Sediment-bound Cd Research Articles

Abundance and characteristics of sediment-bound magnetic minerals and trace elements in karst ditch wetland: A case study from Guizhou Province, China

This study investigated sediment-bound magnetic properties and selected trace elements level in the karst ditch wetland, Caohai National Nature Reserve, Guizhou Province, China. Sediment-bound magnetic signals were quantified using low-frequency mass magnetic susceptibility (χLF), anhysteretic remanent magnetization susceptibility (χARM), saturation isothermal remanent magnetization (SIRM), and percentage frequency-dependent susceptibility (χfd%). Concentrations of Cd, Cr, Sb and Zn were determined using inductively coupled plasma mass spectrometry. Sediment χLF, χARM, SIRM, and χfd% were higher than those of bedrocks and mainly altered by the pedogenic processes. The estimated χfd% ranged from 6.15 % to 14.62 % and reflected the magnetic grain sizes were largely concentrated in the range of superparamagnetic particles. The elevated concentrations of sediment-bound Cd, Cr, Sb, and Zn supported the significant contribution of the anthropogenic sources in the karst ditch wetlands. The weak relationship between magnetic signals and selected trace elements (p < 0.05) suggested the occurrence of few sediment-bound iron-containing minerals associated with selected trace elements. These results indicated that a minor contribution of anthropogenic sources of selected trace elements to the elevated sediment magnetic signals in the karst ditch wetlands.

Assessment of some trace elements accumulation in Karst lake sediment and Procambarus clarkii, in Guizhou province, China

Lake wetland quality has decreased with the elevated concentrations of some trace elements. The consumption of crayfish in the trace elements concentrated lake wetland can be a hazard for the waterbirds and human health. Thus, the bioaccumulations of Cd, Ni, Pb and Zn in sediments and abdominal muscles of Procambarus clarkii in Caohai lake wetland, China were quantified. Sediment-bound Cd, Ni, Pb and Zn were remarkably elevated compared to the parent rock, while 64.71–94.12% of adverse effect index in sediment-bound Cd, Ni, Pb and Zn were > 1. Abdominal muscle-bound Cd, Pb and Zn in several samples were all above the maximum permissible limits. Pb, Zn and Ni in abdominal muscles were significantly linked with those in sediments (R2 =0.60–0.89, p < 0.01) and lake sediment might be the important feed sources of P. clarkii. Target hazard quotients of Cd, Ni, Pb and Zn at the 95th percentile was all below the benchmark, normal consumption of the abdominal muscle of P. clarkii posed low or no probabilistic health risk to the Grus nigricollis and local inhabitants.

Relationship between the lability of sediment-bound Cd and its bioaccumulation in edible oyster

A linkage between Cd speciation in sediments and its bioaccumulation in edible oyster (Crassostrea sp.) from a tropical estuarine system was established. Bioaccumulation of Cd in edible oyster increased with the increasing lability and dissociation rate constants of Cd-sediment complexes in the bottom sediments. Total Cd concentration in sediment was not a good indicator of Cd-bioavailability. Increasing trace metal competition in sediments increased lability and bioavailability of Cd in the tropical estuarine sediment. Low thermodynamic stability and high bioavailability of Cd in the estuarine sediment were responsible for high bioaccumulation of Cd in edible oysters (3.2–12.2mgkg−1) even though the total concentration of Cd in the bottom sediment was low (0.17–0.49mgkg−1).

Risk assessment of heavy metals in surface sediments from the Yanghe River, China.

The magnitude and ecological relevance of metal pollution from the upstream of water sources after emergency pollution events was investigated by applying a set of complementary sediment quality assessment methods: (1) geochemical assessment based on background value (the geoaccumulation index); (2) comparisons with sediment quality guidelines (SQGs); (3) an evaluation of the combined pollution according to the risk index (RI); and (4) investigation of the chemical patterns of target heavy metals (Cd, Zn, Cr, Pb, Ni). The geoaccumulation indices (Igeo) suggested that the magnitude of heavy metal pollution of the sediment of Yanghe River decreased in the order of Cd > Zn > Pb > Cr > Ni. Risk analysis also suggested that Cd and Zn concentrations were sufficiently elevated as to cause adverse biological effects in this study area. According to the RI values, 27% of total sampling sites showed considerable ecological risk for the water body, and 53% of total sampling sites showed very high ecological risk for the waterbody. Sediment-bound Cd was found to be predominantly associated with the exchangeable phase of the sediment (25%–68%), while Cr, Ni, Zn and Pb showed the strongest association with the residual fractions (60%–92%, 53%–67%, 24%–85% and 35%–67%, respectively).

