Chromium, nickel, copper, zinc, arsenic, selenium, cadmium, mercury and lead in Dutch fishery products 1977-1984

Within the framework of a monitoring programme, carried out by order of the Dutch Ministry of Agriculture and Fisheries, fishery products from Dutch coastal waters, estuaries and inland waters were investigated for the presence of trace elements. In this report the results for the period 1977-1984 are presented. The investigated fishery products included sole, cod, plaice, herring, eel, pike-perch, shrimp and mussel, in which the elements chromium, nickel, copper, zinc, arsenic, selenium, cadmium, mercury and lead were determined. The results are compared with data from the literature and with the trace element levels usually found in other animal products. The daily intake of trace elements in The Netherlands through the consumption of Dutch fishery products is calculated.     

Total mercury,methylmercury and selenium in mercury polluted areas in the province Guizhou,China

The province of Guizhou in Southwestern China is currently one of the world's most important mercury production areas. Emissions of mercury from the province to the global atmosphere have been estimated to be approximately 12% of the world total anthropogenic emissions. The main objective of this study was to assess the level of contamination with Hg in two geographical areas of Guizhou province. Mercury pollution in the areas concerned originates from mercury mining and ore processing in the area of Wanshan, while in the area of Quingzhen mercury pollution originates from the chemical industry discharging Hg through wastewaters and emissions to the atmosphere due to coal burning for electricity production. The results of this study confirmed high contamination with Hg in soil, sediments and rice in the Hg mining area in Wanshan. High levels of Hg in soil and rice were also found in the vicinity of the chemical plant in Quingzhen. The concentrations of Hg decreased with distance from the main sources of pollution considerably. The general conclusion is that Hg contamination in Wanshan is geographically more widespread, due to deposition and scavenging of Hg from contaminated air and deposition on land. In Quingzhen Hg contamination of soil is very high close to the chemical plant but the levels reach background concentrations at a distance of several km. Even though the major source of Hg in both areas is inorganic Hg, it was observed that active transformation of inorganic Hg to organic Hg species (MeHg) takes place in water, sediments and soils. The concentration of Hg in rice grains can reach up to 569 microg/kg of total Hg of which 145 microg/kg was in MeHg form. The percentage of Hg as MeHg varied from 5 to 83%. The concentrations of selenium can reach up to 16 mg/kg in soil and up to 1 mg/g in rice. A correlation exists between the concentration of Se in soil and rice, indicating that a portion of Se is bioavailable to plants. No correlation between Hg and Se in rice was found. Exposure of the local population to Hg may occur due to inhalation of Hg present in air (in particular in Hg mining area) and consumption of Hg contaminated food (in particular rice and fish) and water. Comparison of intake through these different routes showed that the values of Hg considerably exceed the USA EPA Reference Concentration (RfC) for chronic Hg exposure (RfC is 0.0004 mg/m(3)) close to the emission sources. Intake of Hg through food consumption, particularly rice and fish, is also an important route of Hg exposure in study area. In general, it can be concluded that the population mostly at risk is located in the vicinity of smelting facilities, mining activities and close to the waste disposal sites in the wider area of Wanshan. In order to assess the real level of contamination in the local population, it is recommended that biomonitoring should be performed, including Hg and MeHg measurements in hair, blood and urine samples.     

Levels of antimony,arsenic, cadmium,copper, lead,mercury, selenium,silver, tin and zinc in bone tissue of industrially exposed workers

The contents of the elements antimony, arsenic, cadmium, copper, lead, mercury, selenium, silver, tin and zinc in bone tissue from autopsy specimens of the femur of workers who had been exposed to a large number of metals in a smeltery and refinery in Northern Sweden as well as of a control group have been quantitatively assayed.The analytical techniques used were atomic absorption spectrophotometry, neutron activation analysis and particle induced X-ray emission analysis (PIXE) in a proton microprobe. Increased levels of lead in the bone tissue of exposed workers compared to a non-exposed control group were observed. The median level of lead in the group of exposed workers exceeded the corresponding value of the control group about 5 times.Using the proton microprobe in the PIXE-mode, concentration profiles of copper, lead and zinc were examined within the Haversian system of the bone samples.     

