Metals In Pore Water Research Articles

Indirect effects of climate change on zinc cycling in sediments: The role of changing water levels.

Increased variability in lake and river water levels associated with changing climate could impact the fate and effects of metals in redox-sensitive sediments through the alteration of microbial communities and of acid-base and redox chemistry. The objective of the present study was to determine the influence of water level fluctuation on metal speciation in porewater and predict environmental risk to high-carbonate systems. Using experimental microcosms with sediments collected from 4 metal-contaminated coastal freshwater wetlands in Michigan, USA, we conducted water level fluctuation experiments. Porewater and sediment metals (Ca, Cu, Fe, Mg, Mn, Ni, Zn) and important metal binding phases (iron-oxide speciation, acid-volatile sulfide) were quantified. In a short-term drying (seiche) experiment, there were decreases in all porewater metals after inundation of saturated sediments. During a drought experiment, re-inundation of oxidized sediments increased porewater Cu, Zn, Mg, Ca for most sites. Porewater Zn increased after inundation to levels exceeding the US Environmental Protection Agency threshold for chronic toxicity. These data show that the dissolution of metal carbonates and metal sulfates contributes to metal release after re-flooding and indicate that we might expect increased ecological risk to organisms present in drought-sensitive regions where altered hydroperiods are likely to increase metal bioavailability. Environ Toxicol Chem 2017;36:2456-2464. © 2017 SETAC.

Bioavailability and Toxicity of Copper, Manganese, and Nickel in Paronychiurus kimi (Collembola), and Biomarker Discovery for Their Exposure.

Bioavailability and toxicity of Cu, Mn, and Ni in Paronychiurus kimi were investigated after 28days of exposure to OECD artificial soil spiked with these metals. Uptake and effect of Cu, Mn, and Ni on the reproduction of P. kimi were related to different metal fractions (water-soluble, 0.01M CaCl2-extractable or porewater metal concentrations). Cu and Mn concentrations in P. kimi increased with increasing Cu and Mn concentrations in the soil, while Ni contents in P. kimi reached a plateau at a concentration higher than 200mg/kg in soil. Both uptake and juvenile production related well to different metal fractions, suggesting that these metal fractions are suitable for assessing bioavailability and toxicity of metals in P. kimi. When toxicity for reproduction was compared, as reflected by EC50 values, the order of metal toxicity varied depending upon how exposure concentration was expressed. Moreover, the results of proteomic analysis showed that several proteins involved in the immune system, neuronal outgrowth, and metal ion binding were up-regulated in P. kimi following short-term (7days) exposure to sublethal level (corresponding to 50% of the EC50) of Cu, Mn, or Ni, respectively. This suggests that the ecotoxicoproteomic approach seems to be a promising tool for early exposure warnings below which significant adverse effects are unlikely to occur. This study demonstrated that a combination of chemical and biological measures can provide information about metal bioavailability and toxicity to which P. kimi has been exposed.

An investigation of the effects of elevated phosphorus in water on the release of heavy metals in sediments at a high resolution

Excessive phosphorus (P) input plays an important role on the release of heavy metals in sediments under the eutrophic environment. In this study, a microcosm experiment with 40-day incubation using homogenized sediments was performed to investigate this aspect at a millimeter resolution. Diffusive gradient in thin films (DGT) and dialysis (Peeper) techniques were employed to simultaneously measure labile and dissolved P, Pb, Cd, Zn, Co and Ni in sediments at a millimeter scale, respectively. The results showed that an increase of water P from 0.02mgL−1 to 0.20 and 2.4mgL−1 generally led to intensified decrease of DGT-labile metals from the 10th to 20th days after the onset of incubation. The decrease in dissolved metals in pore water also appeared on the 20th day. The degree of decrease in the five metals was in the order of Pb>Cd>Zn>Co>Ni, which has a negative correlation with the solubility constants (Ksp) of each metal-P precipitate. This indicated that the negative effect was caused by the precipitation of metal P. On the 40th day during incubation, the concentrations of DGT-labile metals had different increasing pattern compared to those on the 20th day. The extent of metal recovery was positively correlated with the change of desorption rate constant (k−1) and negatively correlated with the change in the characteristic time (Tc) to reach equilibrium from DGT perturbation derived from DGT-induced fluxes in sediments (DIFS) modeling. This suggested that the recovery of metal lability from elevated water P was a result of the increased releases of metals from sediment solids.

