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1.
Since the new outfall for Boston's treated sewage effluent began operation on September 6, 2000, no change has been observed in concentrations of silver or Clostridium perfringens spores (an ecologically benign tracer of sewage), in bottom sediments at a site 2.5 km west of the outfall. In suspended sediment samples collected with a time-series sediment trap located 1.3 km south of the outfall, silver and C. perfringens spores increased by 38% and 103%, respectively, in post-outfall samples while chromium, copper, and zinc showed no change. All metal concentrations in sediments are <50% of warning levels established by the Massachusetts Water Resources Authority. An 11-year data set of bottom sediment characteristics collected three times per year prior to outfall startup provides perspective for the interpretation of post-outfall data. A greater than twofold increase in concentrations of sewage tracers (silver and C. perfringens) was observed in muddy sediments following the exceptional storm of December 11-16, 1992 that presumably moved contaminated inshore sediment offshore.  相似文献   

2.
The Barwon Region Water Authority in Victoria, Australia, commissioned a new subtidal ocean sewage outfall in February 1989. This outfall replaced an old intertidal outfall, and presently discharges via a diffuser in an average depth of 15m some 1.2km offshore in Bass Strait. Examination of biological communities around the old outfall prior to the change revealed distinct differences in biotic assemblages close to the outfall. An ongoing monitoring programme, implemented in 1986, has assessed not only the recovery in this intertidal area, but also the major changes to macroalgal communities on surrounding reefs, subtidal infauna populations in sandy sediments, and rocky shore communities.  相似文献   

3.
In December 2001, acid mine drainage (AMD) from an abandoned copper mine at Britannia Beach (British Columbia, Canada) was diverted to flow from Britannia Creek into an outfall at 30 m depth in Howe Sound. Britannia Beach was studied in early 2003 to determine whether AMD diversion resulted in improved conditions for intertidal organisms. Species number and abundance have increased at the intertidal zone since AMD diversion, although they were still lower than at an unpolluted control site nearby (Furry Creek). Survivorship and growth rates of transplanted Mytilus trossulus (mussel) have increased since AMD diversion, although they were still significantly lower than at the control site. Transplanted Fucus gardneri (seaweed) performed better than before the AMD diversion; at Britannia Beach the chlorophyll a concentration in tissues was not significantly different from that at the control site, although the concentration of chlorophyll c in tissues and the chlorophyll c to a ratio was lower than at the control site six weeks after transplantation. Britannia Beach is still subject to leaching of metals from surrounding soils, low levels of AMD coming down the creek, and AMD discharge from the deep outfall. Although there has been an improvement, the intertidal environment at Britannia Beach still seems unable to support normal growth and survival of organisms.  相似文献   

4.
Sediment disturbance patterns in the coastal area off the Tagus Estuary (Portugal) have been assessed using a set of combined techniques. The potential sources of disturbance in the area include chronic contamination of the fine sediments originating from the estuary, a local input from a long-sea sewage outfall and occasional high runoff episodes following torrential rain. The Sediment Quality Triad approach, combining environmental chemistry (namely organic contaminants), macrofaunal benthic communities and laboratory sediment toxicity assays, was performed on sediment samples from 20 sites. The samples were collected before the outfall commenced operation and four years after commissioning, in order to evaluate the relative magnitudes of the three potential sources of disturbance. The sediment contamination created by the estuary was identified as the most important cause of reduced sediment quality, as disturbance in all three components of the Sediment Quality Triad were only found in a site located near the estuary.  相似文献   

