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1.
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.
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   

3.
《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   

4.
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   

5.
Sediment from the sewage sludge dump site area in the New York Bight contains bacteria resistant to antibiotics and heavy metals. The purpose of this study was to determine if antibiotic resistance could be transferred from donor to recipient Escherichia coli strains inoculated into glass vessels containing sediment and seawater obtained near the dump site. Temperature was maintained at 10°C, the mean winter temperature of benthic water at the dump site. Transconjugants (recipients which inherit donor genes for tetracycline resistance) were isolated from the seawater and sediment within one hour after inoculation and were found in all subsequent sediment samples for one month. Donor and recipient E. coli remained viable in the sediment for at least one month. Our results indicate that sewage sludge polluted sediment may serve as an environment conducive to conjugal transfer of antibiotic resistance genes.  相似文献   

6.
We studied the distribution of planktonic and epiphytic ciliates coupled with environmental factors and microalgae abundance at five stations in Ghar El Melh Lagoon (Tunisia). Planktonic ciliates were monitored for a year and epiphytic ciliates were sampled during summer 2011 in concordance with the proliferation of the seagrass Ruppia cirrhosa. Ciliate assemblage was largely dominated by Spirotrichea followed respectively by Tintinnida of and Strombidiida. No significant difference was found in the distribution of ciliate species among the stations. Redundancy analysis indicates that abiotic factors (temperature and nutriments) have a significant effect on the dynamics of certain ciliates. For epiphytic ciliates, 4 species were identified: Tintinnopsis campanula, Aspidisca sp., Strombidium acutum and Amphorides amphora. Based on PERMANOVA analyses, ciliates exhibit significant correlations among months and stations. According to ACP, epiphyte distribution follows roughly those of R. cirrhosa and pH. Significant correlations were found between harmful dinoflagellates and both planktonic and epiphytic ciliates.  相似文献   

7.
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   

8.
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   

9.
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   

10.
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   

11.
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   

12.
Influence of the rainfall regime on erosion and transfer of suspended sediment in a 905‐km² mountainous catchment of the southern French Alps was investigated by combining sediment monitoring, rainfall data, and sediment fingerprinting (based on geochemistry and radionuclide concentrations). Suspended sediment yields were monitored between October 2007 and December 2009 in four subcatchments (22–713 km²). Automatic sediment sampling was triggered during floods to trace the sediment origin in the catchment. Sediment exports at the river catchment outlet (330 ± 100 t km‐2 yr‐1) were mainly driven (80%) by widespread rainfall events (long duration, low intensities). In contrast, heavy, local and short duration storms, generated high peak discharges and suspended sediment concentrations in small upstream torrents. However, these upstream floods had generally not the capacity to transfer the sediment down to the catchment outlet and the bulk of this fine sediment deposited along downstream sections of the river. This study also confirmed the important contribution of black marls (up to 70%) to sediment transported in rivers, although this substrate only occupies c. 10% of the total catchment surface. Sediment exports generated by local convective storms varied significantly at both intra‐ and inter‐flood scales, because of spatial heterogeneity of rainfall. However, black marls/marly limestones contribution remained systematically high. In contrast, widespread flood events that generate the bulk of annual sediment supply at the outlet were characterized by a more stable lithologic composition and by a larger contribution of limestones/marls, Quaternary deposits and conglomerates, which corroborates the results of a previous sediment fingerprinting study conducted on riverbed sediment. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

13.
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   

14.
A total of 120 samples comprising of water (45), sediment (45) and mangrove originated food (30) collected from mangrove ecosystems of Goa were screened for Escherichia coli employing ISO-16654 method. Seventy-one (59.16%) samples were positive for E. coli. The E. coli isolates were further characterized by serotyping, virulence gene profiling and pulsed field gel electrophoresis (PFGE). Water and sediment samples were analyzed for physico-chemical parameters. The serotypes reported were O1, O10, O13, O17, O36, O41, O50, O68, O105, O116, O141, O148, O159, O162 and rough types while, 23 strains could not be typed. The stx1 and stx2 genes were detected in 33(46.47%) and 16(22.53%) isolates, respectively. The XbaI restriction digestion patterns of the stx positive strains were diverse. Interestingly, few strains isolated from diarrheal patients and from water, sediment and food from mangrove sources were genetically similar. The study showed that the mangrove ecosystem could be a potential reservoir for pathogenic E. coli.  相似文献   

15.
The aim of this study was to present quantitative data on the population dynamics of Chlorella-bearing ciliates (Stentor, Ophrydium) compared to the total zooplankton community in a deep, oligotrophic North Patagonian lake. Mixotrophic and heterotrophic ciliates, rotifers and microcrustaceans, and important ecological parameters were sampled during a 1-year study. The results showed a low biodiversity with only a few dominant species in every zooplankton group. Three mixotrophic ciliates - Stentor araucanus, S. amethystinus and Ophrydium naumanni - were found. They peaked in summer and autumn with maximum values of 152-313 Ind L−1 (Stentor) and 1880 Ind L−1 (Ophrydium). Their contribution to the total ciliate abundance was 16±17% (annual average). Both Stentor species displayed a distinct vertical zonation during the stratification period with peak depth between 10 and 15 m (metalimnion). The contribution to total zooplankton biomass was 59.4% on an annual average (Stentor: 41%, O. naumanni: 18.4%) and 83% during the stratification period. Both abundance and biomass of mixotrophic ciliates correlated strongly with temperature and to a lesser degree with copepods, rotifers and small cladocerans. According to this study mixotrophic ciliates were by far the dominant zooplankton group in Lake Caburgua. We report for the first time the importance of O. naumanni in a deep Chilean North Patagonian lake.  相似文献   

