Effects of bioturbation on the fate of oil in coastal sandy sediments--an in situ experiment

Effects of bioturbation by the common lugworm Arenicola marina on the fate of oil hydrocarbons (alkanes and PAHs) were studied in situ during a simulated oil spill in a shallow coastal area of Roskilde fjord, Denmark. The fate of selected oil compounds was monitored during 120 d using GC-MS and bioturbation activity (feces production and irrigation) was measured regularly during the experiment and used as input parameters in a mechanistic model describing the effects of A. marina on the transport and degradation of oil compounds in the sediment. The chemical analytical data and model results indicated that A. marina had profound and predictable effects on the distribution, degradation and preservation of oil and that the net effect depended on the initial distribution of oil. In sediment with an oil contaminated subsurface-layer A. marina buried the layer deeper in the sediment which clearly enhanced oil persistence. Conversely, A. marina stimulated both the physical removal and microbial degradation of oil compounds in uniformly oil contaminated sediments especially in deeper sediment layers (10-20 cm below the surface), whereas the fate of oil compounds deposited in surface layers (0-5 cm) mainly was affected by removal processes induced by wave actions and other bioturbating infauna such as Nereis diversicolor, Corophium volutator and Hydrobia spp. present in the experimental plots.     

Cadmium and methylmercury bioaccumulation by nymphs of the burrowing mayflyHexagenia rigida from the water column and sediment

Based on a three compartment microcosm-water column, natural sediment,Hexagenia rigida nymphs-an experimental study was set up to compare cadmium (Cd) and methylmercury (MeHg) bioaccumulation by a burrowing mayfly species, after exposure via the water column or the sediment as initial contamination sources. Results from a wide concentration range for each exposure condition revealed very marked differences between the two metals: MeHg was readily accumulated from the two contamination sources, leading to important metal concentrations in the nymphs after the 2 weeks’ exposure; Cd bioaccumulation, on the other hand, was negligible when the metal was added to the water compartment, even though significant transfers were observed from the sediment source. The average Cd concentrations in the nymphs were proportional to the sediment contamination levels. Turbidity measurements in the water column, reflecting the bioturbation activity of the nymphs, revealed that the effect of Cd was significant, but only when the metal was initially added to the sediment. The results are discussed according to the uptake routes and the structural and functional properties of the biological barriers involved (gills and gut).     

Influence of Chironomus riparius (Diptera, Chironomidae) and Tubifex tubifex (Annelida, Oligochaeta) on oxygen uptake by sediments. Consequences of uranium contamination

The diffusive oxygen uptake (DOU) of sediments inhabited by Chironomus riparius and Tubifex tubifex was investigated using a planar oxygen optode device, and complemented by measurements of bioturbation activity. Additional experiments were performed within contaminated sediments to assess the impact of uranium on these processes. After 72 h, the two invertebrate species significantly increased the DOU of sediments (13-14%), and no temporal variation occurred afterwards. Within contaminated sediments, it was already 24% higher before the introduction of the organisms, suggesting that uranium modified the sediment biogeochemistry. Although the two species firstly reacted by avoidance of contaminated sediment, they finally colonized it. Their bioturbation activity was reduced but, for T. tubifex, it remained sufficient to induce a release of uranium to the water column and an increase of the DOU (53%). These results highlight the necessity of further investigations to take into account the interactions between bioturbation, microbial metabolism and pollutants.     

Effects of black carbon on bioturbation-induced benthic fluxes of polychlorinated biphenyls

It is unknown whether carbonaceous geosorbents, such as black carbon (BC) affect bioturbation by benthic invertebrates, thereby possibly affecting sediment-water exchange of sediment-bound contaminants. Here, we assess the effects of oil soot on polychlorinated biphenyl (PCB) mass transfer from sediment to overlying water, for sediments with and without tubificid oligochaeta as bioturbators. PCB levels were so low that toxicity to the oligochaeta played no role, whereas soot levels and binding affinity of PCBs to soot were so low that pore water PCB concentrations were not significantly affected by binding of PCBs to soot. This setup left direct effects of BC on bioturbation activity as the only explanation for any observed effects on mass transfer. Mass transfer coefficients (K_L) for benthic boundary layer transport were measured by a novel flux method using Empore™ disks as a sink for PCBs in the overlying water. For the PCBs studied (logK_ow 5.2-8.2), K_L values ranged from 0.2 to 2 cm × d⁻¹ in systems without tubificids. Systems with tubificids showed K_L values that were a factor of 10-25 higher. However, in the presence of oil soot, tubificids did not cause an increase in mass transfer coefficients. This suggests that at BC levels as encountered under field conditions, the mechanism for reduction of sediment-water transfer of contaminants may be twofold: (a) reduced mass transfer due to strong binding of the contaminants to BC, and (b) reduced mass transfer of contaminants due to a decrease in bioturbation activity.     