Intakes of copper,zinc, cadmium,tin, iron,nickel and arsenic in a population exposed to lead from water

Adult diets obtained from a population in Ayr, Scotland, U.K., known to be exposed to lead from water were analysed for arsenic, cadmium, copper, iron, nickel, tin and zinc to assess the intake of these elements. With few exceptions, the concentration of each element varied little from diet to diet, and therefore the range of intakes varied only in proportion to the weights of the diets. With the exception of nickel, the difference between the observed average dietary intakes of the metals studied and those expected on the basis of a nationwide Total Diet Study is largely accounted for on the basis of the difference between the weights of the duplicate diet and the weight for the Total Diet Study.     

Levels of cadmium, mercury and lead in otter and mink faeces from the United Kingdom

Over 500 faeces of otter (Lutra lutra) from Britain, with a small sample from northeast Greece, were analyzed for Cd, Hg and Pb. A small sample of mink (Mustela vison) faeces was also analyzed. Mean concentrations of metals (mg kg-1 dry weight) in otter faeces ranged from 1.53 to 3.97 Cd, 0.25 to 0.74 Hg and 12.4 to 20.9 Pb. Mink faeces generally contained less Cd and Hg, but more Pb. Metal concentrations in faeces may reflect both natural and anthropogenic sources. Estimates of daily Cd and Pb intake were made from faecal concentrations and these were in good agreement with concentrations in major fish prey. The estimates of daily Cd and Pb intake are high, but nevertheless most samples came from thriving otter populations. The value of faecal analysis in assessing metal burdens during surveys of otters is discussed.     

Mercury, arsenic, cadmium, chromium lead, and selenium in feathers of pigeon guillemots (Cepphus columba) from Prince William Sound and the Aleutian Islands of Alaska

Arsenic, cadmium, chromium, lead, manganese, mercury and selenium were analyzed in the feathers of pigeon guillemots (Cepphus columba) from breeding colonies in Prince William Sound and in the Aleutian Islands (Amchitka, Kiska) to test the null hypothesis that there were no differences in metal levels as a function of location, gender, or whether the birds were from oiled or unoiled areas in Prince William Sound. Birds from locations with oil from the Exxon Valdez Oil Spill in the environment had higher levels of cadmium and lead than those from unoiled places in Prince William Sound, but otherwise there were no differences in metal levels in feathers. The feathers of pigeon guillemots from Prince William Sound had significantly higher levels of cadmium and manganese, but significantly lower levels of mercury than those from Amchitka or Kiska in the Aleutians. Amchitka had the lowest levels of chromium, and Kiska had the highest levels of selenium. There were few gender-related differences, although females had higher levels of mercury and selenium in their feathers than did males. The levels of most metals are below the known effects levels, except for mercury and selenium, which are high enough to potentially pose a risk to pigeon guillemots and to their predators.     

Lead, cadmium, mercury and selenium in Greenland marine biota and sediments during AMAP phase 1

Lead, cadmium, mercury and selenium levels in the Greenland marine environment from the first phase of the AMAP are presented. Samples were collected in 1994-1995 covering four widely separated regions in Greenland. Samples included sediments, soft tissue of blue mussel; and liver of polar cod, shorthorn sculpin, glaucous gull, Iceland gull and ringed seal. Concentrations of lead were found to increase with the size of blue mussel, but not with the age of gulls or ringed seal. Both cadmium and mercury concentrations were found to increase with the size/age of all species. Selenium concentrations decreased with increasing size of blue mussel, but increased with the age of gulls and ringed seal. Element levels found are within the range of those found in previous studies in Greenland. Relative to global background levels, lead levels must be considered low, whereas levels of cadmium, mercury and selenium in Greenland marine biota are high. Significant differences in element levels in sediments and biota among regions in Greenland were seen in several cases. There was a tendency for the highest lead and mercury concentrations to be found in east Greenland, whereas the highest cadmium concentrations were found in central west Greenland. However, the geographical differences among the media did not show a consistent pattern.     