Toward a Quality-Controlled and Accessible Pitzer Model for Seawater and Related Systems

We elaborate the need for a quality-controlled chemical speciation model for seawater and related natural waters, work which forms the major focus of SCOR Working Group 145. Model development is based on Pitzer equations for the seawater electrolyte and trace components. These equations can be used to calculate activities of dissolved ions and molecules and, in combination with thermodynamic equilibrium constants, chemical speciation. The major tasks to be addressed are ensuring internal consistency of the Pitzer model parameters (expressing the interactions between pairs and triplets of species, which ultimately determines the calculated activities), assessing uncertainties, and identifying important data gaps that should be addressed by new measurements. It is recognised that natural organic matter plays an important role in many aquatic ecosystems, and options for including this material in a Pitzer-based model are discussed. The process of model development begins with the core components which include the seawater electrolyte and the weak acids controlling pH. This core model can then be expanded by incorporating additional chemical components, changing the standard seawater composition and/or broadening the range of temperature and pressure, without compromising its validity. Seven important areas of application are identified: open ocean acidification; micro-nutrient biogeochemistry and geochemical tracers; micro-nutrient behaviour in laboratory studies; water quality in coastal and estuarine waters; cycling of nutrients and trace metals in pore waters; chemical equilibria in hydrothermal systems; brines and salt lakes.

Distribution, diffusive fluxes, and toxicity of heavy metals and PAHs in pore water profiles from the northern bays of Taihu Lake.

Pore water plays a more significant role than do sediments in pollutant cycling dynamics. Also, concentrations of pollutants in pore water provide important information about their bioavailability or eco-toxicity; however, very few studies have focused on this topic. In this study, four duplicate sediment cores from three typical northern bays as well as the central part of Taihu Lake were collected to investigate the distribution, diffusive fluxes, and toxicity of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in pore water profiles, which will be good in understanding the mobility and toxicity of these toxic pollutants and achieving better environmental management. The diffusive fluxes of heavy metals across the sediment-water interface was estimated through Fick's First Law, and the toxicity of heavy metals and PAHs in pore water was assessed by applying a water quality index (interstitial water toxicity criteria unit, IWCTU) and a hazard index (HI), respectively. The average concentrations of Cr, Cu, Ni, Pb, and Zn in surface pore water were 18.8, 23.4, 12.0, 13.5, and 42.5μgL-1, respectively. Also, concentrations of the selected heavy metals in both overlying water and pore water from Taihu Lake were all lower than the standard values of the environmental quality standards for surface water. The concentrations as the pore water depth increased, and the highest detected concentrations of heavy metals were recorded between 3 and 5cm below the sediment surface. The average diffusive fluxes of these metals were 27.3, 24.8, 7.03, 7.81, and -3.32μg (m2 day)-1, respectively, indicating export from sediment into overlying water, with the exception of Zn. There was a potential risk of toxicity, mainly from Pb and Cu, indicating that heavy metals in pore water had slight to moderate impact on sediment-dwelling organisms by values of the IWCTU and the Nemeraw index. The total PAH concentrations in pore water were higher than those in overlying water, and such gradient implies a potential flux of PAHs from pore water to overlying water. The average HI value of PAHs in surface pore water showed no or low ecological risk. While there may be occasional risk due to the HI values in some sites being greater than 1, the dominant contributors were carcinogenic PAHs. Because of their potential biological impact, heavy metals and PAHs and their comprehensive toxic effects in pore water should be given priority attention to keep the safety of Taihu Lake.