Tissue concentrations, bioaccumulation, and biomagnification of synthetic musks in freshwater fish from Taihu Lake, China

Synthetic musks are ubiquitous pollutants in aquatic environments. As hydrophobic chemicals, they can accumulate in terrestrial and aquatic organisms. Investigations into the bioaccumulation of these chemicals in aquatic ecosystem have, however, been limited, and previous results were inconsistent among species and ecosystem. Studies on this topic have been carried out in European countries, the USA, and Japan, but very few are known of the situation in China. The aim of this study was to investigate contaminant levels of musks in fish from Taihu Lake, the second largest freshwater lake in China, as well as bioaccumulation and biomagnification of the pollutants in the freshwater food chain. Five polycyclic musks and two nitro musks were determined in 24 fish species and nine surface sediment samples from Taihu Lake. HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[γ]-2-benzopyran) and AHTN (7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene) were the predominant contaminants in the fish samples, with concentrations ranging from below the limit of detection (LOD) to 52.9 and from <LOD to 7.5 ng/g lipid weight, respectively. Other contaminants were at low detection frequencies. The results indicated low concentrations of musks yet widespread occurrence of these contaminants in fish from Taihu Lake. Species-specific and lipid-related bioaccumulation characteristics were suggested, but no significant region-specific differences were observed. Normalized biota-sediment accumulation factors for HHCB and AHTN were noted to increase with trophic levels in fish. Trophic magnification factors were estimated at 1.12 for HHCB and 0.74 for AHTN. A biomagnification for HHCB, and probably biodilution for AHTN, in the freshwater food chain are indicated, when trophic magnification factors were concerned. However, the correlations between logarithmic concentrations of the chemicals and trophic levels were not statistically significant. Further study using long food chains in this lake is still needed.     

Sorption and desorption of carbamazepine, naproxen and triclosan in a soil irrigated with raw wastewater: estimation of the sorption parameters by considering the initial mass of the compounds in the soil

The amphipod Hyalella azteca was exposed for 28 d to different combinations of Zn contaminated sediment and food. Sediment exposure (+clean food) resulted in increased Zn body burdens, increased mortality and decreased body mass when the molar concentrations of simultaneously extracted Zn were greater than the molar concentration of Acid Volatile Sulfide (SEM_Zn-AVS > 0), suggesting that dissolved Zn was a dominant route of exposure. No adverse effect was noted in the foodexposure (+clean sediment), suggesting selective feeding or regulation. Combined exposure (sediment + food) significantly increased adverse effects in comparison with sediment exposure, indicating contribution of dietary Zn to toxicity and bioaccumulation. The observed enhanced toxicity also supports the assumption on the presence of an avoidance/selective feeding reaction of the amphipods in the single sediment or food exposures. During 14 d post-exposure in clean medium, the organisms from the same combined exposure history received two feeding regimes, i.e. clean food and Zn spiked food. Elevated Zn bioaccumulation and reduced reproduction were noted in amphipods that were offered Zn spiked food compared to the respective organisms that were fed clean food. This was explained by the failure of avoidance/selective feeding behavior in the absence of an alternative food source (sediment), forcing the amphipods to take up Zn while feeding. Increasing Zn body burdens rejected the assumption that Zn uptake from food was regulated by H. azteca. Our results show that the selective feeding behavior should be accounted for when assessing ecological effects of Zn or other contaminants, especially when contaminated food is a potential exposure route.     

Bioaccumulation of 51Cr, 63Ni and 14C in Baltic Sea benthos

The Baltic Sea is a species-poor, semi-enclosed, brackish sea, whose sediments contain a wide range of contaminants, including sediment-associated metals and radionuclides. In this study, we have examined and compared bioaccumulation kinetics and assimilation efficiencies of sediment-associated (51)Cr, (63)Ni and (14)C in three key benthic invertebrates (the deposit-feeding Monoporeia affinis, the facultative deposit-feeding Macoma baltica, and the omnivorous Halicryptus spinulosus). Our results demonstrate that (i) all radionuclides were accumulated, (ii) the different radionuclides were accumulated to various extents, (iii) small changes in organic carbon concentration can influence the accumulation, and (iv) the degree of accumulation differed only slightly between species. These processes, together with sediment resuspension and bioturbation, may remobilise trace metals from the sediment to the water and to higher trophic levels, and therefore should be taken into account in exposure models and ERAs.     

