Average Trace Metal Concentrations Research Articles

Status of Trace Metals Contamination and Ecological Risk Assessment in Intertidal Sediments Along the Gulf of Guinea

Surface sediments from the intertidal area of Côte d’Ivoire were sampled to investigate trace metals (Hg, Cd, Cr, Cu, Pb, Zn, and As) concentrations to illustrate their spatial distribution and ecological risk of pollution. The average total organic carbon content was 2.04 ± 0.01%. Except for Cr and Zn, the spatial distribution exhibited a similar pattern for TOC, Hg, Cd, Cu, Pb, and As. The average concentrations of trace metals were less than their corresponding upper continental crust (UCC) values, except for Cd and Cr. The pollution indices indicated that sediment quality in the studied area has been impacted by Cd and the Assinie and Bleron sites were the most contaminated. A few ecological risks were posed by Hg, Cd, Cr, and Cu, based on sediment quality guidelines (SQGs). The Pearson correlation showed a significant (p < 0.05) correlation between As, Cd, Pb, Cr, and Hg, suggesting a common origin in sediments. The principal component analysis (PCA) identified As, Cr, Pb, Zn, and Hg might originate from natural source, Cd and Cu might be from natural and anthrogenic sources. Although this study presents the current status of littoral trace metals contamination level in sediments, further studies should integrate the statistical multivariate approach to determine the anthropogenic sources of the trace metals in the intertidal area of Côte d’Ivoire.

Impact of air quality on the health of present-day workers in an Asbestos roof manufacturing industry, Sri Lanka.

The study's objective was to determine the air quality in an asbestos-related industry and its impact on current workers' respiratory health. Seventy-seven air and 65 dust samples were collected at 5-day intervals in an asbestos roofing sheets production factory in Sri Lanka having two production facilities. Sampling was performed in ten sites: Defective sheets-storage, Production-plant, Pulverizer, Cement-silo, and Loading-area. A detailed questionnaire and medical screening were conducted on 264 workers, including Lung Function Tests (LFT) and chest X-rays. Asbestos fibres were observed in deposited dust samples collected from seven sites. Free chrysotile fibres were absent in the breathing air samples. Scanning Electron Microscopy confirmed the presence of asbestos fibres, and the Energy Dispersive X-ray analysis revealed Mg, O, and Si in depositions. The average concentrations of trace metals were Cd-2.74, Pb-17.18, Ni-46.68, Cr-81.01, As-7.12, Co-6.77, and Cu-43.04mg/kg. The average Zn, Al, Mg, and Fe concentrations were within 0.2-163g/kg. The highest concentrations of PM2.52.5 and PM1010, 258 and 387µg/m3, respectively, were observed in the Pulverizer site. Forty-four workers had respiratory symptoms, 64 presented LFT abnormalities, 5 indicated chest irregularities, 35.98% were smokers, and 37.5% of workers with abnormal LFT results were smokers. The correlation coefficients between LFT results and work duration with respiratory symptoms and work duration and chest X-ray results were 0.022 and 0.011, respectively. In conclusion, most pulmonary disorders observed cannot directly correlate to Asbestos exposure due to negligible fibres in breathing air, but fibres in the depositions and dust can influence the pulmonary health of the employees.

Appraisal of trace metals toxicity and human health risk using a novel approach in wastewater of four gas fields, Bangladesh