Influence of silver nanoparticles on heavy metals of pore water in contaminated river sediments

Despite the increasing knowledge on the discharge of silver nanoparticles (AgNPs) into the environment and their potential toxicity to microorganisms, the interaction of AgNPs with heavy metals remains poorly understood. This study focused on the effect of AgNPs on heavy metal concentration and form in sediment contaminated with heavy metals from the Xiangjiang River. The results showed that the concentration of Cu, Zn, Pb and Cd decreased and then increased with a change in form. The changes in form and concentrations of heavy metals in pore water suggested that Cu and Zn were more likely to be affected compared to Pb and Cd. The concentrations of Hg in sediment pore water in three AgNPs-dosed containers, increased greatly until they reached their peaks at 4.468 ± 0.133, 4.589 ± 0.235, and 5.083 ± 0.084 μg L−1 in Bare AgNPs, Citrate AgNPs and Tween 80 AgNPs, respectively. The measurements of Hg concentrations in the sediment pore water, combined with SEM and EDX analysis, demonstrated that added AgNPs stabilized in pore water and formed an amalgam with Hg0, which can affect Hg transportation over long distance.

DGT as a useful monitoring tool for radionuclides and trace metals in environments impacted by uranium mining: Case study of the Sagnes wetland in France

The Diffusive Gradients in Thin films (DGT) technique was used to analyse U, 226Ra and other trace metals in stream water and soil porewater in a wetland in France impacted by uranium mining. High resolution profiles of metals in soil porewater obtained by DGT could be measured for the first time up to a depth of 75 cm by the construction of a novel DGT holder. In stream water, the DGT technique was compared to speciation carried out by filtration (0.45 μm) and ultrafiltration (UF) (500 kDa/100 kDa/10 kDa) and DGT porewater profiles were compared with piezometer data obtained in a parallel study. An increase in the trace concentrations of dissolved (0.45 μm) and particulate U, 226Ra, and elements such as Al, Fe, Mn and Ba was observed in the stream water as it passes through the bog as a results of mobilization from the wetland. The porewater results indicate DGT labile metals species to be present in porewater and mobilization of uranium and other elements linked to the presence of enriched clays. In stream water, colloids and particles govern the behavior of U, Al and Fe, whereas Mn, Ba and Ra are essentially transported as truly dissolved metal species with DGT labile concentrations accounting for 100% of the dissolved fraction. The combined approaches of DGT and UF allow us to obtain a better understanding on the biogeochemical processes involved in the retention and mobility of U and 226Ra in the wetland.

Legacy impacts of acid sulfate soil runoff on mangrove sediments: Reactive iron accumulation, altered sulfur cycling and trace metal enrichment

The off-site impacts of iron-rich, acidic runoff from drained acid sulfate soils (ASS) on the geochemistry of estuarine sediments are relatively poorly constrained. In this study, we examine the geochemistry of intertidal zone mangrove sediments and porewaters from an estuarine tributary that received ~15–20years of acute ASS drainage, compared to adjacent control sites. Mixing of acidic, iron-rich ASS drainage waters with circumneutral pH estuarine waters drove precipitation of Fe(III) floc and has led to significant, localized accumulation of reactive-Fe species (FeR; Σ1M HCl and citrate-buffered dithionite extracts; up to 4200μmolg−1) as well as significantly elevated porewater Fe2+ (>1000μM) in ASS impacted sediments. X-ray diffraction indicates that goethite, lepidocrocite and ferrihydrite are important Fe(III) minerals in surficial sediments at ASS impacted sites. The abundant FeR is shifting the equilibrium of reduced inorganic sulfur (RIS) mineral-formation pathways towards accumulation of S(0) and acid volatile sulfide (AVS) species and is buffering porewater S(-II) to low concentrations. In contrast, RIS speciation at the control sites is dominated by pyrite (SCR) and porewater S(-II) is present. Some porewater metals (i.e. Al, Mn, Cu, Cr) are significantly elevated at sites proximal to the source of ASS drainage compared to control sites. Abundant FeR also provides a substrate for sorption and accumulation of metals and correspondingly there is significant relative enrichment of reactive metal fractions (1M HCl extractable) in sediments at the ASS impacted sites, with Al≈Mn≈U>Cu>Cr>Ni. This study demonstrates that ASS drainage, which causes accumulation of reactive Fe in mangrove environments, can substantially influence sediment biogeochemistry by altering reduced inorganic sulfur cycling and enhancing the availability of some trace metals.

