Trace metal behaviour in the Conwy estuary,North Wales

The distribution of trace metals Zn, Ni, Mn, Fe, Cu, Pb, Cd and Cr between suspended particulate matter (SPM) and water in the Conwy estuary, North Wales, has been studied in three surveys in 1998. Dissolved Cu and Mn showed some monthly variations. Most of the dissolved trace metals displayed a negative association with salinity, indicating rivers as a major source of inputs for them. Particulate Zn, Mn and Fe showed a decreasing concentration seaward, whilst the levels of Ni, Cu, Cr and Pb increased with salinity. SPM concentration was the most important variable significantly related to trace metal concentrations in SPM, with an inverse relationship between the two parameters. This was explained by the relative enrichment of trace metals in fine particles at low SPM concentrations and relative depletion of trace metals in coarse particles at high SPM concentrations. Particulate Zn, Mn and Pb were dominated by the fraction available to acetic acid (non-detrital), whilst particulate Ni, Fe and Cr were dominated by the fraction available to nitric acid (detrital). The partition coefficient of trace metals between SPM and water declined with increasing SPM concentration, consistent with the so-called "particle concentration effect". Such a phenomenon may be explained by the presence of fine particles (including colloids) enriched with trace metals at low SPM concentrations, and the salinity-induced desorption.     

Metal concentrations in Kandalaksha Bay, White Sea (Russia) following the spring snowmelt

Elevated concentrations of dissolved and particulate Cd, Cu, Pb and Zn have been determined in the waters of Kandalaksha Bay (White Sea, Russia), following the ice melt in the spring of 2000. Dissolved metal maxima in the surface waters were observed at some stations and concentrations generally decreased with depth. The suspended particulate matter (SPM) comprised a non-lithogenic fraction in the range 12-83%, and had elevated metal concentrations that showed no trend with depth or salinity and was compositionally distinct from the sediments. A log-linear relationship existed between the concentrations of metals in sediments and in SPM and their respective Al concentrations, indicating a source of metal-rich particles, with low Al content, to the Bay. The results suggest that Kandalaksha Bay has been impacted by industrial activity on the Kola Peninsula and that restricted water exchange will hinder its recovery from metal contamination.     

Challenges with tracing the fate and speciation of mine-derived metals in turbid river systems: implications for bioavailability

The fast-flowing and highly turbid Lagaip River (0.5–10 g/L suspended solids) in the central highlands of Papua New Guinea receives mine-derived metal inputs in both dissolved and particulate forms. Nearest the mine, metal concentrations in suspended solids were 360, 9, 90, 740 and 1,300 mg/kg for As, Cd, Cu, Pb and Zn, while dissolved concentrations were 2.7, 0.6, 3.1, 0.1 and 25 μg/L, respectively. This creates a significant metal exposure source for organisms nearer the mine. However, because the Lagaip River is diluted by a large number of tributaries, the extent to which mine-derived metals may affect biota in the lower catchments is uncertain. To improve our understanding of the forms of potentially bioavailable metals entering the lower river system, we studied the partitioning and speciation of metals within the Lagaip River system. Dissolved and particulate metal concentrations decreased rapidly downstream of the mine due to dilution from tributaries. As a portion of the particulate metal concentrations, the more labile dilute acid-extractable forms typically comprised 10–30 % for As and Pb, 50–75 % for Cu and Zn, and 50–100 % for Cd. Only dissolved Cd, Cu and Zn remained elevated relative to the non-mine-impacted tributaries (<0.03, 0.5 and 0.3 μg/L), but the concentrations did not appreciably change with increasing dilution downriver. This indicated that release of Cd, Cu and Zn was likely occurring from the more labile metal phases of the mine-derived particulates. Chelex-labile metal analyses and speciation modelling indicated that dissolved copper and lead were largely non-labile and likely complexed by naturally occurring organic ligands, while dissolved cadmium and zinc were predominantly present in labile forms. The study confirmed that mine-derived particulates may represent a significant source of dissolved metals in the lower river system; however, comparison with water quality guidelines indicates the low concentrations would not adversely affect aquatic life.     

Stomata and plant water relations: does air pollution create problems?