A field study on phytoremediation of dredged sediment contaminated by heavy metals and nutrients: the impacts of sediment aeration

Compared to traditional chemical or physical treatments, phytoremediation has proved to be a cost-effective and environmentally sound alternative for remediation of contaminated dredged sediment. A field study was conducted in a sediment disposal site predominantly colonized by Typha angustifolia under different sediment moisture conditions to estimate the phytoremediation effects of dredged sediment. The moisture content was 37.30 % and 48.27 % in aerated and waterlogged sediment, respectively. Total nitrogen (TN) content was higher in the waterlogged sediment than in the aerated sediment. The total Cd contents were lower in aerated sediment, which was mainly resulted from the lower exchangeable fraction of Cd. The bioaccumulation of P, Cu and Pb in T. angustifolia was promoted by waterlogging, and the belowground tissue concentrations and accumulation factors (AFs) of Cu were higher than that of other metals, which can be explained by that Cu is an essential micronutrient for plants. Consistent with many previous studies, T. angustifolia showed higher metal levels in roots than in above-ground tissues at both the sediment conditions. Due to the improved biomass produced in the aerated sediment, the removals of nutrients and the metals by plant harvest were higher from aerated sediment than from waterlogged sediment. It was indicated that maintaining the dredged sediment aerated can avoid release risk and plant uptake of metals, while the opposite management option can promote phytoextraction of these contaminants.     

Validation and use of in vivo solid phase micro-extraction (SPME) for the detection of emerging contaminants in fish

A variety of emerging chemicals of concern are released continuously to surface water through the municipal wastewater effluent discharges. The ability to rapidly determine bioaccumulation of these contaminants in exposed fish without sacrificing the animal (i.e. in vivo) would be of significant advantage to facilitate research, assessment and monitoring of their risk to the environment. In this study, an in vivo solid phase micro-extraction (SPME) approach was developed and applied to the measurement of a variety of emerging contaminants (carbamazepine, naproxen, diclofenac, gemfibrozil, bisphenol A, fluoxetine, ibuprofen and atrazine) in fish. Our results indicated in vivo SPME was a potential alternative extraction technique for quantitative determination of contaminants in lab exposures and as well after exposure to two municipal wastewater effluents (MWWE), with a major advantage over conventional techniques due to its ability to non-lethally sample tissues of living organisms.     

The origin of speciation: trace metal kinetics over natural water/sediment interfaces and the consequences for bioaccumulation

The speciation of heavy metals was measured over a variety of natural and undisturbed water/sediment interfaces. Simultaneously, two benthic species (oligochaete Limnodrilus spp. and the midge Chironomus riparius) were exposed to these sediments. Under occurring redox conditions, free ion activities of trace metals Cd, Cu, Ni, Pb, and Zn were measured with a chelating exchange technique, while geochemical conditions (i.e., redox) remained in tact. Free ion activities were compared with total dissolved concentrations in pore waters and surface waters in order to relate speciation to bioaccumulation. Limnodrilus spp. and C. riparius have accumulation patterns that could be linked to time-dependent exposure concentrations, expressed as chemical speciation, in the surface water and the sediment's pore water. Concentrations of free metal ions in the overlying surface water, rather than in sediment pore water, proved to be the best predictor for uptake. For the first time, measurements are obtained from sediments without disturbing physical-chemical conditions and thus bioavailability, a major restriction of other studies so far.     

Contrasting effects of black carbon amendments on PAH bioaccumulation by Chironomus plumosus larvae in two distinct sediments: role of water absorption and particle ingestion

Two sediment matrices with different characteristics were amended with chars from different sources for bioaccumulation assay with filter-feeding Chironomus plumosus larvae. Chars greatly decreased porewater concentrations of PAHs (C_iw) measured using polyethylene devices in sediments. In organic rich sediment matrix-based systems where suspended char particles were absent, PAH concentrations in larvae (C_iB) were significantly correlated with C_iw, and there was no difference in water-based bioaccumulation factors (BAFs) between different treatments, suggesting that water absorption was the main contaminant uptake route for larvae. In organic poor sediment matrix-based systems where suspended char particles were present, poor Pearson correlation between C_iB and C_iw was found, but there was a significant linear increase of BAF values with char contents, which indicated that ingestion of suspended char particles could also be important for PAH bioaccumulation. Therefore, we need to rethink of the effectiveness and risks for the application of black carbon to sediment/soil remediation.     