The objective of this study is to assess the toxicity of trace metals (TMs) and associated environmental, ecological and health risks in the gas fields located in the Sylhet region of Bangladesh. Gas well-produced water, gas field discharge water, and drinking water surrounding the gas fields were collected for analysis. This study analyzed carcinogenic and noncarcinogenic TMs such as Cr, As, Co, Cd, Fe, Ni, Mn, Zn, and Pb, as well as physical parameters pH and EC in the collected samples using various instruments. The TMs were measured using Atomic Absorption Spectrometer (AAS), Flame AAS and physical parameters were evaluated using portable water multiparameter. The Fe and EC concentrations in produced and discharged water samples were incredibly high. The average concentrations of TMs in produced water samples during the summer and rainy seasons were found to be Fe > Mn > Zn > Ni > Co > Cu > Cr > Pb > As > Cd. The observed metal concentration in discharge water was higher during the summer than in the rainy season. Most samples met national and international standards for trace elements, while a few samples exceeded the threshold value.The Heavy Metal Evaluation Index (HMEI) results indicate that most produced water is highly polluted, while discharge and drinking water are moderate to lightly polluted. The Environmental Pollution Index (EPI) indicates environmental pollution for some produced water samples, while it indicates a moderate to low risk for discharge and drinking water samples. The source of trace metals (TMs) was determined using positive matrix factorization. However, all water samples have an ecological risk index of less than 150, indicating lower risk. Furthermore, the Heavy Metals Toxicity Load (HMTL) was below the allowable toxicity load for all water samples, indicating minimal contamination in the studied water. The non-cancer hazard score (HI) of the studied HMs is more significant for children and females than males. The cancer risk from Ni is a concern, while the cancer risk from Cd and Cr is also a matter of concern. In the end, policymakers can utilize this study's findings to monitor, and control produced water contamination.

Impacts of land use/cover and slope on the spatial distribution and ecological risk of trace metals in soils affected by smelting emissions.

The soil contamination around smelting sites shows high spatial heterogeneity. This study investigated the impacts of distance, land use/cover types, land slopes, wind direction, and soil properties on the distribution and ecological risk of trace metals in the soil around a copper smelter. The results demonstrated that the average concentrations of As, Cd, Cu, Pb, and Zn were 248.0, 16.8, 502.4, 885.6, and 250.2 g mg kg-1, respectively, higher than their background values. The hotspots of trace metals were primarily distributed in the soil of smelting production areas, runoff pollution areas, and areas in the dominant wind direction. The concentrations of trace metals decreased with the distance to the smelting production area. An exponential decay regression revealed that, depending on the metal species, the influence distances of smelting emissions on trace metals in soil ranged from 450 to 1000 m. Land use/cover types and land slopes significantly affected trace element concentrations in the soil around the smelter. High concentrations of trace metals were observed in farmland, grassland, and flatland areas. The average concentrations of trace metals in the soil decreased in the order of flat land > gentle slope > steep slope. Soil pH values were significantly positively correlated with Cd, Cu, Pb, Zn, and As, and SOM was significantly positively correlated with Cd, Pb, and Zn in the soil. Trace metals in the soil of the study area posed a significant ecological risk. The primary factors influencing the distribution of ecological risk, as determined by the Ctree analysis, were land slope, soil pH, and distance to the source. These results can support the rapid identification of high-risk sites and facilitate risk prevention and control around smelting sites.

Monitoring trace element concentrations with environmentally friendly biomonitors in Artvin, Turkey.

Air pollution is the change in air composition that disrupts human health and environmental balance. Although natural and anthropogenic processes include crustal movements, photosynthesis, and plant and animal emissions, other sources of contamination also include industrial operations, transportation activities, household resources, and the chemical and metal industries. Thus, biomonitoring can be employed as a quick, affordable, and efficient method for estimating air pollution. In this study, some inorganic pollutants were detected using olive trees (Olea europaea L.) at eleven different points, depending on the traffic density in Artvin, Turkey. Trace element concentrations (Cr, Ti, Fe, Ni, Co, Cu, Zn, Pb, Al, and Mn) were measured in soil once a year and seasonally in plant samples with ICP-OES. Furthermore, basic component analyses total carbon (TC), total nitrogen (TN), total hydrogen (TH), and total sulfur (TS) were done with an elemental analyzer, total chlorophyll contents with a portable chlorophyll meter, and morphological and particle-based plant analyses with SEM-EDS. The pollution levels of these metals were calculated using the enrichment factor (EF) and geoaccumulation index (Igeo) parameters. Furthermore, the accuracy and validity tests of the analyses for trace metals were tested by applying certified reference materials (CRM) (ERM-CD281) for the plant samples and CRM (LGC-6187) for soil samples. Results indicated that soil trace element pollution distributions were ranked according to the following descending order: Fe (37,873.33mg/kg) > Al (13,300mg/kg) > Mn (1101.33mg/kg) > Ti (353.5mg/kg) > Zn (252.86mg/kg) > Cu (87.77mg/kg) > Cr (30.52mg/kg) > Pb (19.65mg/kg) > Ni (17.07mg/kg) > Co (7.65mg/kg). Moreover, air pollution from anthropogenic sources substantially increased average trace metal concentrations and sulfur emissions in autumn and winter. The average highest values of Fe (321.08mg/kg) > Al (304.05mg/kg) > Mn (32.75mg/kg) > Zn (31.01mg/kg) > Cu (17.92mg/kg) > Ti (11.07mg/kg) Cr (2.57mg/kg) > Ni (17.07mg/kg) were found in leaf samples taken from the roadside in autumn and winter. According to the EF and Igeo values, the main polluting trace elements in the soil were Zn, Cu, and Pb, while in the plant, these were detected as Fe, Al, Ti, Cr, Ni, and Cu. Kruskal-Wallis and correlation analysis statistically supported this relationship among metals. Results show that olive leaves are an effective bioindicator for detecting urban air pollution.