Suspended particulate matter (SPM), sandy sediments and Asiatic clams were collected at seven sites along 150 km of the Río de la Plata coast to assess the magnitude of trace metal pollution in the area. Metal concentrations in SPM (Cu: 7.4-109; Cr: 75-408; Mn: 525-1341 microg(-1)), sediments (Cr: 16-27; Zn: 26-99; Mn: 221-489 microg(-1)) and bivalves (Cd: 0.5-1.9; Ni: 1.3-6.4; Cr: 1.3-11; Mn: 15-81; Cu: 28-89; Zn: 118-316 microg g(-1)) are comparable to those reported for other moderately polluted world rivers. Cu levels in Asiatic clams are among the highest, similar to those reported for heavily polluted sites. SPM Cu and Cr concentrations displayed a clear geographical trend with values increasing with proximity to major urban centers. Sediments showed a less clear pattern possibly due to their coarse nature (>98% sand) and higher proportion of mineral-associated residual metals. The clams showed a complex pattern due to the variability introduced by size-related factors and the natural dynamics of SPM in the estuary. Cr and Mn showed an apparent reverse industrial trend with higher concentrations in clams collected at distant stations near the turbidity maximum zone, possibly reflecting enhanced particle retention. Cu, Cd and Ni showed no clear geographical pattern, whereas Zn increased in the clams collected in the most industrialized area. A significant relationship with clam size was observed for Cu (positive) and Zn (negative) suggesting different physiological requirements for both metals with age. A principal component analysis confirmed these geographical and size-related trends.     

Impact of industrial and mine drainage wastes on the heavy metal distribution in the drainage basin and estuary of the Sado River (Portugal)

This paper presents results from a survey of the heavy metal distribution in sediments in the drainage basin and estuary of the Sado River (Portugal). In the drainage basin, heavy metals originate mostly from pyrite outcrop erosion and mining activities (Cd, Zn, Cu and locally Hg, Pg), and also from crust erosion (Sn, Ni, Ti, Zr). These sources are not correlated with the particulate organic carbon (POC) and so the metals are thought to be in inorganic forms in this area. Anthropogenic heavy metal sources (urban and industrial) are found in the lower estuary (Sn, Cd, Hg, Zn, Pb and Cu) along with high POC concentrations. In this zone, these metals are thought to be strongly adsorbed onto organic particles. Furthermore, organo-metallic species are likely to be present, as demonstrated in the case of Sn, since methyl- and butyl-tin species were detected in sediments from this area. This suggests the need for the detection of organo-metallic species to understand the heavy metal geochemical cycles. No long-term changes in metal concentrations are found in sediment cores, except in the middle estuary (Zn, Cu) due to the development of mining activities on an industrial scale in the 1860s.     

The asiatic clam, Corbicula fluminea: An indicator of trace metal pollution in the Shatt al-Arab River, Iraq

The potential of Corbicula fluminea (Müller) as an indicator for trace metal pollution was investigated. Laboratory experiments show that Corbicula has the capability to accumulate and eliminate trace metals in relation to their concentrations in ambient water. However, an effect of individual size was observed. Seasonal variations in the concentrations of Cd, Co, Cu, Fe, Mn, Ni, Pb, V and Zn in Corbicula, water and particulate matter from the upper section of the Shatt al-Arab River were studied. Sediment samples were also analysed. Metal concentrations were determined by means of flameless AAS. It was found that Corbicula is a suitable bio-indicator for monitoring of trace metal pollution. Metal concentrations in Corbicula tissues correlated better with their corresponding concentrations in particulate matter than with the dissolved form. Temporal variations in metal concentrations were attributed to several factors, including fluctuations in metal inputs, and in geochemical and hydrological characteristics of the water. The obtained levels of trace metals were comparable to those reported for control sites, with the exception of Cd, Cu and Zn whose concentrations were higher in both Corbicula and particulate matter.     

Octanol-solubility of dissolved and particulate trace metals in contaminated rivers: implications for metal reactivity and availability