Bioaccumulation and uptake routes of perfluoroalkyl acids in Daphnia magna

Perfluoroalkyl acids (PFAs), one kind of emerging contaminants, have attracted great attentions in recent years. However, the study about their bioaccumulation mechanism remains scarce. In this research, the bioaccumulation of six kinds of PFAs in water flea Daphnia magna was studied. The uptake rates of PFAs in D. magna ranged from 178 to 1338 L kg^?1 d^?1, and they increased with increasing perfluoroalkyl chain length; the elimination rates ranged from 0.98 to 2.82 d^?1. The bioaccumulation factors (BAFs) of PFAs ranged from 91 to 380 L kg^?1 in wet weight after 25 d exposure; they increased with increasing perfluoroalkyl chain length and had a significant positive correlation with the n-octanol/water partition coefficients (log K_ow) of PFAs (p < 0.05). This indicated that the hydrophobicity of PFAs plays an important role in their bioaccumulation. The BAFs almost kept constant when the PFA concentrations in aqueous phase increased from 1 to 10 μg L^?1. Scenedesmus subspicatus, as the food of D. magna, did not significantly affect the bioaccumulation of PFAs by D. magna. Furthermore, the body burden of PFAs in the dead D. magna was 1.08–2.52 times higher than that in the living ones, inferring that the body surface sorption is a main uptake route of PFAs in D. magna. This study suggested that the bioaccumulation of PFAs in D. magna is mainly controlled by their partition between organisms and water; further research should be conducted to study the intrinsic mechanisms, especially the roles of protein and lipid in organisms.     

Evidence of population genetic effects in Peromyscus melanophrys chronically exposed to mine tailings in Morelos, Mexico

Effects of environmental chemical pollution can be observed at all levels of biological organization. At the population level, genetic structure and diversity may be affected by exposure to metal contamination. This study was conducted in Huautla, Morelos, Mexico in a mining district where the main contaminants are lead and arsenic. Peromyscus melanophrys is a small mammal species that inhabits Huautla mine tailings and has been considered as a sentinel species. Metal bioaccumulation levels were examined by inductively coupled plasma mass spectrometry and genetic analyses were performed using eight microsatellite loci in 100 P. melanophrys individuals from 3 mine tailings and 2 control sites. The effect of metal bioaccumulation levels on genetic parameters (population and individual genetic diversity, genetic structure) was analyzed. We found a tissue concentration gradient for each metal and for the bioaccumulation index. The highest values of genetic differentiation (Fst and Rst) and the lowest number of migrants per generation (Nm) were registered among the exposed populations. Genetic distance analyses showed that the most polluted population was the most genetically distant among the five populations examined. Moreover, a negative and significant relationship was detected between genetic diversity (expected heterozygosity and internal relatedness) and each metal concentration and for the bioaccumulation index in P. melanophrys. This study highlights that metal stress is a major factor affecting the distribution and genetic diversity levels of P. melanophrys populations living inside mine tailings. We suggest the use of genetic population changes at micro-geographical scales as a population level biomarker.     

Biota–sediment accumulation factor (BSAF), bioaccumulation factor (BAF), and contaminant levels in prey fish to indicate the extent of PAHs and OCPs contamination in eggs of waterbirds

Samples of pond sediment, fish, and shrimp were collected from the Ramsar site at Mai Po marshes, Hong Kong (south China), and samples of pond sediment, fish, and shrimp, as well as eggs of water birds (Chinese Pond Herons (Ardeola bacchus) and Little Egrets (Egretta garzetta)), were collected from two smaller wetland sites at Jiangsu Province (mid-China), between 2004 and 2007. Accumulation levels of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in the biota were used to calculate biota–sediment accumulation factor (BSAF) and bioaccumulation factor (BAF). For fish and shrimp, BSAFs of OCPs (3.8–56) were greater than those of PAHs (0.12–6.3). BSAFs and BAFs of 11–79 and 4–34, respectively, were registered for OCPs in eggs of the birds and were greater than those for PAHs (0.11–1.5 and 0.02–1.3, respectively). Assuming that fish were the main prey of the birds, greater bioaccumulation of OCPs was detected for both bird species (BAFs?=?4.5–34), while accumulation of PAHs was only detected in Little Egret (BAF?=?1.3). A significant linear relationship (p?<?0.01) was observed between concentrations of OCPs in bird eggs and in the prey fish. The present study provides a new possibility of using OCP levels detected in prey fish to predict the extent of OCPs contamination in eggs of waterbirds including the endangered species, as a noninvasive method.     

