首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 46 毫秒
1.
The burrowing responses of a common tropical bivalve, the short-neck clam Ruditapes philippinarum, to cadmium (Cd)-spiked sediment, variations of sediment grain size and natural sediments collected from 15 locations in Hong Kong's inshore waters were investigated through a series of laboratory tests. Results showed that the burrowing response exhibited a negative relationship with an increase in Cd concentration in the spiked sediments. The level of Cd was also found to be directly proportional to the percent mortality of the clam. However, there was no significant difference (p>0.05) in the time elapsed for the clam to burrow into sediments with different grain size composition. The elapsed time for 50% of the test clams to burrow into the sediment (ET50) over a period of 48 h was calculated for the sediment samples collected from the 15 locations. Results of ANOVA showed significant difference (p<0.05) among the sediment samples. Tukey's multiple comparison test revealed two groups of sediments: group 1 containing 3 sediment samples collected from Victoria Harbour and group 2 containing 12 samples obtained from other coastal areas of Hong Kong. The ET50 value for group 1 sediments was found to be greater than 2880 min whilst the ET50 for group 2 sediments had a mean of 173.9 min. Agglomerative classification of the sediment samples, based on metal content (As, Cd, Cr, Cu, Ni, Pb, Zn), also showed two similar groups, suggesting that the ET50 values were correlated with the metal level of the sediment samples. Group 1 sediments collected from Victoria Harbour had greater concentrations of Cd, Cr, Cu, Ni and Zn as compared to that in group 2. The present study demonstrated that high metal content in the sediment tends to inhibit the burrowing responses of the clam and that there is potential to develop the burrowing responses of R. philippinarum as a sublethal sediment toxicity test.  相似文献   

2.
Burrowing into riverbanks by animals transfers sediment directly into river channels and has been hypothesised to accelerate bank erosion and promote mass failure. A field monitoring study on two UK rivers invaded by signal crayfish (Pacifastacus leniusculus) assessed the impact of burrowing on bank erosion processes. Erosion pins were installed in 17 riverbanks across a gradient of crayfish burrow densities and monitored for 22 months. Bank retreat increased significantly with crayfish burrow density. At the bank scale (<6 m river length), high crayfish burrow densities were associated with accelerated bank retreat of up to 253% and more than a doubling of the area of bank collapse compared with banks without burrows. Direct sediment supply by burrowing activity contributed 0.2% and 0.6% of total sediment at the reach (1.1 km) and local bank (<6 m) scales. However, accelerated bank retreat caused by burrows contributed 12.2% and 29.8% of the total sediment supply at the reach and bank scales. Together, burrowing and the associated acceleration of retreat and collapse supplied an additional 25.4 t km−1 a−1 of floodplain sediments at one site, demonstrating the substantial impact that signal crayfish can have on fine sediment supply. For the first time, an empirical relation linking animal burrow characteristics to riverbank retreat is presented. The study adds to a small number of sediment budget studies that compare sediment fluxes driven by biotic and abiotic energy but is unique in isolating and measuring the substantial interactive effect of the acceleration of abiotic bank erosion facilitated by biotic activity. Biotic energy expended through burrowing represents an energy surcharge to the river system that can augment sediment erosion by geophysical mechanisms.  相似文献   

3.
以泥鳅（Misgurnus anguillicaudatus）、铜锈环棱螺（Bellamya aeruginosa）、河蚬（Corbicula fluminea）为受试生物,以死亡率、渗血率、体质量变化、行动迟钝率、挖洞率为测试指标,探究沉积物中Zn和Cd对底栖生物的21 d慢性毒性效应,并对鄱阳湖Zn和Cd的沉积物基准值进行了验证.结果表明,沉积物中Cd对底栖生物的毒性效应强于Zn,沉积物中Zn、Cd对泥鳅、铜锈环棱螺、河蚬的LC50（半数致死浓度）分别为644和61 mg/kg、751和54 mg/kg、652和81 mg/kg,EC50（半数效应浓度）值分别为526和49 mg/kg、589和35 mg/kg、474和45 mg/kg.经验证,沉积物Zn和Cd的TEL（临界效应浓度）、PEL（必然效应浓度）值比较合理,具有一定适用性,即当Zn、Cd的加标含量低于TEL值时,QTEL<1,不具有毒性;当加标含量高于PEL值时,QPEL>1,毒性明显.  相似文献   