Geochemical evaluation and environmental risk assessment of heavy metals: A case study from Ireland using Tellus stream sediment data (2011–2017)

A comprehensive assessment of the distribution, spatial mapping and ecological risk of heavy metals in stream sediments of 17 counties of Ireland based on the Tellus geochemical survey programme in Ireland was carried out. Average trace metal concentrations of chromium (Cr), nickel (Ni), copper (Cu), lead (Pb), zinc (Zn), vanadium (V), cobalt (Co), arsenic (As), and major and minor oxides iron oxide (Fe2O3), manganese oxide (MnO) in the stream sediments were above the background values, but lower than Irish sediment quality guidelines for livestock and Canadian sediment quality guidelines (ISQG); threshold effect level (TEL) and probable effect level (PEL). 69.65% of Ni, 22.13% of Zn, and 96.7% of Pb samples exceeded the low-effect-range (ERL) values, whereas only 21%, 1.80% and 0.69% of the same elements exceeded the median effect range (ERM) values. Hotspots of Zn (>12000 mg kg−1), Pb (>10,000 mg kg−1), Fe2O3 (61.38%), MnO (26%), Cr (>2300 mg kg−1) and Ni (874.2 mg kg−1) were observed at Wicklow, Dublin, Mayo, Galway and Cavan counties. Catchment geochemistry was identified for the presence of heavy metals in the stream sediments. The geo-accumulation index (Igeo) indicated Kildare to be the least contaminated county with Igeo < 0 for Cr, Ni, Cu, Zn, Pb and As for 50% of the samples. The enrichment factor (EF) indicated that some sites located in Mayo and Donegal were highly contaminated. PInemerow followed the trend, Tipperary > Dublin > Waterford > Monaghan > Donegal > Wexford > Galway > Wicklow > Cavan > Meath > Kilkenny > Leitrim > Mayo > Louth > Sligo > Kildare > Carlow. Based on potential ecological risk index (PERI), 83.1% of the sites posed low ecological risk (PERI <150), 11.9% sites posed moderate risk (150 < RI < 300) and high ecological risk was posed by 0.3% (PERI >1200) of the sites. Lithology, topography and anthropogenic factors influenced the distribution and ecological risks of heavy metals. Non-carcinogenic and carcinogenic risk for adults and children were above the recommended value.

Characterizing the Changes in the Source Apportionment of Metal in Surface Waters by an Integrated Approach

Based on long-term monitoring data of typical surface water from 1999 to 2016, this study evaluated the temporal, spatial, and source changes of seven trace metals. The results show that average concentrations of trace metals were Zn (248.61 μg L–1) ≫ Mn (74.27 μg L–1) > Ba (72.4 6 μg L–1) > Al (44.11 μg L–1) > As (6.36 μg L–1) > Ni (3.29 μg L–1) > Cd (2.98 μg L–1). There is a decreasing trend in the concentrations of Al, Cd, Mn, Ni, and Zn. Pollution levels in the midstream are relatively higher than in the upstream and downstream. A wavelet analysis suggested that the Al and As contamination levels exhibited clear periodic oscillations. According to the source apportionment analysis, the pollution sources of A, B, and C periods were determined, among which historical mining, industrial, agricultural, and geological natural sources were the main contributors. Anthropogenic pollution sources during stage B accounted for the largest proportion, reaching 76.54%. Historical mining source emissions remained relatively stable (43.17, 34.99, and 40.83%), but the proportion remained at the highest level. The health risk assessment shows that there is no obvious health risk, and As and Cd have certain cancer risk.

