Multi-level assessment of chronic toxicity of estuarine sediments with the amphipod Gammarus locusta: I. Biochemical endpoints

We report on biomarker responses conducted as part of a multi-level assessment of the chronic toxicity of estuarine sediments to the amphipod Gammarus locusta. A companion article accounts for organism and population-level effects. Five moderately contaminated sediments from two Portuguese estuaries, Sado and Tagus, were assessed. Three of them were muddy and two were sandy sediments. The objective was to assess sediments that were not acutely toxic. Three of the sediments met this criterion, the other two were diluted (50% and 75%) with clean sediment until acute toxicity was absent. Following 28-d exposures, the amphipods were analysed for whole-body metal bioaccumulation, metallothionein induction (MT), DNA strand breakage (SB) and lipid peroxidation (LP). Two of the muddy sediments did not cause chronic toxicity. These findings were consistent with responses at organism and population levels that showed higher growth rates and improvement of reproductive traits for amphipods exposed to these two sediments. Two other sediments, one muddy and one sandy, exhibited pronounced chronic toxicity, affecting SB, MT induction (in muddy sediment), survival and reproduction. Potential toxicants involved in these effects were identified. The last sandy sediment exhibited some loss of DNA integrity, however growth was also enhanced. Present results, together with the organism/population-level data, and also benthic communities information, were analysed under a weight-of-evidence approach. By providing evidence of exposure (or lack of it) to contaminants in sediments, the biomarkers here applied assisted in distinguishing toxicants' impacts in test organisms from the confounding influence of other geochemical features of the sediments.     

Effects of water-borne copper on metallothionein and lipid peroxidation in the marine amphipod Gammarus locusta

The aim of the current work was to determine over 10 days the effects of water-borne exposure of the marine amphipod Gammarus locusta to 4 microgCu l(-1) on the metallothionein (MT; measured by differential pulse polarography) protection system and lipid peroxidation (LP: thiobarbituric acid-reactive malondialdehyde equivalents) as a measure of oxidative damage. MT levels in exposed animals increased significantly at day 2 (36% > control; P < 0.001) and remained high at days 6 and 10 (55 and 38%, respectively, P < 0.001). The maximum level of MT at day 6 coincided with the highest Cu body-burden. LP increased within I day of exposure, indicative of Cu as an oxidative stressor. However, in contrast to MT, the highest LP level was seen at day 4 (68% > control, P < 0.001) before returning to control values by day 6, indicating a protective role of MT against the pro-oxidant effects of Cu.     

Method for assessing the chronic toxicity of marine and estuarine sediment-associated contaminants using the amphipod Corophium volutator

Acute sediment toxicity tests do not test key life stage events such as moulting and reproduction and therefore do not reveal the longer-term effects of contaminant exposure. A laboratory method is described for determining the chronic toxicity of contaminants associated with whole sediments. The test is conducted using neonates of the estuarine amphipod Corophium volutator at 15 degrees C, salinity 25 psu and a 12 h light:12 h dark photoperiod. The endpoints are survival and growth after 28 days and survival, growth and reproduction of amphipods upon termination of test i.e. reproduction within all control vessels (ca 75 days). The sediment chronic toxicity test was used to investigate the effects of sediments spiked with environmentally relevant preparations of slightly weathered Alaskan North Slope crude oil, including a water-accommodated-fraction (WAF) and a chemically-dispersed (Corexit 9527) WAF. Sediment oil concentrations were quantified using ultra-violet fluorescence. The amphipods exposed to chemically dispersed oil had higher mortality and lower growth rates than control-, Corexit 9527- and WAF-exposed organisms, resulting in reduced reproduction. The described method supplements the standard acute sediment test and would be particularly useful when long-term ecological effects are suspected but acute tests reveal no significant mortality. The sediment chronic test reported herein has shown that sediment that was not evidently toxic during 10-day acute tests could have population-level effects on sediment-dwelling amphipods.     