4.
Concentrations of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were determined in 14 sediment samples collected from four sites in the Mai Po Marshes Nature Reserve (within a RAMSAR Site) and from another six sites in Victoria Harbour and along the Hong Kong coastline. Elevated levels of PCDDs, and particularly OCDD, were detectable in all samples collected from the Mai Po Marshes and five of the six sites. In contrast to PCDDs, PCDFs were mainly found in sediment samples collected from industrial areas (Kwun Tong and To Kwa Wan) in Victoria Harbour. PCDD/F levels and congener profiles in the samples from the Mai Po Marshes Nature Reserve in particular show strong similarities to those reported in studies which have attributed similar elevated PCDD concentrations to nonanthropogenic PCDD sources.  相似文献   

5.
Cadmium (Cd) has become an important heavy metal contaminant in the sediment and seawater along the Bohai Sea and been of great ecological risk due to its toxic effects to marine organisms. In this work, the toxicological effects caused by environmentally relevant concentrations (10 and 40 µg L?1) of Cd were studied in the gill tissues of Manila clam Ruditapes philippinarum after exposure for 24, 48, and 96 h. Both low (10 µg L?1) and high (40 µg L?1) doses of Cd caused the disturbances in energy metabolism and osmotic regulation and neurotoxicity based on the metabolic biomarkers such as succinate, alanine, branched chain amino acids, betaine, hypotaurine, and glutamate in clam gills after 24 h of exposure. However, the recovery of toxicological effects of Cd after exposure for 96 h was obviously observed in clam to Cd exposures. Overall, these results indicated that NMR‐based metabolomics was applicable to elucidate the toxicological effects of heavy metal contaminants in the marine bioindicator.  相似文献   

6.
Gravel sediment freshly enriched with over 4.4 μg Cu g?1 significantly increased the burrowing and reburrowing times of Littleneck marine clams (Protothaca staminea). Abnormal burrowing behaviour was observed with time-lapse video. Aged (1 day) copper-enriched sediment did not affect clam burrowing time. Copper in sediment porewater declined three days after sediment enrichment to background levels without change in total sediment copper. In a long-term experiment, clams with increased burrowing time into copper-enriched sediment had up to 25% mortality after 12–29 days burial in the sediment. The majority of clam mortality was found in clams burrowing within the first 48 h. Over 7 weeks there was blackening of sediment and clam shells proportional to sediment copper enrichment.  相似文献   

7.
The toxicity of marine sediments in Victoria Harbour, Hong Kong   总被引：4，自引：0，他引：4  
When the toxicity of marine sediment in Hong Kong was evaluated, it was found that the seven sediments collected within Victoria Harbour were severely contaminated with heavy metals, at concentrations many times higher than those in sediments collected from outside the harbour. The highest metal content was recorded in site VS14 (located near the airport runway and the industrialized area), with copper, zinc, lead and chromium values of 3789, 610, 138 and 601 mg kg−1 dry wt, respectively. This site also had the greatest alkaline phosphatase activities (15 fluorescent intensity unit g−1 wet wt), the largest number of total coliforms (910 CFU g−1 wet wt) and sulphate-reducing bacteria (8.5 × 104 cells g−1 wet wt), implying that site VS14 was also contaminated with organic matter and nutrients. Sediment bioassays, Microtox and algal tests, demonstrated that sediment elutriates obtained from site VS14 were of greatest toxicity. The EC10 value in Microtox tests was 17% elutriate, and the 96-h IC50 values using Skeletonema costatum and Dunaliella tertiolecta were 40 and 79% elutriate, respectively. No toxic effects were found in sediment samples collected from the control site outside Victoria Harbour. Significant correlations were found between the results of the algal toxicity test (using S. costatum) and the coliform count and metal content of the sediments. The Microtox test was less sensitive than the algal bioassay, and no sediment elutriate, even from the site mostly contaminated by heavy metals, caused more than 50% inhibition of the light-emitting activity of the bacteria. In this study, S. costatum (the diatom) provided a more sensitive and reliable test species than D. tertiolecta (the flagellate) in differentiating the toxicity of marine sediments.  相似文献   

