Assessment of Zn, Cu, Pb and Ni contamination in wetland soils and plants in the Lake Victoria basin

The impact of waste disposal on trace metal contamination was investigated in eleven wetlands in the Lake Victoria Basin. Samples of soil, water and plants were analysed for total Zn, Cu, Pb and Ni concentrations using flame atomic absorption spectrophotometry. The trace metal concentrations in soil were the highest in Katanga wetland with the highest mean concentrations of 387.5±86.5 mg/kg Zn, 171.5±36.2 mg/kg Pb, 51.20±6.69 mg/kg Cu and 21.33±2.23 mg/kg Ni compared to the lowest levels observed at Butabika (30.7±3.2 mg/kg Zn, 15.3±1.7 mg/kg Pb, 12.77±1.35 mg/kg Cu and 6.97±1.49 mg/kg Ni). Katanga receives waste from multiple industrial sources including a major referral city hospital while Butabika is a former solid waste dumpsite. Wetland soil near a copper smelter had a Cu concentration of 5936.3±56.2 mg/kg. Trace metal concentrations in industrial effluents were above international limits for irrigation water with the highest concentrations of 357,000 μg/L Cu and 1480 μg/L Zn at a Cu smelter and 5600 μg/L Pb at a battery assembling facility compared to the lowest of 50 μg/L Cu and 50 μg/L Zn in water discharged from Wakaliga dumpsite. Uptake of trace metals from soil differed from plant to plant and site to site. Higher levels of trace metals accumulated in the root rather than in the rhizome and the least amount was in the leaf. The study identifies industry as a potential source of trace metal contamination of water and the environment pent-up need for policy intervention in industrial waste management.     

Occurrence of nonylphenol an endocrine disrupter in Karun River,Khuzestan Province,Iran

The important Iranian Karun River has never been investigated for the presence of potentially endocrine-disrupting chemicals, nonylphenol (NP). In this study, concentrations of NP were measured in water from Karun River and five wastewater discharge points into this river, collected during April to July 2010. The analytes were extracted by solid-phase extraction, and quantitative analyses were performed by HPLC–FLD. NP was detected in water and wastewater samples with 0.17–1.83 and 15.27–21.79 μg/L, respectively. The results showed that the NP content of aqueous phase of all wastewater samples higher than particulate phase, which were detected in the aqueous and particulate phases with mean concentrations of 12.8 ± 2.4 and 5.2 ± 1.2 μg/L, respectively. These data suggest that the NP levels in Karun river water are likely attributable to untreated municipal wastewaters discharged directly into the river. To our knowledge; this is the first study to evaluate NP concentrations in water and wastewater in Iran.     

Use of Pyracantha coccinea Roem. as a possible biomonitor for the selected heavy metals

In this study, copper, iron, manganese and nickel levels of branches and leaves of Pyracantha coccinea Roem. (firethorn) were measured for determining the heavy metal pollution in Mugla Province. Plant samples were collected from 34 different localities in four different areas of Mugla Province, during 2006 vegetation period. Unwashed and washed leaf samples and unwashed branch samples were subjected to analysis and copper, iron, manganese and nickel concentrations of samples were measured by inductively coupled plasma optical emission spectrometry. The obtained data were analyzed with “statistical package for the social sciences” statistics program. As a result of measurements, the highest average and lowest values and their collected stations were as follows; the highest average (5.89 ± 0.04 μg/g dw) and the lowest (5.20 ± 0.03 μtg/g dw) values of copper were measured near highways. The average highest iron value (9.53 ±1.68 μtg/g dw) was in industrial area while the lowest was near highways (1.73 ± 0.54 μtg/g dw). The highest value of magnesium accumulation (1.00 ± 0.16 μtg/gdw) was measured near highways. The lowest value was determined in urban area (0.40 ± 0.14 μtg/g dw). The average highest level of nickel was in industrial area while the lowest was determined in urban area. The values were 14.34 ± 1.59 μtg/g and 4.05 ± 0.51 μtg/g dw. As a result, it was proven that P. coccinea could be used as a biomonitor species for some of these heavy metals especially for copper and nickel.     

