Speciation of heavy metals in marine sediments vs their bioaccumulation by mussels.

Total contents and speciation of selected heavy metals, including Al, Fe, Co, Ni, Pb, Zn, Cu, Cr, were measured in sediment samples and mussels Mya arenaria and Astarte borealis collected in the Horsund Fjord off Spitsbergen (Norwegian Sea) and the Bay of Gdansk (Baltic Sea). The investigation aimed at revealing differences in the accumulation pattern of heavy metals in mussels inhabiting sediments characterized by varying metal bioavailability. The contents of metals adsorbed to sediments and associated with iron and manganese hydroxides, which were obtained by sequential extraction, were utilized as a measure of metal bioavailability. The contents of Cd, Pb, Zn, Cu and Cr in mussels collected off Spitsbergen were generally lower than those in mussels from the Baltic Sea. In sediments collected off Spitsbergen the bioavailable fraction represented a small proportion (0-3.7% adsorbed metals and 0-11% associated with metals hydroxides) of total heavy metal contents. In sediments from the Baltic Sea the percentages of metals adsorbed and bound to hydroxides were 1-46% and 1-13%, respectively. The differences in bioavailable metal contents measured in sediments were utilized to explain the different contents of metals in mussels collected in the corresponding sites.     

Coprostanol distribution in marine sediments off southwestern Taiwan

One of the major industries in southern Taiwan is pigfarming along the Kaoping River; some two million animals are being raised along the river banks. Excretions from pigs, treated and untreated, are discharged directly into the river and eventually carried to the sea. Twenty-four surface sediments and one sediment core off southwestern Taiwan were analyzed to determine quantitatively the extent of coprostanol addition and its distribution and to obtain the input of coprostanol over the past. Geographically, the percent coprostanol is highest around the river mouth, and decreases to about 1% at the shelf break and about 0% at a distance of approximately 40 nautical miles (74 km) from the river mouth. The progressive seaward decline of percent coprostanol from the river mouth can be attributed to [1] dilution of coprostanol by uncontaminated sediment and/or sediment containing relatively lower levels of coprostanol, [2] dilution of coprostanol by biogenic sterols, and [3] probably degradation of coprostanol. Further, the Kaoping Canyon sediments contain relatively high percent coprostanol; this can be attributed to [1] a more direct input of the river sediments because the canyon is well aligned with the river, [2] currents in the canyon being alternate upcanyon and downcanyon which tend to keep sediments in the canyon, and [3] the possible blocking effect of a topographic high in the canyon. A sediment core exhibits comparatively higher percent coprostanol in the top 15 cm, indicating an increased input of coprostanol over the past 20 years.     

Relationship between water solubility of organic chemicals and their bioaccumulation by the alga

This paper reports the bioaccumulation of 34 organic chemicals in and on the green alga and their relationship to water solubility.     

Interactions between Zn and bacteria in marine tropical coastal sediments

Purpose  

The main goals of this study were (1) to examine the effects of zinc on the microbial community structure of anthropogenically impacted sediments in a tropical coastal ecosystem and (2) to determine whether these microbial benthic communities may enhance the adsorption of zinc.     

Nickel bioaccumulation in bivalves from the New Caledonia lagoon: seawater and food exposure

The New Caledonian lagoon is submitted to intense heavy metal input from land-based Ni mining. Therefore, the use of sentinel species is strongly recommended in order to develop and implement coastal zone management programmes of the metal contamination. The tropical oysters Isognomon isognomon and Malleus regula and the clam Gafrarium tumidum were previously proposed as such possible sentinel organisms and were thus investigated in this context. The three species were exposed to Ni via seawater or food using radiotracer techniques. Results indicate that uptake and retention efficiencies of Ni are independent of the dissolved Ni concentrations in the surrounding seawater. Hence, for the three species, body concentrations of Ni taken up from the dissolved phase are directly proportional to the ambient dissolved concentrations. Biokinetic patterns indicated that the major part of Ni was rapidly lost from bivalves during the first days of depuration, whereas 7 to 47% of 63Ni were retained in tissues with a biological half-life not significantly different from infinity. Finally, feeding experiments showed that Ni ingested with food (phytoplankton) was assimilated more efficiently in clams (assimilation efficiency, AE = 61%) than in oysters (AE = 17%), and was strongly retained (T(b1/2) > or = 35 d) in the tissues of both bivalves. It is concluded that the investigated species examined are efficient bioaccumulators of Ni from both the surrounding seawater and the food, and that they would be useful bioindicators for monitoring the status of Ni contamination in tropical coastal waters.     

