Impact of anthropogenic activity on the Hg concentrations in the Piracicaba river basin (São Paulo State, Brazil)

A sampling and analysis program has been completed between 1995 and 1998 in order to determine mercury concentrations in water, sediments, soils and fish in the Piracicaba river basin, one of the most populated and industrialized regions in Brazil. In sediment, the average Hg concentrations varied between 33 ± 17 ng g^?1 and 106 ± 78 ng g^?1, in samples collected during the rainy and dry season, respectively. The same averages were also found for soil samples (35 ± 14 and 109 ± 61 ng g^?1). In water, the total Hg concentration varied between < 1.1 and 24.0 ng L^?1. In piscivore fish, up to 943 μ g Hg kg^?1 was found. Our results show that all compartments undergo Hg contamination, in view of the levels found in pristine environments. Water contamination seems to be due mainly to diffuse processes of soil erosion and suspension of river bed sediment during the rainy season. Also untreated wastewaters generated by industrial activities and from domestic sewage appear to be potential non-point sources in the most industrialized and populated part of the basin. On the other hand, atmospheric transport of mercury originating from the Campinas Metropolitan Region could be another source of mercury contamination, especially in the basin headwaters.     

Assessment of Mercury Levels in Soils,Waters, Bottom Sediments and Fishes of Acre State in Brazilian Amazon

Mercury in the aquatic biota and geologic materials in areas without anthropogenic sources has been stimulating the discussion about the possibility of natural Hg occurrence in the Amazon region. In this study the dispersion of Hg in different geologic materials as well as its relationship with high Hg levels, detected in some species of carnivorous fish consumed in the Rio Branco city, is evaluated. Bottom and suspended sediments, river water and fishes were sampled in the Acre and Purus Rivers and in some of their tributaries. Total mercury as well as physical and chemical characterization of the waters were done. Hg on top soil and upper horizons samples were also determined to evaluate the potential Hg accumulation in these materials. In addition the dominant minerals were determined by X-ray Diffraction analysis. Furthermore, ten samples of fossilized material were analyzed. The Hg analysis were carried out by CVAAS. The Hg mean levels in the bottom and suspensed sediments were 0.042 and 0.060 μg g^-1, respectively. In the river water samples, the Hg levels were below the detection limit. The Hg mean values in the different soil samples were as follow: soil samples (0.077 μ g^-1), lower (50–60 cm depth) horizons samples (0.117 μ g^-1), ferruginous nodules within the clayey matrix (0.190 μ g^-1) and fossilized material (0.379 μ g^-1). In the fishes the Hg levels are high with mean of the 1.287 μ g^-1 in the carnivorous species. These levels indicate a possible bioaccumulation of Hg mostly in the carnivorous fishes. Although low concentrations of Hg were found in the river waters, it is assumed here that the bioavailable Hg can is original large from the ferruginousnodules and fossilized materials.     

Arsenic Contamination and Dispersion in the Engenho Inlet,Sepetiba Bay,SE, Brazil

Arsenic distribution and dispersion in sediments of the EngenhoInlet and the Sepetiba Bay were investigated in order to evaluate the extent of the contamination caused by a metallurgical plant installed in the Sepetiba Bay watershed. The ore used in the smelting process, the soil around the plant, and ore waste collected inside the plant were also analyzed for As. Very high As concentrations in the stronglyand weakly bound fractions (up to 63 000 and 52 700 μgg^-1, respectively) were found in the ore waste. The soilsalso contained high concentrations of both the strongly andweakly bound fractions (748 and 636 μg g^-1, repectively), although the ore itself contained lower levelsof the two fractions (63 and 13 μg g^-1, respectively).The sediments of the Engenho Inlet had a high degree of contamination (up to 347 μg g^-1) decreasing toward Sepetiba Bay where the lowest concentrations were found (up to 50 μg g^-1). Altough lower concentrations were found in the Sepetiba Bay sediments, they are 5 times higher than the world average. The results showed that there is an As transport from the Engenho Inlet to the Sepetiba Bay. These results suggests that the bay's fish and mollusk stock my be contaminated. This contamination may adversely affect the health of the local population, whose main protein supply is seafood.     

