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1.
《Marine pollution bulletin》2009,58(6-12):689-694
To complement physical and chemical data, information of biological communities is important to assess the qualities of mangrove sediments receiving wastewater. Ciliate communities have cosmopolitan distribution, short life cycle and high sensitivity to pollutants, which make them useful as biological indicators of the sediment environment. In most literature, ciliates are widely used as bioindicators for the state of water quality. In this study, the physico-chemical parameters and ciliate community structure of surface sediment collected at different sampling points from two constructed mangrove (Aegiceras and Sonneratia) belts for treatment of municipal sewage in southern China were investigated. Results showed that most (> 80%) of the 216 species ciliates identified at the two constructed mangrove belts were either omnivorous or bacterivorous. Sediment redox potential (Eh) was considered an important factor to govern the distribution of ciliate species within the mangrove sediment. The saprobic system originally derived from freshwater ecosystem was used to evaluate the saprobic degrees of these constructed mangrove belts. Saprobic index (SI) values declined from the sewage inlet to the outlet points of the constructed belts, suggesting better sediment quality at the outlet point caused by treatment processes within the mangrove belt system. Sediment quality of the sewage outlet area of the constructed Aegiceras belt was determined as class II-III (SI = 2.48), while that of the Sonneratia belt was as class III (SI = 2.71) according to the saprobic classification, indicating that a better sewage treatment efficiency was apparent in the Aegiceras than Sonneratia belt. The present data suggested that ciliates could serve as a good bioindicator in assessing organically polluted sediment qualities.  相似文献   

2.
A pilot-scale mangrove wetland was constructed in Futian, Shenzhen for municipal sewage treatment. Three identical belts (length: 33m, width: 3m, depth: 0.5m) were filled with stone (bottom), gravel and mangrove sand (surface). Seedlings of two native mangrove species (Kandelia candel, Aegiceras corniculatum) and one exotic species (Sonneratia caseolaris) were transplanted to the belts with one species for each belt. The hydraulic loading was 5m(3)d(-1) and hydraulic retention time 3d. High levels of removal of COD, BOD(5), TN, TP and NH(3)-N were obtained. The treatment efficiency of S. caseolaris and A. corniculatum was higher than that of K. candel. Faster plant growth was obtained for S. caseolaris. The substrate in the S. caseolaris belt also showed higher enzyme activities including dehydrogenase, cellulase, phosphatase, urease and beta-glucosidase. The removal rates of organic matter and nutrients were positively correlated with plant growth. The results indicated that mangroves could be used in a constructed wetland for municipal sewage treatment, providing post-treatment to remove coliforms was also included.  相似文献   

3.
In wetlands constructed for treating municipal and industrial wastewater, including mangroves, the effect of wastewater discharged on the substrate has often been neglected. Ciliates, an important group of protozoa, are sensitive to pollutants and any changes in ciliate diversity and community structure reflects the habitat quality. The ciliate communities at six sections along a constructed mangrove belt (33 m in length) planted with Aegicerascorniculatum were investigated in Shenzhen, South China. In all samples collected in both rainy and dry seasons, 183 ciliate species were observed. Most species (56%) were free-swimming forms, while only 10.8% were sessile ciliates. The abundance and species number of ciliates were both found to decrease from the anterior (the wastewater inlet) to the posterior (the outlet) parts of the wetland belt, indicating that organic matter and bacteria in wastewater, which served as food for most ciliates, were gradually removed by the constructed wetland. The r/K (number of r- and K-selected species) ratios at the six sections were relatively small, between 0.2 and 0.4, whereas the C/P (abundance of colpodids and polyhymenophorans) quotient at some sections was higher than 1. These results indicate that although most of the environments along the constructed wetland belt were not stressful for ciliate communities, there were habitats that favored colpodids in high abundances.  相似文献   