The lipid-like, amphiphilic solvent, n-octanol, has been used to determine a hydrophobic fraction of dissolved and particulate trace metals (Al, Cd, Co, Cu, Mn, Ni, Pb, Zn) in contaminated rivers. In a sample from the River Clyde, southwest Scotland, octanol-solubility was detected for all dissolved metals except Co, with conditional octanol-water partition coefficients, D(ow), ranging from about 0.2 (Al and Cu) to 1.25 (Pb). In a sample taken from the River Mersey, northwest England, octanol-solubility was detected for dissolved Al and Pb, but only after sample aliquots had been spiked with individual ionic metal standards and equilibrated. Spiking of the River Clyde sample revealed competition among different metals for hydrophobic ligands. Metal displacement from hydrophobic complexes was generally most significant following the addition of ionic Al or Pb, although the addition of either of these metals had little effect on the octanol-solubility of the other. In both river water samples hydrophobic metals were detected on the suspended particles retained by filtration following their extraction in n-octanol. In general, particulate Cu and Zn (up to 40%) were most available, and Al, Co and Pb most resistant (<1%) to octanol extraction. Distribution coefficients defining the concentration ratio of octanol-soluble particle-bound metal to octanol-soluble dissolved metal were in the range 10(3.3)-10(5.3)mlg(-1). The presence of hydrophobic dissolved and particulate metal species has implications for our understanding of the biogeochemical behaviour of metals in aquatic environments. Specifically, such species are predicted to exhibit characteristics of non-polar organic contaminants, including the potential to penetrate the lipid bilayer. Current strategies for assessing the bioavailability and toxicity of dissolved and particulate trace metals in natural waters may, therefore, require revision.     

Metals in a northern Nile Delta lake: water,suspended particulates,sediments, and biota

Lake Edku is one of the important fishing areas in the Nile Delta. It is exposed to different quantities of serious pollutants in particular metals. To overall appraise the risk and status of metals in the lake, a comprehensive study of total concentrations of cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), and zinc (Zn) in sediments and spatial-temporal variations of these metals in the dissolved and suspended particulates, and some tissues of Tilapias niloticus, was conducted from ten sampling sites during 2016. Results showed that none of the investigated metals exceeded the limits considered as hazardous for aquatic life in water. The highest concentrations of Cd, Cu, Ni, and Zn were observed in suspended particulate matter, which may precipitate on the surface of the sediments. Potential ecological risk analysis of the majority of the investigated metals in the sediment indicated that Lake Edku posed a low ecological risk. The estimated values of all metals in tissues of Tilapia niloticus were below the international permissible limits. Moreover, the potential risk of metals to human via the consumption of Tilapia niloticus was estimated using the weekly intake levels, which was lower than the WHO’s safe provisional tolerant weekly intake levels. These results prove the importance of performing measurements of contaminants in various compartments of Lake Ecosystem including sediment, biota, and suspended particulate matter for proper management.     

Modification of trace metal accumulation in the green mussel Perna viridis by exposure to Ag, Cu, and Zn

To examine the Cd, Hg, Ag, and Zn accumulation in the green mussel Perna viridis affected by previous exposure to Cu, Ag, or Zn, the dietary metal assimilation efficiency (AE) and the uptake rate from the dissolved phase were quantified. The mussel's filtration rate, metallothionein (MT) concentration, and metal tissue burden as well as the metal subcellular partitioning were also determined to illustrate the potential mechanisms underlying the influences caused by one metal pre-exposure on the bioaccumulation of the other metals. The green mussels were pre-exposed to Cu, Ag, or Zn for different periods (1-5 weeks) and the bioaccumulation of Cd, Hg, Ag, and Zn were concurrently determined. Pre-exposure to the three metals did not result in any significant increase in MT concentration in the green mussels. Ag concentration in the insoluble fraction increased with increasing Ag exposure period and Ag ambient concentration. Our data indicated that Cd assimilation were not influenced by the mussel's pre-exposure to the three metals (Cu, Ag, and Zn), but its dissolved uptake was depressed by Ag and Zn exposure. Although Hg assimilation from food was not affected by the metal pre-exposure, its influx rate from solution was generally inhibited by the exposure to Cu, Ag, and Zn. Ag bioaccumulation was affected the most obviously, in which its AE increased with increasing Ag tissue concentration, and its dissolved uptake decreased with increasing tissue concentrations of Ag and Cu. As an essential metal, Zn bioaccumulation remained relatively stable following the metal pre-exposure, suggesting the regulatory ability of Zn uptake in the mussels. Zn AE was not affected by metal pre-exposure, but its dissolved uptake was depressed by Ag and Zn pre-exposure. All these results indicated that the influences of one metal pre-exposure on the bioaccumulation of other metals were metal-specific due to the differential binding and toxicity of metals to the mussels. Such factors should be considered in using metal concentrations in mussel's soft tissues to evaluate the metal pollution in coastal waters.     