5.
The impact of sewage and stormwater effluents on phytoplankton is investigated by comparing organic-walled dinoflagellate cyst abundance and diversity from 38 surface sediment samples, flanking southern Vancouver Island. Site locations include those directly adjacent to wastewater outfall at Clover and Macaulay Points and Saanich Peninsula, as well as from a variety of near-shore environments with differing tidal flow influences. Excellently preserved dinoflagellate cyst assemblages have been recovered and 36 cyst taxa were identified. Local assemblages are characterized by a high relative proportion (average 56%) of cysts produced by heterotrophic dinoflagellates, which is typical for regions of high primary production. Relative proportional increases of cysts from heterotrophic species with particular increases of Polykrikos kofoidii/schwartzii and Dubridinium species, known to reflect areas affected by eutrophication, occur directly adjacent to all three sewage outfalls, as well as in the more stagnant waters of Esquimalt and Victoria Harbours and at the mouth of Cadboro Bay. Further effects of an anthropogenic effluent can be seen in the relatively higher concentrations of organic carbon and the diatom production proxy, biogenic opal. Results from this study clearly indicate a much larger impact zone than predicted by a sewage effluent plume model or trends found in monitored benthic biota and sediment chemistry that evidence primary outfall affects <800 m eastward of Macaulay Point and about 200 m eastward of the Clover Point. Enhanced production of cysts from potentially toxic Alexandrium species is also observed near locations of sewage outfalls.  相似文献   

6.
Analyses of living foraminiferal and environmental parameters near an outfall at Mar Grosso Beach (Laguna, SC, Brazil) demonstrate its usefulness as indicators of domestic sewage pollution. The low species diversity may be due to sand accumulation in the central part. Higher diversity was noted closer to the mouth of Laguna estuarine system where reduced salinity and higher temperatures indicate freshwater influence, suggesting a relationship between increased diversity and greater availability of terrestrial food. On the basis of foraminiferal diversity and average coliform count the higher values are closer to the mouth of the estuarine system and under the influence of the outfall. Due to the effect of local hydrodynamics, the particulate organic waste derived from the outfall does not settle down locally, and thus, do not accumulate nearby. Our hypothesis is that the fine material derived from the outfall is accumulating on the southwestern and northwestern parts of the beach.  相似文献   

7.
The Massachusetts Water Resources Authority (MWRA) conducts monitoring to address concerns related to the 2000 diversion of secondarily treated effluent discharge into Massachusetts Bay. Baseline data (1992-2000) showed multiple regions defined by physical and chemical composition. Near the Massachusetts Bay outfall, there is a series of heterogeneous sediments in relatively close proximity to the primary historic source of contaminants (Boston Harbor). Farfield sediments exhibited greater compositional definition from one another, which was attributed to the greater spatial separation of the sampling locations. Factors that influence contaminant variability include local and distributed sources, and are primarily related to gradients in depositional environments. Post-diversion sediment data suggest that 4 years of treated effluent discharge has not increased contaminant concentrations to the bay system. However, abundance of the sewage tracer, Clostridium perfringens, has increased variably in sediments located within 2 km of the outfall, providing a distinct effluent signal near the outfall.  相似文献   

8.
Surf Scoters and Greater Scaup and samples of species which comprise the major part of their diets, from Iona Island and Roberts Bank tidal flats, near Vancouver, British Columbia, were analysed for metal residues. Significantly higher silver, copper, lead and zinc levels were found in Greater Scaup than Surf Scoters. The latter species had higher mercury levels. Differences in residue levels between the species reflect interspecific variation in prey as well as feeding habitat. Significantly higher silver, mercury, lead and zinc in Surf Scoters and silver and lead in Greater Scaup observed at Iona Island than at Roberts Bank can be explained by higher levels of those metals occurring in a more metal-contaminated prey and sediment near the Iona Island sewer outfall. Ducks feeding on organisms in different intertidal zones show different accumulation of metal residues and constitute valuable indicators of pathways of toxic chemicals in specific estuarine regions.  相似文献   

