Accumulation of cadmium from contaminated water and sediment by the shrimp Callianassa australiensis

The burrowing marine shrimp Callianassa australiensis (Dana) was collected from an uncontaminated area in Western Port, Victoria, Australia in 1977. The shrimp were exposed to cadmium-contaminated water and sediment for 8 wk. The concentrations ranged from 0.5 to 63 g Cd 1^-1 for water and 0.5 to 63 g Cd g^-1 for sediment. The shrimp accumulated cadmium from water at a rate commensurate with increases in the concentration of cadmium in water and the duration of the experiment. Although the cadmium concentration in the sediments was 10³ times higher than that in water, it hat no effect on cadmium uptake by the shrimp. The concentration factors decreased with increasing concentration of cadmium in water but increased as the duration of exposure increased. The shrimp dry weight decreased with increasing concentration of cadmium in water and duration of exposure. As was the case with cadmium uptake by the shrimp, these two factors acted interactively on the shrimp dry weight, but the third factor, concentration of cadmium in sediment, had no effect.     

Biodegradation of paclobutrazol by a microbial consortium isolated from industrially contaminated sediment

Biodegradability of the plant growth retardant paclobutrazol by a microbial consortium in which Pseudomonas was the predominant strain was investigated in batch culture. The consortium which had been isolated from an industrially contaminated sediment was proven to be useful for the treatment of effluents containing paclobutrazol. Paclobutrazol was degraded by the pure isolated strain of Pseudomonas sp. as well as the microbial consortium. Paclobutrazol was utilized as the sole source of carbon and energy. Sixty percent of the paclobutrazol was degraded by the microbial consortium from an initial concentration of 54 mg L^?1 within 48 h and more than 98% of an initial concentration of 3.4 mg L^?1 was degraded within 36 h. The optimum temperature and pH were determined to be 30°C and 7.0, respectively. A pure strain of a bacterium, isolated from the enrichment culture was identified as Pseudomonas sp. The microbial consortium was tolerant of high pH and could degrade paclobutrazol faster than the pure strain. The degradation rate of this plant growth regulator in an aerobic environment was greater than that under anaerobic conditions.     

Mobilization kinetics of heavy metals from contaminated river sediment of northern Taiwan by complexing agents

A laboratory experiment was used to investigate the mobilization kinetics of heavy metals from the sediment of a contaminated river located in northern Taiwan with varied concentrations of NTA and EDTA. We found that there were two stages of desorption in the mobilization of heavy metals from the sediment. As the concentrations of NTA and EDTA ranged 0–3.9 x 10^‐4M (0–100mg/l) and 0–2.7 x 10^‐4M (0–100mg/l) respectively, the mobilization percentages of heavy metals were proportional to the logarithm values of the concentrations of NTA and EDTA. The physical meaning of the multiple first‐order reaction was significant for the actual condition, but occasionally, it had more errors for Cu and Zn in the initial phase. The two‐constant model was most appropriate for describing the rates of mobilization of Pb, Cu, Zn, and Cr. The agreement between the diffusion model and the experimental data was satisfactory for Pb, Cu, Zn, and Cr only in the initial 5 h.     

Role of the nutritive value of sediment in regulating population dynamics of the deposit-feeding polychaete Streblospio shrubsolii

The importance of changes in nutritive value of the sediment in regulating the dynamics of the small deposit-feeding polychaete Streblospio shrubsolii (Buchanam, 1890) was examined. First, fluctuations in the population dynamics of S. shrubsolii and in the nutritive content of the sediment were studied on a seasonal scale. Subsequently, a manipulative field experiment was used to test the hypothesis that, in summer, availability of food regulates aspects of the population dynamics of S. shrubsolii. In summer 1997, sharp increases in protein concentrations and in the number of individuals of S. shrubsolii were found compared to all the other seasons. Densities of S. shrubsolii also showed an increase in the subsequent season. Newly recruited juveniles (19-31 setigers) were abundant in summer and autumn 1997, whereas the number of juveniles (32-42 setigers) increased in autumn 1997. Large numbers of adults were found in summer 1997. Significant negative correlations occurred in summer 1997 between the concentrations of proteins and the total number of individuals, the number of newly recruited juveniles and the density of adults. No differences in densities of juveniles, adults or total number of individuals were found among plots before starting the experiment. After 20 days of experimental enrichment, proteins showed a tendency to increase. After 40 days of enrichment, the total number of individuals was significantly greater in the enriched plots. Large numbers of newly recruited larvae and postlarval adults were found in the enriched plots. The experiment corroborated the model that the growth of population was limited by the availability of food in summer. Thus, in this season, patches of food could have a fundamental role in determining the population dynamics of small deposit-feeders under natural conditions and over short time scales.     