4.
《Marine pollution bulletin》2009,58(6-12):735-743
A pilot-scale mangrove wetland was constructed in Futian, Shenzhen for municipal sewage treatment. Three identical belts (length: 33 m, width: 3 m, depth: 0.5 m) were filled with stone (bottom), gravel and mangrove sand (surface). Seedlings of two native mangrove species (Kandelia candel, Aegiceras corniculatum) and one exotic species (Sonneratia caseolaris) were transplanted to the belts with one species for each belt. The hydraulic loading was 5 m3 d−1 and hydraulic retention time 3 d. High levels of removal of COD, BOD5, TN, TP and NH3–N were obtained. The treatment efficiency of S. caseolaris and A. corniculatum was higher than that of K. candel. Faster plant growth was obtained for S. caseolaris. The substrate in the S. caseolaris belt also showed higher enzyme activities including dehydrogenase, cellulase, phosphatase, urease and β-glucosidase. The removal rates of organic matter and nutrients were positively correlated with plant growth. The results indicated that mangroves could be used in a constructed wetland for municipal sewage treatment, providing post-treatment to remove coliforms was also included.  相似文献   

5.
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   

6.
To investigate the influence of mangrove reforestation on the accumulation of PCBs, the concentrations and homologue patterns of polychlorinated biphenyls in surface sediments from different mangrove forests and their adjacent mud flats in Guangdong Province were determined. The total PCB concentrations in the sediments ranged from 3.03 to 46.62 ng g?1 (dry weight). Differences in the accumulation and distribution of PCBs were found between the mangrove sites and the mud flats. Furthermore, the natural forests and restored mangrove forests of native species showed slight PCB contamination, whereas the exotic species Sonneratia apetala exacerbated the PCB pollution at certain sites. It was suggested that the native mangrove species Kandelia candel and Aegiceras corniculatum could represent good choices for the phytoremediation of PCB contamination.  相似文献   

7.
In January 2006, 25 tonnes of heavy fuel oil spilled into the Port of Gladstone in Queensland, Australia, from the breached hull of a bulk carrier ship. While approximately 18 tonnes of the oil was recovered, a certain amount of oil was deposited in the intertidal areas of Port Curtis leaving a highly visible, viscous residue. The objectives of this research were to assess the short-term (one month post-spill) and medium-term (six months post-spill) impacts on the intertidal habitat.Sediment polycyclic aromatic hydrocarbons (PAHs) and metal concentrations, mangrove communities and intertidal macroinvertebrates were assessed at oil impacted sites, adjacent sites which were not visibly impacted and reference sites which were located outside the recorded distribution of the oil spill.At one month post-spill, highest PAH concentrations were found at the impacted sites, with concentrations of some PAHs exceeding Australian and New Zealand sediment quality guidelines (SQG) [ANZECC/ARMCANZ, 2000. Sediment Quality Guidelines. Australia and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand]. However, by six months post-spill PAH concentrations had significantly decreased. PAH concentrations tended to be higher in the back (upper) intertidal zone than at the front of the mangrove stand, and sediment cores indicated that PAH contaminants had remained in the top 4 cm of the sediment. These results indicate that the overall decreased PAH concentrations are likely to be due to evaporation, photoxidation and tidal flushing of the residual oil in these impacted sites.During the initial survey, the impact site contained very few or no crabholes in the high intertidal area, indicating a low crab density in comparison to reference sites. However, at six months post-spill mangrove crab communities appeared to be fully recovered with crabhole densities in impact sites similar to reference sites.While little immediate impact was evident on mangrove parameters, significantly higher seedling mortality and defoliation was apparent at six months post-spill, particularly in the upper intertidal zone. Intertidal macrobenthic communities did not appear to be impacted, either immediately or at six months post-spill. Monitoring of these oil impacted intertidal areas will continue to examine the long-term impacts/recovery from the oil spill.  相似文献   

8.
《Marine pollution bulletin》2012,64(5-12):318-325
Sediment quality, meiofaunal and nematode communities were monitored across six time points at two inside-harbour and three outside-harbour sites over a three-year period in Victoria Harbour, Hong Kong, after the implementation of a sewage treatment project. Twenty-one meiofaunal groups comprising mainly free-living nematodes and harpacticoid copepods and 188 species of free-living nematodes were identified. The outside-harbour area had a more diverse and significantly different nematode community structure as compared to that in the inside-harbour area. Such spatial difference was highly correlated with the total Kjeldahl nitrogen content of the sediments. Over the study period, there was no significant improvement in sediment quality within the harbour. However, in the last sampling time, an increase in meiofaunal abundance and a closer similarity in nematode composition between one of the inside- and outside-harbour sites suggested signs of recovery of the meiofauna as a response to abatement of sewage pollution.  相似文献   

