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1.
Benthic invertebrate communities were surveyed in a 233 km reach of the middle and lower Suwannee River in Northwestern Florida in the winter 1987 and early summer 1988 to determine their abundance and distribution as potential foods of the Gulf sturgeon, Acipenser oxyrhynchus desotoi, and to determine the effects of possible natural and human-induced disturbances to the communities. In substrates of the tidal oligohaline to mesohaline lower reach of the East Pass site I (km 2) and site II West Pass (km 5) near the Gulf of Mexico, densities of tube dwelling and free swimming amphipods, polychaetes, oligochaetes, and dipterans in the PONAR grabs were moderate (100–999 {iex} individuals/m2) to abundant (1000–9999 {iex} individuals m–2). Also, at sites I and II, low (10–99 {iex} individuals m–2) to moderate densities of dipteran Chironomidae and olive nerite snail were collected in hardboard multiplate artificial substrate samplers. Diversities of benthic invertebrates in both grabs and hardboard multiplates were relatively low. Baetid mayflies were moderately abundant in the dip net samples. Upriver from sites I and II, the transition of an oligohaline tolerant benthic community to a freshwater one was abrupt due to strong freshwater flow. At sites III (km 48) and IV (km 89), benthic invertebrate populations were low to moderate in hardboard multiplate and dip net samples. In the middle reach (km 101 to km 233), aquatic insects were predominant and included; chironomids, mayflies, and beetles, and also, freshwater gammarid amphipods, gastropods, and the Asian clam. In winter, the bottom substrates at sites VII (km 153) and VIII (km 205) contained diverse and dense populations of Chironomidae (5932 m–2), the greatest density for a major taxonomic group recorded in this survey. Crayfish were collected in low densities only in artificial substrate samplers from sites IV to IX. Leeches were widespread in the study area. Empirical Biotic Index values that reflect impacts of organic wastes on benthic invertebrate communities were within a narrow range, 3.16 to 6.38, and indicated slightly enriched to enriched water. Of the total 186 benthic invertebrate taxa, 82% had quality values 0 to 5 that indicate overall clean water conditions. The predominant benthic invertebrates in the Suwannee River were detritivorous and the communities reflected oligotrophic to mesotrophic waters.  相似文献   

2.
陆源有机污染对舟山海域大型底栖生物分布的影响   总被引:2,自引:1,他引:1  
2009年4月对舟山海域进行了25个站位的底栖生物调查,结合同期进行初级生产力、海水水质等的调查数据,分析了初级生产力、富营养化等环境因子对舟山海域大型底栖生物分布的影响。结果表明,舟山海域大型底栖生物共获得84种,多毛类是主要优势类群。舟山海域大型底栖生物平均生物量为11.62g/m2,平均丰度为208.5个/平方米,多样性指数(H')为1.64。舟山海域大型底栖生物的生物量、丰度和多样性指数均呈现由近岸向外海递增的趋势。应用相关性统计分析表明,舟山海域大型底栖生物的分布与海水化学耗氧量(COD)、无机氮(DIN)、磷酸盐(DIP)、富营养化指数和底层溶解氧(DO)存在显著负相关;与初级生产力、盐度和透明度存在显著正相关。说明陆源有机污染、盐度、透明度、初级生产力和底层溶解氧是影响舟山海域大型底栖生物分布的主要因素,其中陆源有机污染是最主要的影响因素。  相似文献   

3.
2009年4月对长江口及其邻近海域的21个站位进行了大型底栖生物调查,分析了大型底栖动物的环境质量状况,并结合环境因子数据进行了典范对应分析。结果表明,调查共鉴定大型底栖生物56种,多毛类为主要类群。平均生物量为11.26 g/m2,平均丰度为237.4个/m2。生物量、丰度均呈现由近岸向外海递增的趋势。水深、盐度、初级生产力和有机质、重金属是影响调查海域大型底栖生物群落的主要环境因子。大型底栖生物的分布呈现出对有机污染与重金属污染显著的躲避趋势,表明有机污染与重金属污染已显著影响该海域大型底栖生物的生长。而小头虫、寡节甘吻沙蚕、长手沙蚕和丝鳃虫对有机污染和重金属污染展现出较强的的耐受性。  相似文献   