Selectivity in feeding by the deposit-feeding bivalve Macoma nasuta

Macoma nasuta Conrad is primarily a deposit-feeding bivalve sucking the top millimeter of the sediment surface. Growth experiments show that surface sediment supports growth better than detritus falling from the water column. Gut clearance time is between 1 and 9 h (12°C). Fecal pellets are ejected in a regular rhythm. However, the total amount of feces per unit time shows considerable individual variation. Due to sorting in the mantle cavity, about 97% (dry weight) of the surface material is ejected again as pseudofeces. Selectivity by the bivalve is estimated by comparison of particle size and organic composition of sandy and muddy sediments and compared with feces produced by clams fed these sediments. Fecal pellets are in all cases richer in organic components than the sediment, indicating a high degree of selectivity. Ingestion and digestion of small animals (meiofauna) occur, but many of the ingested specimens survive. It is not possible to estimate the assimilation of organic matter by simple difference between the ingested sediment and the ejected feces. The difficulties in calculating energy budgets which arise from selective feeding and associated bacteria are discussed.     

Modified pretreatment method for total microbial DNA extraction from contaminated river sediment

Extraction of high-quality microbial DNA from contaminated environmental samples is an essential step in microbial ecological study. Based on previously published methods for soil and sediment samples, a modified pretreatment method was developed for extracting microbial DNA from heavily contaminated river sediment samples via selection of optimal pretreatment parameters (i.e., reagent solution, reaction duration, and temperature). The pretreatment procedure involves washing the river sediment sample for three times with a solution containing 0.1 mol·L^-1 ethylene diamine tetraacetic acid (EDTA), 0.1 mol·L^-1 Tris (pH 8.0), 1.5 mol·L^-1 NaCl, 0.1 mol·L^-1 NaH₂PO₄, and Na₂HPO₄ at 65°C with 180 r·min^-1 for 15 min to remove humic materials and heavy metals prior to the employment of standard DNA extraction procedures. We compared the results of standard procedure DNA extraction following pretreatment, without pretreatment, and with using a commercial PowerSoil^TM DNA Isolation Kit. The results indicated that the pretreatment significantly improved the DNA quality based on DNA yield, DNA fragment length, and determination of prokaryotic diversity. Prokaryotic diversity exhibited in the DNA with the pretreatment was also considerably higher than that extracted with the PowerSoil^TM DNA Isolation Kit only. The pretreatment method worked well even with a small amount of sediment sample (0.25 g or even lower). The method provides a novel, simple, cost-effective tool for DNA extraction for microbial community analysis in environmental monitoring and remediation processes.     

河流泥沙对污染河水中污染物的吸附特性研究

泥沙是河流水体的重要组成部分,在迁移过程中吸附一定的氮、磷进入底层或下游,从而改变水中污染物的分布。通过模拟试验,选择粒径76μm以下泥沙研究不同泥沙含量、不同污染程度等条件下,河流泥沙对污染河水中氮、磷等污染物的吸附特性。结果表明:河流泥沙对污染河水的氮、磷及高锰酸盐指数均有一定的吸附效果,特别是对氮、磷的等温吸附比较明显;与对照相比,含泥沙的试验组水体磷质量浓度最大降低值达0.53mg·L-1;水体溶解性总氮随时间延长,含量逐渐下降。污染物含量、泥沙含量、粒径等均会影响泥沙对污染物的吸附,污染物含量越高、泥沙含量越大、粒径越小吸附效果相对越好。泥沙吸附和富集污染物后沉降进入水体底层,离开水相,因而可以降低水中污染物含量,达到净化水质的作用。     

Uptake of bacterial extracellular polymer by a deposit-feeding holothurian (Isostichopus badionotus)

A laboratory experiment shows that exopolymer (=mucopolysaccharide) produced by the estuarine marine bacterium Pseudomonas atlantica can be a source of nutrition for the deposit-feeding holothurian Isostichopus badionotus (Selenka). Holothurians fed sediment prepared with ¹⁴C-labeled exopolymer incorporated radioactive carbon into their rete mirabile.     