Pools and fluxes of mercury and methylmercury in two forested catchments in Germany

Mercury (Hg) and methylmercury (CH3Hg+) are global pollutants, but little information is available on rates of atmospheric input, distribution and mobility in soils and catchments of central Europe. The objectives of this study were to investigate input and output fluxes of these compounds in a deciduous and a coniferous catchment in NE Bavaria (Germany), and to estimate pools and mobility of total Hg (Hgtot) and CH3Hg+ at the catchment scale. Bulk precipitation, throughfall, litterfall and runoff were collected biweekly from April 1998 to April 1999. Several soil profiles were sampled to estimate pools of Hg compounds in the catchments. In both catchments highest contents of Hgtot were found in the Oa layer of the forest floor (up to 500 ng g(-1)) and the soil storage of Hgtot calculated for a soil depth of 60 cm was approximately 890 g ha(-1) in the coniferous and 190 g ha(-1) in the deciduous catchment. Highest contents of CH3Hg+ in upland soils were observed in the Oi layer of the forest floor, and soil storage of CH3Hg+ was 4.35 g ha(-1) in the coniferous and 0.59 g ha(-1) in the deciduous catchment. The annual total deposition of Hgtot (total deposition not measured directly but calculated from throughfall and litterfall) was 541 mg ha(-1) year(-1) in the coniferous and 618 mg ha(-1) year(-1) in the deciduous catchment. Total deposition rates of CH3Hg+ were 3.5 and 2.6 mg ha(-1) year(-1). The contribution of litterfall to the total deposition of Hgtot and CH3Hg+ was 55% in the deciduous catchment. In the coniferous catchment, the contribution of litterfall to total deposition was only 29% for Hgtot, but 55% for CH3Hg+. By far the largest proportion of the deposited CH3Hg+ and Hgtot remained in the catchments (85% in the coniferous, 95% in the deciduous). As compared to remote Swedish catchments, deposition and output via runoff of Hgtot, were higher, but deposition and output of CH3Hg+ were lower in our catchments. In contrast to other studies, the annual budget revealed no differences in the mobility between the two species at the catchment scale. However, temporal patterns of the runoff fluxes and converse gradients of CH3Hg+ and Hgtot contents in the forest floor indicated differences in mobility on shorter time scales.     

The distribution of mercury, cadmium and lead between water and suspended matter in the Loire Estuary as a function of the hydrological regime

We examined Hg, Pb, Cd in filtered water and suspended sediments from the Loire Estuary. The metal concentration in both varies widely and is a function of hydrodynamic and hydraulic parameters. We classified them according to geographical repartition, salinity, tidal state etc. A laboratory study, monitored under the same conditions of salinity, showed the affinity of suspended material for Hg, Pb and Cd. The results of the two studies, in vivo and in vitro emphasize the importance of salinity in the metal repartition between water and sediments.     

Total arsenic, lead, and cadmium levels in vegetables cultivated at the Andean villages of northern Chile

Various vegetables (broad beans, corn, potato, alfalfa and onion) were sampled in northern Chile, Antofagasta Region. They are the basis of human nutrition in this region and of great relevance to human health. This region is characterized by volcanic events (eruptions, thermal springs, etc.). Most of the vegetables cultivated in this area enter the local markets for a population of approximately 4000 people, whose ancestors were mainly atacame?os and quechuas (local indigenous people). The cadmium and lead in these foods was determined by differential pulse anodic stripping voltammetry (DPASV). Results indicate that the highest concentration of Pb and Cd are in the potato skin, while the edible part of the potatoes contained a lower concentration of these metals. The INAA analyses of As in the vegetables from Socaire and Talabre, two towns located close to active volcanoes (e.g. Lascar), show a very high As content: 1850 microg/kg in corn (Socaire) and 860 microg/kg in potatoes (+ skin) (Talabre). These values exceed the National Standard for arsenic (500 microg/kg) by approximately 400% and 180%, respectively. In general, the data show a concentration of Pb greater than Cd with the potential for some vegetables to accumulate heavy metals, The values, expressed in fresh weight, vary from 0.2 to 40 microg/g for Cd and from 0.6 to 94 microg/g for Pb. These concentration intervals, except that of arsenic, are within the recommended standards in the Food Sanitary Regulation (Decree 977), which, expressed as fresh weight, must be equal to or smaller than 500 microg/kg for Pb. There is no legal standard for Cd.     