9.
Intertidal habitats provide numerous ecosystem services, including the sequestration and storage of carbon, a topic of great recent interest owing to land‐cover transitions and climate change. Mangrove forests and seagrass meadows form a continuum of intertidal habitats, alongside unvegetated mudflats and sandbars, however, studies that consider carbon stocks across these spatially‐linked, threatened ecosystems are limited world‐wide. This paper presents the results of a field‐based carbon stock assessment of aboveground, belowground and sediment organic carbon stock to a depth of 1 m at Chek Jawa, Singapore. It is the first study of ecosystem carbon stocks of both vegetated and unvegetated intertidal habitats in the tropics. Ecosystem carbon stocks were 497 Mg C ha‐1 in the mangrove forest and 138 Mg C ha‐1 in the seagrass meadow. Sediment organic carbon stock dominated the total storage in both habitats, constituting 62% and >99% in the mangrove forest and seagrass meadow, respectively. In the adjacent mudflat and sandbars, which had no vegetative components, sediment organic carbon stock ranged from 124–143 Mg C ha‐1, suggesting that unvegetated habitats have a carbon storage role on the same order of importance as seagrass meadows. This study reinforces the importance of sediment in carbon storage within the intertidal ecosystem, and demonstrates the need to consider unvegetated habitats in intertidal ‘blue carbon’ stock assessments. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

10.
A study of foraminiferal assemblages was carried out in 24 sediment samples collected from the Montevideo coastal zone (south-eastern coastal region of South America) to assess the response of the benthic foraminifera to the polluted sediments. The area is affected by different pollutants such as sewage, hydrocarbons and heavy metals derived from different sources. Biological data were analyzed with multivariate techniques of cluster analysis and a principal component analysis (PCA) was performed for abiotic factors. The results allowed the recognition of different species assemblages corresponding to different sub-environments, which reflected the prevalent ecological conditions. The Montevideo Bay, particularly, its inner part showed an extremely poor foraminiferal fauna-including a totally azoic station-and high percentages of abnormal tests, when compared with the adjacent Punta Carretas and Punta Yeguas zones. Mean faunal density showed a strong relationship with organic matter, oxygen and heavy metal concentrations, as well as redox potential and pH values of each sub-environment. Although the adjacent zones presented a moderate pollution degree, it was noticed that a positive effect on the foraminiferal density specially on Ammonia tepida, caused by the sewage pipe located in Punta Carretas, a pure organic contamination. Differences among foraminiferal assemblages seemed to be related to the combined action of the several kinds of pollutants and the natural abiotic variables, like the rapid salinity changes that occurred in this area.  相似文献   

11.
Toxicity of 1,4-dichlorobenzene in sediments to juvenile polychaete worms   总被引：1，自引：0，他引：1  
Investigation of sediment contamination associated with a marine sewage outfall in Victoria (BC, Canada) found elevated concentrations of 1,4-dichlorobenzene (1,4-DCB). Juvenile polychaete worm (Neanthes) growth was significantly reduced at or near the outfall, roughly corresponding to elevated 1,4-DCB concentrations. There are few data on 1,4-DCB toxicity to marine organisms and no published literature on its toxicity to benthic marine organisms. To determine whether reduced polychaete growth (measured as dry weight) was due to 1,4-DCB exposure, a laboratory investigation was conducted. Uncontaminated marine sediment was spiked with 1,4-DCB and juvenile Neanthes were exposed in 20-d sublethal toxicity tests. There were no adverse effects on survival at any test concentration; mean survival was 80–100%. Statistically significant decreases in average dry weight only occurred at the highest 1,4-DCB concentration (19,900 μg/kg, dry weight); this represented a 1,4-DCB concentration more than 10 times higher than previously measured at the outfall (1710 μg/kg, dry weight). There were no adverse effects on survival or dry weight at the range of concentrations previously measured in sediments from the vicinity of the outfall.  相似文献   

