Total Trace Metal Research Articles

Influence of graded EDTA applications on mobilization and translocation of trace elements—a soil column experiment

AbstractIncreasing concerns about potential environmental effects of ethylenediaminetetraacetic acid (EDTA) accumulation in soils require better understanding of its behavior and its effect on trace element mobilization. In this study we investigated the effect of EDTA on soil trace element mobilization in undisturbed soil columns taken from a heavy metal contaminated field. The columns were leached by EDTA solutions of different concentrations under unsaturated, steady‐state conditions. The transport of trace elements (Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sn, Zn) and EDTA was monitored by regularly collecting the leachates. After the termination of the leaching experiment the soil columns were divided into 5 layers to determine trace elements and EDTA concentrations in the soil. The results revealed that the soil analysis alone was not suitable to infer mobilization or immobilization patterns in relation to the EDTA concentration, as the mobilized fraction was too small in relation to the total trace metal concentrations in the soil. Analysis of the leachates displayed that after 2–4 pore volumes the EDTA output concentration reached about 80% of the input concentration. The trace element concentrations in the leachates showed that some elements were mobilized by EDTA (Cd, Cu, Fe, Pb, Co, Ni, Zn) while others were immobilized (Mn, Cr, Mo, Sn) in the soil columns after EDTA application.

Impact of surface ocean conditions and aerosol provenance on the dissolution of aerosol manganese, cobalt, nickel and lead in seawater

Abstract Atmospheric deposition is an important pathway by which bioactive trace metals are delivered to the surface ocean. The proportions of total aerosol trace metals that dissolve in seawater, and thus become available to biota, are not well constrained and are therefore a key uncertainty when estimating atmospheric fluxes of these elements to surface waters. The aim of this study was to elucidate the main physico-chemical controls on the dissolution of the bioactive trace metals manganese (Mn), cobalt (Co), nickel (Ni) and lead (Pb). To this end, aerosol and surface seawater samples were collected in the Sargasso Sea and subsequently used in sequential seawater leach dissolution experiments to assess the role of aerosol source, seawater temperature, pH, and concentrations of dissolved oxygen and organic ligands, on aerosol trace metal dissolution. Results reveal that changes in key physico-chemical parameters in seawater leaches had little effect on the proportions of Mn, Co, Ni and Pb released from aerosols, although organic ligand amendments impacted the size distribution of aerosol-derived Mn in solution. Conversely, aerosol source and composition had the most significant effect on the dissolution of aerosol Co and Pb, with the most ‘anthropogenic’ aerosol samples displaying the highest fractional solubilities in seawater (up to 58% for Co and 112% for Pb). Fractional solubilities over the range of samples and conditions tested were in the range of 50–104% for Mn, 29–58% for Co, 40–85% for Ni and 67–112% for Pb. A large proportion (36–100%, median 89%) of the total dMn, dCo, dNi and dPb was mobilised rapidly during the first leaching step (5 min), with less dTM being released in leaches 2 through 4. Furthermore, investigation of the size distribution of the aerosol-derived trace metals in seawater showed that dissolved Pb was mostly colloidal (0.02–0.4 μm), dissolved Mn and Co were mostly soluble (

The Backwater Clam (Meretrix casta) as a bioindicator species for monitoring the pollution of an estuarine environment by genotoxic agents

The coast of Goa receives anthropogenic stress through its major rivers, which carry mining wastes, including iron and manganese ores from upstream mining sites, and petroleum hydrocarbons from shipping activities. These contaminants show seasonal variation in concentration and may be bioaccumulated by fauna inhabiting these waters. These fauna, including the bivalve molluscs, are particularly at risk due to these insults. In the present study, the use of the backwater clam, Meretrix casta (Chemnitz), as a bioindicator species was evaluated, comparing two sites (Vasco and Palolem) on the Goan coast. DNA damage was assessed in the gill cells using the micronucleus and comet assays; physiological condition was determined from the condition index. These values were tested for correlations with the concentrations of total petroleum hydrocarbons and trace metals in the whole soft tissues and with the physico-chemical parameters of water from these sites. Specimens collected from Vasco showed high incidence of micronuclei and % tail DNA and a low condition index ratio compared to those from Palolem, which correlates with the higher level of pollutants in the bivalves the former site. We believe that M. casta is a suitable species for biomonitoring studies of this type.