Diversity and vertical distributions of sediment bacteria in an urban river contaminated by nutrients and heavy metals

The aim of this study was to investigate the benthic bacterial communities in different depths of an urban river sediment accumulated with high concentrations of nutrients and metals. Vertical distributions of bacterial operational taxonomic units （OTUs） and chemical para- meters （nutrients： NH4＋, NO3, dissolved organic carbon, and acid volatile sulfur; metals： Fe, Zn, and Cu） were characterized in 30 cm sediment cores. The bacterial OTUs were measured using the terminal restriction fragment length polymorphism analysis. Biodiversity indexes and multivariate statistical analyses were used to characterize the spatial distributions of microbial diversity in response to the environmental parameters. Results showed that concentrations of the nutrients and metals in this river sediment were higher than those in similar studies. Furthermore, high microbial richness and diversity appeared in the sediment. The diversity did not vary obviously in the whole sediment profile. The change of the diversity indexes and the affiliations of the OTUs showed that the top layer had different bacterial community structure from deeper layers due to the hydrological disturbance and redox change in the surface sediment. The dominant bacterial OTUs ubiquitously existed in the deeper sediment layers （5-27 cm） corresponding to the distributions of the nutrients and metals. With much higher diversity than the dominant OTUs, the minor bacterial assemblages varied with depths, which might be affected by the sedimentation process and the environmental competition pressure.     

Bioaccumulation of organochlorine pesticides from contaminated soil by cattle

The study aimed to quantitate the uptake by beef cattle of organochlorine pesticides in from soil. Although such uptake is known to occur, uptake rates have not been accurately measured for these animals and cannot be inferred from data obtained with dairy cattle. In this study, cattle received a diet, of a standard feedlot ration supplemented with organochlorine-pesticide (aldrin?+?dieldrin) contaminated soil. The levels of pesticides in the feed would approximate uptake through normal grazing. Samples of the subcutaneous fat were removed periodically and analysed for pesticide content. Uptake of dieldrin (but not other pesticides present in the soil) was rapid and substantial. Uptake from sandy soils was more efficient than that from clay soils. The experiment was terminated after 8 weeks, because of the high levels of dieldrin in the tissues. Depuration of the accumulated pesticides was a slow and complex process, requiring a longer period than accumulation.     

Feeding and bacteriolytic responses of the deposit-feeder Abarenicola pacifica (Polychaeta: Arenicolidae) to changes in temperature and sediment food concentration

Deposit-feeders can respond to seasonal fluctuations in food concentration both functionally (e.g. by adjusting feeding rates) and physiologically (e.g. by changing the concentration of bacteriolytic agents in gut fluids). Laboratory feeding experiments were carried out (11 to 21 July 1997) with the arenicolid polychaete worm Abarenicola pacifica (Healy and Wells). Objectives were to test for separate and interactive effects of sediment food concentration and temperature (6, 11, and 16 °C) on deposit-feeder functional (feeding rates) and physiological (bacteriolytic activity of gut fluids) responses. Food concentration was varied experimentally using sieved (1 mm) natural sediments (Md φ=2.00; 0.6% organic) mixed with combusted (500 °C, 8 h) sediments for final concentrations of 25, 50, and 100% natural sediment. Sediment food quality was measured as: (1) bioavailable amino acids (EHAA), (2) chlorophyll a (chl a), and (3) bacterial abundance. Feeding rates were inferred from egestion rates (ER, g h⁻¹) and analyzed with respect to worm size. Bacteriolytic activity of midgut fluids was assayed turbidimetrically against two bacterial isolates, after worms had fed on experimental sediments for 15 d. Temperature and food concentration both significantly affected feeding rates, with maxima occurring at 50 and 100% natural sediment mixtures, and at high (16 °C) temperature. ER was positively, but not significantly correlated with EHAA and chl a; a positive, significant correlation was detected between ER and sediment bacterial abundance. Overall, functional responses agreed with earlier compensatory intake models for deposit-feeders. However, the size and direction of these responses was temperature-sensitive, suggesting that these models need to be adjusted for changes in absorption rates. No effects of ambient temperature or food concentration on bacteriolytic rates were observed, possibly due to compensatory mechanisms or the presence of multiple bacteriolytic agents in gut fluids. Received: 28 June 1999 / Accepted: 14 March 2000     