12.
The study aimed at investigating the effects of sewage loadings on the behaviour of two fiddler crabs species maintained in a system of experimental mesocosms, built in a mangrove area in Tanzania and inundated with different seawater/sewage mixtures. Our results show that sewage loads led to a modification of the overall activity budget of the crab community as a result of increased hypertrophic conditions (high COD, increased chlorophyll-a concentrations). During their activity period, crabs inside contaminated mesocosms seemed to satisfy their feeding demand faster than those of the control cells, spending a significant longer time in other activities like courtship and territorial defence. Apart from being a good biological indication of ecosystem eutrophication, such a reduced foraging activity by fiddler crabs also depresses their sediment bioturbation activity, important factor for the health of mangrove systems, suggesting practical implications regarding the efficiency of mangrove-based wetlands for treatment of domestic sewage.  相似文献   

13.
The impact of dead discards, originating from beam trawl fishing on the nematode community from the Tagus estuary was investigated in terms of vertical distribution of the dominant nematode groups. Sediment cores were collected from a mud-flat from the Tagus estuary. Crangoncrangon (Linnaeus, 1758) carcasses were added to the surface of the cores, simulating the settling of dead discards on the sediment. The vertical distribution of the dominant nematode groups was determined up to 4 cm deep at four different moments in time post deposition (0, 2, 4 and 6 h) and compared to control cores. The C.crangon addition to the sediment led to the formation of black spots and therefore oxygen depleted areas at the sediment surface. The Chromadora/Ptycholaimellus group, normally dominant at the surface layer, migrated downwards due to their high sensibility to toxic conditions. Sabatieria presented the opposite trend and became the dominant group at the surface layer. Since Sabatieria is tolerant to oxygen stressed conditions and high sulphide concentrations, we suggest that it migrated opportunistically towards an unoccupied niche. Daptonema, Metachromadora and Terschellingia did not show any vertical migration, reflecting their tolerance to anoxic and high sulphidic conditions. Our study showed that an accumulation of dead discards at the sediment surface might therefore alter the nematode community vertical distribution. This effect is apparently closely related to toxic conditions in the sediment, induced by the deposition of C.crangon at the sediment surface. These alterations might be temporal and reflect an adaptation of the nematode community to dynamic intertidal environments.  相似文献   

14.
A long-term benthic study has been undertaken in the Firth of Forth to assess the environmental impact of a new sewage treatment scheme for the city of Edinburgh. The Sewage Scheme reduces the suspended solids content of the liquid effluent by approximately 60% and achieves a lowering of the concentration of materials in solution through more efficient dilution and dispersion. Marked changes in the intertidal benthic flora and fauna have been recorded along the Edinburgh coastal zone. These changes have been apparent as the decline and disappearance of populations of certain pollution indicator species and the appearance and establishment of several species previously unrecorded along the more polluted parts of the Edinburgh shoreline. Study of the sublittoral benthos has shown no deleterious effect arising from the new effluent outfall, although there does appear to be some enhancement of the fauna in the area.  相似文献   

15.
Marine sediment cores collected from several depths of water and distances from a California sewage outfall were tested to see if sediments influenced by sewage solids were a reservoir of enteric pathogens, and if concentrations of indicator bacteria were related to the presence of sewage solids. Vertical distributions of microorganisms in marine sediments were determined; there was a decrease of indicator bacteria with increasing sediment depth. Aeromonas was randomly isolated, but none of the enteric bacterial pathogens or viruses were detected. While classic indicator bacteria were of little value in predicting the presence of pathogens, or relative amounts of sewage solids, Clostridium perfringens may be a suitable indicator. Clostridium perfringens concentrations were not related to the presence of pathogens in sediments.  相似文献   