Polychlorinated biphenyls and organochlorine pesticides in Baltic Sea sediments and bivalves

Insecticide resistance is an evolutionary response to insecticides and, as such, important for environmental biomonitoring and for pest management. Fitness disadvantage in the absence of insecticide is a frequent assumption in models of insecticide resistance evolution, which was observed in different insect species. Fitness studies are based in demographic performance of isolated populations without direct interaction between insecticide-resistant and -susceptible populations. Here we reported a study of direct competition following a factorial bivariate design between an insecticide-susceptible population of the maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), and one of two insecticide-resistant populations - one exhibiting fitness disadvantage based on demographic studies (Juiz de Fora) and other not exhibiting it (Jacarezinho). Total number of insects, mortality by insecticide, insect body mass and respiration rate were recorded after three generations of competition. Indeed, fitness disadvantage was observed in the resistant population from Juiz de Fora, but not in the population from Jacarezinho, as expected. The higher body mass and respiration rate of the insecticide-resistant insects from Jacarezinho are probably mitigating the physiological costs associated with the insecticide resistance minimizing their fitness disadvantage, what does not take place with the insecticide-resistant insects from Juiz de Fora. These distinct responses between the insecticide-resistant populations are probably related to the length and intensity of field-selection with insecticides.     

Toxicity and bioaccumulation of copper in three green microalgal species

The effective concentrations of copper on the inhibition of the growth of Scenedesmus obliquus, Chlorella pyrenoidosa and Closterium lunula at 96 h (96 h EC50) were determined to be 50, 68 and 200 microg/l, respectively. The low initial bioaccumulation of Cu by C. lunula was found to be responsible for its tolerance to Cu. The amount of Cu accumulated by all three microalgae reached the maximum value and decreased quickly after the peak followed by a slow decrease over the next 6 d. Bioaccumulation of Cu by C. lunula was directly proportional to the initial Cu concentration. After reaching the first peak after 1 d, the bioconcentration factor of Cu by microalgae declined to its minimum value during the exponential growth phase but increased in the stationary growth phase again. This indicates that desorption of Cu from microalgae was higher during the exponential growth phase but lower in the stationary growth phase. Smaller microalgae with low 96 h EC50 values are more efficient in removing Cu from wastewater.     

Contamination in sediments, bivalves and sponges of McMurdo Sound, Antarctica

This study examined the concentrations of total hydrocarbons (THC), polychlorinated biphenyls (PCB), polyaromatic hydrocarbons (PAH), and trace metals (Cu, Zn, Cd, Pb, Hg and As) in marine sediments off Scott Base (NZ) and compared them with sediments near the highly polluted McMurdo Station (US) as well as less impacted sites including Turtle Rock and Cape Evans. The Antarctic mollusc, Laternula elliptica and three common sponge species were also analysed for trace metals. The mean THC concentration in sediments from Scott Base was 3 fold higher than the pristine site, Turtle Rock, but 10 fold lower than samples from McMurdo Station. McMurdo Station sediments also contained the highest concentrations of PAHs, PCBs and the trace metals, Cu, Zn, Pb, Cd and Hg. Copper was significantly higher in bivalves from McMurdo Station than other sites. Trace metal concentrations in sponges were generally consistent within sites but no spatial patterns were apparent.     