Microbial communities biostimulated by ethanol during uranium (VI) bioremediation in contaminated sediment as shown by stable isotope probing

Stable isotope probing (SIP) was used to identify microbes stimulated by ethanol addition in microcosms containing two sediments collected from the bioremediation test zone at the US Department of Energy Oak Ridge site, TN, USA. One sample was highly bioreduced with ethanol while another was less reduced. Microcosms with the respective sediments were amended with ¹³C labeled ethanol and incubated for 7 days for SIP. Ethanol was rapidly converted to acetate within 24 h accompanied with the reduction of nitrate and sulfate. The accumulation of acetate persisted beyond the 7 d period. Aqueous U did not decline in the microcosm with the reduced sediment due to desorption of U but continuously declined in the less reduced sample. Microbial growth and concomitant ¹³C-DNA production was detected when ethanol was exhausted and abundant acetate had accumulated in both microcosms. This coincided with U(VI) reduction in the less reduced sample. ¹³C originating from ethanol was ultimately utilized for growth, either directly or indirectly, by the dominant microbial community members within 7 days of incubation. The microbial community was comprised predominantly of known denitrifiers, sulfate-reducing bacteria and iron (III) reducing bacteria including Desulfovibrio, Sphingomonas, Ferribacterium, Rhodanobacter, Geothrix, Thiobacillus and others, including the known U(VI)-reducing bacteria Acidovorax, Anaeromyxobacter, Desulfovibrio, Geobacter and Desulfosporosinus. The findings suggest that ethanol biostimulates the U(VI)-reducing microbial community by first serving as an electron donor for nitrate, sulfate, iron (III) and U(VI) reduction, and acetate which then functions as electron donor for U(VI) reduction and carbon source for microbial growth.     

Uptake of 55Fe from contaminated sediments by the polychaete Nereis diversicolor

The polychaete Nereis diversicolor O. F. Müller was exposed to marine sediments which had been contaminated with ⁵⁵Fe either through the testing of nuclear devices or by the release of liquid waste effluent from a nuclear fuel reprocessing plant. The amount of ⁵⁵Fe taken up reached a concentration in the worms about 6% of the concentration in both types of sediment. Bioavailability of ⁵⁵Fe was shown to depend on its concentration in sediment and not on sediment type, stable iron concentration, or the source of contamination. N. diversicolor may not extract from sediment the same fraction of ⁵⁵Fe as does 0.1N HCl and caution should be exercised in using such measurements to represent the bioavailable fraction.     

Uptake and depuration of organic contaminants by blue mussels (Mytilus edulis) exposed to environmentally contaminated sediment

Experiments were designed to expose blue mussels (Mytilus edulis) to contaminated sediment collected from Narragansett Bay, Rhode Island, USA in 1982. Measurements were taken to allow comparisons of the uptake and depuration of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). In addition, concentration factors in the mussels were calculated separately against the dissolved and particulate phase concentrations and the results from the exposure and control systems were compared. Both PAHs and PCBs were rapidly accumulated by the mussels exposed to the contaminated sediment. After the mussels were transferred to control seawater, individual PAHs were depurated with half-lives ranging from 12 to 30 d. Individual PCBs showed depuration half-lives which ranged from 16 to 46 d. Concentration factors in the mussels calculated against the particulate phase concentrations were very different in the exposure and control systems. Concentration factors calculated using only the dissolved phase concentrations (bioconcentration factors) showed excellent agreement in the two systems, possibly an indication that the dissolved phase was the direct source of the contaminants accumulated by the mussels. The bioconcentration factors for PCBs were higher than those of PAHs when compounds with similar n-octanol/water partition coefficients were compared.     