Effects of contaminated sediments and sediment-exposed effluent water on an estuarine fish: Acute toxicity

The Elizabeth River is Virginia's most heavily populated, industrialized and contaminated subestuary. Its sediments contain the residues of wastes discharged for several hundred years. To examine some of the effects of sediment from a particularly noxious location, we chose the spot (Leiostomus xanthurus), a bottom-feeding sciaenid and naturally occurring spring-summer migrant of the river whose juveniles adapt readily to laboratory conditions. Spot from the Ware River, a nearby uncontaminated reference subestuary, were placed in two 380 liter (100 USgal), flow-through tanks (70 each). One tank contained Elizabeth River sediments contaminated with PAHs. The second tank contained uncontaminated sediment from the York River as a control. 13 spot each were placed in two aquaria that received the overflow from the sediment-containing tanks. Animals from the reference estuary were examined and processed to provide baseline information.Results obtained to date show the following: (1) spot experimentally exposed to contaminated sediment developed penetrating integumental lesions within 8 days after exposure began and later severe fin and gill erosion; (2) their hematocrits were significantly reduced and no weight gain occurred; (3) pancreatic and liver alterations were observed in some of the chemically stressed fish; (4) control fish exhibited no fin erosion or integumental lesions; (5) control fish showed no hematocrit or growth reduction; and (6) dead fish were first observed in the contaminated-sediment tank after 8 days while no control fish died. Clearly, one or more factors associated with Elizabeth River sediments and/or water closely associated with those sediments (probably the heavy concentrations of PAHs) are capable of causing serious injury, disease and death in experimental spot populations.     

长江口河口锋的悬沙及动力特征初探

通过对2002年9月、2003年4月和2004年10月在长江口滨外区多船同步定点观测的数据进行分析,捕捉到了长江口河口锋带位置,并利用调查数据分析了河口锋带的动力特征.结果表明:长江口河口锋的位置大约位于122°10′E,30°50′N至122°20′E,31°00′N一线附近,在河口锋带有着较为强烈的河海相互作用,流速不符合典型的对数流速曲线,河水与海水的相互消长局限于海面以下5 m的表层范围,观测表明在河口锋面区悬浮泥沙为泥沙流伏在海水之上输运.     

江苏省黄海海域生物质量调查及污染评价

调查了自山东日照至长江口范围内江苏黄海海域18个站位的野生鱼类和甲壳类经济动物体内的污染物水平,监测项目包括:重金属Cu,Pb,Cr,Cd,Hg,总As和石油烃,并对调查结果进行了污染负荷评价。从地域分布来看长江口和吕四港的整体污染水平较高,污染负荷指数为0.35;海州湾和东沙污染水平相当,污染负荷指数为0.25;东沙Cd污染较突出。从生物种类来看鱼类和甲壳类的总As含量较高;大部分生物均发现中度石油烃污染;甲壳类生物体内Cd含量濒临超标限;其余各类生物重金属含量均远低于标准值。     

Studies in seawater and lake water on interactions of trace metals with humic substances isolated from marine and estuarine sediments: II. Voltammetric investigations on trace metal complex formation in the dissolved phase

In seawater and lake water the complexation of several heavy metals, present in the dissolved state at relevant trace levels, with humic substances isolated from two marine and an estuarine sediment has been studied by differential pulse anodic stripping voltammetry (DPASV) at a hanging mercury drop electrode (HMDE). Taking Zn(II) as an example, the aim of this study was to gain direct information on the general level of importance of humic substances for the speciation of certain heavy metals in fresh and saline waters.In seawater humic acids originating from different sediments have very similar complexing properties for Zn(II), decreasing slightly in the order HAN > HAL > HAM. In lake water HAL is most efficient for complexing Zn(II), followed by HAN and HAM.In both types of natural waters, the sedimentary fulvic acid is less efficient in complexing Zn(II) than the respective humic acid from the same site. In general, the complexing efficiency decreases in the order EDTA > NTA > humic acids > fulvic acid.The problem of humic acid adsorption at the electrode, which somewhat limits the investigation of Pb(II) and Cd(II), and the impact of pH on the amount of complexed Zn(II) are also discussed.The findings provide further direct evidence for the conclusion previously drawn from existing complexation data that because of the rather low levels of dissolved humics in large parts of the oceans, the complexation efficiency of humics for Cd, Pb and Zn is too low to affect the speciation pattern of these three heavy metals.     