Sorption-desorption behaviour of 2,4-dichlorophenol by marine sediments

Batch kinetic and isotherm experiments were conducted to determine the sorption-desorption behavior of 2,4-dichlorophenol from seawater solutions by marine sediments containing various amounts of organic carbon (from 1.02% to 12.72% dry weight). The results indicated linear type isotherms for sorption and desorption in all marine sediments studied. The observed difference in linear sorption coefficients between sorption and desorption was indicative of sorption hysteresis. The kinetic experiments showed that equilibrium was established in less than 20 h. The study is significant with respect to sediment remediation in contaminated harbors and coastal areas.     

Mercury accumulation in marine bivalves: influences of biodynamics and feeding niche

Differences in the accumulation of mercury (Hg) in five species of marine bivalves, including scallops Chlamys nobilis, clams Ruditapes philippinarum, oysters Saccostrea cucullata, green mussels Perna viridis, and black mussels Septifer virgatus, were investigated. The bivalves displayed different patterns of Hg accumulation in terms of the body concentrations of methylmercury (MeHg) and total Hg (THg), as well as the ratio of MeHg to THg. Parameters of the biodynamics of the accumulation of Hg(II) and MeHg could reflect the species-dependent Hg concentrations in the bivalves. With the exception of black mussels, we found a significant relationship between the efflux rates of Hg(II) and the THg concentrations in the bivalves. The interspecific variations in the MeHg to THg ratio were largely controlled by the relative difference between the elimination rates of Hg(II) and MeHg. Stable isotope (δ¹³C) analysis indicated that the five bivalve species had contrasting feeding niches, which may also affect the Hg accumulation.     

Comparative bioaccumulation kinetics of trace elements in Mediterranean marine sponges

While marine organisms such as bivalves, seagrasses and macroalgae are commonly used as biomonitors for the environment pollution assessment, widely distributed sponges received little attention as potential helpful species for monitoring programmes. In this study, the trace element and radionuclide bioaccumulation and retention capacities of some marine sponges were estimated in a species-comparative study using radiotracers technique. Six Mediterranean species were exposed to background dissolved concentrations of ^110mAg, ²⁴¹Am, ¹⁰⁹Cd, ⁶⁰Co, ¹³⁴Cs, ⁵⁴Mn, ⁷⁵Se and ⁶⁵Zn allowing the assessment of the uptake and depuration kinetics for selected elements. Globally, massive demosponges Agelas oroides, Chondrosia reniformis and Ircinia variabilis displayed higher concentration factor (CF) than the erectile ones (Acanthella acuta, Cymbaxinella damicornis, Cymbaxinella verrucosa) at the end of exposure, suggesting that the morphology is a key factor in the metal bioaccumulation efficiency. Considering this observation, two exceptions were noted: (1) A. acuta reached the highest CF for ^110mAg and strongly retained the accumulated metal without significant Ag loss when placed in depuration conditions and (2) C. reniformis did not accumulate Se as much as A. oroides and I. variabilis. These results suggest that peculiar metal uptake properties in sponges could be driven by specific metabolites or contrasting biosilification processes between species, respectively. This study demonstrated that sponges could be considered as valuable candidate for biomonitoring metal contamination but also that there is a need to experimentally highlight metal-dependant characteristic among species.     

Relationship between carbonaceous materials and polychlorinated biphenyls (PCBs) in the sediments of the Danshui River and adjacent coastal areas, Taiwan