4.
为了解海州湾潮间带大型底栖动物群落结构,分析人类养殖活动对其影响,于2012-2017年对该区域大型底栖动物进行调查。结果表明:6年间共发现120种大型底栖动物,依据种类组成进行聚类分析可分为4组;调查中总平均丰度为3 495.9 ind./m2,范围为506.7~17 864.0 ind./m2;总平均生物量为197.26 g/m2,范围为1.58~489.17 g/m2。光滑河蓝蛤(Potamocorbula laevis)为第一优势种,其繁殖盛期在每年9-10月。调查期间生物多样性整体呈下降趋势,人类的养殖活动主导着海州湾潮间带大型底栖动物群落结构的变化。  相似文献   

5.
The results of measurements of Krypton-85 (85Kr) concentrations in the ground-level air of Prague between 1983 and 1992 are presented and time-related changes analysed. The long-term trend in activity level of 85Kr has been steadily increasing with a growth rate of 0.04 Bq.m–3 (STP) per year. Some peaks of 85Kr activity were observed due to the influence of undispersed radioactive plumes coming from distant sources. Short-term variations within a typical range of concentrations from 0.61 to 1.25 Bq.m–3 (STP) were found to be seasonally dependent, with the maximum occurring in spring.  相似文献   

6.
Throughfall and bulk precipitation samples were collected for two watersheds at Acadia National Park, Maine, from 3 May to 16 November 2000, to determine which landscape factors affected mercury (Hg) deposition. One of these watersheds, Cadillac Brook, burned in 1947, providing a natural experimental design to study the effects of forest type on deposition to forested watersheds. Sites that face southwest received the highest Hg deposition, which may be due to the interception of cross-continental movement of contaminated air masses. Sites covered with softwood vegetation also received higher Hg deposition than other vegetation types because of the higher scavenging efficiency of the canopy structure. Methyl mercury (MeHg) deposition was not affected by these factors. Hg deposition, as bulk precipitation and throughfall was lower in Cadillac Brook watershed (burned) than in Hadlock Brook watershed (unburned) because of vegetation type and watershed aspect. Hg and MeHg inputs were weighted by season and vegetation type because these two factors had the most influence on deposition. Hg volatilization was not determined. The total Hg deposition via throughfall and bulk precipitation was 9.4 μg/m2/year in Cadillac Brook watershed and 10.2 μg/m2/year in Hadlock Brook watershed. The total MeHg deposition via throughfall and bulk precipitation was 0.05 μg/m2/year in Cadillac Brook watershed and 0.10 μg/m2/year in Hadlock Brook watershed.  相似文献   

7.
Precipitation and streamwater samples were collected from 16 November 1999 to 17 November 2000 in two watersheds at Acadia National Park, Maine, and analyzed for mercury (Hg) and dissolved inorganic nitrogen (DIN, nitrate plus ammonium). Cadillac Brook watershed burned in a 1947 fire that destroyed vegetation and soil organic matter. We hypothesized that Hg deposition would be higher at Hadlock Brook (the reference watershed, 10.2 μg/m2/year) than Cadillac (9.4 μg/m2/year) because of the greater scavenging efficiency of the softwood vegetation in Hadlock. We also hypothesized the Hg and DIN export from Cadillac Brook would be lower than Hadlock Brook because of elemental volatilization during the fire, along with subsequently lower rates of atmospheric deposition in a watershed with abundant bare soil and bedrock, and regenerating vegetation. Consistent with these hypotheses, Hg export was lower from Cadillac Brook watershed (0.4 μg/m2/year) than from Hadlock Brook watershed (1.3 μg/m2/year). DIN export from Cadillac Brook (11.5 eq/ha/year) was lower than Hadlock Brook (92.5 eq/ha/year). These data show that ∼50 years following a wildfire there was lower atmospheric deposition due to changes in forest species composition, lower soil pools, and greater ecosystem retention for both Hg and DIN.  相似文献   