Concentrations, diffusive fluxes and toxicity of heavy metals in pore water of the Fuyang River, Haihe Basin

While the concentrations of heavy metals in pore water provide important information about their bioavailability, to date few studies have focused on this topic. In this study, pore water in river sediments collected from nine sampling sites (S1–S9) was examined to determine the concentrations, fluxes, and toxicity of heavy metals in the Fuyang River. The results showed that the average concentrations of Cr, Ni, Cu, As, Zn, and Pb in pore water were 17.06, 15.97, 20.93, 19.08, 43.72, and 0.56μgL−1, respectively; these concentrations varied as the pore water depth increased. The diffusive fluxes of Cr, Ni, Cu, As, Zn, and Pb were in the following range: (−0.37) to 3.17, (−1.37) to 2.63, (−4.61) to 3.44, 0.17–6.02, (−180.26) to 7.51, and (−0.92) to (−0.29)μg(m2day)−1, respectively. There was a potential risk of toxicity from Cu to aquatic organisms, as indicated by a value of the Interstitial Water Criteria Toxic Units that exceeded 1.0. Values of the Nemeraw Index were 2.06, 0.48, 0.11, 0.20, 1.11, 1.03, 0.99, 0.88, and 0.89 from S1 to S9, respectively. Only S1 was moderately polluted by heavy metals in pore water.

Distributions, fluxes, and toxicities of heavy metals in sediment pore water from tributaries of the Ziya River system, northern China.

The distributions and mobilities of metals in pore water strongly influence the biogeochemical processes and bioavailabilities of metals at sediment-water interfaces. Heavy metal concentrations were measured in pore water samples from the Shaocun River (SR), the Wangyang River (WR), and the Xiao River (XR), tributaries of the Ziya River system, northern China. The aim was to assess heavy metal contamination in the system and the associated environmental risks. The mean Cd, Cr, Cu, Ni, Pb, and Zn concentrations in all three tributaries were 0.373, 57.1, 37.7, 20.4, 14.0, and 90.6 μg/L, respectively. The calculated Cd, Cr, Cu, Ni, Pb, and Zn diffusion fluxes in the rivers were -0.427 to 0.469, -71.8 to 42.5, 3.16 to 86.6, 5.29 to 14.0, 7.24 to 19.0, and -204 to 21.9 μg/(m(2) day), respectively, showing that the pore water was a source of most of the metals to the water column. Only Cu and Pb in the XR and Cu in the WR exceeded the final chronic value recommended by the US Environmental Protection Agency, but the metals in the WR sediment could have caused toxic effects. These results are likely to be useful to the authorities responsible for sustainable river management.

Effects of biochar and Arbuscular mycorrhizae on bioavailability of potentially toxic elements in an aged contaminated soil

Biochar pyrolyzed from corn stalks at 300 °C/500 °C and arbuscular mycorrhizae (AMF) were examined independently and in combination as possible treatments for soil remediation contaminated with Cd, Cr, Ni, Cu, Pb, Zn after 35 years following land application of sewage sludge in the 1970s. The results showed that biochar significantly decreased the heavy metal concentrations and their bioavailability for plants, and both biochars had similar such effects. AMF inoculation of corn plants had little effect on heavy metal bioavailability in either control or biochar amended soil, and no interaction between biochar and AMF was observed. Changes in DTPA extractable metals following biochar addition to soil were correlated with metal uptake by plants, whereas pore water metal concentrations were not predictive indicators. This research demonstrates positive benefits from biochar application for contaminated soil remediation, but remain ambiguous with regard to the benefits of simultaneous AMF inoculation on reduction of heavy metal bioavailability.