Chemical speciation of fine particle bound trace metals

This study reported quantifications of fine particle bound trace metals and their potential health risks for residents in Guangzhou, a rapidly developing and most populated city in South China. The fine particle samples were collected from October 29^th. to November 8^th. of 2006 at two different elevations in a mainly residential area and analyzed for the total concentration of aluminum, iron, zinc, lead, manganese, copper, arsenic, chromium, nickel, cadmium, molybdenum and cobalt. Results showed that the fine particle concentrations ranged from 95.8μg/m³to 194.7 μg/m³ at the ground and 83.3-190.0 μg/m³ on the roof, which were much higher than the 24 h fine particle standard (35 μg/m³) recommended by USEPA. The total concentrations of zinc, lead, arsenic, chromium and cadmium in fine particle were 504.8, 201.6, 24.3, 7.7 and 4.4 ng/m³, respectively, which were comparable to other major cities of China, but much higher than major cities outside of China. A sequential extraction procedure was used to fractionate these fine particle bound metals into four different fractions. Results indicated that most toxic metals were mainly distributed in bioavailable fractions. For instance, about 91 % of cadmium, 85 % of lead and 74 % of arsenic were in bioavailable forms. Risk calculations with a simple exposure assessment model showed that the cancer risks of the bioavailable fractions of arsenic, chromium and cadmium were 3 to 33 times greater than usual goal, indicating serious health risks to the residents in this urban area.     

Bioaccumulation of heavy metals in some fauna and flora

Bioaccumulation of heavy metals in fauna and flora in the Ijaw area of the Niger Delta of Nigeria were investigated. The fauna-molluscs and Crustacea, and flora Hibiscus esculentus and vernonia amygdalina were selected for this study. Results show that Molluscs and Crustacea accumulate considerable amounts of heavy metals. Higher levels of all the metals determined Hg, Pb, Cr, Cu, Ni, and Zn were observed in the shells than in the fleshly tissues. Hibiscus esculentus and vernonia amygdalina also accumulated these heavy metals. The mercury levels in the roots of Hibiscus esculentus and vernonia amygdalina is 0.010 μg/g ± 0.00, while the stem 0.17 ± 0.03 μg/g and leaves 0.25 ± 0.02μg/g was recorded for the v. amygdalina. The H. esculenta fruit has lead levels of 0.22 ± 0.03 μg/g. The levelsof Cu, Ni, and Zn are generally higher than those of Hg, Pb and Cr in all the samples analyzed. There is a growing concern about the physiological and behavioral effects of environmental trace metals in human population. The toxicity of lead at high levels of exposure is well known but of a major concern is the possibility that continual exposure to relatively low levels of these heavy metals through the consumption of these fauna and flora may entail adverse health effects.     

The comparative study of trihalomethanes in drinking water

The purpose of this study was to assess exposure of four trihalomethanes (chloroform, bromodichloromethane, dibromochloromethane and bromoform) in drinking water of Okinawa Island and Samoa. Trihalomethanes compounds were determined in the drinking water samples that were collected from the selected consumption sites and treatment plants of both Okinawa and Samoa in 2003–2004. The Chatan and Nishihara Water Treatment Plants (Okinawa) uses both ozonation and chlorination for primary and secondary disinfection. For Samoa Water Treatment Plants only chlorination is used as primary disinfection. Results showed that the mean concentration of trihalomethanes from treatment plants in Okinawa ranged from 0.30 ± 1.81 ?g/L to 11 ± 2.68 ?g/L and from the consumption sites ranged from 2.08 ± 0.32?g/L to 19.39 ± 100 ?g/L. In comparison, the mean concentration of trihalomethanes from the treatment plants in Samoa ranged from 226 ± 81.2 ?g/L to 267 ± 92.3 ?g/L and from the consumption sites were in the ranges 212 ± 101 ?g/L to 387 ± 125 ?g/L. Brominated compounds were commonly seen in all samples collected in Okinawa. Among the trihalomethanes compounds, chloroform was the common detected trihalomethanes in the samples collected from Samoa. The trihalomethanes levels in all samples collected in Okinawa and Samoa were generally below the guideline values in Japan, but some samples displayed levels which exceeded the level of Japan Water Quality and WHO Standards for chlorinated and brominated compounds.     