9.
Sediment quality, meiofaunal and nematode communities were monitored across six time points at two inside-harbour and three outside-harbour sites over a three-year period in Victoria Harbour, Hong Kong, after the implementation of a sewage treatment project. Twenty-one meiofaunal groups comprising mainly free-living nematodes and harpacticoid copepods and 188 species of free-living nematodes were identified. The outside-harbour area had a more diverse and significantly different nematode community structure as compared to that in the inside-harbour area. Such spatial difference was highly correlated with the total Kjeldahl nitrogen content of the sediments. Over the study period, there was no significant improvement in sediment quality within the harbour. However, in the last sampling time, an increase in meiofaunal abundance and a closer similarity in nematode composition between one of the inside- and outside-harbour sites suggested signs of recovery of the meiofauna as a response to abatement of sewage pollution.  相似文献   

10.
Restoring belts of perennial vegetation in landscapes is widely recognized as a measure of improving landscape function. While there have been many studies of the transport of pollutants through grass filter strips, few have addressed sediment related processes through restored tree belts. In order to identify these processes and quantify their relative contribution to sediment trapping, a series of rainfall simulations was conducted on a 600 m2 hillslope comprising a pasture upslope of a 15 year old tree belt. Although the simulated events were extreme (average recurrence intervals ～10 and 50 yr), the trapping efficiency of the tree belt was very high: at least 94% of the total mass of sediments was captured. All the size fractions were trapped with a minimum Sediment Trapping Ratio (STR) of 91% for the medium‐sized fragments. Fractions < 1·3 µm and > 182 µm were totally captured (STR = 100%). Through the joint analysis of sediment budgets and soil surface conditions, we identified different trapping processes. The main trapping process is the sedimentation (at least 62% of trapped sediment mass) with deposits in the backwater and as micro‐terraces within the tree belt. Modelling results show that the coarsest size fractions above 75 µm are preferentially deposited. Joint infiltration of water and sediments has also been noticed, however, this process alone cannot explain the selective trapping of the finest fractions. We suggest that the finest fractions transported by the overland flow may be trapped by adsorption on the abundant litter present within the tree belt. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

11.
The remediation of mangrove sediment contaminated with mixed polycyclic aromatic hydrocarbons (PAHs) having 3-, 4- and 5-rings by natural attenuation, bioaugmentation, phytoremediation and its combination was compared by greenhouse microcosm studies. At Days 90 and 154, the decreases of PAHs in contaminated mangrove sediment by phytoremediation, planted with one-year old Aegiceras corniculatum, and bioaugmentation, the inoculation of PAH-degrading bacterial strains isolated from mangrove sediment, either SCSH (Mycobacterium parafortuitum) or SAFY (Sphingobium yanoikuyae), were not better than that by natural attenuation (the non-vegetated and un-inoculated microcosms). The populations of SCSH and SAFY in sediment could not be maintained even with repeated inoculation, suggesting that the two isolates were not able to compete with the indigenous microbes and had little enhancement effect. Although some PAHs were accumulated in roots, root uptake only accounted for <15% of the spiked PAHs and the effect of plants on remediation were also insignificant. At the end of the 154-day experiment, the mass balance calculation revealed that the overall losses of PAHs by phytoremediation were comparable to that by bioaugmentation but were lower than that by natural attenuation, especially for the high molecular weight PAHs. Under natural attenuation, around 90% fluorene, 80% phenanthrene, 70% fluoranthene, 68% pyrene and 32% benzo[a]pyrene in contaminated sediment were removed. These results demonstrated that the mangrove sediment itself had sufficient indigenous microorganisms capable of naturally remedying PAH contamination.  相似文献   

12.
Wu Y  Tam NF  Wong MH 《Marine pollution bulletin》2008,57(6-12):727-734
The effects of salinity on the removal of dissolved organic carbon and nutrients from municipal wastewater by constructed mangrove microcosms planted with Aegiceras corniculatum were investigated. During the four-month wastewater treatment, the treatment efficiency was reduced by high salinity, and the removal percentages of dissolved organic carbon, ammonia-N and inorganic N dropped from 91% to 71%, from 98% to 83% and from 78% to 56%, respectively, with salinity increasing from 0 to 30 parts per thousands (ppt). In spite of such inhibition at high salinity, 100% of the effluents discharge from the constructed mangrove microcosms still complied with the discharge standards set by the Hong Kong Government for Coastal Water Control Zones. These results suggested that constructed mangrove wetland treatment systems were promising to effectively treat municipal wastewater, even those with high salinity. In addition, the denitrification potential in soil was found to be retarded by the high salinity while mangrove plants grew best at 15 ppt salinity condition.  相似文献   