Consumption of homegrown products does not increase dietary intake of arsenic, cadmium, lead, and mercury by young children living in an industrialized area of Germany

The dietary intake of arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) was studied among young German children with different food consumption behaviour (consumption of own grown foodstuffs and of products from the supermarket). The study area comprised an industrialized and a rural area of West Germany. Dietary intake of contaminants was measured by the duplicate method according to the WHO guideline. A total 588 duplicate portions were collected daily from 84 individuals between May and September 1998. Intake of food groups was calculated from dietary records. Determination of As, Cd, Hg, and Pb was performed following high-pressure digestion of lyophilized samples by atomic absorption spectrometry (AAS). Geometric mean weekly intake [microg/(kgbw x week)] was as follows: As 1.4, Cd 2.3, Hg 0.16, and Pb 5.3. Geometric mean intake corresponded to the percentage of the provisional tolerable weekly intake (PTWI) as follows: As 9.7%, Cd 32%, Hg 3.3%, Pb 21%. As and Hg intake were mainly influenced by fish consumption. The amount of cereals and bakery wares mainly determined the Cd and Pb intake. Children living in the industrialized area with a substantial food consumption of own grown vegetables or products from domestic animals products had no increased dietary intake of the metals.     

An inter-laboratory trial of the unified BARGE bioaccessibility method for arsenic, cadmium and lead in soil

The Bioaccessibility Research Group of Europe (BARGE) has carried out an inter-laboratory trial of a proposed harmonised in vitro physiologically based ingestion bioaccessibility procedure for soils, called the Unified BARGE Method (UBM). The UBM includes an initial saliva phase and simulated stomach and intestine compartments. The trial involved the participation of seven laboratories (five European and two North American) providing bioaccessibility data for As (11 samples), Cd (9 samples) and Pb (13 samples) using soils with in vivo relative bioavailability data measured using a swine model. The results of the study were compared with benchmark criteria for assessing the suitability of the UBM to provide data for human health risk assessments. Mine waste and slag soils containing high concentrations of As caused problems of poor repeatability and reproducibility which were alleviated when the samples were run at lower soil to solution ratios. The study showed that the UBM met the benchmark criteria for both the stomach and stomach & intestine phase for As. For Cd, three out of four criteria were met for the stomach phase but only one for the stomach & intestine phase. For Pb two, out of four criteria were met for the stomach phase and none for the stomach & intestine phase. However, the study recommends tighter control of pH in the stomach phase extraction to improve between-laboratory variability, more reproducible in vivo validation data and that a follow up inter-laboratory trial should be carried out.     

Lead, zinc, cadmium, mercury, selenium and copper in Greenland caribou and reindeer (Rangifer tarandus)

Samples of caribou and reindeer muscle (127 samples) and liver (126 samples) were collected from four locations during two seasons plus 3 years in Greenland. The levels of lead, zinc, cadmium, mercury, selenium, and copper were determined, and analyzed in relation to location, two seasons, age and year of sampling. The lead concentrations (geometric mean) ranged from below the detection limit to 0.007 microgram/g wet weight (wet wt.) in muscle and from 0.027 to 0.926 microgram/g wet wt. in liver. Zinc geometric mean concentrations ranged from 17.5 to 39.6 micrograms/g wet wt. in muscle and from 23.2 to 31.7 micrograms/g wet wt. in liver. For cadmium, the geometric mean concentrations were at, or below the detection limit in muscle, while concentrations in liver ranged from 0.121 to 0.695 microgram/g wet wt. Mercury levels ranged from 0.003 to 0.043 microgram/g wet wt. in muscle and from 0.040 to 0.618 microgram/g wet wt. in liver. Selenium concentration levels in muscle ranged from 0.030 to 0.252 microgram/g wet wt., and from 0.085 to 0.984 microgram/g wet wt. in liver. Copper levels in muscle ranged from 2.09 to 3.60 micrograms/g wet wt., and from 21.8 to 71.0 micrograms/g wet wt. in liver. Mercury concentrations were higher than those found at lower latitudes in Norway and Canada, especially in Isortoq in southern Greenland. Selenium levels were also high compared to other Arctic regions. Concentrations of lead, zinc, cadmium and copper are similar to those reported in caribou from Canada and Norway. Concentrations of elements generally decreased in the following order: Isortoq > Akia > Itinnera > Kangerlussuaq, and there was only found minor variation in the annual levels during 3 years in Itinnera. Late winter levels were generally significantly higher than early winter levels especially in the lichen-rich localities, and it is suggested that the availability of lichens as winter forage is the key determining the level of elements. Accordingly, when using caribou and reindeer as monitoring organism, knowledge of winter forage is very important for interpretation of results.     