Reproduction and genetic variation in the deposit-feeding sea star Ctenodiscus crispatus

The gonad index in the deposit-feeding asteroid Ctenodiscus crispatus (Retzius) in the Gulf of Maine (USA) is seasonally less variable than in any other sea star, ranging from 2.99 to 4.98% of dry body weight in females and from 2.28 to 3.42% in males, and varies in concert with, rather than reciprocal to, the pyloric caecum index. Biochemical composition and, hence, caloric content, of the gonads also show little seasonal change, suggesting that reproduction is aseasonal and continuous in this population. Oocyte development is asynchronous, all females having a full size range of oocytes (from less than 30 m to greater than 400 m diameter) throughout the year. Seasonally determined size-frequency distributions of juveniles, oocyte cytology and size-frequency distributions, responsiveness of adult females to 1-methyladenine, and oxygen uptake rates indicate that variations in reproductive intensity are superimposed on continuous reproduction, and seem related to changes in phytoplankton production rather than to temperature. The rich neutral lipid content (ca. 50% of total lipid) and large egg size (>400 m) in the ovaries suggest that development is direct. The population is extremely variable genetically, polymorphism among 13 enzyme-coding genes being 77% and average heterozygosity being 0.174. The reproductive pattern and genetic variation in the eurybathic C. crispatus are similar to those in deep-sea echinoderms. This may be related to the constancy of the population's detrital food source, to small-scale heterogeneity of its physical environment, and to low individual vagility.     

Four kinds of capping materials for controlling phosphorus and nitrogen release from contaminated sediment using a static simulation experiment

• Lanthanum modified bentonite (LMB) can effectively absorb phosphorus (P). • Water treatment plant sludge (WTPS) capping is effective for controlling P release. •Aluminum-based P-inactivation agent (Al-PIA) is an efficient P control material. •The P adsorbed by WTPS and Al-PIA is mainly in the form of NAIP. We determined the effects of quartz sand (QS), water treatment plant sludge (WTPS), aluminum-based P-inactivation agent (Al-PIA), and lanthanum-modified bentonite (LMB) thin-layer capping on controlling phosphorus and nitrogen release from the sediment, using a static simulation experiment. The sediment in the experiment was sampled from Yundang Lagoon (Xiamen, Fujian Province, China), which is a eutrophic waterbody. The total phosphorus (TP), ammonium nitrogen (NH₄⁺-N), and total organic carbon (TOC) levels in the overlying water were measured at regular intervals, and the changes of different P forms in WTPS, Al-PIA, and sediment of each system were analyzed before and after the test. The average TP reduction rates of LMB, Al-PIA, WTPS, and QS were 94.82, 92.14, 86.88, and 10.68%, respectively, when the release strength of sediment TP was 2.26–9.19 mg/(m²·d) and the capping strength of the materials was 2 kg/m². Thin-layer capping of LMB, WTPS, and Al-PIA could effectively control P release from the sediment (P<0.05). However, thin-layer capping of LMB, Al-PIA, and QS did not significantly reduce the release of ammonium N and organic matter (P > 0.05). Based on our results, LMB, Al-PIA, and WTPS thin-layer capping promoted the migration and transformation of easily released P in sediment. The P adsorbed by WTPS and Al-PIA mainly occurred in the form of NAIP.     

Historical trends of trace metals in a sediment core from a contaminated tidal salt marsh in San Francisco Bay

Sedimentation of metals preserves historical records of contaminant input from local and regional sources, and measurement of metals in sediment cores can provide information for reconstruction of historical changes in regional water and sediment quality. Sediment core was collected from Stege Marsh located in central San Francisco Bay (California, USA) to investigate the historical input of trace metals. Aluminum-normalized enrichment factors indicate that inputs from anthropogenic sources were predominant over natural input for Ag, Cu, Pb, and Zn. Among these, lead was the most anthropogenically impacted metal with enrichment factors ranging from 32 to 108. Depth profiles and coefficients of variation show that As, Cd, and Se were also influenced by anthropogenic input. The levels of these anthropogenically impacted metals decline gradually towards the surface due to regulation of the use of leaded gasoline, municipal and industrial wastewater discharge control, and closure of point sources on the upland of Stege Marsh. Although trace metal contamination is expected to be continuously declining, the rates of decline have slowed down. For lead, it is estimated to take 44, 82, and 153 years to decrease to probable effects level (112 μg/g), the San Francisco Bay ambient surface sediment level (43.2 μg/g), and the local baseline levels (5 μg/g), respectively. Some metals in surface sediments (0–6 cm) are still higher than sediment quality guidelines such as the probable effects level. To further facilitate the recovery of sediment quality, more efficient management plans need to be developed and implemented to control trace metals from non-point sources such as stormwater runoff.     