Geochemical thermodynamics of cadmium removal from water with limestone

Limestone-based material can reduce concentrations of cadmium below 0.001 mg/L (1 ppb) in water, resulting in > 99% removal efficiency. Thermodynamic constraints appear to be favorable for reactions involving the formation of otavite during cadmium removal. Thermodynamic values for these reactions yield a theoretical removal limit of 0.0015 mg/L or better for cadmium, in reasonable agreement with tests on laboratory and field samples that show cadmium removal at levels less than 0.001 mg/L.     

Geochemical distribution of trace metal pollutants in water and sediments of downstream of an urban river

A study was conducted to investigate the trace metal pollution of water and sediments of downstream of Tsurumi River, Yokohama, Japan. Twenty samples of water and sediments were collected from the river starting from Tokyo bay side up to the junction point of the Yagami River. Results show that the mean concentrations of chromium, cupper and nickel in water greatly exceed (>100 times) the surface water standard. The concentration of molybdenum and lead was also higher than standard values while iron and manganese was lower than that of surface water standard. The mean concentration of zinc, cupper, cadmium, lead, chromium, vanadium, bromine and iodine was 381.1, 133.0, 1.0, 40.8, 102.9, 162.0, 71.5 and 10.6 μg/g sediments, respectively and was greatly exceed the average worldwide shale concentrations and average Japanese river sediment values. However, mean concentration of arsenic, nickel and strontium was 11.0, 36.6 and 164.6 μg/g sediments, respectively which was lower than the average shale value. Other analyzed trace metals, including barium, zirconium, rubidium, yttrium, tin, antimony, cesium, lanthanum, cerium, praseodymium and neodymium were detected in river sediments; the concentration of which was close to the Japan’s river sediment average values. Pollution load index values of the sites of the studied area ranged from 1.24 to 7.65 which testify that the river sediments are polluted. The PLI value of the area was, however, high (6.53) as the concentration of trace metals like zinc, cupper, cadmium, lead and chromium were very high and were the major pollutants.     

Assessment of heavy metal pollution in soil and their implications within and around mechanic villages

Analysis of nine composite soil samples, each made of three replicate core samples and their respective background samples collected from Okigwe, Nekede and Orji automobile mechanic villages were conducted. Metal concentrations (mg/kg) above the background levels in the top 100 cm soil profile ranges as follows: 748-70,606 (± 10114.3) for iron; 99-1090 +- 251.3 for lead; 186-600 ± 180 for manganese; 102–1001± 201.9 for copper; 8–23 ± 12.9 for cadmium; 4–27 ± 6.0 for chromium; and 3–10 ± 2.2 for nickel. The order of abundance is: iron > lead > manganese > copper> cadmium > chromium > nickel, with Okigwe > Nekede > Orji. Pollution indexes show that the metals have similar pollution trends in the three layers (L₁–L3), with L₁ (0–10 cm) > L₂ (10–20 cm) > L₃ (90–100 cm) in Okigwe, L₃ >L₁>L₂ in Nekede, and L₃ >L₂ >L₁ in Orji. In effect, the shaly Okigwe soil is more polluted in the top layer while the sandy Nekede and Orji are more polluted in the lower layers. Despite this order, metal bioavailability may be less in the Okigwe soil due to its high clay-silt content (47 %–64 %). Pollution factor for Okigwe is 0.8, Nekede is 0.7 and Orji is 0.5. Nekede is under severe to excessive pollution while Orji and Okigwe are under moderate to excessive pollution, with weathered depths 7.4m at Orji and Nekede and 4m at Okigwe as most implicated in the pollution process. Above provides the bases for introducing the innovative concepts of environmentally friendly mechanic village.     