8.
In this study, dry season radon flux densities and radon fluxes have been determined at the rehabilitated Nabarlek uranium mine in northern Australia using conventional charcoal canisters. Environmental background levels amounted to 31± 15 milli Becquerel per m2 per second (mBq m−2 s−1). Radon flux densities within the fenced rehabilitated mine area showed large variations with a maximum of 6500 mBq m−2 s−1 at an area south of the former pit characterised by a disequilibrium between 226Ra and 238U. Radon flux densities were also high above the areas of the former pit (mean 971 mBq m−2 s−1) and waste rock dump (mean 335 mBq m−2 s−1). The lower limit for the total pre-mining radon flux from the fenced area (140 ha) was estimated to 214 kBq s−1, post-mining radon flux amounted to 174 kBq s−1.Our study highlights that the results of radon flux studies are vitally dependant on the selection of individual survey points. We suggest the use of a randomised system for both the selection of survey points and the placement of charcoal canisters at each survey point, to avoid over estimation of radon flux densities. It is also important to emphasize the significance of having reliable pre-mining radiological data available to assess the success of rehabilitation of a uranium mine site.2006 Springer. The Australian Government's right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledged.  相似文献   

9.
Biomass is an important entity to understand the capacity of an ecosystem to sequester and accumulate carbon over time. The present study, done in collaboration with the Delhi Forest Department, focused on the estimation of growing stock and the woody biomass in the so-called lungs of Delhi—the Asola-Bhatti Wildlife Sanctuary in northern Aravalli hills. The satellite-derived vegetation strata were field-inventoried using stratified random sampling procedure. Growing stock was calculated for the individual sample plots using field data and species-specific volume equations. Biomass was estimated from the growing stock and the specific gravity of the wood. Among the four vegetation types, viz. Prosopis juliflora, Anogeissus pendula, forest plantation and the scrub, the P. juliflora was found to be the dominant vegetation in the area, covering 23.43 km2 of the total area. The study revealed that P. juliflora forest with moderate density had the highest (10.7 m3/ha) while A. pendula forest with moderate density had the lowest (3.6 m3/ha) mean volume. The mean woody biomass was also found to be maximum in P. juliflora forest with moderate density (10.3 t/ha) and lowest in A. pendula forest with moderate density (3.48 t/ha). The total growing stock was estimated to be 20,772.95 m3 while total biomass worked out to be 19,366.83 t. A strong correlation was noticed between the normalized difference vegetation index (NDVI) and the growing stock (R 2?=?0.84)/biomass (R 2?=?0.88). The study demonstrated that growing stock and the biomass of the woody vegetation in Asola-Bhatti Wildlife Sanctuary could be estimated with high accuracy using optical remote sensing data.  相似文献   

10.
通过调研20世纪90年代以来国外主流水生态评价项目中采用的生境指标,统计了14个类型生境指标的使用频率,并针对不同的河流类型,筛选出物理形态特征、河岸带状况、生境组成、生境复杂性、人类干扰和水质状况等6个类型的11项评价指标,推荐作为长江流域河流生境评价指标.随后,利用层次分析法对国外水生生物评价指标进行了统计分析,并...  相似文献   

11.
Because moderate to over-abundant white-tailed deer (Odocoileus virginianus) herbivory impacts biodiversity and can alter community function, ecological benchmarks of herbivory impact are needed to assess deer impacts. We evaluated spatial patterns of deer herbivory and their relation to herbivory assessment by evaluating woody vegetation along 20 transects at each of 30 sites spread across a wide range of deer herd densities and vegetative condition throughout the biodiverse Appalachian Mountains of Virginia, USA. Surprisingly, herbivory patterns and the availability of woody forage generally were unchanged among physiographic regions and land use diversity classes. However, some relationships between browsing pattern and vegetation varied with scale. The total quantity of vegetation browsed on a given site and at the transect scale were related positively to the availability of forage, as the proportion of stems browsed decreased as stem density increased. However, this was only true when all stems were considered equally. When stem densities by species were weighted for deer preference, the proportion of stems browsed had no relationship or increased with stem density. Compared to the value from all transects sampled, on average, the mean of ≥?3 transects within a site was within 0.1 of the browsing ratio and stem densities were within 0.5 stems m?2. Our results suggest that one transect per square kilometer with a minimum of three transects may be sufficient for most browsing intensity survey requirements to assess herbivory impacts in the Appalachian region of Virginia. Still, inclusion of spatial factors to help partition variation of deer herbivory potentially may allow for improved precision and accuracy in the design of field herbivory impact assessment methods and improve their application across various landscape contexts.  相似文献   