Accumulation of cadmium, mercury and lead by vegetables following long-term land application of wastewater

Several vegetable species which are part of the daily diet of Tehran's population were examined for potential uptake of cadmium, mercury and lead from soil following longterm land application of wastewater. The three study sites located in the south of Tehran have been receiving untreated domestic wastewater by flood irrigation for many years. Elevated levels of cadmium, mercury and lead were found in the upper layers of soil. Examined vegetables accumulated some cadmium, mercury and lead from treated soils, but accumulation was relatively low. Due to the low concentration of these metals and their poor absorption from the gastrointestinal tract (excluding absorption of lead in children), it does not appear that the short-term consumption of these contaminated vegetables would produce acute toxicity. However, since absorption of dietary lead in children is relatively high and children are very sensitive to lead toxicity, short-term consumption of these vegetables plus other environmental sources of these metals in Tehran may produce chronic effects in children.     

Geographical differences of zinc, cadmium, mercury and selenium in polar bears (Ursus maritimus) from Greenland

Muscle, liver, and kidney tissues from 100 polar bears (Ursus maritimus), caught in the Avanersuaq area, north-west Greenland, and Ittoqqortoormiit area, central-east Greenland, were analysed for zinc, cadmium, mercury and selenium. The zinc concentrations in muscle and liver were higher than in kidney. Mean zinc concentrations ranged from 19.7 to 76.0 micrograms/g (all data are presented as geometric means on a wet wt. basis). The presented cadmium concentrations by area and age groups were all low in muscle and in many cases below the detection limit (range: < 0.015-0.048 microgram/g). Cadmium concentrations were intermediate in liver (range: 0.120-1.98 micrograms/g) and highest in kidney tissue (range: 2.16-28.9 micrograms/g). Mercury was likewise lowest in muscle tissue (range: 0.034-0.191 microgram/g). Mercury concentration ranged quite similarly in liver and kidney tissue (liver range: 2.13-22.0 micrograms/g; kidney range: 2.87-32.0 micrograms/g). The selenium concentration increased from muscle (range: < 0.2-0.452 microgram/g) over liver (range: 1.20-9.80 micrograms/g) to kidney (range: 2.34-13.9 micrograms/g). No age accumulation was found for zinc. A weak increase was found for selenium, whereas cadmium and mercury clearly accumulated with age. An exception was mercury concentrations in muscle tissue, where no clear pattern was observed. Polar bears had significantly lower cadmium concentrations than ringed seals from the same area in all three tissues. Likewise mercury was significantly lower in the muscle tissue of polar bears than in ringed seals, whereas liver and kidney concentrations were higher. Biomagnification factors are provided for different tissues and age groups. Tissue ratios are given for different age groups and metals to enable a rough extrapolation from one tissue to another. Tissue ratios for cadmium, selenium and for mercury vary up to a factor of 6 with age. No significant differences could be detected between the elements analysed in bears from two management zones in north-west Greenland. This finding is in agreement with the genetic pattern in the two areas. In central-east Greenland, however, cadmium, selenium, and some of the mercury concentrations in polar bears from the southern area were higher than from the northern area, indicating that the east Greenland area represents two different ecological regions with different polar bear populations. Geographical differences between polar bears from north-west and east Greenland were only found for mercury and cadmium in liver tissue, where the concentrations were highest in bears from north-west Greenland. The geographical trend of increasing cadmium concentrations in polar bear liver tissue from west to east, which has been found previously in Canada, could be extended to cover north-west Greenland as well. East of this region a decrease was found. Mercury concentrations in polar bear liver tissue showed an increase from Svalbard over east and north-west Greenland, peaking in bears from south-west Melville Island. A marked decrease was found west of Melville Island, and the lowest concentrations were found in the Chukchi Sea.     