Distribution and coassociations of trace elements in soft tissue and byssus of Mytilus galloprovincialis relative to the surrounding seawater and suspended matter of the southern part of the Korean Peninsula

The concentrations of Cd, Co, Cu, Cr, Fe, Hg, Mn, Ni, Pb, Sn, Ti and Zn were analyzed by AAS, ICP MS and AFS in soft tissues and byssal threads of Mytilus galloprovincialis from Masan Bay and Ulsan Bay, Korea. Spatial variations in metal concentrations were found. The levels of Cd, Pb, Hg, Cu, Zn, Co and Mn were very high in the mussels from Ulsan Bay (Sts. U1, U2) and comparable with elevated concentrations of these elements in Mytilus sp. reported to date for other geographical areas. Seasonal differences in some metal concentrations were also observed. These variations may be caused by factors such as: a large difference in seawater temperature, food supply for the mussel population and/or freshwater runoff of particulate metal to the coastal water and weight changes brought about by gonadal development and the release of sexual products. Pb, Cu, Zn, Co, Ni, Fe and Mn were more enriched in byssal threads than in the soft tissues, hence the byssus seems to be more sensitive in reflecting the availabilities of trace metals in the ambient waters. Concentrations of trace metals varied with respect to the size of mussels and season, depending on many factors like sexual development, and seawater temperature, etc. The levels of some trace metals in seawater, especially in suspended matter were correlated significantly with those in soft tissues and byssal threads. There were spatial variations in metal concentrations in the soft tissue and byssus attributed to different sources of trace elements located near the sampling sites. There were significant relationships between concentrations of some metals (Cd, Cu, Pb, and Zn) in mussel soft tissues and byssal threads and suspended matter. This suggests that M. galloprovincialis can be used as a sensitive biomonitor for the availabilities of trace elements in the coastal waters off Korea.     

An 'artificial mussel' for monitoring heavy metals in marine environments

A new chemical sampling device, artificial mussel (AM), has been developed for monitoring metals in marine environments. This device consists of a polymer ligand suspended in artificial seawater within a Perspex tubing, and enclosed with semi-permeable gel at both ends. Laboratory and field experiments were carried out to examine the uptake of five metals (Cd, Cr, Cu, Pb and Zn) by the AM. Uptake of metals by AM was proportional to the exposure metal concentrations, and the AM was able to accumulate the ASV labile fractions of metals. Uptake and release of the metals of AM are similar to those of the mussel Perna viridis, but less affected by salinity and temperature. Field studies demonstrated that the AM can not only provide a time-integrated estimate of metals concentrations, but also allows comparisons of metal levels in different environments and geographical areas beyond the natural distribution limits of biomonitors.     

Trace metal speciation and bioavailability in urban soils

Urban soils often contain concentrations of trace metals that exceed regulatory levels. However, the threat posed by trace metals to human health and the environment is thought to be dependent on their speciation in the soil solution rather than the total concentration. Three inactive railway yards in Montréal, Québec, were sampled to investigate the speciation and bioavailability of Cd, Cu, Ni, Pb and Zn. Soil solutions were obtained by centrifuging saturated soil pastes. In the soil solutions, up to 59% of the dissolved Cd was in its free ionic form. For Cu, Pb and Zn, organic complexes were the predominant species. Over 40% of Ni was present as inorganic complexes if the solution pH exceeded 8.1. Multiple regression analyses showed that pH and total metals in soil were significantly correlated with the activities of free metal ions, except for Cd(2+), which only had a weak correlation with soil pH. Free, dissolved and total soil metals were tested for their ability to predict metal uptake by plants in the field. However, none of these metal pools were satisfactory predictors. The results indicated that in these urban soils, trace metals were mainly in stable forms and bioavailability was extremely low.     

Potentially toxic metals in ombrotrophic peat along a 400 km English-Scottish transect

Four samples of ombrotrophic peat were collected from each of 10 upland locations in a transect from the southern Pennines to the Highland Boundary Fault, a total distance of ca. 400 km. Bulk compositions and other properties were determined. Total contents of Al and heavy metals (Ni, Cu, Zn, Cd, Pb) were determined following digestion with hydrofluoric acid, and concentrations of metals extractable with dilute nitric acid were also measured. Supernatants obtained from aqueous extractions of the peat samples were analysed for pH, major cations and anions, dissolved organic carbon and dissolved metals, and concentrations of free metal ions (Al(3+), Ni(2+), etc.) were estimated by applying a chemical speciation model. Both total and HNO(3)-extractable metal concentrations varied along the transect, the highest values being found at locations close to industrial and former mining areas. The HNO(3)-extractable soil metal contents of Ni, Cu and Cd were appreciably lower than lowest-observed-effect-concentrations (LOEC) for toxicity towards microorganisms in acid, organic rich soils. However, the contents of Zn at two locations, and of Pb at five locations exceeded LOECs, suggesting that they may be exerting toxic effects in the peats. Soil solution concentrations of free heavy metal ions (Cu(2+), Zn(2+), Cd(2+), Pb(2+)) were substantially lower than LOECs for toxicity towards vascular plants, whereas concentrations of Al(3+) were near to toxic levels at two locations.     

