations of various heavy metals. A significant difference was observed in transfer factor (TF) among vegetables, and highest TFsoil-veg was observed for Fe in lettuce and the lowest for Cr in eggplant. Estimated daily intake (EDI) was the lowest in adults and highest in children. Target hazard quotient (THQ) of Cu, Zn, and Fe being < 1.0 appears relatively safe in all the tested vegetables. Risk index (RI) values showed that heavy metals were lower than 1.0 and hence lower risk for human. The combined HI values for Cu, Zn, Cd, Cr, and Pb were substaintionaly higher 12.8 and 9.21 after consumption of lettuce and carrot. So, consumption of these vegetables should be avoided after irrigation with TWW. Spinach exhibited maximum total coliform loading, while ecological risk was negligible due to sandy nature of soil type. Health risks to human could be reduced through proper selection of suitable vegetables, time of maturity, and consumed organs (leaf, fruit, or root part). Appropriate should be followed to decontaminate the microbial load in order to avoid any risks to human health (both adults and children).

Seasonal Variation of Heavy Metal Concentrations in Water and Sediment Samples of Erelu Reservoir and their Effects on its Macro-Invertebrates

Seasonal Variation of Heavy Metal Concentrations in Water and Sediment Samples of Erelu Reservoir and their Effects on its Macro-Invertebrates

Plant growth stage influences heavy metal accumulation in leafy vegetables of garden cress and sweet basil

BackgroundContamination of vegetable crops with heavy metals is a great threat to human health. On the other hand, monitoring plant tissue content of heavy metals at different growth stages could have important implications. In this study, shoot and root samples of garden cress and sweet basil were collected from five farms, from heavy metal polluted fields located in Shahre Rey, south of Tehran, Iran, in either young (3 weeks old) or mature (7 weeks old) plants. The concentrations of cadmium (Cd), lead (Pb), nickel (Ni), arsenic (As), chromium (Cr), cobalt (Co), copper (Cu), manganese (Mn) and zinc (Zn) in plant tissues were determined using atomic absorption spectroscopy. In another study, 2 weeks (young) or 6 weeks old (mature) plants of garden cress were subjected to three concentrations of Cd and Pb (0, 5, 10 mg L−1) under hydroponic sand culture for 5 days, in which Hoagland formula was used for nutrient solution preparation.ResultsThe results showed that root concentration of various heavy metals, particularly Cd, As, Ni, Co, Cu, Mn and Zn but not Pb were significantly higher than their shoot concentration in either crop under field sampling. The leaf concentration of some heavy metals was significantly different in seedling and older (mature) plant samples of either crop. Young plant leaves of sweet basil had significantly less Cd, Pb, As and higher Cu than mature plants, whereas young garden cress plants had similar Cd, Pb and higher As and Zn concentrations than mature plants. The Cr, Co, Mn and Zn concentrations were similar in young and mature plants of sweet basil. The Mn, Co, Cr and Ni concentration of young and mature plants of either crop was also similar. The result of hydroponic study showed that young plants of garden cress had higher potential to accumulate lead in shoot and root, particularly in lower (5 mg L−1) than higher (10 mg L−1) lead concentration; however, root Pb concentration at 10 mg L−1 Pb of nutrient solution showed no difference between young and mature plants. Regarding cadmium, young garden cress plants accumulated higher Cd than mature plants in their shoot, particularly under higher Cd levels (10 rather than 5 mg L−1) of nutrient solution; however, a wide difference in root Cd concentration was observed under low (5 mg L−1) than higher (10 mg L−1) cadmium concentration of nutrient solution.ConclusionThe results of these two studies indicate that despite that young plants have a higher potential for heavy metal uptake and accumulation, the low difference in young and mature plants in the polluted fields may be due to the longer period of plant growth of mature plants that may increase the risk of exposure to polluted air and dust deposition containing high levels of heavy metals.

Pollution characteristics and health risk assessment of heavy metals in dry atmospheric deposits from Sfax solar saltern area in southeast of Tunisia