12.
The State of Minas Gerais represents one of Brazil's most outstanding mining resources. The contamination of river waterfrom kaolin processing activities may be harmful to people inthe way of slow but chronic poisoning. On the other hand, the discharge of untreated or inadequately treated domestic sewage into aquatic environments can also cause deleterious effects to the health. However, no reliable figures are available for pollutant occurrences in river water. This draws attention to thevery precarious situation that exists with respect to pollutionby organic and inorganic toxic wastes, especially with respect to humans and fauna in all its expressions. Thus, with the purpose of establishing a preliminary report to trace out industrialisation outcomes, samples of river water, vegetation and fish were collected and analysed to detect pollutant inputs.The concentration of metals was determined in suspended particle,vegetation and fish, while those of nitrite, nitrate, phosphateand chloride were determined in river water samples. The concentration of dissolved oxygen (DO) was measured in river water at the time of collection. Chemical oxygen demand (COD) and biochemical oxygen demand (BOD) were also determined. Metalinputs in the samples analysed appeared to be related to effluentdischarges into the rivers. The suspended particles showed highconcentrations (in mg kg-1) of zinc (62 600) and aluminium(559 000), while vegetation samples collected near rivers wereheavily contaminated with iron (7680). The fishes examined werecontaminated with chromium (1.5 mg kg-1). In general, the concentrations of nitrite, nitrate, chloride, phosphate and BOD in river water were lower than the maximum values established bythe Brazilian Environmental Standards.  相似文献   

13.
Amphipod crustaceans belong to the most successful invaders of aquatic environments. The work provides information concerning the spatial and temporal scales of expansion of four alien gammarid amphipods (three of them of Ponto-Caspian and one of North American origin): Pontogammarus robustoides (G.O. Sars, 1894), Obesogammarus crassus (G.O. Sars, 1894), Dikerogammarus haemobaphes (Eichwald, 1841), and Gammarus tigrinus Sexton, 1939 in the Vistula Lagoon (VL) and the Vistula Delta (VD) in 2008–2010. The mean abundance of these gammarids in nearshore zones was 382 ind?m?2 in VL and 89 ind?m?2 in VD. Their mean biomasses were likewise greater in VL (0.91 g?m?2) than in VD (0.49 g?m?2). G. tigrinus was the most dominant species in both nearshore zones of VL and VD and attained the highest frequency in these areas. The study gives evidence of total extinction of native gammarid species.  相似文献   

14.
舟山群岛夏季潮间带大型底栖生物群落生态学研究   总被引:3,自引:2,他引:1  
为了解舟山群岛潮间带大型底栖生物生态环境质量的现状,2009年7月对舟山群岛潮间带7个断面进行了大型底栖生物的分类、组成、栖息密度、生物量、多样性及群落稳定性等的研究。结果表明,该调查共鉴定大型底栖生物103种,软体动物、甲壳动物和多毛类构成主要类群。生物量平均值为96.19 g/m2,栖息密度平均值为223.1个/m2,多样性指数平均值为2.14。根据相似性系数聚类分析可将舟山群岛的潮间带各潮区分为2个组群。底质和潮汐是影响潮间带大型底栖生物群落结构的主要因子。嵊泗断面潮间带群落稳定性良好,其他断面的潮间带生物群落受到中度程度的污染或扰动,群落结构不稳定。总体上,舟山群岛潮间带大型底栖生物的种类相对贫乏,群落结构简单,多样性指数较低,生态环境质量较差。  相似文献   