13.
Benthic metabolism (measured as CO2 production) and carbon oxidation pathways were evaluated in 4 mangrove mesocosms subjected daily to seawater or 60% sewage in the absence or presence of mangrove trees and biogenic structures (pneumatophores and crab burrows). Total CO2 emission from darkened sediments devoid of biogenic structures at pristine conditions was comparable during inundation (immersion) and air exposure (emersion), although increased 2-7 times in sewage contaminated mesocosms. Biogenic structures increased low tide carbon gas emissions at contaminated (30%) and particularly pristine conditions (60%). When sewage was loaded into the mesocosms under unvegetated and planted conditions, iron reduction was substituted by sulfate reduction and contribution of aerobic respiration to total metabolism remained above 50%. Our results clearly show impacts of sewage on the partitioning of electron acceptors in mangrove sediment and confirm the importance of biogenic structures for biogeochemical functioning but also on greenhouse gases emission.  相似文献   

14.
Ciliated protozoans are important constituents of periphytic communities in aquatic habitats, including river-floodplain ecosystems. As the knowledge about the diversity and ecological importance of periphytic ciliates in floodplain habitats is still limited, the main objectives of this study were to analyse the temporal variations in the community structure and functional role and reveal the main environmental factors controlling community dynamics. The study was conducted in one of the Danube's largest conserved floodplains – Kopački Rit in Croatia. In situ research included two experimental series in a lake, the first from spring till winter and the second from summer till winter. Samples were collected biweekly using glass slides as artificial substrates for periphyton development. During the study, two hydrological (low-water and high-water) periods interchanged. High-water periods were characterized by greater water transparency and nutrient concentrations, while electrical conductivity, chlorophyll a concentration, total suspended solids and particulate organic matter in water were higher during low-water periods. Furthermore, hydrological changes greatly affected the periphytic ciliate communities and the highest abundances were registered during low water levels. We identified a total of 133 ciliate taxa, among which the peritrichs, sessile filter feeders, were the dominant representatives in the periphyton, with the highest densities registered in the absence of floods. During extremely high water levels, the composition of the ciliate community in periphyton changed, with mobile ciliates, predators and filter feeders, becoming dominant. This study indicates that the main food source for periphytic ciliates in a floodplain lake are bacteria and algae, confirming the important role of these microorganisms in the lake food web, by making the carbon fixed in bacteria and algae available for the organisms of higher trophic levels. Additionally, periphytic ciliates have a considerable effect on planktonic organisms in the lake, thus connecting benthic and pelagic food webs, especially during low-water periods.  相似文献   

15.
《Marine pollution bulletin》2009,58(6-12):727-734
The effects of salinity on the removal of dissolved organic carbon and nutrients from municipal wastewater by constructed mangrove microcosms planted with Aegiceras corniculatum were investigated. During the four-month wastewater treatment, the treatment efficiency was reduced by high salinity, and the removal percentages of dissolved organic carbon, ammonia-N and inorganic N dropped from 91% to 71%, from 98% to 83% and from 78% to 56%, respectively, with salinity increasing from 0 to 30 parts per thousands (ppt). In spite of such inhibition at high salinity, 100% of the effluents discharge from the constructed mangrove microcosms still complied with the discharge standards set by the Hong Kong Government for Coastal Water Control Zones. These results suggested that constructed mangrove wetland treatment systems were promising to effectively treat municipal wastewater, even those with high salinity. In addition, the denitrification potential in soil was found to be retarded by the high salinity while mangrove plants grew best at 15 ppt salinity condition.  相似文献   

16.
Ephemeral channels in arid regions convey larger amounts of sediment than perennial channels in humid regions. Sediment graphs at the outlet of channels have been derived by the standard sediment rating curve technique and by a lumped model based on the instantaneous unit sediment graph (IUSG) concept. The IUSG gives estimates of sediment transport that are better than those derived with the sediment rating curve as it takes into account the availability of erodible material within the channel bed.  相似文献   