Copper and zinc adsorption by softwood and hardwood biochars under elevated sulphate-induced salinity and acidic pH conditions

Biochar adsorption may lower concentrations of soluble metals in pore water of sulphidic Cu/Pb–Zn mine tailings. Unlike soil, high levels of salinity and soluble cations are present in tailing pore water, which may affect biochar adsorption of metals from solution. In the present study, removal of soluble copper (Cu) and zinc (Zn) ions by soft- (pine) and hard-wood (jarrah) biochars pyrolysed at high temperature (about 700°C) was evaluated under typical ranges of pH and salinity conditions resembling those in pore water of sulphidic tailings, prior to their direct application into the tailings. Surface alkalinity, cation exchange capacity, and negative surface charge of biochars affected Cu and Zn adsorption capacities. Quantitative comparisons were provided by fitting the adsorption equilibrium data with either the homogeneous or heterogeneous surface adsorption models (i.e. Langmuir and Freundlich, respectively). Accordingly, the jarrah biochar showed higher Cu and Zn adsorption capacity (Qmax=4.39 and 2.31mg/g, respectively) than the softwood pine biochar (Qmax=1.47 and 1.00mg/g). Copper and Zn adsorption by the biochars was favoured by high pH conditions under which they carried more negative charges and Cu and Zn ions were predicted undergoing hydrolysis and polymerization. Within the tested range, salinity had relatively weak effects on the adsorption, which perhaps influenced the surface charge and induced competition for negative charged sites between Na+ and exchangeable Ca2+ and/or heavy metal ions. Large amounts of waste wood/timber at many mine sites present a cost-effective opportunity to produce biochars for remediation of sulphidic tailings and seepage water.

Assessing the Variability of Heavy Metal Concentrations in Liquid-Solid Two-Phase and Related Environmental Risks in the Weihe River of Shaanxi Province, China

Accurate estimation of the variability of heavy metals in river water and the hyporheic zone is crucial for pollution control and environmental management. The biotoxicities and potential ecological risks of heavy metals (Cu, Zn, Pb, Cd) in a solid-liquid two-phase system were estimated using the Geo-accumulation Index, Potential Ecological Risk Assessment and Quality Standard Index methods in the Weihe River of Shaanxi Province, China. Water and sediment samples were collected from five study sites during spring, summer and winter, 2013. The dominant species in the streambed sediments were chironomids and flutter earthworm, whose bioturbation mainly ranged from 0 to 20 cm. The concentrations of heavy metals in surface water and pore water varied obviously in spring and summer. The degrees of concentration of Cu and Cd in spring and summer were higher than the U.S. water quality Criteria Maximum Concentrations. Furthermore, the biotoxicities of Pb and Zn demonstrated season-spatial variations. The concentrations of Cu, Zn, Pb and Cd in spring and winter were significantly higher than those in summer, and the pollution levels also varied obviously in different layers of the sediments. Moreover, the pollution level of Cd was the most serious, as estimated by all three assessment methods.

Mobility and sulfidization of heavy metals in sediments of a shallow eutrophic lake, Lake Taihu, China

The technique of DGT (diffusive gradients in thin films) using three diffusive gel thicknesses was applied to estimate the mobility and bioavailability of heavy metals in sediments and porewater of Lake Taihu, China. The DGT results showed significantly positive correlations between Co, Pb, Cd and Mn, and Ni and Fe concentrations in porewater. Cu and Zn showed a significantly negative correlation with Mn, due to Cu combination with carbonates and Zn derived from agricultural pollution, respectively. The rank order of average concentrations of Co, Ni and Cd at each station was DGT1.92>DGT0.78>DGT0.39, suggesting stronger resupply from sediments to porewater when using thicker diffusive gels. Comparing centrifugation and DGT measurements, Co, Ni and Cd are highly labile; Mn and Fe are moderately labile; and Cu, Zn and Pb are slightly labile. The variations of AVS concentrations in sediment cores indicate that metal sulfides in deeper layers are easily diffused into surface sediments.