Bioaccumulation of trace metals and total petroleum and genotoxicity responses in an edible fish population as indicators of marine pollution

The present study reports the genetic damage and the concentrations of trace metals and total petroleum hydrocarbons prevailing in natural populations of an edible fish, Arius arius in different seasons along the coast of Goa, India as an indicator of the pollution status of coastal water. Fish were collected from a suspected polluted site and a reference site in the pre-monsoon, monsoon and post-monsoon seasons. Physico-chemical parameters as well as the concentrations of total petroleum hydrocarbons (TPH) and trace metals in the water and sediment as well as the tissues of fish collected from these sites were recorded. The genotoxicity status of the fish was assessed employing the micronucleus test and comet assay. A positive correlation (p<0.001) was observed between the tail DNA and micronuclei in all the fish collected. Multiple regression analysis revealed that tissue and environmental pollutant concentrations and genotoxicity were positively associated and higher in the tissues of the fish collected from the polluted site. Pollution indicators and genotoxicity tests, combined with other physiological or biochemical parameters represent an essential integrated approach for efficient monitoring of aquatic ecosystems in Goa.

Sediment-bound trace metals in Golfe-Juan Bay, northwestern Mediterranean: Distribution, availability and toxicity

The concentration, potential mobility, cation exchange capacity and toxicity of eight sediment-bound metals in Golfe-Juan Bay, France were examined. Results revealed significant spatial gradient of metal contamination along Golfe-Juan coast. The distribution and concentration of the metals appear to be influenced by the geochemical properties of the sediment, proximity to anthropogenic sources and general water circulation in the bay. The portion of trace metals found in the exchangeable, carbonate, oxidizable and reducible fractions of the sediment constitute 31%–58% of the total sediment-bound trace metal content, suggesting significant potential for remobilization of metals into the water column. Pb and Ni content of the sediment exceed the limits of the French marine sediment quality. Whole sediment extracts showed acute toxicity to marine rotifers. This study concludes that monitoring and management of sediment-bound trace metals in Golfe-Juan Bay are important so as not to underestimate their availability and risk to the marine ecosystems.

Speciation analysis and bioaccessibility evaluation of trace elements in goji berries (Lycium Barbarum, L.)

Goji berries (Lycium Barbarum, L.) are known for their nutritional potential as a great source of trace metals (e.g., copper, zinc and manganese) which are present in the form of highly bioaccessible compounds. In order to assess the bioaccessibility of trace elements and to identify compounds responsible for better bioaccessibility of copper and zinc, an in vitro simulation of gastrointestinal digestion was used in this study.The total content of trace metals was evaluated using sample digestion followed by inductively coupled plasma mass spectrometry. Bioaccessibility of trace elements was estimated by size exclusion chromatography coupled to inductively coupled plasma mass spectrometry. These analytical methods were used to analyse samples of goji berries to determine the highest amount of elements. For total trace metal content in goji berries, Zn had the highest level of the three studied (10.6μgg−1), while the total content of manganese and copper was 9.9μgg−1 and 6.1μgg−1, respectively.Additionally, the analysed metals were found to be highly bioaccessible to the human body (about 56% for Mn, 72% for Cu and 64% for Zn in the gastric extract and approximately 35% for Mn, 23% for Cu and 31% for Zn in the case of gastrointestinal extract). To obtain information about metal complexes present in goji berries, extraction treatment using different solutions (ionic liquid, HEPES, SDS, Tris-HCl, ammonium acetate, water) was performed. Enzymatic treatment using pectinase and hemicellulase was also checked. Extracts of berries were analysed by SEC-ICP-MS and μHPLC–ESI–MS/MS techniques. The ionic liquid and pectinase extraction helped efficiently extract copper (seven compounds) and zinc (four compounds) complexes. Compounds identified in goji berries are most likely to be responsible for better bioaccessibility of those elements to the human organism.