Identification of potential soil adsorbent for the removal of hazardous metals from aqueous phase

The present study attempted to identify the efficient hazardous metal-removing sorbent from specific types of soil, upper and middle layer shirasu, shell fossil, tuff, akadama and kanuma soils of Japan by physico-chemical and metal (arsenic, cadmium and lead) removal characterizations. The physico-chemical characteristics of soil were evaluated using X-ray diffraction and scanning electron microscopy with energy dispersive spectroscopy techniques, whereas metal removal properties of soil were characterized by analyzing removal capacity and sorption kinetics of potential metal-removing soils. The chemical characteristics revealed that all soils are prevalently constituted of silicon dioxide (21.83–78.58 %), aluminum oxide (4.13–38 %) and ferrous oxide (0.835–7.7 %), whereas calcium oxide showed the highest percentage (65.36 %) followed by silicon dioxide (21.83 %) in tuff soil. The results demonstrated that arsenic removal efficiency was higher in elevated aluminum oxide-containing akadama (0.00452 mg/L/g/h) and kanuma (0.00225 mg/L/g/h) soils, whereas cadmium (0.00634 mg/L/g/h) and lead (0.00693 mg/L/g/h) removal efficiencies were maximum in elevated calcium oxide-containing tuff soil. Physico-chemical sorption and ion exchange processes are the metal removal mechanisms. The critical appraisal of three metal removal data also clearly revealed cadmium > lead > arsenic order of removal efficiency in different soils, except in tuff and akadama soils followed by lead > cadmium > arsenic. It clearly signified that each type of soil had a specific metal adsorption affinity which was regulated by the specific chemical composition. It may be concluded that akadama would be potential arsenic-removing and tuff would be efficient cadmium and lead-removing soil sorbents.     

Dissolved and particulate organic carbon in Chesapeake Bay

We measured dissolved and particulate organic carbon (DOC and POC) in samples collected along 13 transects of the salinity gradient of Chesapeake Bay. Riverine DOC and POC end-members averaged 232±19 μM and 151±53 μM, respectively, and coastal DOC and POC end-members averaged 172±19 μM and 43±6 μM, respectively. Within the chlorophyll maximum, POC accumulated to concentrations 50–150 μM above those expected from conservative mixing and it was significantly correlated with chlorophylla, indicating phytoplankton origin. POC accumulated primarily in bottom waters in spring, and primarily in surface waters in summer. Net DOC accumulation (60–120 μM) was observed within and downstream of the chlorophyll maximum, primarily during spring and summer in both surface and bottom waters, and it also appeared to be derived from phytoplankton. In the turbidity maximum, there were also net decreases in chlorophylla (?3 μg l^?1 to ?22 μg l^?1) and POC concentrations (?2 μM to ?89 μM) and transient DOC increases (9–88 μM), primarily in summer. These occurred as freshwater plankton blooms mixed with turbid, low salinity seawater, and we attribute the observed POC and DOC changes to lysis and sedimentation of freshwater plankton. DOC accumulation in both regions of Chesapeake Bay was estimated to be greater than atmospheric or terrestrial organic carbon inputs and was equivalent to ≈10% of estuarine primary production.     

Determination of lead, naphthalene, phenanthrene, anthracene and pyrene in street dust

Street dust is a potential source of lead exposure to humans, however scarce information about the pollution levels with lead and polyromatic hydrocarbons exists in Venezuela, limiting the appropriate evaluation of the levels of risk of the people. This work was aimed in the determination of the concentrations of lead, naphtalene, anthracene, phenanthrene and pyrene in the street dust of the most transited avenues and streets of Maracay city. Thirty street dust samples were collected at the streets and avenues, troll and bus main station. Lead was determined by atomic absorption spectrometry after acid digestion (Pb-total), also the fractions of lead soluble in 1 M MgCl₂ and 0.5 M ammonium acetate (pH = 7) were quantified. The polyaromatic hydrocarbons concentrations were determined by capillary gas chromatography equipped with a flame ionization detector. The Pb-total ranged between 734 and 11.439 μg/g with the higher values at the most transited streets and avenues. About 60 % of samples exhibited concentrations between 1.000 and 2.500 μg/g, similar to the values reported in the literature for soils of urban areas. The fraction of lead soluble in magnesium accounted for less than 3 % of Pb-Total, while the 0.5 M ammonium acetate solution represented more than the 75 % of the total loads of the pollutant. The most contaminated samples were those taken at the toll with concentrations of 695.5 and 252.1 μg/g phenanthrene and anthracene were the most abundant, while at the bus station all compounds were detected.     