Risk assessment of trace metals in Mefou River sediments, West-Africa

This study focuses on risk assessment of Cr, V, Ni, Co, Pb, Cu, and Zn in the Mefou River sediments located at Yaoundé, West-Africa. Sediment samples were collected from five stations in the downstream of the Mefou River, which drains the urban area of Yaoundé between latitudes 3°30′ and 3°58′ North and longitudes 11°20′ and 11°40′ East. The geochemistry data were analyzed statistically and the pollution indices were calculated in order to identify and estimate the sources of metal contamination in the Mefou River sediments. The results obtained show that the average concentrations of trace metals are almost higher than those of the upper continental crust (UCC) and the metal average in the Simbock Lake cores. However, the concentrations of Ni, Cu, Pb, and Zn in sediments located in most urbanized sites are lower than those of the UCC and the average of Simbock Lake sediments. The pollution indices such as enrichment factor (EF), geo-accumulation index (Igeo), and pollution load index (PLI) showed that trace metals were mainly influenced by human sources, except for Pb, Cu, and Zn, which stemmed from natural sources. The sediments of the Mefou River would therefore be affected with low to moderate pollution levels. The low values of potential ecological risk (RI: 22.36–41.53) suggest a low potential ecological risk effect. The multivariate statistical analysis indicates that Ni, Cu, Pb, Co, and Zn have been derived mainly from natural sources, while V and Cr would partially derive from human activities. The results of this research can be a reference for trace metal pollution along an African urbanized river corridor. This can be considered as an act of prevention of urban watercourses in Cameroon and in other parts of the world, especially in major African urban metropolis.

Distribution and environmental risk assessment of trace metals in sludge from multiple sources in Taiwan

ABSTRACT: This study evaluated the level of the contaminant of the heavy metals in sludge from different sources and the ecological risk criteria associated with it was also analyzed to establish its reuse in agriculture. The sludge samples were collected from the water plant (WTP), wastewater treatment plant (WWTP), and industrial water treatment plant (IPT) in Taiwan. The inductively coupled plasma mass spectrometry was used to measure the trace metals in sludge. The pollution level and ecological risk criteria for heavy metals in sludge were also used to evaluate its reuse in agriculture. The result shows the average concentrations of trace metals in sludge for three groups (WTP, WWTP, and ITP). Significant correlations were found between concentrations of Zn-Ag (p < 0.001). The higher values of I geo showed in ITP, indicated Hg to be a major pollutant. In Taiwan, the regulations did not establish the reuse of sludge in agriculture. However, the concentration level of trace metals in sludge was particularly lower than the regular levels in most groups, like WTP and WWTP groups. The industrial sludge was not recommended for the use in agriculture. The results of this study can be used for regular monitoring to establish a reference for sludge management and application to agriculture.

Evidence of Natural and Anthropogenic Impacts on Rainwater Trace Metal Geochemistry in Central Mexico: A Statistical Approach

Trace metals Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd, and As were determined on a monthly basis in a total of 52 rain samples collected from six different locations in the central region of Mexico during March 2016–April 2017. The average concentrations of trace metals (mg/L) in the rainwater samples showed an order of Zn (0.873) &gt; Fe (0.395) &gt; Mn (0.083) &gt; Cr (0.041) ≥ Cu (0.041) &gt; Pb (0.031) &gt; Ni (0.020) &gt; Co (0.013) &gt; As (0.0003) &gt; Cd (0.002). The differences observed in metal concentrations are related to variations in the influence of continental air masses, local transport, regional advection, and the solubility of trace metals. High concentrations of metals were observed in the months of March to May at all sites, probably due to the less extensive removal of air/air pollutants. The values obtained from the enrichment factor (EF) per metal showed relatively high values for Cd, Zn, Cu, Pb, Co, Ni, and Cr, suggesting anthropogenic origin. Pearson’s correlation matrix validated the distribution of trace metal sources and their relationships with local/regional meteorological characteristics. This paper presents relevant basic information for the evaluation of the toxic potential of rainwater and the possible health risks when using this source of water for human consumption.