Enrichment and toxicity of trace metals in near-shore bottom sediments of Cuddalore, SE coast of India

In order to identify contaminating trace metals and their sources, studies on trace metals are often included in routine environmental monitoring programs. Twenty-five near-shore bottom sediment samples from the inner shelf region (near Cuddalore) of the Bay of Bengal were analysed for sediment texture, organic matter, carbonate (CaCO3) concentrations and total trace metal concentrations (TTMs) (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn and Cd) in order to evaluate geochemical processes such as enrichment and their origin. The presence of carbonates (2.5–5.8 %) indicates the dominance of calcareous shells in the region. A relatively high percentage of organic matter (0.2–3.9 %) is attributed to the predominance of finer sediments entering through the minor rivers. High concentrations of TTMs in fine and organic-rich sediments are influenced by municipal and industrial sources, which contention is well supported by correlations of TTMs concentrations with Fe–Mn fractions. Geoaccumulation index (Igeo) calculations indicate that Cr, Cu, Ni, Pb and Cd concentrations are above the values expected from their presence in the discharge of effluents from the industrial zones bordering the shoreline. Comparing the findings of the present study with those from different parts of the World, Cr, Cu, Ni, Pb appear to be enriched in the sediments of the region.

Llandovery green/grey and black mudrock facies of the northern Holy Cross Mountains (Poland) and their relation to early Silurian sea-level changes and benthic oxygen level

The Llandovery mudrock facies in the northern Holy Cross Mountains reveal lithological variability allowing their interpretation in the context of post-Ordovician climate and sea-level changes in the Caledonian foredeep basin developed along the present SW margin of Baltica. They form a succession up to 50m thick made up of grey and greenish clayey mudstones interrupted by black shales. The sedimentary and geochemical data (total organic carbon, pyrite framboids and trace metals) clearly show that the black shales document periods of the significant sediment starvation and oxygen- deficient conditions. Their occurrence is confined to the persculptus–acuminatus, vesiculosus, cyphus, convolutus–sedgwickii, turriculatus–crispus, crenulata and spiralis graptolite biozones and they can be correlated with post-glacial transgressions. In contrast, the grey and greenish mudstones are interpreted as lithofacies reflecting permanent benthic oxygenation driven by deep-water ventilation during the Aeronian and Telychian regressions supported by sedimentary and geochemical studies, and diameters of pyrite framboids

Significance of groundwater discharge along the coast of Poland as a source of dissolved metals to the southern Baltic Sea

Fluxes of dissolved trace metals (Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) via groundwater discharge along the southern Baltic Sea have been assessed for the first time. Dissolved metal concentrations in groundwater samples were less variable than in seawater and were generally one or two orders of magnitude higher: Cd (2.1–2.8nmolL−1), Co (8.70–8.76nmolL−1), Cr (18.1–18.5nmolL−1), Mn (2.4–2.8μmolL−1), Pb (1.2–1.5nmolL−1), Zn (33.1–34.0nmolL−1). Concentrations of Cu (0.5–0.8nmolL−1) and Ni (4.9–5.8nmolL−1) were, respectively, 32 and 4 times lower, than in seawater. Groundwater-derived trace metal fluxes constitute 93% for Cd, 80% for Co, 91% for Cr, 6% for Cu, 66% for Mn, 4% for Ni, 70% for Pb and 93% for Zn of the total freshwater trace metal flux to the Bay of Puck. Groundwater-seawater mixing, redox conditions and Mn-cycling are the main processes responsible for trace metal distribution in groundwater discharge sites.

Trace metal distributions in the sediments of the Little Akaki River, Addis Ababa, Ethiopia.

The levels and distribution of trace metals (Cr, Mn, Co, Ni, Cu, Zn, Cd and Pb) at eleven water and sediment stations on the Little Akaki River (LAR) in Addis Ababa, Ethiopia, were determined. The binding forms of the metals in various geochemical fractions of the sediments were also quantified. The molar ratio of the sum of the simultaneously extractable metals (∑SEM) and acid-volatile sulphide (AVS)-as a measure for predicting metal-induced toxicity-was estimated. LAR trace levels in water for Cu, Zn, and, particularly Mn were, in most instances, higher than the recommended guidelines for healthy aquatic ecosystems. Total trace metal (TTM) contents in the LAR sediments at certain stations exceeded "threshold effect concentrations" and even "probable effect concentrations", especially in the cases of Zn, Cu, Ni, Pb, and at all stations for Mn. This became more apparent after applying "normalizations" to the relatively lower TTM adsorption capacities of coarse-grained, organic-poor sediments. Sequential extraction of the sediments showed that trace metals generally have a higher affinity for Fe-Mn oxide and organic matter/sulphidic fractions, followed by the residual fraction. Mn was relatively strongly bound to the exchangeable, carbonate bound fractions, whereas a large proportion of Cr was found in the residual fraction. The Σ[SEM]/[AVS] ratio pointed to potential metal-induced toxicity of sediments collected from seven out of the eleven stations. The results indicate that trace metal pollution pose risks to the health of ecosystems, and to human communities that use the river for a range of different purposes.