17.
Sediment cores from the vicinity of sewage outfalls off McMurdo Station as well as surface grab samples from different locations in the McMurdo Sound, Antarctica were analysed for coprostanol (5β-cholestan-3β-ol) and epicoprostanol (5β-cholestan-3-ol) to assess the degree of sewage addition to the Sound. Sediment samples close to the point source contain as much as 3 mg g−1 dry sediment of coprostanol, whereas samples farther from the source, for example from New Harbour and Granite Harbour, contain only trace levels to 40 ng g−1. Coprostanol in the sediments of latter locations most likely originates from seals rather than from sewage outfalls. It appears that sewage particles are very quickly incorporated into the sediment layers close to the discharge point in the eastern Sound. However, significant levels (930 ng g−1) of fecal sterols were detected in Cape Armitage surface sediments, indicating that the sewage plume could also have reached the seawater intake station, situated in between the outfall and Cape Armitage sampling site. These results suggest the need for a sound environmental monitoring and assessment of the existing wastewater practices in the region.  相似文献   

18.
Long‐term erosion monitoring data in the Ethiopian highlands are only available from the Soil Conservation Research Program (SCRP) watersheds including the Anjeni watershed. The 113 ha Anjeni watershed was established in 1984 and fanya juu terraces were installed in 1986. Runoff and erosion data are available from three different plot sizes and at the watershed outlet. The objective of this study was to investigate how erosion processes and sediment rating parameters vary with plot size and the progression of the rainy monsoon phase. We analyzed runoff and sediment loss data from 40 plots and the watershed outlet. The dataset included erosion data from 24 newly constructed plots (3 m length) during the rainy monsoon phase of 2012 and 2013, and 16 long‐term plots (with 12, 16, 22, and 24% slopes and 3, 15 and 30 m lengths) and the watershed outlet during the period between 1986 to 1990. Sediment concentration (C) was fitted to runoff (Q) using a power regression equation (C = aQb). Sediment concentration and yield increased with increasing plot length from 3 m to 15 m, but sediment yield decreased as plot length increased to 30 m.The coefficients (a and b) were affected by plot size and the progression of the rainy monsoon phase. As plot size increases, the a value increased, while the b value decreased. Greater a values were observed during the beginning of the monsoon phase, while values of b were greater towards the end of the monsoon phase. Overall findings suggest that erosion from cultivated fields is primarily controlled by transport limitations at the beginning of the monsoon phase, while towards the end of the monsoon phase, as surface covers emerge, sediment availability will be reduced, and thus sediment source would be a limitation. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

19.
The present study examines the benthos within western inner Swansea Bay (Wales, UK), for the period before, during and immediately after the cessation of a major, sewage discharge from Mumbles Head. There have been significant improvements in seawater quality and changes in the species composition of the benthic communities following the cessation of the sewage discharge. There has been an increase in the diversity of deposit feeders, especially the amphipods, and a decrease in the diversity of the filter feeders, especially the polychaetes. Changes are not attributable either to sediment organic matter content or to gross changes in sediment type, but are related to the significant reduction in suspended particulate organic material and sewage contaminants discharged to the Bay. A recovery model has been proposed to describe how soft sediment benthic communities in a shallow, sublittoral, high tidal energy environment respond to the abrupt cessation of a major sewage discharge.  相似文献   

20.
Numerical simulation experiments of water erosion at the local scale (20 × 5 m) using a process‐based model [Plot Soil Erosion Model_2D (PSEM_2D)] were carried out to test the effects of various environmental factors (soil type, meteorological forcing and slope gradient) on the runoff and erosion response and to determine the dominant processes that control the sediment yield at various slope lengths. The selected environmental factors corresponded to conditions for which the model had been fully tested beforehand. The use of a Green and Ampt model for infiltration explained the dominant role played by rainfall intensity in the runoff response. Sediment yield at the outlet of the simulated area was correlated positively with rainfall intensity and slope gradient, but was less sensitive to soil type. The relationship between sediment yield (soil loss per unit area) and slope length was greatly influenced by all environmental factors, but there was a general tendency towards higher sediment yield when the slope was longer. Contribution of rainfall erosion to gross erosion was dominant for all surfaces with slope lengths ranging from 4 to 20 m. The highest sediment yields corresponded to cases where flow erosion was activated. An increase in slope gradient resulted in flow detachment starting upstream. Sediment exported at the outlet of the simulated area came predominantly from the zone located near the outlet. The microrelief helped in the development of a rill network that controlled both the ratio between rainfall and flow erosion and the relationship between sediment yield and slope length. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

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