Heavy metals in the Derwent Estuary

Analyses of the concentrations of Cd, Cr, Co, Cu, Fe, Pb, Mn, Hg, Ni, and Zn in filtered waters, suspended particulates, sediments, shellfish, fish, airborne particulates, and sewage have confirmed work of other investigators showing that the Derwent Estuary is heavily contaminated, particularly withmercury, cadmium, lead, andzinc, and have added further information regarding the distribution of each metal. Apparently most of the contamination originated from the earlier operation of a zinc refining plant. A study of shellfish growing in variously contaminated regions found that more than 20 species could be listed in order of their respective abilities to accumulate each heavy metal. For example, the mussel (Mytilus edulis) was found to be a good indicator of cadmium and mercury contamination, but less valuable as an indicator of zinc. The surf barnacle, (Catophragmus polymerus) was found to be one of the most sensitive biological indicators of cadmium contamination. An indication of the steps by which a waste metal is eventually accumulated at high and even toxic concentrations in seafoods, may be seen from a comparison of the relative concentrations of cadmium, lead, mercury, and zinc found in mussels, sediments, suspended particulates, and filtered waters. The high concentrations recorded for metals include: 1,100 μg/g Hg, 10,000 μg/g Zn, and 862 μg/g Cd in dried sediments; 1,500 μg/g Cd in airborne dust fallout; 200 μg/g Cd and 100,000 μg/g Zn in dried oysters; and 16 μg/l Hg, 15 μg/l Cd and 1,500 μg/l Zn in filtered waters.     

Hydrogeochemical contrast between two study areas of Bengal delta,India: A comparative insight to understand arsenic mobilization process in shallow aquifers

A comparative hydrogeochemical study evaluated arsenic release mechanism and differences in contamination levels in the shallow groundwater of two areas within the deltaic environment of West Bengal (i.e. Karimpur and Tehatta blocks of Nadia district) in India. Groundwaters from both the areas are Ca-Na(K)-Cl-HCO₃ type with highly reducing character (−110.16 ± 16.85 to −60.77 ± 16.93 mV). Low correlations among As, Fe, and Mn and the higher association between As and DOC are indicative of microbial decomposition of organic matter enhancing the weathering of shallow aquifer materials. Arsenic contamination in groundwater is higher in Karimpur (95 ± 81.17 μg/L) than that in Tehatta (43.05 ± 41.06 μg/L). The release mechanism of arsenic into groundwater is very complex. Low Fe (0.27–4.78 mg/L and 0.81–4.13 mg/L), Mn (0.08–0.2 mg/L and 0.03–0.22 mg/L), and SO₄²⁻ (3.82 ± 0.31 and 2.78 ± 0.40 mg/L) suggest that the mechanism of arsenic release is not a single mechanistic pathway. Clustering of redox-active parameters in the principal component planes indicate that the reductive dissolution, and/or weathering/co-precipitation of Fe/Mn-bearing minerals in the shallow aquifer sediments control the dominant mechanistic pathway of arsenic release.     

Removal of heavy metals from paint industry’s wastewater using Leca as an available adsorbent

The ability of light expanded clay aggregate to remove lead and cadmium from paint industry’s effluents was studied at different levels of adsorbent, contact time and pH in April 2008. For this purpose, lead and cadmium removal from paint industry effluents were studied in batch reactors. lead and cadmium measurements have been taken with non-flame atomic absorption techniques and test methods were adapted from 19^th. Ed. of standard methods for the examination of water and wastewater. In this study, different amounts of Leca (1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 g/L) were investigated. The amount of adsorbed lead and cadmium exposure to Leca increased from 1.41 to 3 mg/g and 0.22 to 0.75 mg/g, respectively. The maximum removal efficiency for Pb was 93.75 % at pH = 7 and exposure to 10 g/L of Leca, while for cadmium, it was nearly 89.7 % at the same condition. In this study, adsorption process of lead and cadmium was fitted with Freundlich adsorption isotherm (R² _Pb = 0.97 and R² _Cd = 0.98). The sufficient contact time was deemed 1–2 h for lead and cadmium. According to the results, Leca is recommended as a low cost and available adsorbent to remove lead and cadmium from industrial wastewater.     