Fractionation and ecotoxicological implication of potentially toxic metals in sediments of three urban rivers and the Lagos Lagoon, Nigeria, West Africa.

The potential environmental impact of sediment-bound Cd, Cr, Cu, Pb and Zn in three trans-urban rivers in Lagos state and in the Lagos Lagoon was assessed by use of the modified Community Bureau of Reference (BCR) sequential extraction. The quality of the data was checked using BCR CRM 143R and BCR CRM 701. Good agreement was obtained between found and certified/indicative values. Of the rivers, the Odo-Iyaalaro, was generally the most contaminated and the Ibeshe the least. Higher concentrations of metals were generally found in the dry season compared to the wet season. Cadmium and Zn were released mostly in the acid exchangeable step of the sequential extraction, indicating that they have the greatest potential mobility and bioavailability of the analytes studied. Chromium and Cu were associated mainly with the reducible and oxidisable fractions, and Pb predominantly with the reducible and residual fractions. Sediments with the highest pseudototal analyte concentrations also released higher proportions of analytes earlier in the sequential extraction procedure. The study suggests that, during the dry season, potentially toxic metals (PTM) may accumulate in sediments in relatively labile forms that are released and can potentially be transported or bioaccumulate in the rainy season. Application of risk assessment codes and Hankanson potential risk indices indicated that Cd was the element of greatest concern in the Lagos Lagoon system. The study indicated that there is a need to strengthen environmental management and pollution control measures to reduce risk from PTM, but that even relatively simple strategies, such as seasonal restrictions on dredging and fishing, could be beneficial.

Coupling geochemical and biological approaches to assess the availability of cadmium in freshwater sediment

Sediments are considered as a sink for metals, and the assessment of metal bioavailability for benthic organisms represents a great challenge. Diffusive Gradient in Thin films (DGT), developed to measure labile metals in aquatic media, have more recently been applied to sediment. Nevertheless, few studies have determined the relation between measurements from DGT and bioaccumulation in different benthic organisms. The aim of our work was to determine if labile metal measured by DGT in sediment is representative of bioavailable metal for benthic organisms. We focused our work on Cd and chose to use the diversity of ecological traits from different organisms to better understand the measurement given by DGT. We exposed simultaneously DGT and 3 macroinvertebrates species (the chironomid, Chironomus riparius; the amphipod, Gammarus fossarum; the mudsnail, Potamopyrgus antipodarum) to a natural sediment Cd-spiked at environmental relevant concentrations. The nature of sediment-bound Cd was also determined by means of sequential extractions in order to better interpret DGT measurements. Cadmium concentrations were determined in DGT and in the 3 organisms after one week of exposure. Results provided by DGT indicated that Cd was poorly released from particulate phase to pore water, suggesting that Cd measured by DGT was representative of the pore water labile fraction. Sequential extractions showed that the percentage of Cd bound to carbonate fraction increased simultaneously with Cd-spiking level; hence, this Cd fraction was poorly reactive to supply DGT demand. Cadmium accumulation rates were similar between DGT measurements and P. antipodarum, suggesting that labile Cd in pore waters was representative of bioavailable Cd for this species. Cadmium accumulation rates in C. riparius were higher than in DGT, demonstrating that C. riparius can mobilize Cd bound to carbonate phase. G. fossarum showed the lowest Cd accumulation rates, suggesting that they were mainly exposed to Cd from overlaying waters.