Plutonium and Americium: Uptake from contaminated sediments by the polychaete Nereis diversicolor

The polychaete Nereis diversicolor O.F. Müller was exposed to marine sediments which had been contaminated with plutonium and americium either through the testing of nuclear devices or by the release of liquid waste effluent from a nuclear fuel reprocessing plant. The uptake of both plutonium and americium was small, about 0.5% of the concentration of these transuranics in the sediments. The degree of relative uptake of plutonium from both sediments was comparable; relative uptake of americium from sediments contaminated by waste effluent was greater than that from nuclear sediment and those previously determined from water-uptake experiments to environmentally determined plutonium concentrations in sediments and overlying waters leads to the tentative conclusion that water may be the predominant pathway for plutonium accumulation by deposit-feeding worms like N. diversicolor.     

Effects of organic additions to sediment,and maternal age and size,on patterns of offspring investment and performance in two opportunistic deposit-feeding polychaetes

The investment made by a reproducing organism in its offspring can be affected by both extrinsic (environmental) and intrinsic (female condition) factors. The purpose of this study, conducted between December 1990 and June 1992, was to examine the influence of organic additions to sediment, and female age and size, on patterns of offspring investment and performance in the opportunistic polychaete Capitella sp. I (cf. Capitella capitata Farbricius). Sediment treatments were composed of marsh mud enriched with sewage or algae, or spiked with #2 fuel oil. All three of these additions are associated with opportunistic responses in Capitella sp. I populations in the laboratory and field. As a means of comparison,effects of sewage additions were also examined on the spionid Streblospio benedicti Webster. Organic additions to mud had no detectable effect on the C or N content of embryos in either species. However, sewage had a positive effect on juvenile performance in Capitella sp. I. Juveniles produced by adult Capitella sp. I in the sewage treatment grew 2 times larger (in 2 wk) than juveniles produced by adults in the mud treatment when these juveniles were raised in the same sediment type (mud). Such effects may facilitate opportunistic responses in Capitella sp. I offspring by reducing time to first reproduction. In addition to treatment sediment effects, maternal age and size had a strong influence on patterns of offspring investment in Capitella sp. I. The material investiment measured in collected embryos declined with maternal age in the oil and sewage treatments. The C:N ratio of embryos increased with maternal age for Capitella sp. I except in the algae treatment, which showed no effect of maternal age. Juvenile growth decreased with maternal age in the sewage treatment for Capitella sp. I. Maternal size appeared to have a positive effect on embryo investment in the mud and oil treatments, where reproducing worms were smallest. Previous studies of Capitella sp. I have documented a broad range of environmentally induced responses in growth and fecundity.The results of this study emphasize the importance of maternal environment, age, and size effects on the relationship between offspring investment and performance.Such effects may have profound consequences for the dynamics of populations and the fitness of individuals. Present address: WES-ES-F, USAE Waterways Experiment Station, 3909 Halls Ferry Rd., Vicksburg, Mississippi 39180-6199, USA     

Polychlorinated biphenyls: Accumulation from contaminated sediments and water by the polychaete Nereis diversicolor

Comparisons were made of the accumulation of a polychlorinated biphenyl (PCB) mixture from sediments and from water by the benthic worm Nereis diversicolor. Uptake from sediments was dose-dependent, attaining equilibrium concentration factors of approximately 3 to 4 after 2 months. Subsequent PCB elimination rates were concentration-dependent, with higher initial loss rates evident in the worms containing higher levels of PCBs. Accumulation of PCBs from water was much more rapid; concentration factors reached approximately 800 after only 2 weeks. Estimates were made of the relative importance of sediments and water as a source of PCBs to worms exposed to these contaminants in the natural environment. Calculations based on experimentally derived PCB concentration factors and ambient PCB levels in sediments and water suggest that compared to water, sediments contribute the bulk of these compounds to the worms. The possible mechanisms involved in the uptake of sediment-associated PCBs are discussed.