Accumulation and persistence of chlorobiphenyls, organochlorine pesticides and faecal sterols at the Garroch Head sewage sludge disposal site, Firth of Clyde

The sediment concentrations of organic carbon, faecal sterols, individual chlorobiphenyl congeners and organochlorine pesticides have been measured in seabed cores from the sewage sludge disposal area at Garroch Head in the Firth of Clyde. The measurements confirm the accumulative nature of the site with high levels of sedimentary faecal sterols (152 mg kg(-1) coprostanol). Levels of chlorobiphenyls, DDT compounds and dieldrin in surface sediment were elevated by factors of 12, 40 and 120, respectively, over those observed at a site remote from the effects of dumping. Total chlorobiphenyl levels of 515 microg kg(-1) Arochlor 1254 in surface sediment were comparable to levels found in other areas heavily contaminated with sewage sludge. The 20-cm depth of heavily sludge-contaminated sediment overlays a mixed sludge/basal sediment layer some 10 cm in depth. Levels of organochlorine contaminants were elevated to depths of 90 cm in the sediment, suggesting that the surface layer is a source of contaminants to the deeper sediment. Within the upper 15-20 cm sediment in the disposal area, chlorobiphenyls are conservative, the variation in their concentration with respect to depth being related to historical input. Lindane and possibly dieldrin, and hexachlorobenzene are not conservative. Faecal sterols are removed in sub-surface sediment, in contrast to conservative behaviour previously found at other sewage polluted sites.     

Using enriched stable isotope technique to study Cu bioaccumulation and bioavailability in Corbicula fluminea from Taihu Lake,China

In this study, we measured trace metals (Cd, Cr, Cu, Ni, Pb, and Zn) in water and sediment from representative sites of Taihu Lake, with focus on the analysis of trace metal accumulation in Corbicula fluminea (bivalve). The results showed that the quality of water in Taihu Lake was generally good and the correlation was not found between Cu bioaccumulation in C. fluminea and the concentration in water and sediment. Thus, using the stable isotope tracer method, we studied Cu uptake from the water phase, the assimilation of Cu from the food phase, and the efflux of Cu in vivo by C. fluminea. The result revealed that this species exhibited a relatively lower efflux rate constant of Cu compared with other zoobenthos species. Using a simple bioenergetics-based kinetic model, Cu concentrations in the C. fluminea were calculated with the measured efflux rate. We put forward a novel method, which was taking the influence of biological kinetic on metal bioaccumulation into account to explain the field survey data.     

Arsenic and mercury bioaccumulation in the aquatic plant, Vallisneria neotropicalis

Arsenic (As) and mercury (Hg) are among the most toxic metals/metalloids. The overall goal of this study was to investigate the bioaccumulation of these trace elements in Vallisneria neotropicalis, a key trophic species in aquatic environments. For this purpose, As and Hg concentrations were determined in sediments and natural populations of V. neotropicalis in sub-estuaries of Mobile Bay (Alabama, USA), differing with respect to past and present anthropogenic impact. Analyses indicate that the Fish River is the most contaminated among the sub-estuaries investigated; levels of As found in Fish River sediments fall within a range that could potentially cause adverse effects in biota. Sediment As concentrations were only moderately correlated with those in V. neotropicalis; no correlation was found between sediment and plant Hg levels. However, several parameters could have masked such potential relationships (e.g., differences in sediment characteristics and “biological dilution” phenomena). Results presented herein highlight the numerous parameters that can influence metal/metalloids accumulation in aquatic plants as well as species-specific responses to trace element contamination. Finally, this study underscores the need for further investigation into contaminant bioaccumulation in ecologically and economically important coastal environments.     

Distribution of feminizing compounds in the aquatic environment and bioaccumulation in wild tilapia tissues

This study sampled six times of river water, sediment, and tilapia (Oreochromis niloticus) in the Dan-Shui River, Taipei, Taiwan; 10 feminizing compounds were analyzed using ultra-performance liquid chromatography-tandem mass spectrometry. Bisphenol A (508?±?634 ng/L, geometric mean (GM) 303 ng/L) and nonylphenol (491?±?570 ng/L, GM 328 ng/L) were the most abundant among analytes in the river water. Nonylphenol (770?±?602 ng/g wet weight, GM 617 ng/g wet weight) was also the highest in sediment. Fish may uptake nonylphenol and nonylphenol ethoxylates from river water and sediment because there were significant correlations between the concentrations in these matrixes and those in fish tissues (r _s ranged from 0.21 to 0.49, p?相似文献   

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.