15.
We present the extension and application of the mesoscale atmospheric meteorology model METRAS for dispersion of oak pollen. We incorporated functions for pollen emission, pollen viability and pollen deposition into METRAS and simulated pollen dispersal on a scale of up to 200 km. The basis of the simulations is a real landscape structure that includes topography, land use, and the location and size of oak stands. We simulated the oak pollen dispersion of one single oak stand with an estimated annual pollen production of 1 billion pollen grains/m2 forest surface on two exemplary days of the flowering season in 2000. Depending on the meteorological situation of the simulated days, a pollen cloud with about 10 pollen/m3 may extend up to 30 km from the source. Downstream of the oak stand, approximately 1,000 pollen/m2 deposited up to a distance of 25 km, and lower amounts of pollen deposited up to 100 km away. These values of pollen concentration and deposition lay within the range of published field studies. Overall, it is shown that mesoscale atmospheric models are applicable to simulate pollen dispersal on the landscape level.  相似文献   

16.
Vegetation, environmental characteristics, and forest productivity were studied in the boreal forest in the North Klondike River Valley, Yukon Territory, Canada. The concept and approach of biogeoclimatic ecosystem classification were followed. For the treed vegetation, five ecosystem types were distinguished based on vegetation structure and physical and chemical properties of soils. They were: 1) spruce-lichen type, 2) spruce-moss type, 3) spruce-Equisetum type, 4) spruce-willow type, and 5) bog forest type. These types were differentiated mainly by moisture regime and base status of soils. The sequence of the ecosystem types reflected their topographical position from slope summit to valley bottom. The spruce-lichen type developed in the driest and nutritionally impoverished habitats, the spruce-Equisetum type occurred in moist and nutritionally enriched sites, and the spruce-moss type was found in between them. The bog forest type occurred where peat had accumulated sufficiently to generate ombrotrophic conditions in habitats of high water table underlain with permafrost. The spruce-willow type developed along small creeks where substrates were very coarse. Tree growth characteristics were measured, except for the bog forest type that did not have trees over 5 m tall. Total volume of standing trees ranged from 29 to 582 m3/ha, with an overall mean of 216.9 m3/ha. The spruce-Equisetum type exhibited the highest figure, 413.5 m3/ha, while spruce-lichen type the lowest one, 87.7 m3/ha. Mean annual increment ranged from 0.15 to 2.66 m3/ha, with an overall mean of 1.10 m3/ha. A similar tendency was noted for all other forestry characteristics, i.e., the spruce-Equisetum type showed the highest productivity while the spruce-lichen type the lowest. This tendency was considered to be attributed to the availability of moisture and basic cations in soils.  相似文献   

17.
底栖动物是水生态系统的重要组成部分,其群落特征通常用来评价水生态环境质量。研究了2012—2019年松花江干流水生态环境质量状况、变化趋势,并应用冗余分析(RDA)探究底栖动物群落结构特征与水环境因子之间的响应关系。结果表明:8年间共鉴定出底栖动物246个分类单元,隶属于4门、9纲、25目、58科、69属,其中水生昆虫的EPT物种为99个分类单元,占总物种数的40.24%;水生昆虫的其他物种为68个分类单元,占总物种数的27.64%;软体动物为36个分类单元,占总物种数的14.63%;环节动物为25个分类单元,占总物种数的10.16%;甲壳动物为18个分类单元,占总物种数的7.32%。底栖动物密度总体呈上升趋势,种类组成总体有所增多,其中环节动物、软体动物和甲壳动物有向水生昆虫转变的趋势,群落结构相对稳定且主要以水生昆虫占比最多,底栖动物密度平均值为5.97×103个/m2,变化范围为2.86×103~8.98×103个/m2,优势科(属)主要为小蜉属Ephemerella、小寡脉蜉属Oligoneuriella、扁蜉属Heptagenia、等蜉属Isonychia、纹石蛾科Hydropsychidae、缺叉多距石蛾属Polycentropus、摇蚊科Chironomidae和圆田螺属Cipangopaludina等。生物指数评价结果多数为"中等"及以上,评价结果趋于稳定,且下游评价结果好于上游。松花江干流的水环境质量变化阶段性明显,溶解氧含量升高,氨氮呈下降趋势,其余指标呈波动变化。冗余分析(RDA)结果表明:影响松花江干流底栖动物群落结构变化的主要环境因子是随时间推移而变化的,其中溶解氧、生化需氧量、化学需氧量、总磷、氨氮和总氮等指标是影响该监测区域底栖动物群落分布的重要环境因子。  相似文献   