Studies in seawater and lake water on interactions of trace metals with humic substances isolated from marine and estuarine sediments: I. Characterisation of humic substances

Two humic acids, HAL and HAN, isolated from marine sediments (Adriatic and Norwegian Sea) and humic (HAM) and fulvic (FAM) acids isolated from an estuarine sediment (Mahakam, Borneo) were characterized.The following characteristics: carbon content, hydrophobicity, degree of condensation and the content of aliphatic groups, are most pronounced for HAN, less pronounced for HAL and the least pronounced for HAM. The abundance of trace metals in the humic acids decreases in the following order: Al > Cu > Zn > Pb > Cd.Fulvic acid (FAM) has a lower carbon and a higher oxygen content than humic acids. It is hydrophilic and hardly any aliphatic groups were recorded. At pH 7 the predominant fraction of FAM has the apparent molecular weight of 20 000 daltons while the humic acids are of higher molecular weight.     

象山港沉积物类型变化及沉积环境现状评价

根据2002年6~7月对象山港进行生态调查所获得的资料,评价了象山港水域的沉积物类型变化和沉积环境质量状况,结果表明:与20世纪80年代相比,象山港沉积物类型已发生了较大的变化,由80年代的粉砂质粘土、粘土质粉砂、粘土-粉砂-砂及砾砂4种沉积物类型变为2002年的粉砂质粘土、砂、砂-粉砂、粘土-砂、砂-粉砂-粘土、中细砂、中砂7种沉积物类型。象山港沉积物的质量良好,底质中总氮的含量较高,普遍出现超标现象;部分测站的多氯联苯(PCB)略有超标,各测站总磷硫化物、有机质、石油类等指标均符合一类标准。     

The effect of biological and physical disturbances on the transport of arsenic from contaminated estuarine sediments

From the distribution of dissolved and solid arsenic species in a contaminated estuarine sediment and measured rates of flux of the various arsenic species we propose an empirical model for the cycling of arsenic between sediments and water column. The chemical form of arsenic in the sediment was largely determined by the redox state of the sediment. Arsenite was the dominant dissolved and solid species in the deeper reduced sediment, and arsenate was dominant in the oxidized surface layer. Arsenite in the interstitial water diffused toward the surface layer, where it was mostly oxidized to arsenate prior to leaving the sediments. Some arsenate adsorbed to the surface sediments and produced a surface layer enriched in arsenic. Small concentrations of methyl and dimethyl arsenic were produced in the sediments, and these also diffused into the overlying water.Nereis succinea, a burrowing polychaete, affected distribution and flux of arsenic from the sediments by its production of irrigated burrows. These burrows increased both the effective surface area of the sediment and the diffusion of arsenic by a factor of five. When the relative effects of the activities of Nereis succinea and physical resuspension are compared, results indicate that although physical resuspension can produce large pulses of materials from contaminated sediments, continuous biological activity is likely to be more important in the mobilization of contaminants from sediments in many estuarine environments.     

Statistical analysis of estuarine profiles: II application to arsenic in the Tamar estuary (S.W. England)

By combining field observations with a statistical approach and a simple but effective estuarine analogue, the main features of the cycling of arsenic in the Tamar estuary have been elucidated. As(III) and As(V) enrichment in the water column is due to a combination of localized inputs and effective recycling of sediment interstitial waters. The profiles of As(V) are similar to those of NH₄⁺ and are dominated by an estuarine maximum resulting from an input from the sediments. As(III) profiles are correlated with those of dissolved manganese and exhibit both fresh water and estuarine maxima. As(III) appears to be effectively removed at the freshwater/brackish water interface by a combination of heterogenous oxidation, catalysed by hydrous manganese dioxide, and adsorption on to iron oxyhydroxide. The estuarine distribution of As(III) within the water column is consistent with the published rates of oxidation of As(III) to As(V) by both inorganic and microbiological processes. The reduction of As(V) to As(III) in the sediments is incomplete. On the basis of our observations a tentative estuarine arsenic cycle is presented.     