The Effects of Aquatic Plant Vallisneria Natans on the Distribution of Metals under Different Hydrodynamic Conditions

Heavy metals will be released to the water column during the sediment resuspension, causing the secondary pollution to the water ecosystem. In this study, the sediment collected from Zhushan Bay was placed in three similar pneumatic annular flumes where the wind speeds supplied by blast blowers were 3.21m/s, 5.95m/s and 8.78m/s respectively. The physicochemical parameters of the water and concentrations of metals in the water, plants and sediment were measured during the relevant experiments. The result showed that the concentrations of metals in the overlying water increased while it decreased in the pore water with the hydrodynamic disturbance. The aquatic plant Vallisneria natans bioaccumulated metals in the sediment and water, and the plant roots showed a higher ability in assimilating metals than the leaves. Meanwhile a positive correlation was found between wind speed and release amount of metals in pore water. In addition, the relationship between the wind speed and the biota-sediment accumulation factor (BSAF) was different due to the different features of metals.

Heavy Metal Concentrations in Pores and Surface Waters during the Emptying of a Small Reservoir

The impact of reservoir emptying on the concentrations of dissolved heavy metals (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in pore and surface waters was studied in the Aar Reservoir, a small reservoir in central Germany, during and after the emptying process. This study was conducted to observe binding changes within pore waters as well as the input of dissolved heavy metals in waters of the Aar Creek, what becomes possible when the reservoirs water table is removed and lake sediments become exposed. In pore waters, no clear shifting tendencies between dissolved and sorbed heavy metal fractions could be found after the completed sediment exposure. These relatively low dynamics in pore waters can be explained by the fine texture of the lake sediments, which are characterized by a high water holding capacity, what led to high remaining water contents and therefore slowed down the redox changes. A few days after the completed emptying, a general increase of dissolved heavy metal concentrations occurred in running waters of the Aar Creek as a result of pore water drainage. Here, element specific differences in mobilization and transportation abilities were found, what can be reconstructed by the ratio of dissolved heavy metals in pore and surface waters.

A Simulated Study on the Effect of Acuatic Vegetation on Distibution of Metals under Hydtrodynamic Disturbance

Heavy metal stored in the sediment of shaollow lake will be released into water bodies when sediment resuspension occurs, causing secondary pollution. This study was conducted to probe the distribution and transportation of Zn, Cu, Cr, Pb among overlying water, pore water, SS and vegetation in 30d using three annular flumes. Iris pseudacorus L was planted in two flumes at the wind speed of 8.7m/s,6.5m/s respectively. Another flume was designed as a control at the wind of 8.7m/s under the condition of no plants. The results reavaled Iris pseudacorus L had strong enrichment on heavy metals. Total heavy metal (Zn、Cu、Cr、Pb) concentrations in sediment slightly decreased. The diffusion of metals in pore water showed greatly downward and the concentration in SS decreased with fluctuation with the increasing contents of dissolved metals in overlying water. Correspondingly, plants also appeared a gradual upward trend. The results of the study may work as a foundation for the phytoremediation of heavy metal pollution in shallow lake.

Effect of a controlled sub-seabed release of CO2 on the biogeochemistry of shallow marine sediments, their pore waters, and the overlying water column