Comparative approach for trace metal risk evaluation in settling particles from the Uruguay River, Argentina: enrichment factors, sediment quality guidelines and metal speciation

The source and potential risks of trace metals in settling material collected with sediment traps in the Uruguay River were evaluated utilizing enrichment factors (EF), sediment quality guidelines (SQG) and speciation using a 4-step sequential extraction procedure. The total organic carbon content of the settling material was relatively high and homogeneous (2.5 ± 0.3 %) and showed no correlation with the metal concentrations. Total trace metal concentrations decrease from Fe (48,969 ± 7380 µg g−1), Mn (1859 ± 233 µg g−1), Zn (84 ± 7.6 µg g−1), Cu (56 ± 6.9 µg g−1), Cr (19 ± 2.7 µg g−1), Ni (16 ± 2.0 µg g−1) and Pb (13 ± 1.2 µg g−1). The average EF of Zn, Cr, Ni and Pb are below 1.5 indicating natural sources, whereas those of Cu and Mn are consistently higher (EF > 2) insinuating some anthropogenic influence. Consistently, Cu concentrations duplicated the SQG (35.7 μg g−1) suggesting that adverse biological effects may be observed occasionally. However, speciation results revealed that most metals are associated with the residual fraction, strongly linked to the mineral matrix, and therefore unavailable to aquatic organisms. The sole exception is Mn which is mainly found in the non-residual fractions (∑F1 − F3 = 82 %). Trace metal mobility/bioavailability decreased from Mn (82 %) ≫ Pb (37 %) > Cr (26 %) ~ Ni (25 %) > Zn (20 %) > Cu (14 %) > Fe (10 %). These results demonstrate the utility of metal speciation studies to assess the real risk for aquatic organisms of high Cu concentrations, but associated to relatively immobile fractions of reduced bioavailability.

Spatial distribution of living (Rose Bengal stained) benthic foraminifera in the Loire estuary (western France)

Ninety-seven surface sediment samples were collected in September 2012 from intertidal and subtidal areas along the Loire estuary (western France). The main objective of this work is to study the spatial distributional patterns of living benthic foraminifera and their link to the environmental parameters (distance to sea, elevation, grain size, total organic carbon, trace metals, sedimentary carbonates, and polycyclic aromatic hydrocarbons) in the Loire estuary. Foraminiferal analysis was also extended to the dead assemblages in thirty-three surface samples from the lower inner estuary. The highest absolute densities of living benthic foraminifera are found in the lower inner estuary within the polyhaline domain. This is attributed to the presence of mudflats with abundant food source, i.e. microphytobenthos. The low densities found in the outer estuary (euhaline domain) are attributed partly to the sandy nature of the sediments and the food source inhabiting this substrate. The near absence of foraminifera in the inner estuary (mesohaline and polyhaline domains) is inferred to the physical disturbance resulting from the regular dredging of the navigation channel. The living assemblages are dominated by three typical estuarine species: Ammonia tepida and Haynesina germanica in the intertidal mudflats of the lower inner estuary and Cribroelphidium excavatum in the sandy subtidal sediments of the lower inner and outer estuary. In the Loire estuary, H. germanica has an unusual intermediate geographical distribution along the estuary between A. tepida and C. excavatum while in most temperate estuaries this species is present upstream in the mesohaline domain. This is most likely the result of the regular dredging of the navigation channel damaging its natural habitat. This might be also the explanation for the total absence of agglutinated species usually dominating the oligohaline domain. The canonical correspondence analysis shows that elevation (and its link to time of emersion), distance to sea (and its correspondence with salinity), and organic carbon content appear to be the primary drivers of foraminiferal distribution. The present study provides for the first time ecological and distribution patterns of living benthic foraminiferal communities in the Loire estuary. This baseline knowledge is necessary for the future studies focusing on the use of benthic foraminifera as bio-indicators in the Loire estuary and in transitional environments in general.