Laboratory effects of microcosm size and the pesticide chlorpyrifos on benthic macroinvertebrate colonization of soft estuarine sediments

A 42-d flow-through experiment was conducted to evaluate the effects of the organo-phosphate pesticide, chlorpyrifos, and microcosm size (small: 144 cm²; large: 400 cm²) on benthic estuarine macroinvertebrate colonization. Nested central and perimeter (outside margin) cores were used to assess animal distribution within microcosms. Fine-grained, organically-rich (approximately 4.0% organic carbon and 20% dry wt) sediments were nominally fortified with chlorpyrifos controls, low (1.0) and high treatments (10.0 μg⁻¹ wet sediment). Large microcosms contained a significantly (p < 0.05) higher average taxa richness (10.9) than small microcosms (8.6) but small microcosms contained a significantly greater average animal density (295.8; numerical abundance adjusted to unit area) than large microcosms (120.5). Density of the polychaete, Neanthes succinea, the amphipod, Corophium acherusicum, and the barnacle, Balanus sp., was significantly greater in small microcosms but density of Ensis minor was significantly greater in large microcosms. In small and large microcosms, respectively, densities averaged significantly greater numbers in perimeter cores (e.g. 203.1 and 75.1) vs central cores (71.9 and 45.4). Average density decreased significantly with increasing chlorpyrifos concentration from controls (326.8), to low (123.8) and high (78.8) treatments. The density decrease was significantly related only to C. acherusicum whose densities decreased from controls (285.8) to low (88.5) and high (43.9) dosed microcosms. Application of an equilibrium partitioning model indicated that density of C. acherusicum was sensitive to an estimated interstitial water concentration of approximately 0.48 μg liter⁻¹. Non-metric multidimensional scaling ordination analyses provided important insights into response patterns not available through ANOVA procedures. A permutation procedure (ANOSIM) detected a significant size effect (p < 0.0001) and a significant effect between controls and low (p < 0.042) and high doses (p < 0.013) but not between low and high chlorpyrifos treatments (p < 0.465). A single species, C. ascherusicum, as in the ANOVA analyses, dominated contributions to community average percent dissimilarity in most combinations of microcosm size and chlorpyrifos treatment effects (range: 8.4–21.9%). Community structure differed significantly in several combinations of microcosm size, core position and chlorpyrifos treatment. Results confirm earlier work that intrinsic design factors influence benthic macroinvertebrate community structure and determine taxa available to pesticide exposure in microcosms.     

Crude oil bioremediation in sub-Antarctic intertidal sediments: chemistry and toxicity of oiled residues

The effectiveness of fertilizers for crude oil bioremediation in sub-Antarctic intertidal sediments was tested over a one-year period in a series of ten (10) experimental enclosures. Chemical, microbial and toxicological parameters demonstrated the effectiveness of various fertilizers in a pristine environment where hydrocarbon degrading bacteria (HDB) had not been stimulated by previous accidental spills or human activities. The low temperature of seawater (3-4 degrees C) had no obvious effects on the HDB community and the bioremediation process. Over 90% of n-alkanes were degraded in the first six months and most light aromatics (2-3 rings) disappeared during the first year of observation. The toxicity of oiled residues (Microtox(R) SP) was significantly reduced in the first 6 months of the process, but it increased again in the last months of the experiment. One of the fertilizers containing fishbone compost enriched with urea, inorganic phosphorus and a lipidic surfactant reduced significantly the toxicity of oil residues in the last 3 months of the experiment. Interstitial waters collected below the oil slicks during the remediation showed no toxicity, and even stimulated Vibrio fischeri. When comparing all fertilizers to the control plots, a good correlation (r(2)=0.82) was found between the growth rate of HDB and the degradation rate of n-alkanes in the first 90 days of the experiment only indicating that fertilizers were efficient for at least 3 months but their beneficial effects were lost after 6 months.     