8.
Sublethal effects of estuarine sediments containing high levels of heavy metals were studied using the marine bivalve, Macoma balthica. Burrowing behaviour was inhibited in all contaminated sediments compared to the control. The time required for 50% of the population to burrow (ET50) ranged from 0.17 h in the control to 4.8 h in the most contaminated substrate. A comparison of linear regressions of the concentrations of individual metals in the sediments vs the burrowing response times showed the regressions for mercury and cadmium to be significant (P < 0.05 and < 0.001 respectively). An active threshold avoidance response by burrowed M. balthica was also demonstrated as clams showed a significant (P < 0.05) avoidance of the sediment containing the highest metal levels. Both behavioural responses were considered useful sublethal tests to assess the impact of polluted sediments.  相似文献   

9.
Concentrations of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were determined in 14 sediment samples collected from four sites in the Mai Po Marshes Nature Reserve (within a RAMSAR Site) and from another six sites in Victoria Harbour and along the Hong Kong coastline. Elevated levels of PCDDs, and particularly OCDD, were detectable in all samples collected from the Mai Po Marshes and five of the six sites. In contrast to PCDDs, PCDFs were mainly found in sediment samples collected from industrial areas (Kwun Tong and To Kwa Wan) in Victoria Harbour. PCDD/F levels and congener profiles in the samples from the Mai Po Marshes Nature Reserve in particular show strong similarities to those reported in studies which have attributed similar elevated PCDD concentrations to nonanthropogenic PCDD sources.  相似文献   

10.
《Marine pollution bulletin》2009,58(6-12):816-825
Victoria Harbour has received substantial loadings of pollutants from industrial and municipal wastewater discharged since the 1950s. Inputs of contaminants have declined dramatically during the last two decades as a result of better controls at the source and improved wastewater treatment facilities. To assess the spatial and temporal changes of metal contaminants in sediments in Victoria Harbour, core and grab sediments were collected. The central harbour areas were generally contaminated with heavy metals. The spatial distribution of trace metals can probably be attributed to the proximity of major urban and industrial discharge points, and to the effect of tidal flushing in the harbour. In the sediment cores, the highest concentrations of trace metals were observed to have accumulated during the 1950s–1980s, corresponding with the period of rapid urban and industrial development in Hong Kong. From the late 1980s, there has been a major decline in the concentrations of trace metals, due to a reduction in industrial activities and to the enactment of wastewater pollution controls in the territory. The Pb isotopic compositions of the sediments revealed the anthropogenic inputs of Pb to the harbour. The 206Pb/207Pb ratios varied from 1.154 to 1.190, which were lower than those of background geological materials in Hong Kong (206Pb/207Pb: 1.201–1.279). The data also indicated that the Pb in the harbour sediments most likely originated from mixed sources, including the leaded gasoline used in the past and other anthropogenic sources.  相似文献   

11.
Sediment samples were collected from 30 different locations in Abu Qir Bay (Mediterranean Sea), East Alexandria, Egypt and analyzed for trace elements. The highest concentrations of most of the elements were observed in the nearshore stations in the vicinity of the major anthropogenic activities as industrial settlements, wastewater discharges, and agricultural drainage. In addition, mussel samples of Mactra corallina and Tapes decussata were collected corresponding to the sediment samples. Concentrations of As, Cd, Cr, Mn, and Zn in the mussel tissues were higher than concentrations in sediments, thus indicating their relatively high bioavailability. Sequential extraction procedure was performed on selected sediment samples. Significant correlations were observed between the concentrations of Cu, Mn, Pb, and Zn in the exchangeable fraction of the sediments and the corresponding tissues of M. corallina. The output of the risk assessment applied on the sediments revealed that adverse ecological effects to benthic species could occur and that a higher level of risk is expected from the exposure to Cd, Cr, Hg, and Zn. No adverse carcinogenic or non‐carcinogenic human health effects are expected from the consumption of the two mussel species from Abu Qir Bay.  相似文献   