Effects of sediment-bound Cd, Pb, and Ni on the growth, feeding, and survival of Capitella sp. I

Anthropogenic metal pollutants bioaccumulated in benthic animals by means of feeding and osmotic diffusion. These metals may affect the physiology of the benthos. In this study, we exposed Capitella sp. I to three metals (Cd, Pb, and Ni), each in eight different concentrations, to determine the effects of metals on the animals. Growth rate, ingestion rate, and percent survival were estimated in three separated experiments. The growth and feeding of the worms were sensitive to even the lowest concentrations of each metal added to the sediments. The lowest observable adverse effect levels for Cd, Ni, and Pb were 0.03, 1.59, and 0.41 μmol g − 1 sediment, respectively. Growth rates in the elevated metal contaminant treatments decreased drastically at slightly contaminated levels, lessened detrimental effects at moderately contaminated levels, and showed incompensable intoxication at heavily contaminated levels. The trends in ingestion rates were similar to those of growth rates. No significant difference in survivorship was found among the different contaminant levels for any of the three heavy metals. Capitella sp. I was most sensitive to Cd, followed by Ni and Pb, which had similar effects. The rapid physiological responses of Capitella sp. I allowed the animals to survive metal exposure. Sediment productivity remained unchanged at different contamination levels of Ni and Pb, but was drastically reduced at 4.75 μmol g − 1 Cd in the sediment. This further demonstrated Capitella sp. I can adjust their ingestion rates to maintain constant sediment productivities in moderate pollution conditions; however, when threshold concentration was exceeded, homeostasis collapsed.

Assessment of the environmental significance of heavy metal pollution in surficial sediments of the River Po

The magnitude and ecological relevance of metal pollution of the middle Po river deriving from the River Lambro tributary was investigated by applying different (complementary) sediment quality assessment approaches: (1) comparisons of concentrations with regional reference data, and (2) comparisons with consensus-based sediment quality guidelines (SQGs), as well as by investigations of the partitioning patterns of target heavy metals (Cd, Cu, Ni, Pb, Zn). Total metal concentrations in the surficial sediments revealed significant pollution inputs on the whole river stretch investigated, with a distinct peak at the inlet of the River Lambro. Based on the geoaccumulation index of target heavy metals, the middle reach of River Po has to be considered as moderately polluted with Cd (1<mean I(geo)<2). At the Lambro inlet the surficial sediments have to be considered as moderately to strongly polluted with Cd (2<mean I(geo)<3) and moderately polluted with Cu, Pb and Zn (1<mean I(geo)<2 for each). Sediment-bound Cd, and Zn were found to be predominantly associated with the exchangeable phase of the sediment (33-58% and 25-43%, respectively), whereas Cu, Ni and Pb showed the strongest association with the Fe/Mn oxides (34-64%, 34-46% and 29-45%, respectively). Based on the consensus-based SQGs, most samples (50-63%) had contamination characteristics associated with moderate probabilities (30-52%) of acute toxicity for all investigated metals, while Cu and Zn in approximately 13% of samples revealed contamination characteristics associated with high probabilities (74-85%) of toxicity.

Heavy metal contamination in the Arieş river catchment, western Romania: Implications for development of the Roşia Montană gold deposit

The Abrud–Arieş river system, western Romania, is subject to ongoing mining activity associated with Cu, Pb and Zn ore extraction. The catchment contains what is believed to be Europe's largest unutilized Au deposit at Roşia Montană that is planned to be exploited by open-cast mining techniques. The magnitude and environmental significance of metal (Cd, Cu, Pb, and Zn) concentrations in surface water and river channel sediment have been investigated along a 140 km reach of the Rivers Abrud and Arieş and 9 tributaries affected by mining. The speciation of sediment-bound metals was established using a 4-stage sequential extraction procedure (SEP) that identified four chemical phases: (1) exchangeable, (2) Fe/Mn oxides, (3) organic matter/sulphides and (4) residual. Peak solute and sediment-bound metal concentrations were found to occur in the River Abrud downstream of the EM Bucium mine and in mining-affected tributaries, with up to 71% of sites containing sediment metal concentrations in excess of Dutch intervention values. The River Arieş was found to be much less polluted than the River Abrud, with only Cu showing concentrations above guideline values, as a consequence of porphyry Cu mineralization in the catchment. The magnitude and spatial extent of metal pollution is influenced by local physico-chemical conditions and hydrological linkages between mining and local river systems. Sediment-bound Cd and Zn were found to be predominantly associated with the exchangeable phase of the sediment (9–74% and 6–65%, respectively), whilst Fe/Mn oxides (5–76%) and organic matter/sulphides (1–45%) generally accounted for a majority of Pb and Cu partitioning, respectively. Sites of environmentally significant sediment-metal pollution were identified in the Rivers Abrud and Arieş where exchangeable metal concentrations exceeded Dutch intervention values. The implications of metal contamination in the Arieş river basin to the proposed mining development at Roşia Montana are discussed in relation to other contaminated Romanian catchments and with the EU Water Framework Directive.