Concentrations of six heavy metals such as Fe, Pb, Cu, Cd, Ni and Zn in dry atmospheric deposits weekly collected through 20 sample sites from Sfax solar saltern during two successive sampling campaigns, selected from a long time monitoring, have been examined in order to evaluate their contamination levels as well as their human health risk; such concentrations (expressed in mg/kg) have shown that Fe varied from 7006.24 to 7856.45, Pb from 8.64 to 344.45, Cu from 9.33 to 298.67, Cd from 0.16 to 85.24, Ni from 6.02 to 150.02, and Zn from 12.23 to 624.57. During the study period, average concentrations (mg/kg) have been 7315.99, 103.08, 82.34, 15.93, 46.21 and 142.39, for Fe, Pb, Cu, Cd, Ni and Zn, respectively. Except for Fe, the other concentrations in dry atmospheric deposits have recorded the highest level during the first campaign especially in the sites which are close and more exposed to emissions of local pollutant industries, as well as nearby main road, resulting from high exposure frequencies. Statistical approaches, such as principal component analysis and hierarchical cluster analysis have been applied to all data, revealing an affinity between analyzed metals resulting from their origins, and confirming the influence of exposure frequencies on the spatial variability of heavy metal concentrations. Human health risk assessment has revealed that ingestion of heavy metals is the main exposure pathway for the local population. Computed Hazardous Quotient and Hazardous Index have been higher for children than for adults, thus indicating that the former may be subjected to potentially higher health risk than the latter especially during the first campaign. Calculated carcinogenic risks through ingestion and dermal contact, as well as the total carcinogenic risk for the selected heavy metals, have shown that cancer could occur more probably through ingestion than dermal contact, for children than adult, and during the first campaign (during C1: average values CRing = 8.72 × 10-4 and CRder = 1.40 × 10-6 for child; average values CRing = 5.61 × 10-5 and CRder = 2.84 × 10-6 for adult) than the second one (during C2: average values CRing = 1.59 × 10-4 and CRder = 2.54 × 10-7 for child; average values CRing = 1.02 × 10-5 and CRder = 5.19 × 10-7 for adult). The total calculated carcinogenic risk through all the sites have infrequently signaled high to very high carcinogenic risk in the first campaign (average CRA = 8.73 × 10-4 for child and CRA = 5.89 × 10-5 for adult) and occasionally exceeded the safe range for the local population in the second one (average CRA = 1.59 × 10-4 for child and CRA = 1.07 × 10-5 for adult).

Characteristics of heavy metal concentrations and risk assessment for giant pandas and their habitat in the Qinling Mountains, China.

High concentrations of heavy metals in the environment threaten the quality of ecosystems and the health of human beings and animals. Giant panda (Ailuropoda melanoleuca), which is endemic to China and a global conservation icon, has the largest density in the Qinling Mountains. This paper investigated the spatiotemporal variation of heavy metal concentrations in soil (N = 44) at the regional scale with three zones of urban areas, mountain edges, and central mountains, the temporal variation of heavy metal concentrations in three bamboo species (N = 19) and two types of feces (N = 10), and assessed the ecological risk and health risk for giant pandas and their habitat in the Qinling Mountains. The results showed that the median concentrations of studiedeight heavy metals mercury (Hg), arsenic (As), copper (Cu), manganese (Mn), zinc (Zn), chromium (Cr), lead (Pb), and cadmium (Cd) in soil exceeded the background values of Shaanxi Province except Pb. The median concentrations of Hg, Zn, Cr, Pb, and Cd in bamboo surpassed the reference standard (RS) of national food safety limits in vegetables for human intake, but the concentration of Zn was within the nutrient range in the bamboo plants. Heavy metals were enriched more in feces of captive than the wild giant pandas, which illustrated either higher ingestion or lower digestibility for captive giant panda. Ecological risk assessment of soil by the geo-accumulation index (Igeo) and risk index (RI) showed strong pollution by Hg and moderate pollution by Cd. Health risk assessment by the hazard index (HI) showed a potential to strong risk for giant pandas exposed to Pb, As, and Hg. In addition, the concentrations of heavy metals in feces showed a higher exposure risk for captive giant pandas than wild giant pandas. We suggest that attention should be paid to and all effective measurements should be taken for reducing the emission of Hg, As, Pb, and Cd in the study area.

Phytoremediation Potential of Pistia stratiotes to Reduce High Concentration of Copper (Cu) in Acid Mine Drainage

Acid mine drainage (AMD) contains high concentration of various heavy metals and low pH levels, ranging between 2-4. The water samples used for this research are an artificial AMD, with varying concentration levels of copper (5 and 7 mg/l). The pH level is designed to be 4, where the designed pH level illustrates the actual characteristics of an AMD. The data for this research—pH and copper levels—are taken for 14 days. This research shows that exposure of the artificial AMD causes physiological effects to Pistia stratiotes, indicated by chlorosis of the plant starting from day 3 of the research. Furthermore, the result of this research illustrates that Pistia stratiotes is able to alter the artificial AMD’s pH level from 4 to 7,3 in 14 days. This plant is also capable of reducing the copper content as much as 92,45% and 88,00% with initial concentrations of 5,3 mg/l and 7,5 mg/l respectively in 14 days, with peak removal at day 3. It can be concluded that Pistia stratiotes is able to neutralize pH level and decrease copper contents in artificial AMD.