Accumulation of acridine from water,food, and sediment by the fathead minnow,Pimephales promelas

Azaarenes are one of several classes of organic compounds which contain mutagenic and carcinogenic substances that are found in synthetic fuels effluents. This study investigated the potential for a mutagenic azaarene, acridine, to accumulate in freshwater fish (Pimephales promelas) via four possible pathways: (1) direct uptake from water, (2) uptake via interaction with contaminated sediments, (3) uptake via ingestion of contaminated zooplankton (Daphnia pulex), and (4) uptake via ingestion of benthic invertebrates (Chironomus tentans) living in contaminated sediments. The results showed that acridine was rapidly accumulated from water by fathead minnows. Equilibrium concentration was attained within 24 h at a concentration factor ([acridine]_{fish, wet wt}/[acridine]_water) of 125±10. Depuration was rapid and appeared to occur in two stages, with a net elimination rate of 0.23 h^?1 [acridine]_fish at equilibrium. Equilibrium concentration factors of 51±5, 30±2, and 874±275 were observed forChironomus, Daphnia, and sediment, respectively. The calculated rates of uptake of acridine via ingestion of contaminated invertebrates (0.02 μg g^?1 h^?1) and ingestion of sediment (0.01 μg g^?1 h^?1) were negligible compared with direct uptake from water (1.40 μg g^?1 h^?1) in a hypothetical system with all compartments in equilibrium.     

Concentrations of Mercury in Wild Growing Higher Fungi and underlying Substrate near Lake Wdzydze,Poland

Fourteen species of wild growing mushrooms and surface (0–10 cm) soils were collected near Lake Wdzydze in the northern part of Poland in 1996–1997 to understand the status of mercury pollution. Concentrations of mercury in mushrooms varied between 100±30 and 2400±1900 ng g^-1 dry matter in caps and 60±1 and 1300±1500 ng g^-1 dry matter in stalks. Concentrations of mercury in underlying soil were between 30±1 and 140±120 ng g^-1 dry matter (between 36±18 and 63±100 ng g^-1 depending on the soil type). Bioconcentration factors (BCF: concentrations in mushroom/concentrationin soil) of total mercury were between 2.3±1.1 and 90±110 for caps, and between 2.1±1.0 and 53±56 for stalks. Scaly tooth (Sarcodon imbricatum) contained the greatest concentrations of mercury in the flesh. However, there was no significant relationship (p >: 0.05) between mercury content in the fruiting bodies of this speciesto soil mercury concentrations. A significant (p < 0.01) positive relationship between mercury content in caps to underlying soil was noted for European cow bolete (Suillus bovinus), while a negative relationship between mercury content in caps and stalks to underlying soil was observed for Sandy knight-cap (Tricholomaflavovirens), Shaggy scale-head (Pholiota squaroso-adiposa),Gypsy mushroom (Rozites caperata) and Pine spike cap (Chroogomphus rutilus).     

Soil and Foliar Mercury Emission as a Function of Soil Concentration

The goal of this study was to investigate net mercury flux associated with seedlings of two species (Populus tremuloides and Pinus ponderosa) grown in three soil exposure concentrations (0.010 ± 0.001, 6.15 ± 0.86, and 25.56 ± 2.10 µg Hg g^-1) and to determine if mercury flux from vegetation was directly correlated with mercury concentration in the soil. Net mercury flux was measured using a gas exchange system. Mercury emission from foliage was not influenced by mercury concentration in the soil. Experiments were also done to assess the significance of mercury emission from vegetation relative to that occurring from associated soils. Mean soil mercury emissions were 1 to 3 orders of magnitude higher than that from plants grown in similar soil mercury concentrations. Light and the addition of water were found to significantly increase mercury emission from soils, and the magnitude of the flux response to watering was correlated with soil mercury concentration.     