Association of trace metals with various sedimentary phases in dam reservoirs

In the present study sediment and water samples collected from Kowsar Dam reservoir in Kohkiluye and Boyerahmad Province, southwest of Iran, are subjected to bulk digestion and chemical partitioning. The concentrations of nickel, lead, zinc, copper, cobalt, cadmium, manganese and iron in water and bed sediment were determined by atomic absorption spectrometry. The concentrations of metals bounded to five sedimentary phases were estimated. On this basis, the proportions of natural and anthropogenic elements were calculated.The anthropogenic portion of elements are as follows: zinc (96 %)> cobalt (88 %)> iron (78 %)> magnesium (78 %)> nickel (78 %)> copper (66 %)> lead (63 %)> cadmium (59 %). The results show sediment contamination by nickel, cadmium and lead, according to the world aquatic sediments and mean earth crust values. Manganese and copper have strong association with organic matter and are of high portion of sulfide bounded ions. Finally, The degree of sediment contamination was evaluated using enrichment factor, geo-accumulation index (Igeo) and pollution index (IPoll). The sediments were identified to be of high cadmium and lead pollution index. The pattern of pollution intensity according to enrichment factor is as follows; manganese (1.25) < copper (1.63) < zinc (1.93) < cobalt (2.35) < nickel (3.83) < lead (12.63) < cadmium (78.32). Cluster analysis was performed in order to assess heavy metal interactions between water and sediment. Accordingly, nickel, cadmium and copper are earth originated. Zinc, copper and manganese are dominated by pH. All the elemental concentrations in water and sediment are correlated except for sedimental copper.     

Mathematical models to predict soil heavy metal toxicity in the 2012 Olympic site

Heavy metal concentrations in samples collected from the London 2012 Olympic Village were determined using a three-step sequential extraction and a rapid extraction method. Metal toxicity was measured by employing the Microtox^? solid phase analysis. Both extraction methods produced comparable results (p?=?0.996), but the rapid method produced higher readings. A number of heavy metals were detected using the two extraction methods, including aluminum, arsenic, cadmium, chromium, copper, iron, nickel, lead and zinc; beryllium, molybdenum, niobium and titanium were also found in low concentration ranging between 0.16 and 27.10?mg/kg in the total acid digestion. The total metal levels in all the soil samples were within the UK Soil Guideline Value (SGV) except for lead which ranged between 62.9 and 776.2?mg/kg. The 30?min EC₅₀ of different soil fractions was 2?C5.8?g/L. In the absence of any of heavy metals in the SGV, the Dutch Guideline values were referred. Mathematical models for a number of metals were generated based on the changes in EC₅₀ values between each (F1, F2 and F3) soil fractions and the initial toxicity in the non-fractionated samples. The resulting models produced good R² values (>96%) for predicting the change in toxicity of lead, cadmium, zinc and copper by measuring their changes in concentrations. These models could substantially reduce the time requires to determine the toxicity in the samples; they would be a useful tool in the clean up process where monitoring of metal toxicity is required.     