Assessing the Effects of Heavy Metal Concentration in Stream Sediments Within Onne and Environs Southeastern Nigeria

This study assessed the seasonal variations in heavy metal concentration of stream sediments in parts of Onne, Rivers state Southeastern Nigeria. River Ogu was mapped for the collection of stream sediments because of its prominence as a receptor of a lot of effluents discharge from the NNPC oil refinery, erosion and weathering of heavy metals from nearby towns. Stream sediment samples were obtained from eleven (11) strategic locations at 3km interval and; a control sample was obtained from Akpajo river to cover both the dry and wet seasons. Samples were analyzed with Atomic Absorption spectrometric method (AAS) and X-ray fluorescence spectroscopy (XRF) for Ni, Cu, Hg, Pb, Zn,Cd, As and Cr. The record of the relative abundance of the heavy metals in the stream sediments in decreasing order for both seasons is as follows; Zinc (Zn) &gt; Nickel (Ni) &gt; Cadmium (Cd) &gt; Copper (Cu) &gt; Chromium (Cr) &gt; Mercury (Hg) &gt; Lead (Pb) &gt; Arsenic (As). Higher mean concentration values were generally recorded in the wet season than in dry season. Four elements (Zn, Cd, Ni and Cu) were found to be far higher than tolerable standard of the Federal Ministry of Environment (FME, 2006). The sources of the heavy metals are attributed to Onne refinery, Onne waste dump, runoff from roadside soil, acidic precipitation and effluents from petrochemical industries. Excessive concentrations of heavy metals in the stream sediments affects the aquatic life of the faunas and floras and have adverse effect on humans and this calls for regular monitoring of the chemistry of stream sediments in the area. Keywords: Heavy metal, stream sediments, Atomic Absorption Spectrometry (AAS), x-ray fluorescence spectroscopy (XRF), River Ogu, Onne . DOI : 10.7176/JEES/9-10-05 Publication date :October 31 st 2019

Seasonal Variations of Heavy Metal Concentrations in Lake Water

Water Basin or tanks are very necessary attribute of either towns or rural environment. While urban lakes are present all over the world, in a country like India, the lakes in rural areas fulfill a variety of functions; drinking, irrigation, live-stock rearing and ground water recharge. In India, several water tanks recently have been astray, because of various manmade movements and the many of remain water tanks are degraded day by day. Many areas of water tanks in the world getting polluted by dumping and discharge of various kinds of effluents, wastes, etc., without any proper treatments., all these leads to degrading the quality of water and leads to changes in environmental conditions. For satisfactions of various water demands in local area, it is necessary to construct rainwater harvesting pits and to make channelizing of water to restore. So that, such water tanks serves many functions in a useful ways i.e. water may use for irrigation, to satisfy domestic demand and also may increase the ground water table and control of floods, etc. (Ganesan M 2008 et al, Mahapatra DM 2011 et al., Sudha M C 2013 et al.,). In this present study attempt has been made during Pre-Monsoon (April to May) and Post-Monsoon (September to October) periods to find the concentration levels of heavy metals, Arsenic (Ar), Copper (Cu), Cadmium (Cd), Chromium (Cr), Lead (Pb), Mercury (Hg), Zinc (Zn) and Boron (B). Sampling has been done by considering the inflow and the other outlet discharges, where the possibility of contaminations may enter into the water body by awning all over of the lake for taking samples, and also discussed the suitability of water for various demands, and suggested required management techniques to make water free from the contamination.

Distribution and ecological risks of heavy metals in Lake Hussain Sagar, India

Lake contamination by anthropogenic activities has become a serious threat to the aquatic ecosystem due to the presence of a high concentration of toxic heavy metals. In this study, a contaminated Lake Hussain Sagar in India was assessed for toxic heavy metal pollutants at sites associated with industrial discharges and idol immersion activities. The observed high concentration of As, Cd, Pb, Zn, Cu, and Ni in the surface water was due to industrial effluent discharge. About 1.5 times the high concentration of the same elements were observed in surface sediments (0–10 cm) by both industrial discharges and idol immersion activities, compared to deep sediments (0–40 cm) associated only with industrial discharge. The depth-wise variation of heavy metal concentration in surface sediments is due to sorption and settling behavior of suspended solids; whereas in deep sediment, it is due to constant loading of effluents, over a period of time. The sorption capacity of surface sediments is in increasing order as Pb > Cd ≥ Ni ≥ Cr ≥ Zn ≥ Cu, and the desorption revealed that Pb and Cu were retained to a greater extent due to high clay and organic content. By fractionation study, 20–50% of Zn and 50–80% of Cd were associated with exchangeable and carbonate fraction of sediments. By risk assessment code, Zn and Cd are classified under high risk to a very high-risk category, and Cr, Pb, Ni, and Cu are classified under the medium risk category. The enrichment factor value of sediments for Cd (20.42–119.48), Zn (2.19–4.85), Cu (2.02–3.19), and Pb (2.85–7.72) signifies the significant pollution by anthropogenic activities. Therefore, this study evaluates the intensity and distribution of heavy metals in the lake environment for remediation and restoration of the lake ecosystem.