12.
Sediment samples were collected from 30 different locations in Abu Qir Bay (Mediterranean Sea), East Alexandria, Egypt and analyzed for trace elements. The highest concentrations of most of the elements were observed in the nearshore stations in the vicinity of the major anthropogenic activities as industrial settlements, wastewater discharges, and agricultural drainage. In addition, mussel samples of Mactra corallina and Tapes decussata were collected corresponding to the sediment samples. Concentrations of As, Cd, Cr, Mn, and Zn in the mussel tissues were higher than concentrations in sediments, thus indicating their relatively high bioavailability. Sequential extraction procedure was performed on selected sediment samples. Significant correlations were observed between the concentrations of Cu, Mn, Pb, and Zn in the exchangeable fraction of the sediments and the corresponding tissues of M. corallina. The output of the risk assessment applied on the sediments revealed that adverse ecological effects to benthic species could occur and that a higher level of risk is expected from the exposure to Cd, Cr, Hg, and Zn. No adverse carcinogenic or non‐carcinogenic human health effects are expected from the consumption of the two mussel species from Abu Qir Bay.  相似文献   

13.
The influence of seasonal and environmental parameters on the occurrence of bacteria was investigated in two clam species (Venerupis pullastra and Ruditapes philippinarum), water and sediment from the Tagus estuary. Total viable counts (TVC), Escherichia coli, Salmonella spp. and Vibrio spp. were evaluated during one-year. Overall, significant seasonal variations were found in both sampling sites, especially for E. coli and Vibrio spp. levels. In summer, significantly higher Vibrio spp. levels were found in R. philippinarum and sediment samples, but not in V. pullastra clams and water samples. In contrast, significantly higher TVC and E. coli levels were observed in winter months in water and sediment samples. Salmonella spp. was generally isolated when higher levels of E. coli were detected, particularly in R. philippinarum. This study is useful for authorities to develop monitoring strategies for coastal contamination and to estimate human health risks associated with the consumption of bivalves.  相似文献   

14.
《Marine pollution bulletin》2009,58(6-12):403-408
Laboratory experiments were carried out to investigate the adsorption behaviour of dibutyl phthalate (DBP) on marine sediments collected from five different sites in Victoria Harbour, Hong Kong. DBP adsorption can be well described by the Langmuir isotherm. The maximum DBP adsorption capacity (Qmax) of the marine sediments ranges from 53 to 79 mg g−1, which has a positive correlation with their organic content. Around 90% of the organic can be removed from the sediments with treatment by H2O2 oxidation, and the Qmax then decreases to a range between 13 and 22 mg g−1. The black carbon content of the sediments has a much greater DBP adsorption capacity than does the natural organic matter of the sediments. The amount of DBP adsorbed on the sediments increases as the salinity of the marine water increases.  相似文献   

15.
The distribution and bioaccumulation features of PCBs, DDTs, and HCHs were investigated in the sediments and Manila clams collected from along the Mid-Western coast of Korea. The measured concentrations of ΣPCBs, ΣDDTs and ΣHCHs were 1.08–3.5, 0.12–0.35 and 0.090–0.30 ng g−1 dw in sediment, and 33–390, 7.4–46 and 6.3–27 ng g−1 lipid in Manila clam, respectively. Their levels were found to be relatively lower than those of other contaminated areas and the consumption of Manila clam from these areas seems to be safe for human health according to calculated lifetime cancer risk and hazard indices. The ΣPCBs and ΣDDTs concentrations in sediments showed a significant relationship to those in clams. The significant correlation was observed between BSAF in clams and Kow for each PCB congeners and DDT metabolites. These findings support that the PCBs and DDTs levels, which are highly hydrophobic chemicals, in clam reflect the sediment pollution through bioaccumulation.  相似文献   

16.
Variation of polycyclic aromatic hydrocarbons (PAHs) levels was assessed in Tapes philippinarum from the Lagoon of Venice. Clams were transplanted from a polluted area next to Porto Marghera to two rearing areas of the Southern Lagoon. Analyses of PAHs were made in sediments and clams by GC/MS at first sampling and after 30, 60 and 180 days. Principal component analysis was performed to elucidate bioaccumulation and depuration pattern and input sources. Biota-Sediment-Accumulation-Factor (BSAF) was applied to evaluate the PAHs input sources from sediment. Condition index was calculated to compare the seasonal variation of clam tissue to PAHs levels. To propose results not affected by seasonal changes in flesh weight of clams, the approach based on the calculation of PAHs/SW index was applied. From the results, it was concluded that PAHs/SW index is more recommendable to asses temporal variation of PAHs levels in Manila clams.  相似文献   