Litterfall Mercury in Two Forested Watersheds at Acadia National Park, Maine, USA

Litterfall can be an important flux of mercury (Hg) to soils in forested landscapes, yet typically the only available data to evaluate Hg deposition is from precipitation Hg monitoring. Litterfall was collected at 39 sampling sites in two small research watersheds, in 2003 and 2004, and analyzed for total Hg. Four vegetation classes were designated in this study as hardwoods, softwoods, mixed and scrub. The mean litter Hg concentration in softwoods (58.8 ± 3.3 ng Hg g^?1 was significantly greater than in mixed (41.7 ± 2.8 ng Hg g^?1 and scrub (40.6 ± 2.7 ng Hg g^?1, and significantly lower than in hardwoods (31.6 ± 2.6 ng Hg g^?1. In contrast, the mean weighted litter Hg flux was not significantly different among vegetation classes. The lack of a significant difference in litter Hg flux between hardwoods and softwoods was attributable to the large autumnal hardwood litter Hg flux being balanced by the higher softwood litter Hg concentrations, along with the higher chronic litterfall flux throughout the winter and spring in softwoods. The estimated annual deposition of Hg via litterfall in Hadlock Brook watershed (10.1 μg m^?2 and Cadillac Brook watershed (10.0 μg m^?2 was greater than precipitation Hg deposition and similar to or greater than the magnitude of Hg deposition via throughfall. These results demonstrate that litterfall Hg flux to forested landscapes can be at least as important as precipitation Hg inputs.     

Mercury in Biota and Surficial Sediments from Coatzacoalcos Estuary, Gulf of Mexico: Distribution and Seasonal Variation

Variation of mercury (Hg) in sediments and biota from Coatzacoalcos estuary during the dry, rainy and windy seasons was estimated. In sediments, Hg concentrations ranged from 0.07 μg g^?1 in site 13 (Ixhuatepec) located upstream, to 1.06 μg g^?1 in site 3 (Coatzacoalcos river), located in the industrialized area. Highest enrichment factor (EF) and index of geoaccumulation (I _geo) in surficial sediments were 53 and 5.1 respectively. From EF and I _geo, it is considered that Coatzacoalcos estuary is from moderately contaminated to contaminated. In most fish species from Coatzacoalcos estuary, the sequence of Hg concentration was liver>muscle>gills. Average Hg concentrations in soft tissue of bivalves ranged from 0.09 μg g^?1 in Corbicula fluminea to 0.18 μg g^?1 in Polymesoda caroliniana. Biota-sediment accumulation factor (BSAF) ranged from 0.9 in P. caroliniana during the rainy season (site 4) to 3.8 in P. caroliniana from the same site during the windy season.     

The Effect of Fire on Mercury Cycling in the Soils of Forested Watersheds: Acadia National Park,Maine, U.S.A.

This study compares mercury (Hg) and methylmercury (MeHg) distribution in the soils of two forested stream watersheds at Acadia National Park, Maine, U.S.A. Cadillac Brook watershed, which burned in 1947, has thin soils and predominantly deciduous vegetation. It was compared to the unburned Hadlock Brook watershed, with thicker soil and predominantly coniferous vegetation. Soils in both watersheds were primarily well drained. The fire had a significant impact on the Cadillac watershed, by raising the soil pH, altering the vegetation, and reducing carbon and Hg pools. Total Hg content was significantly higher (P > 0.05) in Hadlock soils (0.18 kg Hg ha^-1) compared to Cadillac soils (0.13 kg Hg ha^-1). Hadlock O horizon had an average Hg concentration of 134±48 ng Hg g^-1 dry weight, compared to 103±23 ng Hg g^-1 dry weight in Cadillac O horizon. Soil pH was significantly higher in all soil horizons at Cadillac compared to Hadlock soils. This difference was especially significant in the O horizon, where Cadillac soils had an average pH of 3.41±0.22 compared to Hadlock soils with an average pH of 2.99±0.13.To study the mobilization potential of Hg in the O horizons of the two watersheds, batch adsorption experiments were conducted, and the results were modeled using surface complexation modeling. The results of Hg adsorption experiments indicated that the dissolved Hg concentration was controlled by the dissolved organic carbon (DOC) concentration. The adsorption isotherms suggest that Hg is more mobile in the O horizon of the unburned Hadlock watershed because of higher solubility of organic carbon resulting in higher DOC concentrations in that watershed.Methylmercury concentrations, however, were consistently higher in the burned Cadillac O horizon (0.20±0.13 ng Hg g^-1 dry weight) than in the unburned Hadlock O horizon (0.07±0.07 ng Hg g^-1 dry weight). Similarly, Cadillac soils possessed a higher MeHg content (0.30 g MeHg ha^-1) than Hadlock soils (0.16 g MeHg ha^-1). The higher MeHg concentrations in Cadillac soils may reflect generally faster rates of microbial metabolism due to more rapid nutrient cycling and higher soil pH in the deciduous forest. In this research, we have shown that the amount of MeHg is not a function of the total pool of Hg in the watershed. Indeed, MeHg was inversely proportional to total Hg, suggesting that landscape factors such as soil pH, vegetation type, or land use history (e.g., fire) may be the determining factors for susceptibility to high Hg in biota.     