Separate dissolved and particulate trace metal budgets for an estuarine system: an aid for management decisions

The sources and sinks of dissolved and particulate Pb, Cu and Zn were determined for the main basin of Puget Sound to understand the effect man has had on metal concentrations in both the water column and in the sediments. Municipal, industrial and atmospheric sources contributed about 66% of the total Pb added to the main basin of Puget Sound during the early 1980s. Advective inputs were the major sources of total Cu and Zn (approximately 40%) while riverine and erosional sources contributed about 30%. The discharge of the particle-bound trace metals from rivers minimized the influence of particulate anthropogenic sources, which constituted 50%, 23% and 18% of the total particulate Pb, Cu and Zn inputs, respectively. While advective transport was the major source of dissolved Cu and Zn (approximately 60% of all dissolved inputs), industrial, municipal and atmospheric inputs contributed about 85%, 30% and 38% of the dissolved Pb, Cu and Zn inputs, respectively. The sources of dissolved and particulate Cu and Zn were comparable with the sinks within the errors of the analyses indicating their quasi-conservative nature. Advection removed about 60% of the total Cu and Zn added to the main basin while 40% was deposited in the sediments of Puget Sound. Because of this quasi-conservative nature of Cu and Zn, anthropogenic inputs of Cu and Zn were dispersed from the system more than they were contained within main basin sediments. About 75% of the dissolved Pb discharged into the main basin of Puget Sound was lost from the dissolved phase and was balanced by a similar gain in the particulate phase. Because of this extensive scavenging and the effective retention of particles within the main basin, about 70% of the total Pb added to the main basin was retained within its sediments. These separate mass balances have utility in management decisions because they show the relative contributions from different sources and demonstrate whether the influences of dissolved and particulate inputs are reflected solely in the water column or the sediments, respectively.     

Dissolved heavy metal concentrations of the Kralkızı, Dicle and Batman dam reservoirs in the Tigris River basin,Turkey

Water samples were collected at monthly intervals during 1 year of monitoring from Kralk?z?, Dicle and Batman dam reservoirs in the Tigris River basin to assess the concentrations of dissolved heavy metals and to determine their spatial and seasonal variations. The results indicated that dissolved heavy metal concentrations in the reservoirs were very low, reflecting the natural background levels. The lowest total metal concentrations in the three dam reservoirs were detected at sampling sites close to the dam wall. However, the highest total concentrations were observed at sites, which are located at the entrance of the streams to the reservoirs. Fe, Cr and Ni were the most abundant elements in the reservoirs, whereas Cd and As were the less abundant. The mean concentrations of dissolved metals in the dam reservoirs never exceeded the maximum permitted concentrations established by EC (European Community), WHO and USEPA drinking water quality guidelines. All heavy metals showed significant seasonal variations. As, Cd, Cr, Cu, Fe, Ni and Pb displayed higher values in the dry season, while higher values for Zn in the wet season. Cluster analysis grouped all ten sampling sites into three clusters. Clusters 1 and 2, and cluster 3 corresponded to relatively low polluted and moderate polluted regions, respectively. PCA/FA demonstrated the dissolved metals in the dam reservoirs controlled by natural sources.     

Resuspension of contaminated field and formulated reference sediments Part I: Evaluation of metal release under controlled laboratory conditions

In aquatic systems where metal contaminated sediments are present, the potential exists for metals to be released to the water column when sediment resuspension occurs. The release and partitioning behavior of sediment-bound heavy metals is not well understood during resuspension events. In this study, the release of Cd, Cu, Hg, Ni, Pb and Zn from sediments during resuspension was evaluated using reference sediments with known physical and chemical properties. Sediment treatments with varying quantities of acid volatile sulfide (AVS), total organic carbon (TOC), and different grain size distributions were resuspended under controlled conditions to evaluate their respective effects on dissolved metal concentrations. AVS had the greatest effect on limiting release of dissolved metals, followed by grain size and TOC. Predictions of dissolved concentrations of Cd, Ni, Pb and Zn were developed based on the formulated sediment Σ_metal/AVS ratios with Σ_metal being the total sediment metal concentration. Predicted values were compared to measured dissolved metal concentrations in contaminated field sediments resuspended under identical operating conditions. Metal concentrations released from the field sediments were low overall, in most cases lower than predicted values, reflecting the importance of other binding phases. Overall, results indicate that for sulfidic sediments, low levels of the study metals are released to the dissolved phase during short-term resuspension.     