Bioavailability of sedimentary metals from a contaminated bay

Sediments are considered the sink for metals in aquatic environments because of their strong metal-binding capacity, but they are a potential source for metal ingestion by marine benthic animals as well. Sediment contamination is now a major environmental problem in many countries, including China. This study examines the bioavailability to a marine suspension-feeder (the clam Mactra veneriformis) and a deposit-feeder (the peanut worm Sipunculus nudus) of sediment-bound Cd, Cr and Zn along a gradient of metal contamination. To this end, metal assimilation efficiency and metal extraction by gut juice were quantified and compared. Metal concentrations in sediments col- lected from 4 sites were 5.40 to 43.7 mgCd kg -1 , 32.8 to 71.2 mgCr kg -1 , and 278 to 5 380 mgZn kg -1 . Metal assimilation by the clams was independent of the metal concentration in the sediment. In the deposit-feeding sipunculid, the bioavailability of sediment-bound Cd increased with increasing con- tamination of the sediment, as a result of the increasing partitioning of Cd into the easily exchange- able phase, and decreasing partitioning into the reducible phase. Cd assimilation also increased with increasing total organic carbon content in the sediments.The Cd assimilation efficiency was directly correlated to Cd extraction by gut juices collected in vitro from the peanut worm. No such relation- ship was found for Cr and Zn. Geochemical and biological controls on metal bioavailability therefore differ between the metals and with the extent of sediment contamination. The limitation of the radio- tracer technique to quantify metal assimilation efficiency by marine benthic invertebrates from sedi- ments should be recognized when it is used to predict metal concentrations in target animals.

Heavy metal speciation and its biological consequences in a group of lakes polluted by a smelter, Flin Flon, Manitoba, Canada

Abstract Comparative study of lakes polluted with Cd, Zn and Cu from a smelter at Flin Flon, Canada showed that the availability of heavy metals to sedimentary micro-organisms and aquatic food-chain organisms depends on the abundance of DTPA-extractable (bio-available) metal species in the sediments rather than total metal concentrations. Microbial methylation of Hg and resulting accumulation of Hg by northern pike muscle are inhibited by DTPA-extractable Cd but are not significantly affected by total Cd. Similarly, the Cd content of water, plankton and pike liver, and the toxic effects of Cd on heterotrophic sedimentary microbes, are more strongly dependent on DTPA-extractable Cd than on total Cd concentrations in the sediments. The extractability of sediment-bound Cd with DTPA is enhanced by organic matter but is depressed if sulfide exceeds a critical concentration. The DTPA-extractable Cd fraction may include lipophilic complexes that accumulate in fish tissues over time, as suggested by an increasingly significant positive correlation between liver Cd and fork length in pike with increasing abundance of DTPA-extractable Cd. Although Cd is less abundant than Zn or Cu in the DTPA-extractable metal pool, it has the strongest toxic effect on microbial activity, the relative toxicity increasing in the order Zn Among white sucker, concentrations of Hg in muscle tissue and Cd in liver tissue are not significantly dependent on DTPA-extractable Cd but are depressed by sedimentary sulfides and Fe oxyhydroxides, respectively. The contrast between the results for pike and sucker suggests differences in metal uptake pathways and kinds of metal species assimilated, reflecting the difference in the feeding habits of the two fish species.

Effect of adherent bacteria and bacterial extracellular polymers upon assimilation by Macoma balthica of sediment-bound Cd, Zn and Ag

Effect of adherent bacteria and bacterial extracellular polymers upon assimilation by Macoma balthica of sediment-bound Cd, Zn and Ag