Evaluation of the relationships between biochemical endpoints of PAH exposure and physiological endpoints of reproduction in male California Halibut (Paralichthys californicus) exposed to sediments from a natural oil seep

Coal Oil Point (COP) is a natural oil seep off the coast of Santa Barbara, California. Although most studies examining the fate and effects of petroleum have focused upon urbanized or anthropogenic sources of inputs, few have examined the effects of polyaromatic hydrocarbons (PAHs) derived from natural seeps. In order to evaluate the effects of PAHs derived from COP on marine fish populations, hatchery-reared California Halibut (Platichthys californicus) were exposed for 30 days to seven dilutions of sediments collected from COP. Hepatic cytochrome P450 1A (CYP1A), biliary fluorescent aromatic compounds (FACs), gonadal somatic indices, and plasma steroid concentrations. Sixteen USEPA priority PAHs were targeted for analysis in each sediment dilution. In general, biochemical responses were somewhat recalcitrant to dose-response relationships and were less sensitive than the literature values established for the same indicators following exposure to urbanized PAHs. Trends toward reductions in plasma 17beta-estradiol concentrations were observed, but reductions in gonadal somatic indices were not observed. FAC values for naphthalene, benzo(a)pyrene, phenanthrene-related compounds reached maximums at 33-100% COP sediment. The resulting insensitivity may be unique for exposure to "natural" petroleum due to a higher concentration of lower molecular weight PAHs or uncharacterized inhibitors.     

Mercury and the estuarine marsh clam, Rangia cuneata gray. II. uptake, tissue distribution and depuration

During a two-week period, Rangia rapidly accumulates mercury (as mercuric chloride) from dilute solution (0·03–0·05 ppm) with the majority being located in gill and mantle tissue. Initial depuration (5 h) in clean seawater is rapid in all tissues. From 10–192 h concentrations of mercury in gill, foot and adductor muscles remain stable while mantle, haemolymph and viscera levels continue to fluctuate in a manner suggesting internal redistribution of mercury. After eight days of depuration, the viscera contains the most mercury and appears to be the only tissue to increase its proportionate share of the total tissue mercury. After fifteen weeks of depuration, residual mercury in whole clams is about 20% of initial concentrations. Acute decreases in salinity (15% S to 2% S) enhance Rangia's ability to depurate mercury.     

Characteristics and landcover of estuarine boundaries: implications for the delineation of the South African estuarine functional zone

This study investigated whether the current lateral boundary for estuaries in South Africa, i.e. the estuarine functional zone (EFZ), includes all estuarine habitats. The EFZ covers 173 930 ha in 304 estuaries/outlets nationally. Field surveys and analysis of available aerial images showed that 82 (12 956.70 ha) of these estuaries (26%) had estuarine habitats occurring outside of this boundary. As a result of mapping scale, the National Vegetation Map does not represent habitats that are associated with small estuaries (approximately 50% of South Africa's estuaries). For estuaries in the Western and Eastern Cape provinces, most habitats have been lost due to urban development, whereas in subtropical areas (northern Eastern Cape and KwaZulu-Natal), cultivation has removed estuarine habitat. Although delineation of boundaries can be complicated by landcover changes, the estuarine lateral boundary in Cape estuaries could be identified based on sediment characteristics (moisture content, organic content, electrical conductivity), groundwater characteristics (salinity, conductivity and depth) and plant species. The delineation of the EFZ needs to be consistent, inclusive of all estuarine physical and biological processes, and cost-effective to identify so that it can protect estuarine habitats.     

The sea-surface microlayer of puget sound: Part II. Concentrations of contaminants and relation to toxicity

Many aquatic contaminants, because of low water solubility (hydrophobicity) or association with floatable particles, concentrate at the sea surface. Thirty-six samples of the sea-surface microlayer (SMIC), the upper 50 μm, were collected from sites in Puget Sound, Washington State. Sites included three urban bays, central Puget Sound, and a rural reference site. Exposure of floating fish eggs to approximately half of these samples resulted in sublethal and lethal toxic effects (Hardy et al., 1987c).Chemical analyses revealed high concentrations of contaminants in many of the samples. Major temporal and spatial differences in sea-surface chemistry occurred, but maximum (for all) and mean (for 1985) concentrations were aromatic hydrocarbons, 8030 (mean 132) μg liter⁻¹: saturate hydrocarbons, 2060 μg liter⁻¹: pesticides, 43·8 (mean 0·46) ng liter⁻¹; PCBs, 3890 (mean 631) ng liter⁻¹; and total metals, 4750 (mean 626) μg liter⁻¹. Stepwise multivariate regression indicated that the percentage of fish eggs developing to normal live larvae decreased with increasing concentrations of a complex mixture of contaminants. Principal component analysis demonstrated that the major types of contaminants did not differ greatly in their statistical contribution to the toxicity, i.e. no single chemical was responsible for the observed toxicity.The chemical composition of the SMIC samples suggested that contamination originated from a variety of sources including atmospheric deposition, terrestrial runoff of fossil fuel combustion products, and sewage disposal.     