Persistent organic pollutants, POPs (e.g., polychlorinated biphenyls) can seriously and deleteriously affect environmental quality and human health. These organic pollutants are exhibiting high affinities to solid phases and thus, quickly end up in sediments. To better understand the role of carbonaceous materials in the transport and distributions of POPs in terrestrial and near-shore environments, concentrations of PCBs and carbonaceous materials (including total organic carbon, black carbon and total carbohydrates), were determined in surface sediments of the Danshui River and nearby coastal areas, Taiwan. Total concentrations of PCBs in the sediments ranged from non-detectable to 83.9 ngg(-1), dry weight, with the maximum value detected near the discharge point of the marine outfall from the Pali Sewage Treatment Plant. These results suggest that the sewage treatment plant has discharged PCBs in the past and the concentrations are still high due to their persistence; alternatively, PCBs are still being discharged in the estuarine and near-shore environment of the Danshui River. Organic carbon and black carbon concentrations correlated well with those of total PCBs in the sediments, suggesting that both organic carbon and black carbon significantly affect the distribution of trace organic pollutants through either post-depositional adsorption, or by co-transport of similar source materials. The field results demonstrate that black carbon and plays an important role in the general distribution of PCBs, while concentrations of some specific PCBs are affected by both black carbon and organic carbon concentrations.     

Combining bioaccumulation and coping mechanism to enhance long-term site-specific risk assessment for zinc susceptibility of bivalves

The purpose of this study is to conduct a long-term site-specific risk assessment for zinc (Zn) susceptibility of bivalves, green mussel Perna viridis and hard clam Ruditapes philippinarum, based on published experimental data by linking the biologically-based damage assessment model with the subcellular partitioning concept. A comprehensive risk modeling framework was developed to predict susceptibility probability of two bivalve species exposed to waterborne Zn. The results indicated that P. viridis accumulates more Zn toxicity, whereas both toxic potency and the recovery rate of Zn are higher for R. philippinarum. We found that negative linear correlations exist in elimination-recovery and elimination-detoxification relationships, whereas a positive linear correlation was observed in recovery-detoxification relationships for bivalves exposed to waterborne Zn. Simulation results showed that the spatial differences of susceptibility primarily resulted from the variation of waterborne Zn concentration under field conditions. We found that R. philippinarum is more susceptible of Zn than P. viridis under the same exposure condition. Results also suggested that Zn posed no significant susceptibility risk to two bivalve species in Taiwan. We suggested that these two species can be used to biomonitor the water quality on Taiwan coastal areas.     

Species of copper and zinc in sediments collected from the antarctic ocean and the Taiwan Erhjin Chi coastal area

The species of copper and zinc, such as bioexchangeable, skeletal, easily reducible (Fe and Mn oxides), moderately reducible (crystalline Mn oxide), organic combined with sulfides, and detritus with minerals, in mud and sand, separated from the surface Antarctic Ocean and the Taiwan Erhjin Chi coastal (including river and estuarine) sediments, have been analyzed by sequential leaching methods. Results show that in the Antarctic Ocean sediments, high concentrations of total copper (128 mg/kg) and zinc (458 mg/kg) were found in the high mud (99.09%) content samples compared with the low concentrations of total copper (83.8 mg/kg) and zinc (288 mg/kg) in low mud (51.69%) content samples. High concentrations of copper, zinc, manganese and iron are possibly due to the characteristics of manganese nodules, in which the species of copper and zinc are mainly contained in the crystalline Mn oxide phase. In the Taiwan Erhjin Chi coastal sediments, the total copper and zinc concentrations in mud and sand vary with season and location. High values were generally observed in the river sediments during the dry season, and low values were in the estuarine and coastal sediments during the heavy rainy season. High percentages of copper (as high as 49.4%) and zinc (as high as 76.7%) in mud and sand were in the bioexchangeable phase including the skeletal phase. This result might be correlated with the problems arising from human impact on copper and zinc as well as sewage pollution in Taiwan. In the organic combined phase, biogenic particulate matter related to higher primary productivity in the Antarctic Ocean is also discussed.     