16.
The radiation belt dynamics during the extreme solar events in November 2004 and January 2005 is studied based on the measurements of relativistic electrons (with energies of 0.8–8 MeV) on the Express-A2 geostationary satellite and Meteor-3M polar satellite. New radiation belts of relativistic electrons in the space (L ～ 3) between the stationary outer and inner belts were formed as a result of either superstorm (|Dst|max = 373 and 289 nT). The position of the maximums of these belts (L max = 2.9 and 3.1) coincides with the known dependence of L max on the magnetic storm Dst variation amplitude: |Dst|max = 2.75 × 104/L max 4 . In November–December the new belt very slowly (ΔL ～ 0.1 per month) shifted toward the Earth. During the series of moderate (～100 nT) magnetic storms that developed as a result of the extreme solar events in January 2005, the belt in the space shifted toward deeper L shells (L ～ 2.5). The moderate January storms produced new belts with L max ≥ 4.  相似文献   

17.
The Amazon Macrotidal Mangrove Coast (AMMC) is a large (~7500 km2) contiguous mangrove fringe eastwards from the Amazon River mouth. It encompasses dozens of interconnected bays intercalated with mangrove peninsulas. Mud accumulates on the mangrove flats, whereas the bed of the bays and channels is generally sandy. In this study we investigated the circulation, sediment transport and deposition in a central site at one of these mangrove peninsulas. The study was undertaken during the dry period, when there is no influence of the Amazon River plume and minimum local freshwater inflow. Current and suspended-sediment concentration were monitored in a feeder channel on the mangrove flat along a ~1000 m section oriented along the peninsula axis. Sediment deposition was also measured on the flat. Our results show there was a strong exchange between the neighboring bays. Channel currents were flood dominant, reaching up to >1 m s−1, with residual water and sediment transport westwards. Suspended sediment concentration (SSC) in the channel was directly related to velocity magnitude, ranging between 50 and 350 mg L−1. The flat was flooded in a way that indicated the tidal wave evolves westwards, nearly parallel to the AMMC shoreline. Currents on the flats were much slower than those in the channel and showed slight ebb dominance. However, SSC was higher during the flood than ebb, clearly indicating settling during the current deceleration and limited erosion during the following ebb–flow acceleration. The net sediment transport across the section was 60 tons westwards for the period of the experiment (~4 days). The mean deposition rate was 0.006 kg m−2 s−1 (or 1.4 kg m−2 per tide), which was higher than rates from other reported assessments in mangroves. The set of results indicate very large internal sediment reworking in the AMMC. © 2019 John Wiley & Sons, Ltd.  相似文献   

18.
Sediment and seawater samples were taken in a sewage affected channel in Blanca Bay, Argentina. Protein content, ‘humic substances’ and silt-clay percentage were evaluated in the sediments; NH4+, PO43? and ‘dissolved organic matter’ in seawater. A highly significant correlation (r=0.747, n=59) was obtained for the relation between protein and % silt-clay. The ‘humic substances’ distribution depends more on the distance from the outfall than does the protein content, probably because of the important relation of the latter with the sediment particle size. The dissolved components showed a dilution pattern similar to that of a contaminant plume in a moving water mass, reaching normal values at 1700 m from the outfall.  相似文献   

19.
广州市区越秀湖浮游纤毛虫群落的季节变化   总被引：6，自引：0，他引：6  
徐润林  郑永利 《湖泊科学》2000,12(2):124-131
从 1997年 4月到 1998年 3月之间 ,应用定性观察和定量分析的方法对广州市的城市湖泊——越秀湖进行了浮游纤毛虫群落的种类组成、群落的生物多样性、丰度、生物量、优势种的种群季节变化等群落结构参数进行了研究 .共发现了 76种浮游纤毛虫 ;最大丰度为 6 9.1×10 3 ind.· L-1;最大生物量为 7.16 mg· L-1;群落中的优势种为大弹跳虫 (H alteria grandinella)、尾毛虫 (Urotricha spp.)、尾侠盗虫 (Strobilidium caudatum)、小侠盗虫 (Strobilidium humile)和膜袋虫 (Cyclidium spp.) ;群落的生物多样性指数在 2 .4到 3.0之间 .分析了这个湖泊浮游纤毛虫群落结构参数的季节变化 .通过与文献报道的比较、分析 ,从纤毛虫的优势种、总丰度和生物量确定了该城市湖泊的富营养状况为重度富营养化 .  相似文献   

20.
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   

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