A case-control study on the relationship of hearing function and blood concentrations of lead, manganese, arsenic, and selenium

Previous research has suggested that heavy metals may be ototoxic in humans, and further, that a reversal of this toxicity may occur when the trace element selenium is present, through formation of metals selenide complexes. This study investigates the relationship between hearing thresholds and blood concentrations of four elements (selenium, lead, manganese, and arsenic) in factory workers, Taiwan. We conducted a hospital-based case-control study with 294 individuals who received the periodic occupational health examination in the Kaohsiung Medical University Hospital. All control subjects (n=173) had normal hearing. Case subjects (n=121) had average hearing threshold over 25 decibels (dB). In all individuals, blood concentrations of lead (Pb), manganese (Mn), arsenic (As), and selenium (Se) were determined by an ICP-MS and standard methods. Possible confounding factors were collected by a questionnaire and medical history reviews. Relationships were analyzed by multiple linear regressions and mixed model. Geometric means of Pb, Mn, As, and Se were determined for case subjects (107.2, 5.5, 17.8, and 229.1 microg/L) and controls (38.9, 5.4, 15.5, and 234.4 microg/L). In our regression models, age, lead and selenium concentrations (logarithmic transformed) were associated significantly with hearing thresholds. In addition, we found that the selenium was inversely associated with hearing thresholds, and may be an antagonist to lead ototoxicty. The present study demonstrated a dose-response relationship between blood lead and hearing thresholds, after adjusting other potential confounders in multiple regressions. In addition, we found that selenium may be a protection element on auditory function. However, additional studies will be needed to clarify the mechanisms of lead toxicity and selenium on the hearing function in molecular and genetic levels.     

Cadmium,zinc, copper,arsenic, selenium and mercury in seabirds from the Barents Sea: levels,inter-specific and geographical differences

Trace elements Cd, Zn, Cu, As, Se and Hg were analysed in muscle and liver of Brünnich's guillemot, Common guillemot, Puffin, Black guillemot, Little auk, Razorbill, Common eider, King eider, Glaucous gull, Herring gull, Black-legged kittiwake, Northern fulmar and Arctic tern collected in 1991-1992 at the main breeding colonies in the Barents Sea. The highest levels of the most toxic elements Cd and Hg were found in birds nesting north of Spitsbergen. Extremely high levels of As were detected in tissues of all seabird species collected at colonies in Chernaya Guba (Novaya Zemlya), where nuclear tests were carried out in the 1960s. In general, levels of all of the trace elements in the Barents Sea seabirds were similar or lower in comparison with those reported for the same seabird species from the other Arctic areas. Data on metallothionein concentrations in different seabird species need to be collected in order to understand the mechanism of bioaccumulation and possible toxic effects of trace elements in Arctic seabirds.     

Total arsenic, lead, cadmium, copper, and zinc in some salt rivers in the northern Andes of Antofagasta, Chile

Lake Velenje is located in one of the most polluted regions in Slovenia, the Salek Valley. The major source of pollution in the valley is the coal-fired thermal power plant in Sostanj (STPP, capacity 775 MW). It has five separate units. All units have electrostatic precipitators for fly ash removal. Unit 4 also has installed a wet flue gas desulfurisation system (FGD system). Total mercury (THg) concentrations were measured in lignite, slag and ash samples from the STPP. In flue gas, different mercury species (THg, MeHg, Hg2+, Hg0) were determined separately for unit 4 and unit 5 which use different flue gas cleaning technology. Mercury and methyl mercury (MeHg) concentrations were also measured in lake water at different depths, in inflow water, outflow water, rain, snow and lake sediments in order to establish the influence of the power plant on the lake. Most mercury emitted from the power plant is in the elemental form. The ratio between oxidised and elemental Hg depends on the flue gas cleaning technology. Mass balance calculations have been performed for the STPP. The results show that the major sources of mercury in Lake Velenje are wet deposition and lake inflows. Total and MeHg concentrations in the water column are very low and can be compared to other non-contaminated freshwater lakes in the world.     