Source apportionment and risk assessment of PM1 bound trace metals collected during foggy and non-foggy episodes at a representative site in the Indo-Gangetic plain

The concentration, spatial distribution and source of 13-PM1 bound trace metals (Fe, Cu, Mn, Cr, Zn, Cd, Ni, K, Mg, Na, Ca, Pb and V) and adverse health effects of 5-PM1 bound trace metals (Mn, Zn, Ni, Cr and Cd) collected during foggy and non-foggy episodes are presented. Twenty-four samples from each period (foggy and non-foggy episodes) were collected from Kanpur, a typical densely populated city and the most polluted representative site in the Indo-Gangetic plain of India, and were analyzed for carcinogenic (Ni, Cr and Cd) and non-carcinogenic metals (Mn and Zn). The average mass concentration of PM1 during foggy and non-foggy episodes was found to be 160.16±37.70 and 132.87±27.97μg/m3. Source identification via principle component analysis suggested that vehicular emission and anthropogenic, industrial and crustal dust were the dominant sources in this region. During both episodes the decreasing order of hazard quotient (Hq) for adult and children was as Mn>Cr>Cd>Ni>Zn. In a non-foggy episode the hazardous index (Hi) values of these 5 trace metals were found to be ~3.5 times higher than a foggy episode's exposed population, respectively. In a foggy episode, due to the exposure to total carcinogenic trace metals (Ni, Cr and Cd) present in the ambient air, 95% probability total incremental lifetime cancer risks (TIlcR) were ~687 cancer cases and ~402 cancer cases per million in the adult population and children population respectively. These cancer cases were ~1.6 times higher than a non-foggy episode's exposed population.

Use of lidar point cloud data to support estimation of residual trace metals stored in mine chat piles in the Old Lead Belt of southeastern, Missouri

Historic lead and zinc (Pb-Zn) mining in southeast Missouri’s “Old Lead Belt” has left large chat piles dominating the landscape where prior to 1972 mining was the major industry of the region. As a result of variable beneficiation methods over the history of mining activity, these piles remain with large quantities of unrecovered Pb and Zn and to a lesser extent cadmium (Cd). Quantifying the residual content of trace metals in chat piles is problematic because of the extensive field effort that must go into collecting elevation points for volumetric analysis. This investigation demonstrates that publicly available lidar point data from the U.S. Geological Survey 3D Elevation Program (3DEP) can be used to effectively calculate chat pile volumes as a method of more accurately estimating the total residual trace metal content in these mining wastes. Five chat piles located in St. Francois County, Missouri, were quantified for residual trace metal content. Utilizing lidar point cloud data collected in 2011 and existing trace metal concentration data obtained during remedial investigations, residual content of these chat piles ranged from 9247 to 88,579 metric tons Pb, 1925 to 52,306 metric tons Zn, and 51 to 1107 metric tons Cd. Development of new beneficiation methods for recovering these constituents from chat piles would need to achieve current Federal soil screening standards. To achieve this for the five chat piles investigated, 42 to 72% of residual Pb would require mitigation to the 1200 mg/kg Federal non-playground standard, 88 to 98% of residual Zn would require mitigation to the Ecological Soil Screening level (ESSL) for plant life, and 70% to 98% of Cd would require mitigation to achieve the ESSL. Achieving these goals through an existing or future beneficiation method(s) would remediate chat to a trace metal concentration level that would support its use as a safe agricultural soil amendment.