17.
Sediments frequently cause damage to biota due to the accumulation of toxic compounds and the bioavailability of sediment-bound contaminants. Damage can be assessed using biomarkers, such as the degree of genotoxic impact following in vivo exposure to pollutants. Genotoxic damage, expressed as single-strand DNA breaks, was measured in cells isolated from haemolymph, gill and digestive gland from the clam Tapes semidecussatus, using the single cell gel electrophoresis (Comet assay). Clams were exposed for three weeks to sediment samples collected from a polluted site and a ‘clean’ reference site.The level of DNA damage was assessed using an image analysis package and expressed as Tail Moment. Throughout the study, significant differences in DNA damage were recorded for each tissue type between clams exposed to the two sediment samples. We conclude that the Comet assay is a useful tool for the detection of DNA damage in clams chronically exposed to polluted sediments.  相似文献   

18.
Burrowing behaviour is adaptive and allows clams to escape predation; yet the effects of potentially toxic metals on such behaviour have not been adequately investigated. In natural marine sediment contaminated with copper the time for littleneck clams (Protothaca staminea) to achieve complete burial was recorded. Above a threshold of 5.8 μg g−1 Cu added to dry sediment, the time for 50% of the clams to burrow (ET50) increased logarithmically with increasing sediment copper concentration according to:
logET50 = 0.15 (CU) - 1.37 (n = 4, r2 = 0.98)
where ET50=time in hours for 50% of clams to burrow and Cu=μg g−1 Cu in dry sediment. Previously exposed clams had both a lower threshold to Cu and a longer reburrowing time (ET50). Clams exposed to sediment mixed with Chelex-100®-sorbed copper showed no significant change in burrowing time. Bioassays based on claim burrowing behaviour can measure both bioeffectiveness of sediment-sorbed metals and a sublethal effect with ecological meaning.  相似文献   

19.
Caddisfly (Trichoptera) larvae are an abundant and widespread aquatic insect group characterized by the construction of silk structures, including nets and cases. Case-building caddisfly have the potential to modify the sorting and mobility of sand and fine gravel via: (1) case construction, resulting in altered sediment properties; (2) transporting sediment incorporated into cases over the river bed; and (3) changing the structure of river beds via burrowing activity. To investigate these mechanisms, it is necessary to understand the mass, size distribution and spatial variability of sediment use by case-building caddisfly larvae. We quantified the mineral sediment used by individuals and communities of case-building caddisfly in 27 samples, from three sites on a gravel-bed stream. The mass and size distribution of sediment in individual cases varied between taxa (mass = 0.001–0.83 g, D50 = 0.17–4 mm). The mean mass of sediment used by the caddisfly community was 38 g m−2 and varied locally. Sediment use was predominantly coarse sand (D50 = 1 mm). 64% of sediment use was attributable to Agapetus fuscipes (Glossosomatidae). Due to within-species variability in case mass, the abundance of most taxa, including A. fuscipes, was only weakly associated with the mass of sediment used by this species, at the river scale. Whilst the caddisfly community used a small percentage of the total sediment available (average 2.99% of the 1–1.4 mm size fraction), A. fuscipes used more fine sediment in their cases at sites where it was more available. Despite variability in local habitat, all sites supported diverse case-building caddisfly communities utilizing mineral sediment. Consequently, geomorphological effects of case-building caddisfly are potentially widespread. The results provide novel insights into the specific grain sizes and quantities of fine sediment used by caddisfly larvae, which represents an important step towards understanding their zoogeomorphic activities. © 2019 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd.  相似文献   

20.
Abstract

River basin lag time (LAG), defined as the elapsed time between the occurrence of the centroids of the effective rainfall intensity pattern and the storm runoff hydrograph, is an important factor in determining the time to peak and the peak value of the instantaneous unit hydrograph, IUH. In the procedure of predicting a sedimentgraph (suspended sediment load as a function of time), the equivalent parameter is the lag time for the sedimentgraph (LAGs ), which is defined as the elapsed time between the occurrence of the centroids of sediment production during a storm event and the observed sedimentgraph at the gauging station. Results of analyses of rainfall, runoff and suspended sediment concentration event data collected from five small Carpathian basins in Poland and from a 2.31-ha agricultural basin, in central Illinois, USA have shown that LAGs was, in the majority of cases, smaller than LAG, and that a significant linear relationship exists between LAGs and LAG.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号