Temporal and spatial variation of sulfur-gas-transfer between coastal marine sediments and the atmosphere

The spatial and temporal variability of sulfur gas fluxes (H₂S, COS, CH₃SH, DMS, and CS₂) at the sediment–air interface were studied in the intertidal Wadden Sea area of Sylt-Rømø (Germany/Denmark) during eight measuring campaigns between June 1991 and September 1994. Measurements were performed mainly at four sites in a sheltered intertidal bay of approximately 6 km² (Königshafen) and discontinuously in a wider range of the 400 km² Sylt-Rømø tidal flat area. In situ fluxes of the S-gases were determined by a dynamic chamber technique focusing on dry sediment periods. Additional experiments were conducted in order to determine changes in S-gas concentrations in the sediment between the surface and 70 cm depth.In most cases H₂S was the dominant S-gas emitted from the sediment to the atmosphere, contributing up to 70% of the total S-emission at this interface. Mean H₂S emission rates ranged between 0.07 and 9.95 μg S m^-2 h^-1. Both emission rates and relative contribution of H₂S were lowest from fine sand and highest from muddy sites. Diurnal variation of H₂S emission was evident in summer and fall with up to 10-fold higher rates during night than during the day. Distinct seasonal variation of H₂S-transfer between the sediment and the atmosphere was observed with higher emission rates in the summer than in spring or fall. The emission of H₂S to the atmosphere was smaller by a factor of 1600–26 000 than the H₂S produced from sulfate reduction. Apparently, the efficiency by which H₂S produced in the sediment is retained and reoxidized by biogeochemical sediment processes is extremely high. Carbonyl sulfide (COS) was emitted with relatively constant rates in space and time with mean flux rates ranging between 0.24 and 2.0 μg S m^-2 h^-1. Carbon disulfide emission rates were comparable to those of COS and varied between 0.3 and 2.23 μg S m^-2 h^-1. DMS played a minor role in the S-gas transfer from uncovered sediment areas contributing between 3.1 and 23% to total S-emission from the sediment to the atmosphere.     

Changes of copper speciation in maize rhizosphere soil

Chemical forms of copper in the rhizosphere and bulk soil of maize were investigated using rhizobox cultivation and sequential extraction techniques. The copper accumulations were also determined. The results demonstrated that there were continuous changes in copper fractionation within the maize rhizosphere. Initially, the amount of exchangeable copper increased before dropping below the initial level after 40 days or so. Carbonate associated copper followed a similar trend of change, but with a slower pace than the exchangeable copper. The increase in carbonate associated copper only become evident after 30 days, with the net loss occurring after 60 days. There were also initial increases in oxide bound copper as well as decreases in the organic matter associated copper, both followed by a turnover after 40-50 days. The accumulation of copper in the maize plant was found to be biomass dependent. The amount of accumulated copper absorbed in the plant material exceeded the initial quantity of the exchangeable copper in the soil, revealing a transformation from less bioavailable to more bioavailable fractions. During cultivation, decreases in redox potential and increases in pH, dissolved organic carbon (DOC), and microbial activity in the maize rhizosphere were observed. The change in copper speciation may result from root-induced changes in DOC, redox potential, and microbial activity in the rhizosphere.     

Characteristics and chemical speciation of waste copper slag

Environmental Science and Pollution Research - Waste copper slag contains abundant valuable metal element Fe, and residual elements such as Cu, As, Pb, Zn, and Mo. Simply stockpiling or landfilling...     

Phthalate ester speciation in estuarine water, suspended particulates and sediments

Following earlier work (Al-Omran & Preston, 1987) in which phthalate ester speciation was examined in laboratory studies, the present paper describes the results of an attempt to validate the results by field measurements in the River Mersey Estuary, Liverpool, UK. Samples of water, suspended solids and sediments were analysed for their phthalate ester content. Solid samples were also analysed for their carbon, organic carbon and lipid content. A comparison of the field and laboratory results confirms the association between diethylhexyl phthalate and small particles and shows that other phthalates tend to be associated with relatively coarse, lipid-rich particles. Partition coefficients between dissolved phthalate esters and suspended particles are calculated and compared with other laboratory studies.