Arsenic and trace metals in a large reservoir: Seasonal and spatial variations, source identification and risk assessment for both residential and recreational users

The Keban Dam Reservoir in Turkey is an internationally important reservoir, because it is located on the Euphrates River, which is an important transboundary river. Water samples were seasonally collected from 11 sampling sites on the reservoir between autumn 2014 and summer 2015. Spatial and seasonal variations, possible sources and health risks of dissolved trace metals (TMs) were investigated. Among ten TMs, only Cr and Mn showed significant spatial variations, while Cr, Mn and Pb did not show significant seasonal variations. The average concentrations of TMs except As and Cd indicated a decreasing trend from autumn to summer. Also, minimum total metal concentration was recorded in summer due to raised water level of the reservoir. Maximum concentrations of all TMs were lower than the drinking water guideline values set by EC (European Community), WHO and USEPA. Principle component analysis/factor analysis and correlation analysis demonstrated that all TMs originate from natural sources. Non-carcinogenic and carcinogenic risks through ingestion and dermal contact exposure pathways were estimated for both residential and recreational receptors exposed to TMs in reservoir water. Hazard quotient, hazard index (HI) and total HI values were lower than 1. Also, carcinogenic risk (CR) values of As and Cr for each exposure route and total CR values were within the acceptable range of 10−4 and 10−6. Thus, the Keban Dam Reservoir is safe for human health in terms of residential and recreational uses.

Year-round records of bulk aerosol composition over the Zhongshan Station, Coastal East Antarctica

To characterize ionic composition and trace elements in the coastal Antarctic, more than 100 bulk aerosol samples were collected at the Chinese Zhongshan Station from February 2005 to November 2008. Major water-soluble species, including Na+, NH4+, K+, Mg2+, Ca2+, Cl−, NO3−, SO42−, and methane sulfonic acid (MSA), were analyzed by ion chromatography (IC). Trace metals, including Al, V, Cr, Fe, Cu, Zn, and Pb, were measured by inductively coupled plasma mass spectrometry (ICP-MS). Results showed that sea salt was the major component in aerosols at the Zhongshan Station in coastal East Antarctica. Sea salt ions Na+, Mg2+, Ca2+, and Cl− exhibited the maximum concentration in March, and the highest average concentration in September. NH4+, NO3−, SO42−, and MSA exhibited obvious seasonal variations, with higher concentrations in austral summer than in austral winter. During the 4-year observations, the highest aerosol composition loading was showed in 2008, and the high variation and average concentrations of trace metals appeared in January. Based on high NH4+/(Cl− + NO3− + 2 × SO42−) molar ratios, atmospheric aerosol was not that acidic in the austral summer. Sulfate depletion was found by the low SO42−/Na+ ratio in samples collected in the austral winter, especially from May to October. Enrichment factor (EF) and multivariate statistical analysis were utilized to explore potential emission sources of aerosols over the Zhongshan station. Na+, Cl−, K+, Mg2+, and Ca2+ were mainly from sea salt sources, and Al, Fe, Cu, Cr, Pb, and V were mainly from crustal and anthropogenic pollution sources, while S-cycle compounds non-sea-salt sulfate (nss-SO42−) and MSA originated from marine biogenic emissions.

Chemical speciation of trace metals in the industrial sludge of Dhaka City, Bangladesh

The objective of this study was to assess total concentration and chemical fractionation of trace metals in the industrial wastewater and sludge collected from seven different types of industries in Dhaka City, Bangladesh. The sludge from industries is either dumped on landfills or reused as secondary resources in order to preserve natural resources. Metals were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The ranges of Cr, Ni, Cu, As, Cd, and Pb in the sludges were 1.4-9,470, 4.8-994, 12.8-444, 2.2-224, 1.9-46.0 and 1.3-87.0 mg/kg, respectively. As a whole, the average concentrations of trace metals in samples were in the decreasing order of Cr > Ni > Cu > As > Pb > Cd. The results of the Community Bureau of Reference (BCR) sequential extraction showed that the studied metals were predominantly associated with the residual fraction followed by the oxidizable fraction. The study revealed that the mobile fractions of trace metals are poorly predictable from the total content, and bioavailability of all fractions of elements tends to decrease.