ACCUMULATION OF CADMIUM AND ZINC FROM DIFFUSE IMMISSION ON ACID SANDY SOILS,AS A FUNCTION OF SOIL COMPOSITION

Sandy soils, in the border area of Belgium and the Netherlands (the Kempen region), are heavily contaminated by atmospheric deposition of cadmium and zinc from nearby smelters. Groundwater contamination by leaching from these low retention soils is subject of study. There are reports of high cadmium and zinc concentrations in groundwater in the area, but in most cases the direct sources are unknown. In an attempt to predict present or future risk of groundwater contamination by soil leaching, metal binding processes (retardation) were studied that are specific for these soil types under the existing acidifying conditions. From four fields nine contaminated profiles were sampled and analyzed for cadmium and zinc. Average concentrations of 131 μg g^-1 zinc and 1.6 μg g^-1 cadmium with maximum values of 2989 μg g^-1 respectively 16.3 μg g^-1 were found. In addition pH and contents of organic matter, aluminium, iron, and manganese were determined. The relative importance of these soil parameters for metal retardation is derived from the profiles. The data show that organic matter is the most important soil component for binding cadmium and zinc. Adsorption of cadmium and zinc on aluminium, iron and manganese (hydr) oxides appears to be of minor importance at low pH (<5.5).     

Persistent Organic Pollutants in Singapore's Coastal Marine Environment: Part II,Sediments

Polycyclic aromatic hydrocarbons (PAHs) can enter the marine environment from a variety of anthropogenic sources. As some PAHs are known or suspected carcinogens and mutagens, their potential hazard to human health and the natural environment warrants investigation. This is the first reported study on the prevalence and concentration of PAHs in marine sediments from Singapore's coastal environment, and accompanies the report by Basheer et al. (2003) on the measurement of persistent organic pollutants (POPs) in seawater. The concentration of 16 PAH, classified as USEPA priority pollutants were analysed in sediments from 22 sample stations located within the northeastern and southwestern regions of Singapore's marine waters. The total PAH concentration varied between 15.22 μg g^-1 and 82.41 μg g^-1 in the northeastern region and between 13.63 μg g^-1 and 84.92 μg g^-1in the southwestern region. The highest concentration of total PAH i.e. 84.92 μg g^-1 was recorded at a site adjacent to a petrochemical refinery. Among the sixteen individual PAHs, chrysene, indeno[1,2,3-cd]pyrene and benzo[a]anthracene were most prevalent in the sediments. The relatively low kinetic/thermodynamic isomer ratios for PAHs suggest that PAHs of pyrogenic origin are predominant in Singapore's coastal environment. The distribution of higher molecular weight i.e. (4–5 ring) individual PAHs corresponded to mixture profiles typical of those originating from high temperature combustion processes subjected to photolytic degradation during long-range atmospheric transportation. A comparison of total PAH concentration data for sediments collected from Singapore relative to those reported for other countries indicates a moderate level of PAH contamination in Singapore's coastal marine sediments.     

Trace metals concentrations in marine organisms from the coastal areas of Bahrain,Arabian Gulf

A total of 162 fish and shellfish samples representing important species have been collected from different coastal areas of Bahrain in the Arabian Gulf, and analyzed for lead, cadmium, mercury, and arsenic using electrothermal atomic absorption spectrophotometric method. The dverall mean levels for Pb, Cd, Hg and As in fish samples were 0.132, 0.032, 0.084 and 1.7 µg g^?1 wet weight, respectively, whereas for shellfish they were 0.149, 0.045, 0.042 and 3.61 µg g^?1 wet weight. These values indicate higher levels of metals in shellfish when compared with fish, except for mercury, and reveal that generally the levels of metals in these organisms are lower than existing guidelines, except for arsenic. The provisional tolerable weekly intake of Pb, Cd, Hg and As through fish was estimated to be 0.7, 0.17, 0.45 and 9 µg kg^?1 bodyweight per week, respectively. Our results did not reveal a clear pattern regarding variations of metals concentration between areas and species.     