A comparison of the non-essential elements cadmium, mercury, and lead found in fish and sediment from Alaska and California

Concentrations of three non-essential elements (cadmium (Cd), mercury (Hg), and lead (Pb)) were determined in sediment and fish from several locations in Alaska (AK) and California (CA) and used to examine differences in bioaccumulation within and between geographic locations. We analyzed tissue (liver, muscle, gill, and stomach contents) from white croaker (Genyonemus lineatus) and English sole (Pleuronectes vetulus) in California and flathead sole (Hippoglossoides elassodon) in Alaska, in addition to several species of invertebrates (mercury only). As found in previous work on arsenic (As) [Meador et al., 2004], Cd in fish liver exhibited a negative correlation with sediment concentrations. No such correlations were found for Hg and Pb when fish liver and sediment were compared; however, these metals did exhibit a positive relationship between liver and organic carbon normalized sediment concentrations, but only for the CA sites. Sediment concentrations of Hg at the AK sites were lower than those for the CA sites; however, AK invertebrates generally bioaccumulated more Hg than CA invertebrates. Conversely, Hg bioaccumulation was higher in CA fish. Even though ratios of total metal/acid volatile sulfides (AVS) in sediment were one to two orders of magnitude higher for the AK sites, bioaccumulation of these elements was much higher in fish from the CA sites. Bioaccumulation factors ([liver]/[sediment]) (BAFs) were highest at relatively clean sites (Bodega Bay and Monterey), indicating that elements were more bioavailable at these sites than from more contaminated locations. The observation of high BAFs for As in fish from Alaska and low BAFs for the California fish, but reversed for Cd, Hg, and Pb in this study, implies that differences in fish species are less important than the unique geochemical features at each site that control bioavailability and bioaccumulation and the potential sources for each element. Additionally, these data were also used to examine the metal depletion hypothesis, which describes the inverse relationship between elements and organic contaminants documented in some monitoring studies. Our results suggest that the enhanced bioavailability of the metals at some uncontaminated sites is the main determinant for the inverse correlation between metal and organic contaminants in tissue.     

Effect of cadmium, lead and arsenic on the oviposition, hatching and embryonic survival of Biomphalaria glabrata

Biomphalaria glabrata is a widespread freshwater gastropod mollusc. The easy aquaculture of these organisms allow its use as an accessible tool for contamination bioassays. B. glabrata showed marked metabolic responses when exposed to cadmium, lead and arsenic. Those responses could also affect the reproduction of the snails. Taking into account this hypothesis, B. glabrata were exposed for 96 h (acute laboratory bioassays) to different concentrations of cadmium (0.1, 0.05 and 0 mg/L), lead (0.5, 0.1, 0.05 and 0 mg/L) and arsenic (0.5, 0.1, 0.05 and 0 mg/L). Snails were removed from the aquaria while eggs were left in the same contaminant concentrations. The effect of the assayed toxicants on snail reproduction was registered as the alterations of the total number of laid eggs (TNLE), hatching time and embryonic survival.At 0.10 mg/L cadmium significantly decreased the TNLE (p < 0.05) and no embryos survived. The lowest assayed level (0.05 mg/L) of cadmium, delayed the hatching time twice when it was compared with the control group (p < 0.01).Lead decreased the TNLE at 0.5 mg/L level (p < 0.01). The other assayed doses (0.05 and 0.10 mg/L) also decreased embryonic survival significantly (p < 0.05 and p < 0.01 respectively) and extended twice the time to hatching (p < 0.01). The 0.50 mg/L level killed all embryos.Arsenic at all studied concentrations decreased the TNLE (p < 0.05) while the hatching time was increased by 50%. Embryo survival only decreased at the highest level (0.5 mg/L) of arsenic assayed.In summary, the acute exposure (96 h) to cadmium lead and arsenic, altered the reproduction of B. glabrata, modifying the TNLE, hatching time and embryonic survival.