The content of metals in organisms of various trophic levels in freshwater and brackish lakes on the coast of the sea of Japan

Environmental Science and Pollution Research - The content of trace metals (Pb, Zn, Cd, Cu) was examined in water—in the suspended and dissolved forms, in the suspended material and organisms...     

Metal concentrations and mobility in marine sediment and groundwater in coastal reclamation areas: a case study in Shenzhen, China

The concentrations of metals in the buried marine sediment and groundwater were differently affected by land reclamation. Nine metals (V, Cr, Mn, Co, Ni, Cu, Zn, Cd and Pb) in sediment and coastal groundwater from reclamation areas in Shenzhen were examined. The gradually decreased concentrations (V, Cr, Mn, Ni, Cu, Zn) in sediment and relatively higher concentrations (V, Cr, Mn, Co, Ni, Cu and Cd) in groundwater within reclamation areas were observed. The increase of V, Cr, Mn, Ni, Cu and Cd concentrations in groundwater within reclamation areas subsequently after land reclamation should be resulted from the mobilization of these metals accumulated in the sediment. These metals appear to be easily mobilized from solid phase to solution phase after reclamation. The physico-chemical changes such as reduction in pH and salinity in water environment induced by land reclamation appear to be responsible for metal mobility in the sediment-groundwater system.     

Laboratory evaluation of zero-valent iron to treat water impacted by acid mine drainage

This study examines the applicability and limitations of granular zero-valent iron for the treatment of water impacted by mine wastes. Rates of acid-neutralization and of metal (Cu, Cd, Ni, Zn, Hg, Al, and Mn) and metalloid (As) uptake were determined in batch systems using simulated mine drainage (initial pH 2.3-4.5; total dissolved solids 14000-16000 mgl(-1)). Metal removal from solution and acid-neutralization occurred simultaneously and were most rapid during the initial 24 h of reaction. Reaction half-lives ranged from 1.50+/-0.09 h for Al to 8.15+/-0.36 h for Zn. Geochemical model results indicate that metal removal is most effective in solutions that are highly undersaturated with respect to pure-metal hydroxides suggesting that adsorption is the initial and most rapid metal uptake mechanism. Continued adsorption onto or co-precipitation with iron corrosion products are secondary metal uptake processes. Sulfate green rust was identified as the primary iron corrosion product, which is shown to be the result of elevated [SO(4)(2-)]/[HCO(3)(-)] ratios in solution. Reversibility studies indicate that zero-valent iron will retain metals after shifts in redox states are imposed, but that remobilization of metals may occur after the acid-neutralization capacity of the material is exhausted.     

Challenges in understanding the sources of bioaccumulated metals in biota inhabiting turbid river systems

Bioaccumulation of As, Cd, Cu, Pb and Zn by Macrobrachium prawns was observed to occur in the Strickland River downstream of a gold mine at Porgera, Papua New Guinea. This was despite the total metal concentrations of waters and sediments indicating no difference from reference sites within tributaries. To provide information on potential sources and bioavailability of metals to prawns, an extensive range of analyses were made on waters, suspended solids, deposited sediments and plant materials within the river system. Dissolved metal concentrations were mostly sub-micrograms per liter and no major differences existed in concentrations or speciation between sites within the Strickland River or its tributaries. Similarly, no differences were detected between sites for total or dilute acid-extractable metal concentrations in bed sediments and plant materials, which may be ingested by the prawns. However, the rivers in this region are highly turbid and the dilute acid-extractable cadmium and zinc concentrations in suspended solids were greater at sites in the Strickland River than at sites in tributaries. The results indicated that mine-derived inputs increased the proportion of these forms of metals or metalloids in the Strickland River. These less strongly bound metals and metalloids would be more bioavailable to the prawns via the dietary pathway. The results highlighted many of the difficulties in using routine monitoring data without information on metal speciation to describe metal uptake and predict potential effects when concentrations are low and similar to background. The study indicated that the monitoring of contaminant concentrations in organisms that integrate the exposure from multiple exposure routes and durations may often be more effective for detecting impacts than intermittent monitoring of contaminants in waters and sediments.