Quantitative Evaluation of Atmospheric Deposition Flux of Mercury in Sediments within the City of Juarez,Mexico

The city of Juarez is located in the northernpart of Mexico at the border with the United States. This reportinvestigates the mercury (Hg) contribution from atmosphericsources and its accumulation in the Juarez area estimated bymeasuring the concentration of total Hg in sediments of a smallartificial pond located within the urban area of the Juarez-ElPaso metroplex. The pond is intermittently fed by Hg-free(concentration below detection levels) groundwater from a privatewell, with sporadic input of storm overflow from a nearby watertreatment facility. Total Hg concentrations in the sedimentsvaried between 20 (detection level value) and 454 μg kg^-1 dry wt, with an average value of 202.8±153.9 μg kg^-1. Physicalcharacteristics of the sediments varied among samples, althoughnot as drastically as their Hg content did. Among the sedimentparameters, the organic matter content correlated best with theHg content. A simplified balance of total mercury supply in theaquatic system revealed a sediment Hg flux of 336.0 μg m^-2 yr^-1 and a maximum Hg atmospheric flux of 119 mg m^-2 yr^-1.Our unexpected finding of significant concentrations of Hg in thetreated wastewater and in the water column stresses the need ofcareful consideration of all possible sources in determiningmercury atmospheric deposition flux.     

Co-inoculation of indigenous Pseudomonas oryzihabitans and Bradyrhizobium sp. modulates the growth, symbiotic efficacy, nutrient acquisition, and grain yield of soybean

Soil microbes play a vital role in improving plant growth, crop productivity, and soil health through solubilization of essential nutrients. Present investigation was conducted to access the efficacy of Bradyrhizobium sp. LSBR-3 and the indigenous phosphate-solubilizing Pseudomonas oryzihabitans LSE-3 in improving the symbiosis, nutrient accumulation, and yield of soybean. The isolate LSE-3, selected on the basis of phosphate solubilization, was screened for beneficial traits, antagonistic activities, and pathogenicity. The levels of indole acetic acid production (50.34 ±2.35 μg mL^-1), phosphate solubilization (184.4 ±7.4 mg L^-1), biofilm formation (optical density at 560 mm, 1.389 6 ±0.04), siderophore production (121.46 ±1.61 μg mL^-1), and 1-aminocyclopropane-1-carboxylate deaminase activity (0.51 ±0.07 mmol α-ketobutyrate μg^-1 protein h^-1) were significantly higher with the dual inoculants (LSBR-3 and LSE-3) than with the single inoculant LSBR-3. The plant growth-promoting traits of single and dual inoculants were evaluated for the synergistic effects on soybean under field conditions. Soybean plots treated with LSBR-3 + LSE-3 exhibited improvement in seed germination, plant height, plant biomass, and chlorophyll content compared with the uninoculated control. Dual inoculant treatments resulted in significantly higher symbiotic efficacy evidenced by increased nodulation (40.0 ±0.75 plant^-1), nodule biomass (188.52 ±6.29 mg plant^-1), and leghemoglobin content (11.02 ±0.83 mg g^-1 fresh nodule), and significantly increased activities of phosphatase (75.16 ±3.17 and 58.77 ±6.08 μg p-nitrophenol g^-1 h^-1 for alkaline and acid phosphatase, respectively) and dehydrogenase (32.66 ±1.92 μg triphenylformazan g^-1 h^-1) compared with the control. Dual inoculation with LSBR-3 and LSE-3 enhanced the uptake of macro- and micronutrients, reduced Na content in shoots, and resulted in 10.85% higher grain yield and ca. US$96.80 ha^-1 higher profit compared with the control. This is the first report on the effectiveness of combined inoculation of LSE-3 and LSBR-3 in promoting the growth, symbiotic efficacy, and yield of soybean for sustainable agriculture.     