Determination of metals in tuna species and bivalves from Alexandria, Egypt

The concentration levels of eight heavy metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) were measured in the liver, gills, and muscle tissues of tuna fish (Thunnus thynnus) collected from the El-Mex Bay, the Eastern Harbour and Abu-Qir Bay as well as two bivalves (Pinctada radiate and Paphia textile) from the Abu-Qir Bay. Generally, the liver and gills exhibited higher metal concentrations than the muscle. Among the analysed fish species, the average concentrations of heavy metals were as follows: Cd (0.052, 0.243, 0.177), Cr (0.817, 1.503, 1.196), Cu (1.251, 4.368, 2.711), Fe (165.476, 263.557, 186.405), Mn (1.004, 1.509, 3.031), Ni (0.370, 0.624, 0.708), Pb (0.832, 1.113, 1.372), Zn (18.715, 118.308, 78.421)mg/kg wet weight in the muscle, liver and gill tissues, respectively. The average concentrations of trace metals in mussels decreased in the order Fe (296.655)>Zn (88.222)>Mn (5.497)>Cu (1.299)⩾Pb (1.135)⩾Cr (1.072)>Ni (0.659)>Cd (0.347)mg/kg wet weight. The concentrations of the studied heavy metals in all species were found to be within the safe limits suggested by various authorities and thus gave no indication of pollution. The target hazard quotients (THQs) values of Cd, Cr, Cu, Mn, Pb, and Zn for the investigated fish and mussels are much smaller than one, which may indicate that there is no health risk from consuming the investigated fish and mussels.

Trace Metal Enrichment in Sediments from Otofure and Teboga Waste Dump Sites in Benin City, Nigeria

Analyses of lead, copper, chromium, cadmium, nickel, zinc and manganese contents in Otofure and Teboga waste dumps in Benin City, Nigeria were carried out to determine trace metal enrichment and distribution in the soils around the dump sites and environs. Results of analyses show that trace metal concentrations in the waste dumps were greater than those from the reference background sites by magnitude concentration differences of Pb (18.711 mgkg-1), Cu (12.342 mgkg-1), Cr (0.073 mgkg-1), Cd (0.908 mgkg-1), Zn (104.669 mgkg-1), Ni (3.522 mgkg-1), Mn (203.803 mgkg-1) in Otofure area; and Pb (3.522 mgkg-1), Cu (10.466 mgkg-1), Cr (0.556 mgkg-1), Cd (1.026 mgkg-1), Zn (109.026 mgkg-1), Ni (4.307 mgkg-1) and Mn (161.349 mgkg-1) in Teboga area. The calculated contamination/pollution (C/P) index values show that the dump sites were slightly polluted while the reference sites showed insignificant contamination. Analysis of enrichment factor shows that the dump sites are enriched in lead and zinc, and these decreased with distance away from the waste dump sites. The geochemical association of Cr–Cu–Zn in the soil among others shows their inclination towards anthropogenic sources. This study shows slight metal enrichment in lead and zinc content over other metals studied, but generally the average concentrations of trace metals were below international guideline values for environmental quality criteria.

Trace metal geochemistry of organic carbon-rich watercourses draining the NW German coast