Regional distribution characteristics and ecological risk assessment of heavy metal pollution of different land use in an antimony mining area – Xikuangshan, China

Mining activities have introduced various heavy metals and metalloids to surrounding soil environments, causing adverse impacts to the ecological environment system. The extremely high concentration of various heavy metals and metalloids make the Xikuangshan (Hunan, China) an excellent model to assess their ecological risk. In this study, the soil samples from 26 locations of different land use methods in four areas (smelting area, road nearby ore, mining area, and ore tailing area) in Xikuangshan with different levels of various heavy metals and metalloids (Sb, As, Pb, and Cd) were analyzed; in addition, the index of geo-accumulation and the potential ecological risk index were used to evaluate ecological risk. The results showed that the average contents of Sb, As, Pb, and Cd in all soil samples were 4368.222 mg·kg−1, 40.722 mg·kg−1, 248.013 mg·kg−1, and 40.941 mg·kg−1, respectively, implying serious contamination of compound pollution of heavy metals in soil. The concentration of heavy metals in soil among smelting area, road nearby ore, mining area, and ore tailing area showed significant distribution characteristics of region because different mining activities such as smelting, mining, transportation, and stacking caused different pollution intensity. Moreover, the contents of Sb in soil samples decreased successively in residue field, wasteland, forestland, sediment, grassland, and vegetable field, and the contents of Sb in vegetable-field and ecological restoration grassland were relatively low, which indicate that the method of grassland ecological restoration is an effective method to control antimony pollution in soil. The results of ecological risk assessment showed that the antimony mining area was seriously polluted by Sb, As, Pb, and Cd, and had strong ecological risk, and Sb and Cd were the most important pollution factors, which indicated that the pollution of Sb and Cd should be a major concern of relevant departments of environment and health.

Variations in heavy metal concentrations among trophic levels of the food webs in two agroecosystems

Excessive accumulation of trace metal in soil represents a growing environmental problem posing severe risks to biota, humans and ecosystems. Concentrations of Cd, Pb, Cu and Zn were determined in soil, as well as in representatives of some trophic levels in the terrestrial food webs in two Egyptian agroecosystems; El-Manzala (a rural area located in the northeast of the River Nile Delta) and El-Tebbin (an industrial area located in South Cairo). Representatives of trophic levels included arthropods, amphibians, reptiles, birds and small mammals. Metal concentrations were determined in the leaves of wild plants, bodies of arthropods and livers of vertebrates. Levels of metals in the soil, plants and most animal species were higher in El-Tebbin than El-Manzala. Minimal concentrations of metals were detected more often in plants and in the cattle egret, whereas maximum values were common in the soil, amphibians and a mantid. Accumulation of metals was more frequent in arthropods and other taxa at lower trophic levels of food webs, suggesting that the transfer of metals along the vertebrate food web may be of relatively minor importance. However, of all the metals examined, only Pb was bioaccumulated to any appreciable extent in some of the higher trophic levels. A significant increase in liver mass and relative liver mass of the Norway rat from the polluted site was observed.

Heavy metal concentrations in commercial marine organisms from Xiangshan Bay, China, and the potential health risks

Commercial marine organisms were collected from the coast of Xiangshan Bay to investigate the concentrations of eight heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) and evaluate the potential health risks. The results indicated considerable variations in the heavy metal concentrations among six species groups, of them mollusks (seasnail, benthic bivalve, and oyster) generally contained relative high levels of most metals, followed by crustaceans (crab and shrimp), by contrast, fish had low concentrations of all metals, except Hg. Three heavy metal groups were identified to interpret the accumulative characteristics in the marine organisms. Spatial distributions illustrated the geographical variations of heavy metal concentrations in the sampling areas. Moreover, maricultured organisms demonstrated lower heavy metal concentrations than did the wild. Health risks of most heavy metals exposed from marine organism consumption were safe, except for As which is associated with the high target cancer risk values.

Geographical variability of heavy metal concentrations in tissues of medical leeches (Hirudo medicinalis, Hirudo verbana) and in bottom deposit

Geographical variability of heavy metal concentrations in tissues of medical leeches (Hirudo medicinalis, Hirudo verbana) and in bottom deposit