Uranium in spring water and bryophytes at basin creek in central idaho

Arkosic sandstones and conglomerates of Tertiary age beneath the Challis Volcanics of Eocene age at Basin Creek, 10 km northeast of Stanley, Idaho, contain uranium-bearing vitrainized carbon fragments. The economic potential of these sandstones and conglomerates is currently being assessed. Springs abound at the contacts of rock units, and water from these springs supports abundant growths of bryophytes (mosses and liverworts). Water from 22 springs and associated bryophytes were sampled; two springs were found to contain apparently anomalous concentrations (normalized) of uranium — as much as 6.5 μg/L (ppb) in water and 1800 μg/g (ppm) in ash of mosses. Moss samples from both springs also contained anomalous concentrations of arsenic, and one contained highly anomalous amounts of beryllium. Water from a third spring contained slightly anomalous amounts of uranium, and two species of mosses at the spring contained anomalous uranium (400 and 700 μg/g) and high levels of both cadmium and lead. Water from a fourth spring was normal for uranium (0.18 μg/L), but the moss from the water contained a moderate uranium level and highly anomalous concentrations of lead, germanium, and thallium.These results suggest that, in the Basin Creek area, moss sampling at springs may give a more reliable indication of uranium occurrence than would water sampling. The reason for this may be the ability of mosses to concentrate uranium and its associated pathfinder elements and to integrate uranium fluctuations that occur in the spring water over any period of time.     

Evaluation of benzene exposure in adults and urinary s-phenylmercapturic acid in children living in Adelaide, South Australia

Benzene Exposure was evaluated in adults and children living in Adelaide, South Australia by measuring benzene and urinary s-phenylmercapturic acid (SPMA). To determine of benzene exposure in each subject the personal passive samplers was used and samples were analyzed by gas chromatography system equipped to flame ionization detector. The level of SPMA was determined by competitive enzymelinked immunosorbent assay (ELISA) in children. The mean concentration of benzene in Summer and Winter were 1.62±1.43 and 1.36±0.87 ppb respectively. There was a significant difference between exposure to benzene for subjects with less and more than 6 hours activity over days of week (p<0.05). The mean urinary concentrations levels of SPMA adjusted to creatinene for children that living less and more than 200 meters distance from main road were 1.56 and 4.67 μmol/mol creatinene, respectively and the significant difference was seen in two groups (p<0.005). Data shows, that SPMA can be utilized as a biomarker for exposure to benzene in children. Exposure to benzene is more for children that living near to main road compare to other children. Adults have more activity in out side of home has more exposure to benzene than other people.     

Distribution and source of organochlorine pesticides (OCPs) in the sediments of Poyang Lake

The concentrations of typical organochlorine pesticides (OCPs) (DDTs, HCHs, PCP-Na, and HCB) were measured to understand distribution and source of OCPs in surface and columnar sediments of Poyang Lake in 2006. And OCPS concentrations in surface sediment in 2017 were made a comparison with those in 2006 at several same sampling sites. OCPs showed higher concentrations in main stream than in river mouths (entrance of river flow into lake) of the lake. The average concentrations of HCHs and DDTs were 4.63 ± 3.86 and 20.15 ± 26.86 ng/g in surface sediments in 2006, respectively. Concentrations of OCPs in 2017 were lower than in 2006, such as HCHs average 1.98 ± 2.04 ng/g and DDTs average 4.87 ± 1.48 ng/g in 2017, indicating historical residual and degradation. The primary isomers of HCHs and DDTs in the lake were α-HCH, γ-HCH and p,p′-DDD, respectively. HCHs were from historical residual and lindane application. DDTs were from historical residual. PCP-Na total concentrations in surface sediment were 77.36 ng/g in 2006 and 44.04 ng/g in 2017. The concentration of HCB residues in surface sediment was 0.92 ± 0.90 ng/g in 2006 and 0.42 ± 0.38 ng/g in 2017. The concentrations of OCPs in columnar sediments showed annual variations, and the peak concentrations occurred in 1953, 1961, 1974, 1982, and 1995, showing close relations with onset of production OCPs pesticide in 1950s and its later prohibition in 1980s and a large number agricultural cultivated land decrease in 1990s in China. The concentrations of HCB in columnar sediments were average 2.33 ± 1.26 ng/g. OCPs of columnar sediments were from historical residues and lindane input. The main contamination of OCPs was PCP-Na and p,p′-DDD in Poyang Lake. On the whole, the combination of surface samples (0–5 cm in depth) and columnar samples (0–38 cm in depth) in a single study would give insight into OCPs pollution levels in different years (temporal resolution) and in different regions (spatial resolution) in Poyang Lake.