Numerous small watercourses are draining the hinterland of the NW German coast. The waters mainly originate from marsh and fen areas and have yellow to deep brownish color. During their flow path, the waters exhibit gradients in salinity (0.2–3), pH (6.2–8.8), particulate organic carbon (5–25%), and iron oxides (7–12%), which alter the concentrations of most dissolved and particulate trace metals. For example, dissolved Fe is rapidly removed from solution at increasing salinities by flocculation, whereas dissolved U is removed in the very low-salinity zone by Fe- and organic-rich colloids. The waters at the flood-gate of Neuharlingersiel, where a composite sample of the entire study area is collected before the freshwater is discharged into the marine-dominated tidal flat area in front of the mainland dike, have the following average trace metal concentrations: dissolved Fe 11 μM, Mn 4 μM, Mo 10 μM, U 1.8 μM, V 75 μM and particulate Fe 7 mg kg−1, Mn 1200 mg kg−1, Mo 2 mg kg−1, U 1.7 mg kg−1, V 140 mg kg−1. After passing the flood-gate most Mo- and U-salinity distributions fit well to the conservative mixing line that connects the seawater of the Wadden Sea to the low-salinity river water entering the tidal flat area. In contrast, dissolved Fe, Mn, and V are removed from solution, especially at intermediate salinities, which may be due to mixing of freshwater with seawater depleted in these elements, flocculation and/or scavenging by particulate matter. In general, processes similar to those in estuarine systems alter the geochemical signatures on transects from land to sea. Compared to average river water, the watercourses are enriched in dissolved and particulate Fe, Mn, Mo, U, and V. Due to the fast removal of dissolved Fe in the salinity gradient and the high concentrations of Mo and U in seawater, the watercourses only form a source for Mn, V, terrestrial organic carbon, and particulate Fe for the Wadden Sea.

Characterizations of particle-bound trace metals and polycyclic aromatic hydrocarbons (PAHs) within Tibetan tents of south Tibetan Plateau, China

Exposure to trace metals and polycyclic aromatic hydrocarbons (PAHs) adsorbed on particulates is of a serious health concern. Levels of some trace metals in total suspended particulate and 13 PAHs of fine particulate matter were measured from nomadic tents in the southern Tibetan Plateau in summer 2010. The indoor air within the tents was seriously polluted, mainly due to yak dung combustion. Average trace metal concentrations were much higher (range of indoor/outdoor ratio 61-291) than those of the outdoor air. Additionally, enrichment factors of most trace metals of indoor air were similar to those of outdoor air, indicating outdoor air quality of the studied area was possibly influenced by pollutants emitted from local tents. Mean concentrations of total PAHs and BaP within tents was 5372.45 and 364.79 ng/m(3), hundred times higher than that of outdoor air of the Tibetan Plateau. Three- and four-ring PAHs were the predominant components. The diagnostic ratio of BaA/(BaA + Chr) was 0.33. Since Tibetan women typically spend longer time within the tents, they were exposed to PAHs (BaP exposure = 1.81 μg/m(3)) about two times of other family members. Among all the PAHs, Bap contributed the most (82.6%) of the total carcinogenicity. Similarly, the excess lifetime cancer risk for women and other family members were 2.75 × 10(-4) and 1.27 × 10(-4), respectively, indicating Tibetan herdsmen, especially women who are in charge of most house chores were at risk for adverse health effects.

Biomonitoring of Cd, Cr, Hg and Pb in the Baluarte River basin associated to a mining area (NW Mexico)

With the purpose of knowing seasonal variations of Cd, Cr, Hg and Pb in a river basin with past and present mining activities, elemental concentrations were measured in six fish species and four crustacean species in Baluarte River, from some of the mining sites to the mouth of the river in the Pacific Ocean between May 2005 and March 2006. In fish, highest levels of Cd (0.06μgg−1 dry weight) and Cr (0.01μgg−1) were detected during the dry season in Gobiesox fluviatilis and Agonostomus monticola, respectively; the highest levels of Hg (0.56μgg−1) were detected during the dry season in Guavina guavina and Mugil curema. In relation to Pb, the highest level (1.65μgg−1) was detected in A. monticola during the dry season. In crustaceans, highest levels of Cd (0.05μgg−1) occurred in Macrobrachium occidentale during both seasons; highest concentration of Cr (0.09μgg−1) was also detected in M. occidentale during the dry season. With respect to Hg, highest level (0.20μgg−1) was detected during the rainy season in Macrobrachium americanum; for Pb, the highest concentration (2.4μgg−1) corresponded to Macrobrachium digueti collected in the dry season. Considering average concentrations of trace metals in surficial sediments from all sites, Cd (p<0.025), Cr (p<0.10) and Hg (p<0.15) were significantly higher during the rainy season. Biota sediment accumulation factors above unity were detected mostly in the case of Hg in fish during both seasons. On the basis of the metal levels in fish and crustacean and the provisional tolerable weekly intake of studied elements, people can eat up to 13.99, 0.79 and 2.34kg of fish in relation to Cd, Hg and Pb, respectively; regarding crustaceans, maximum amounts were 11.33, 2.49 and 2.68kg of prawns relative to levels of Cd, Hg and Pb, respectively.