Evaluation of total trace metal (TTMs) enrichment from estuarine sediments of Uppanar, southeast coast of India

The present study was carried out to investigate the impact of anthropogenic influences on Uppanar estuary situated at Cuddalore with regard to trace metal concentration in sediment samples of the study area. The Uppanar River runs similar to the coast south of Cuddalore town and a number of small streams of domestic, treated and unprocessed effluents from industries join the coast through the river. Average concentration of Cr, Cu and Ni (106, 87 and 137.1 ppm) is above the continental value indicating that increase in the concentration may be due to metal industries, and surface runoff of the fertilizer remains increases the concentration of the metal in the sediments. There is moderate level of pollution related to anthropogenic activities. The trace metals showed association with Fe and Mn indicating their adsorption on Fe–Mn oxyhydroxides. Correlation coefficient between pairs of metals concentration show that all metals and organic carbon significantly correlate with trace metal except sand and calcium carbonate. Geoaccumulation index and enrichment factors, the sediment is classified as unpolluted to moderately polluted with Fe, and Cu and moderate to considerable with Pb and Co. From the study, it can be revealed the anthropogenic activities are the prime source for the biodegradable toxic metal in the sediment of Uppanar estuary in the Cuddalore coastal zone.

Distribution and Fractionation of Heavy Metals in Sediments of Karra River, Hetauda, Nepal

A five-step sequential extraction procedure was applied for the determination of the distribution of four elements (Cr, Mn, Fe, and Ni) in sediment of the Karra River. Sediment samples were collected from 16 different sites in the Karra River (upstream, industrial belt, downstream). The distribution of trace metals among exchangeable, carbonate, reducible, oxidizable and residual fractions were determined. The total concentration of metals varies in the range of Cr 72–4339.54 mg kg?1, Mn 22–411.93 mg kg?1, Fe 2967.23-32423.0 mg kg?1 and Ni 31.70-180.74 mg kg?1. The accuracy evaluated by comparing total trace metal concentrations with the sum of the five individual fractions proved to be satisfactory. The chemical speciation of Cr, Mn, Fe, and Ni in most sampling stations were in the order of residual &gt; reducible &gt; oxidazable &gt; carbonate&gt; exchangeable. Fractionation analysis showed that dominant metals are in residual fraction. The highest metal concentrations were observed at the most polluted sites of the industrial belt. High concentration of chromium was found in the Fe-Mn oxide and organic fraction in some of the sites of industrial belt.Journal of Institute of Science and Technology, 2014, 19(2): 123-128

Estimation of the Atmospheric Flux of Nutrients and Trace Metals to the Eastern Tropical North Atlantic Ocean*

Abstract Atmospheric deposition contributes potentially significant amounts of the nutrients iron, nitrogen, and phosphorus (via mineral dust and anthropogenic aerosols) to the oligotrophic tropical North Atlantic Ocean. Transport pathways, deposition processes, and source strengths contributing to this atmospheric flux are all highly variable in space and time. Atmospheric sampling was conducted during 28 research cruises through the eastern tropical North Atlantic (ETNA) over a 12-yr period, and a substantial dataset of measured concentrations of nutrients and trace metals in aerosol and rainfall over the region was acquired. This database was used to quantify (on a spatial and seasonal basis) the atmospheric input of ammonium, nitrate, soluble phosphorus, and soluble and total iron, aluminum, and manganese to the ETNA. The magnitude of atmospheric input varies strongly across the region, with high rainfall rates associated with the intertropical convergence zone contributing to high wet deposition fluxes in the south, particularly for soluble species. Dry deposition fluxes of species associated with mineral dust exhibited strong seasonality, with the highest fluxes associated with wintertime low-level transport of Saharan dust. Overall (wet plus dry) atmospheric inputs of soluble and total trace metals were used to estimate their soluble fractions. These also varied with season and were generally lower in the dry north than in the wet south. The ratio of ammonium plus nitrate to soluble iron in deposition to the ETNA was lower than the N:Fe requirement for algal growth in all cases, indicating the importance of the atmosphere as a source of excess iron.

Atmospheric trace metal concentrations, solubility and deposition fluxes in remote marine air over the south-east Atlantic