Spatial Variation and Correlations of Mercury Levels in the Terrestrial and Aquatic Components of a Wetland Dominated Ecosystem: Kejimkujik Park,Nova Scotia,Canada

This study investigates the ranges and spatial variation ofmercury in various media in the wetland ecosystems ofKejimkujik Park, Nova Scotia. Mercury concentrations infive-year-old yellow perch (age based on regression analysesof existing data) ranged from 0.12–0.72 μgg^-1(wet weight basis) in 24 lakes. Mercury concentrations inred maple ranged from 5 to 41 ng g^-1 and levels inwhite pine ranged from 5 to 58 ng g^-1, dry weight.Concentrations of total mercury were found to besignificantly higher in epiphytic lichens (maximum of 660 ngg^-1) and in feather mosses (maximum of 395 ng g^-1)compared to vascular species. The soil Ah horizon exhibitsthe highest concentrations for both mercury and gold, withmaximum values of 466 and 42.8 ng g^-1 respectively;whereas the C-horizon appears to host the most Zn (maximum209.9 μg g^-1). Lake water pH and dissolved organic carbon (DOC) were thevariables most highly correlated with mercury in lake watersand yellow perch. No correlations were observed betweenmercury in terrestrial components and mercury in yellowperch; however, mercury in yellow perch was correlated withP in leaf tissues of both red maple and white pine. Theimportance of understanding linkages between terrestrial andaquatic ecosystems is emphasized through this study.     

Pyro- and tripoly-phosphate contents of sediments

A method to determine pyrophosphate (PP) and tripolyphosphate (TPP) in sediments was developed. Sediment was extracted with 2% EDTA + 0.1 M NH₄F followed by a second extract of 2% EDTA + 1 N NaOH. Orthophosphate (OP), PP, and TPP were separated by anion exchange chromatography, the fractions collected, and P determined after extraction into isobutanol. The limit of detection of the method was 0.5 μg P g^?1 sediment. Fourteen sediments were tested and the highest TPP found was 1.8 μg P g^?1 sediment. Thirteen of the sediment samples contained less than 1 μg P g^?1 as TPP. Only three of the 14 samples contained more than 1 μg P g^?1 as PP. The highest level of PP (8.5 μg P g^?1) was found in sediment from an animal waste lagoon. Estimates of error and reproducibility were made from analysis of samples with added PP and TPP. The error for samples containing 36.9 μg P g^?1 as PP was ± 7.6, and for TPP at 12.3 μg P g^?1 the error was ± 3.3. The values for PP and TPP were underestimated by 6 and 36%, respectively.     

Methylmercury Production and Accumulation in Sediments and Soils of an Amazonian Floodplain – Effect of Seasonal Inundation

This study investigated the spatialand seasonal variations of MeHg concentrations andburdens of different sediments and soils of theTapajós river floodplain, one of the majorclear-water tributaries of the Amazon. The smallfloodplain of the Tapajós is typical of Amazonianfloodplain ecosystems. The studied lakes are borderedby inundated forest (igapó), while floatingmacrophyte mats (Paspalum sp.) develop at themargin of lakes during the flooded season. During theflood, we observed very low MeHg concentrations in theopen water lake sediments (<0.5 ng g^-1 d.w or<0.5 μg m^-2 cm^-1 d.w.) as compared to thesemi-aquatic sediments of the macrophyte zone (0.2–1.4 ng g^-1 d.w or 1–3 μg m^-2cm^-1 d.w.) and the igapó semi-terrestrial soils (0.2–3 ng g^-1 d.w or2–12 μg m^-2 cm^-1 d.w.). The litter horizon fromthe igapó soils showed the highest value of MeHg(4–8 ng g^-1 d.w.) representing 0.2–2 μg m^-2cm^-1 d.w. at the sediment/water interface during theaquatic phase. The inundation had no effect on theconcentrations and burdens of MeHg in the sediment ofthe central part of the lake. The inundation had aclear effect on the methylation of Hg at the surfaceof semi-aquatic shoreline sediments (macrophyte zone)and semi-terrestrial forest soils, where MeHgconcentrations and burdens appeared to be 3 timesgreater following inundation. In all cores, total Hgconcentrations follow those of Fe and Aloxy-hydroxides, whereas the MeHg concentrations arelinked to organic matter quality and quantity. It issuggested that organic matter and inundation controlMeHg production and accumulation at the benthicinterface. These results confirm previousobservations, in the same study area, of net²⁰³Hg methylation potentials. The fresh andlabile organic matter in the litter of the igapóforest appears as the most important factor leading tosignificant enrichment of MeHg in these particularterrestrial/aquatic sedimentary environments.     