16.
The large organic matter flow in tropical coastal areas is recognized as an important process in the global carbon(C)cycle.However,the nature of organic matter flow in semi-enclosed tropical estuaries remains unclear due to the various environmental processes(tidal change,river flow,waves from the sea,and internal circulation)and organic matter sources therein.Thus,sediment organic matter(SOM)sources,and their distribution pattern,are key to understanding ecosystem material flow.Our research in the Batan Bay Estuary,Philippines,a semi-enclosed estuary under large mangrove deforestation,was conducted to determine ecosystem properties through analysis of C and nitrogen stable isotope ratios and environmental factors.First,we determined that mangrove litter,microphytobenthos,and phytoplankton are the main SOM sources in the Batan Bay Estuary.Second,the estuary was classified into three ecological zones(the Bay zone,Back-barrier zone,and River zone).In addition,we estimated SOM source ratios using the Stable Isotope Analysis in R package and determined different organic matter sources in different zone.The high ratios of mangrove litter as SOM indicate that a large amount of terrestrial plant organic matter remains despite the heavy mangrove deforestation that has occurred since the 1980s,and that the Back-barrier zone consists of a different type of ecosystem that promotes accumulation of C from mangrove litter and microphytobenthos.  相似文献   

17.
McMurdo Station, the largest research station in Antarctica, ceased on-site garbage dumping in 1988 and initiated sewage treatment in 2003. In 2003-2004 its sea-ice regime was altered by the massive B-15A and C-19 iceberg groundings in the Ross Sea, approximately 100 km distant. Here we follow macrofaunal response to these changes relative to a baseline sampled since 1988. In the submarine garbage dump, surface contaminants levels have declined but associated macrofaunal recolonization is not yet evident. Although sewage-associated macrofauna were still abundant around the outfall nearly 2 yr after initiation of treatment, small changes downcurrent as far as 434 m from the outfall suggest some community recovery. Widespread community changes in 2003-2004, not seen in the decade previously, suggests that the benthos collectively responded to major changes in sea-ice regime and phytoplankton production caused by the iceberg groundings.  相似文献   

18.
In a dispersive coastal area under multiple organic enrichment sources, stable isotopes were used to trace organic sources of carbon and nitrogen in sediments and benthic macrofauna. The Bivalve Abra alba and the Polychaetes Nephtys sp. and Pectinaria (Lagis) koreni were reliable indicators of the input of terrestrial-derived organic matter into this coastal area, either originated in outfall sewage discharges or estuarine outflow. An isotopic depletion was observed up to 250 m from the outfall branches, much stronger in the biota than in the sediments. An enrichment of 2‰ in the sediments, and 2-6‰ in the species was noticed in sites located farther than 1500 m from the outfall. Depositivores and carnivores/omnivores gave the best picture of the extension of the sewage dispersion and incorporation into the food web.  相似文献   

19.
In 1981–83 sublittoral macroinvertebrates were collected by means of SCUBA diving from artificial substrates submerged near the outfalls from eight sewage treatment plants in Lake Zürich. Pollution around the outfall resulted on the one hand in a reduction of pollution intolerant benthic invertebrates, on the other hand in a considerable increase in the relative abundance of pollution tolerant taxa such as leeches, flatworms and crustaceans. Changes in the faunal composition were related to nutrient enrichment and changes in the nature of the substratum due to sedimentation of sewage sludge. Species diversity (Simpson index) showed low values near the outfall from some plants, high values near the outfall from others. Low species diversity did not always mark the sites where greatest pollution has been observed.   相似文献   

20.
The submarine sewage outfall of Santos (SSOS) is situated in the Santos Bay (São Paulo, Brazil) and is potentially a significant source of contaminants to the adjacent marine ecosystem. The present study aimed to assess the influence of SSOS on the sediment toxicity and contamination at Santos Bay. At the disposal site, sediments tended to be finer, organically richer and exhibited higher levels of surfactants and metals, sometimes exceeding the “Threshold Effect Level” values. The SSOS influence was more evident toward the East, where the sediments exhibited higher levels of TOC, total S and metals during the summer 2000 sampling campaign. Sediment toxicity to amphipods was consistently detected in four of the five stations studied. Amphipod survival tended to correlate negatively to Hg, total N and % mud. This work provides evidence that the SSOS discharge affects the quality of sediments from Santos Bay, and that control procedures are warranted.  相似文献   

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