The potential for leakage of CO2 from a storage reservoir into the overlying marine sediments and into the water column and the impacts on benthic ecosystems are major challenges associated with carbon capture and storage (CCS) in subseafloor reservoirs. We have conducted a field-scale controlled CO2 release experiment in shallow, unconsolidated marine sediments, and documented the changes to the chemical composition of the sediments, their pore waters and overlying water column before, during and up to 1 year after the 37-day long CO2 release. Increased levels of dissolved inorganic carbon (DIC) were detected in the pore waters close to the sediment-seawater interface in sediments sampled closest to the subsurface injection point within 5 weeks of the start of the CO2 release. Highest DIC concentrations (28.8mmolL−1, compared to background levels of 2.4mmolL−1) were observed 6 days after the injection had stopped. The high DIC pore waters have high total alkalinity, and low δ13CDIC values (−20‰, compared to a background value of −2‰), due to the dissolution of the injected CO2 (δ13C=−26.6‰). The high DIC pore waters have enhanced concentrations of metals (including Ca, Fe, Mn) and dissolved silicon, relative to non-DIC enriched pore waters, indicating that dissolution of injected CO2 promotes dissolution of carbonate and silicate minerals. However, in this experiment, the pore water metal concentrations did not exceed levels considered to be harmful to the environment. The spatial extent of the impact of the injected CO2 in the sediments and pore waters was restricted to an area within 25m of the injection point, and no impact was observed in the overlying water column. Concentrations of all pore water constituents returned to background values within 18 days after the CO2 injection was stopped.

A field study of the relationship between sulfide-bound metals and bioaccumulation by Limnodrilus sp. in a heavily polluted river

Acid volatile sulfide (AVS) has been regarded as an important factor controlling metal bioavailability in anoxic sediments, but its effect on metal accumulation under natural conditions is poorly understood. Here, a field study of the influence of AVS on metal accumulation by Limnodrilus sp. in a heavily polluted river is provided. Most of the study area was subject to anaerobic and strongly reducing conditions, and the concentration of trace metals in surface sediments was high, as were the concentration of AVS and simultaneously extracted metals (SEM; average AVS = 20.3μmolg(-1), average ∑SEM5 = 9.42μmolg(-1); ∑SEM5 refers to the sum of SEMCd, SEMCu, SEMPb, SEMNi, and SEMZn). Only a few species and small quantities of benthic invertebrates were found, and Limnodrilus sp. was dominant. There was no correlation between trace metal accumulation and (SEM-AVS), and in stations where (SEM-AVS) <0, the absolute value of bioaccumulation was high (average ∑BIO5 = 4.07μmolg(-1); ∑BIO5 refers to the sum of BIOCd, BIOCu, BIOPb, BIONi, and BIOZn), indicating that there was no relationship between (SEM-AVS) and metal accumulation in Limnodrilus sp. This was likely because Limnodrilus sp. ingest sediment particles as their main food source, so pore water metals play a minor role in their bioaccumulation (BIO) of materials. However, ∑BIO5 was significantly correlated with ∑SEM5 (r = 0.795, p < 0.01), revealing that the large number of sulfide-bound metals (SEM) in sediments may play an important role in metal accumulation in Limnodrilus sp., which can assimilate sulfide-associated metals by the help of the digestive fluids in the digestive systems.

Assessment of Columbia River Sediment Toxicity to White Sturgeon: Concentrations of Metals in Sediment, Pore water and Overlying Water

Concentrations of copper, lead and zinc in sediments downstream of a metallurgical facility on the the Upper Columbia River (UCR) were significantly greater than those in regional reference locations. Sturgeons inhabit benthic habitats and there is concern that they might be at greater risk of exposure. A laboratory based, flow-through, experimental exposure system was used to characterize toxicity of metals in the different matrices associated with sediments collected from the UCR, and to assess risk to early life stages of white sturgeon (Acipenser transmontanus) under chronic bioassay conditions. Bioavailability and concentrations of metals in pore water, overlying water, and at the sediment-water interface were characterized. Several sampling methods including peepers, diffusive gradients in thin films (DGTs), and active sampling/suction techniques were employed. Results indicated that concentrations of metals in site sediments were significantly greater in comparison to upstream reference sediments. Of the four primary metals of concern, concentrations of copper, primarily in pore water, were significantly greater in exposure chambers containing site sediments compared to reference sediments. In addition, the different sampling techniques resulted in varying estimates of concentration depending on matrix, analyte, and method, and the present study highlights challenges in assessing the true risk of exposure. The analytical data reported herein is utilized in a parallel article to characterize risk and compare predictions to the bioassay results.