Total and soluble trace metal concentrations were determined in atmospheric aerosol and rainwater samples collected during seven cruises in the south-east Atlantic. Back trajectories indicated that the samples all represented remote marine air masses, consistent with climatological expectations. Aerosol trace metal loadings were similar to previous measurements in clean, marine air masses. Median total Fe, Al, Mn, V, Co and Zn concentrations were 206, 346, 5, 3, 0.7 and 11pmolm−3 respectively. Solubility was operationally defined as the fraction extractable using a pH4.7 ammonium acetate leach. Median soluble Fe, Al, Mn, V, Co, Zn, Cu, Ni, Cd and Pb concentrations were 6, 55, 1, 0.7, 0.06, 24, 2, 1, 0.05 and 0.3pmolm−3 respectively. Large ranges in fractional solubility were observed for all elements except Co; median solubility values for Fe, Al and Mn were below 20% while the median for Zn was 74%. Volume weighted mean rainwater concentrations were 704, 792, 32, 10, 3, 686, 25, 0.02, 0.3 and 10nmolL−1 for Fe, Al, Mn, V, Co, Zn, Cu, Ni, Cd and Pb respectively (n=6). Wet deposition fluxes calculated from these values suggest that rain makes a significant contribution to total deposition in the study area for all elements except perhaps Ni.

Bioaccumulation of metals in fish species from water and sediments in macrotidal Ennore creek, Chennai, SE coast of India: A metropolitan city effect

Accumulation of trace metals (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd) were investigated in water, sediment (n=20) along with six fish of diverse feeding guilds (Sillago sihama, Liza parsia, Etroplus suratensis, Oreochromis mossambicus, Arius parkii and Gerres oyena) from the Ennore creek, northern part of Chennai metropolitan megacity, southeast coast of India. Dissolved trace metals (DTMs) in surface water samples and total trace metals (TTMs) in surface sediments (top 0–10cm) indicate that concentration pattern of metals was higher in the discharge point of the river/channels entering the main creek. The maximum mean values of DTMs exhibited the following decreasing order (expressed in µg/L): Fe (1698)>Mn (24)>Zn (14.50)>Pb (13.89)>Ni (6.73)>Cu (3.53)>Co (3.04)>Cr (2.01) whereas the trend is somewhat different in sediments (µgg−1): Fe (4300)>Mn (640)>Cr (383)>Zn (155)>Cu (102)>Ni (35)>Pb (32)>Cd (0.51) are mainly due to the industrial complexes right on the banks of the river/channels. Species-specific heterogeneous patterns of tissue metal loads were apparent and the overall metal enrichment exhibited the following decreasing order (expressed in µgg−1): Cu (7.33)>Fe (6.53)>Zn (4.91)>Cr (1.67)>Pb (1.33)>Ni (0.44)>Mn (0.43)>Co (0.36)>Cd (0.11). This indicates that metals are absorbed onto the different organs, which is also endorsed by the calculated values of bioaccumulation factor (BAFs) (avg. muscle 117, gill 126, liver 123, intestine 118) in fishes. The high calculated biota sediment accumulation factor (BSAF) (0.437) for the species Arius parkii is considered to be a potential bioindicator in this region. The enrichment of trace metals is also supported by the association of metals in water, sediments and different body organs (muscle, gill, liver, intestine) of fish samples. Comparative studies with other coastal regions indicate considerable enrichment of DTMs & TTMs in sediments as well as in various organs of fish samples. Holistic spatial, temporal monitoring and comprehensive regional strategies are required to prevent health risks and ensure nutritional safety conditions.

Anthropogenic Effects on Metal Content in Urban Soil From Different Parent Materials and Geographical Locations

Growing safe food crops in urban settings requires soil condition assessment because many sites may be metal contaminated. Of particular concern are trace metals found at urban sites as a result of litter, construction materials, industrial development, and traffic patterns. Although all soils contain trace metals inherited from the parent material, anthropogenic influences can influence and increase metals' plant availability. Different urban activities located on soils derived from three parent materials, marine, glacial marine, and glacial till, were selected in Metro Vancouver to assess trace metal concentrations in the urban soils. Estimates of total (aqua regia) and available (dilute HCl) trace metals (Cu, Mn, Ni and Pb ) were compared among the sites and between the surface soil and the underlying parent material to assess potential environmental risks associated with location of the urban sites. Comparisons were made to metal concentration standards in published government guidelines. Although urban activities do affect metal amounts, parent materials must be considered when assessing anthropogenic effects of trace metals in soils because metal contents vary among different parent materials. Results indicate that surface soil metal concentrations are influenced by geographical location within the urban setting and soil management practices. For a rapid and reproducible determination of potential trace metal concentrations, the use of 0.1 M HCl provides a useful initial assessment.