Acute and sublethal toxicity of naphthalene and three methylated derivatives to the estuarine copepod, Eurytemora affinis

The bi-cyclic aromatic hydrocarbon naphthalene (N) and its alkylated derivatives 2-methylnaphthalene (MN), 2,6-dimethylnaphthalene (DMN) and 2,3,5-trimethylnaphthalene (TMN) were used to investigate possible relationships between increased methylation and toxicity during acute high level and chronic low level exposure experiments using the calanoid copepod Eurytemora affinis Poppe. The 24-h LC₅₀ levels determined indicated an approximate twofold increase in toxicity per methyl group addition: N-3798 μg/litre; MN-1499 μg/litre; DMN-852 μg/litre and TMN-316 μg/litre. Low level chronic exposure of E. affinis to the various naphthalenes in sea water concentrations of about 10 μg/litre for the duration of their adult life (maximum twenty-nine days) resulted in significant reductions in length of life, total numbers of nauplii produced and mean brood size. Exposure to all the naphthalenes at this level (10 μg/litre) resulted in reduced rates of egg production which were, on average, about 50% of those of control animals. Results are discussed in relation to previous work on the fate and effect of petroleum hydrocarbons in marine copepods.     

A field-based population model for the sediment toxicity test organism Leptocheirus plumulosus: II. Model application

A stage-structured population model has been developed for the estuarine amphipod Leptocheirus plumulosus to provide interpretive guidance for sediment toxicity tests with this species. This time-varying, field-based model includes several matrices to reflect seasonal changes in demographics. In this paper, we conduct sensitivity analysis of the model to identify which life history parameters have the greatest potential impact on population growth rate (lambda). Results indicate seasonal variability in the relative demographic importance of vital rates. Over winter, annual population growth is most sensitive to the persistence of juveniles and adults and growth from the juvenile to the adult stage. In spring and fall, changes in fecundity are likely to have large effects on population dynamics. In addition, we demonstrate the applicability of the model by using it to interpret toxicological data from an assessment of sediment contamination in Baltimore Harbor, MD. The model was parameterized with survival data from acute toxicity tests with L. plumulosus to project effects on population growth rate (lambda). Results of these model simulations indicate that relatively small changes in survival can result in large changes in lambda, indicating high risk to benthic populations. Furthermore, population projections mirror observed abundances of L. plumulosus at the test sites. These analyses provide a first indication of the usefulness of the Leptocheirus population model as a tool for exploring ecological effects of sediment contamination.     

椒江沉积物的重金属分布特征及环境评价

沉积物对水体中的重金属具有源和汇的双重作用。河流沉积物中重金属含量与相态分析是研究流域重金属元素循环,评价其生态危害性的基本方法。采用1mol/L的盐酸对椒江悬浮物和河漫滩沉积物进行淋滤,研究重金属(Zn、Pb、Cr、Cu和Cd)在酸溶相和酸不溶相中的分布特征,分析并揭示其主要来源和生态效应。椒江沉积物中Zn、Pb、Cu、Cd的含量明显高于浙东地区土壤背景值,酸淋出率>60%,当环境条件发生变化时,酸溶相中的重金属易释放到水体中,具有较高的生态风险。相关性和主成分分析揭示,酸溶相中的重金属主要吸附、络合于有机质和铁锰氧化物中,其来源受工业、农业排放的控制。富集因子分析和潜在生态危害评价表明,椒江沉积物中Cd的富集程度最高,尤其在上游永安溪河段,Cd达到显著富集。而Zn、Pb、Cr、Cu均为轻度—中度富集。