Trace metal dynamics in zooplankton from the Bay of Bengal during summer monsoon

Trace metal (Fe, Co, Ni, Cu, Zn, Cd, and Pb) concentrations in zooplankton from the mixed layer were investigated at 8 coastal and 20 offshore stations in the western Bay of Bengal during the summer monsoon of 2003. The ecotoxicological importance of trace metal uptake was apparent within the Bay of Bengal zooplankton. There was a distinct spatial heterogeneity of metals, with highest concentrations in the upwelling zones of the southeast coast, moderate concentrations in the cyclonic eddy of the northeast coast, and lowest concentrations in the open ocean warm gyre regions. The average trace metal concentrations (μg g⁻¹) in coastal zooplankton (Fe, 44894.1 ± 12198.2; Co, 46.2 ± 4.6; Ni, 62.8 ± 6.5; Cu, 84.9 ± 6.7; Zn, 7546.8 ± 1051.7; Cd, 46.2 ± 5.6; Pb, 19.2 ± 2.6) were higher than in offshore zooplankton (Fe, 3423.4 ± 681.6; Co, 19.5 ± 3.81; Ni, 25.3 ± 7.3; Cu, 29.4 ± 4.2; Zn, 502.3 ± 124.3; Cd, 14.3 ± 2.9; Pb, 3.2 ± 2.0). A comparison of average trace metal concentrations in zooplankton from the Bay of Bengal showed enrichment of Fe, Co, Ni, Cu, Zn, Cd, and Pb in coastal zooplankton may be related to metal absorption from primary producers, and differences in metal concentrations in phytoplankton from coastal waters (upwelling zone and cyclonic eddy) compared with offshore waters (warm gyre). Zooplankton showed a great capacity for accumulations of trace metals, with average concentration factors of 4 867 929 ± 569 971, 246 757 ± 51 321, 337 180 ± 125 725, 43 480 ± 11 212, 1 046 371 ± 110 286, 601 679 ± 213 949, and 15 420 ± 9201 for Fe, Co, Ni, Cu, Zn, Cd, and Pb with respect to dissolved concentrations in coastal and offshore waters of the Bay of Bengal. © 2009 Wiley Periodicals, Inc. Environ Toxicol, 2009.

Trace Metal Concentrations in Zooplankton from the Eastern Arabian Sea and Western Bay of Bengal

Trace metal contents in zooplankton samples were estimated as a part of the Marine Research–Living Resource program at 24 stations in the Bay of Bengal (November, 2002) and 29 stations in the Arabian Sea (September–October, 2003) during the Cruises 209 and 217 of the Fishery and Oceanographic Research Vessel Sagar Sampada. The average metal concentrations in the Bay of Bengal zooplankton (Fe, 14,073 μg g−1; Co, 24.2 μg g−1; Ni, 29.5 μg g−1; Cu, 46.2 μg g−1; Zn, 2000 μg g−1; Cd, 18.7 μg g−1; and Pb, 6.55 μg g−1) were found to be higher of comparable magnitudes than the Arabian Sea zooplankton (Fe, 1786 μg g−1; Co, 14.2 μg g−1; Ni, 18.6 μg g−1; Cu, 21.5 μg g−1; Zn, 374 μg g−1; Cd, 16.5 μg g−1; and Pb, 4.0 μg g−1). The spatial variability of metal contents in zooplankton from both basins indicates that it is markedly enriched in coastal samples than offshore samples. The metal enrichment in zooplankton from the coastal areas of the eastern Arabian Sea occurs due to a combined effect of upwelling, riverine, and anthropogenic sources, whereas the latter two are only dominating in the coastal Bay of Bengal zooplankton. A comparison of average trace metal concentrations in the zooplankton from the Arabian Sea and Bay of Bengal showed that the enrichment of Fe, Zn, Cd, Ni, Cu, and Pb in the Bay of Bengal zooplankton may be due to high bioaccumulation factor of these elements, whereas the slight Co enrichment may be due to the bioavailability of this metal in the seawater.