The Source of Anthropogenic Heavy Metals in Fluvial Sediments of a Rural Catchment: Coxs River,Australia

A serious health scare involving thesupply of drinking water to Sydney, Australia hasrecently focussed attention on the environmentalstatus of river catchments of the main reservoir, LakeBurragorang. Although the Coxs River – a majorcatchment of Lake Burragorang – comprises mainlyforests and grazing land, it supports a moderate sizedtown, power stations and coal mines. The heavy metal content of stream-bed sedimentscharacterises environmental impact in this ruralcatchment and sources of contamination. Sediment in acreek flowing through a country town (population 12 000) is markedly enriched in Cr, Pb and Zn (3×, 18×and 52×, respectively) over background, probably dueto a long history of metal-based industry. The highestCu, Pb and Zn concentrations (204, 332 and2460 μg g^-1, respectively) in fluvialsediment in the town are, however associated withdischarges from a sewage treatment plant. Twocoal-based power stations in the catchment contributeconsiderable Cu and Ni (maximum concentrations 562 and157 μg g^-1, respectively) to ambient fluvialsediments, possibly from cooling towers and coalstorage areas. The highest Co and Cr concentrations(113 and 490 μg g^-1) in fluvial sediments ofthis catchment are associated with coal-miningactivities. Selective extraction indicates that about50% of the anthropogenic fraction may bebioavailable, whereas sequential extraction proceduressuggest that <25% is associated with the easilyexchangeable/adsorbed phase.Two dams restrict the migration of heavy metals downthe Coxs River and sediment discharging into LakeBurragorang is low in metals.     

Heavy Metal Content of Plant Species along Nilüfer Stream in Industrialized Bursa City, Turkey

The Paraíba do Sul river is located in one of the most developed part of Brazil and receives many organic and industrial effluents directly affecting the ichthyofauna. Concentration of four heavy metals (Cu, Cr, Zn and Pb) were determined in two tissues (muscle and gonads) of three abundant fish species from different trophic levels (Oligosarcus hepsetus—carnivore, Geophagus brasiliensis—omnivore and Hypostomus luetkeni—detritivore) between November 2002 and April 2003. The aim was to test the hypothesis that the trophic level and the proximity from impacted areas influence levels of contamination and to assess if these species are indicators of large-scale habitat quality. Levels of heavy metals were detected by Total Reflection X-ray Fluorescence with Synchrotron Radiation (SR-TXRF) at the Brazilian National Synchrotron Radiation Laboratory (LNLS). Generally, gonads showed higher metal concentration than muscles, except for Cr. All examined metals, but Cu, exceeded the maximum permitted concentration (mpc) by the Brazilian legislation for human consumption in at least one tissue. O. hepsetus (carnivore) showed the highest contamination levels, followed by G. brasiliensis (omnivore) and H. luetkeni (detritivore). The middle-upper segment, which encompasses large urban areas, showed the highest levels of metal contamination in most cases. O. hepsetus showed the highest levels of contamination in muscles for Pb in the middle-upper river segment (7.98?±?3.73; mpc?=?2.0 μg g^?1) and for Cr in the upper (5.53?±?0.05; mpc?=?0.10 μg g^?1) and middle-upper (4.20?±?0.85; mpc?=?0.10 μg g^?1) segments, which indicates that human population should avoid to consume these fishes species from these segments of the Paraíba do Sul river.     

Mercury in the Aquatic Environment of the Village of Caimito at the Mojana Region,North of Colombia

During May–September 1999, several aquatic environmental samples were collected from the village of Caimito, in the San Jorge River basin area, state of Sucre (Colombia), and analyzed for total mercury (T-Hg). Mean T-Hg concentration in sediments from surrounded marshes was 0.155 ± 0.016 g Hg/g. Low Hg concentrations were found in the phytoplanktivorous fish species Prochilodus magdalenae (0.087 ± 0.01 g Hg/g), while four-fold greater concentrations were found in all the carnivorous species. In average, T-Hg concentrations for fish samples did not exceed the limit consumption level (0.5 g Hg/g). However, risk assessment based on the hazard index suggested that the consumption of 0.1 kg per day of carnivorous fish could increase the risk of mercury poisoning in local population.