18.
Organic sewage pollution is the major stressor that affects benthic communities in the coastal waters. In the present study involving a once-off sampling (July–August 2003) of a sewage treatment plant (STP) outfall and areas 6 km farther into the sea, we tried to estimate the severity of organic pollution on marine macrobenthos over a pollution gradient in the inshore waters (station depths, 5–30 m) off a heavily urbanized tropical city, on the east coast of India. Multivariate ordination analyses revealed two different groups of faunal assemblages. Group I is associated with sites impacted by the sewage outfall and group II with the locations 3–6 km away in the open sea. Polychaetes and amphipods were the predominant fauna with significant taxonomic differences between the assemblages. Despite the homogeneity in sediment texture, the two-fold increase in sediment organic matter near the sewage outfall area supported r-strategists, while group II locations favoured K-strategists. Approximation through benthic opportunistic polychaetes amphipods (BOPA) index and information on the key taxa responsible for the observed assemblage patterns corroborated these findings. Thus, the present findings revealed how organic sewage pollution influences benthic diversity in coastal waters by supporting communities of opportunistic characteristics. We advocate inclusion of community traits and compatible analytical tools (statistical approaches) in studies of similar nature so that the observations could be compared and broad remedial measures could be evolved.  相似文献   

19.
In most natural ecosystems heterotrophic microorganisms encountercomplex mixtures of carbon sources, each of which is present at aconcentration of few micrograms per litre. This study examined the biotreatability and kinetics of an upflow anaerobic sludge blanket (UASB) reactor to complex mixtures of chlorophenols encountered in environmental conditions using on-line and off-line experimental studies. Results indicate that (1) steady-state concentration was quite lower (98.3 mg L-1) with complex mixture of chlorophenols than steady-state concentration achieved when only 2.4 dichlorophenol (124 mg L-1) was studied alone on the same reactor; (2) that toxiceffects of chlorophenols increase with increasing concentrationsof toxicant. (Onset of the inhibitory effect occurred at a lowerconcentration in multi-substrate than in single substrate utilization); (3) addition of alternative utilizable substrate can mitigate toxic effects and enhance degradation; (4) the relative concentration of substrate was critical in determiningutilization patterns. HPLC analysis of off-line experimental samples resulted in a steady-state treatment efficiency of68% for COD, 36% for 2-hlorophenol, 40.5% for 4-chlorophenol, 70.7% for 2,4-dichlorophenol, 53.2% for 2,4,6-trichlorophenol and 42% for pentachlorophenol in presence of glucose. Kinetic constant in terms of V max and K s were determined. K s for the five chlorophenols ranged between 0.016 and 0.117 kg m-3 day-1 while V max ranged between 0.056 and 0.244 kg m-3 day-1.  相似文献   

20.
We have evaluated the performance of three satellite-based latent heat flux (LE) algorithms over forest ecosystems using observed data from 40 flux towers distributed across the world on all continents. These are the revised remote sensing-based Penman-Monteith LE (RRS-PM) algorithm, the modified satellite-based Priestley-Taylor LE (MS-PT) algorithm, and the semi-empirical Penman LE (UMD-SEMI) algorithm. Sensitivity analysis illustrates that both energy and vegetation terms has the highest sensitivity compared with other input variables. The validation results show that three algorithms demonstrate substantial differences in algorithm performance for estimating daily LE variations among five forest ecosystem biomes. Based on the average Nash-Sutcliffe efficiency and root-mean-squared error (RMSE), the MS-PT algorithm has high performance over both deciduous broadleaf forest (DBF) (0.81, 25.4 W/m2) and mixed forest (MF) (0.62, 25.3 W/m2) sites, the RRS-PM algorithm has high performance over evergreen broadleaf forest (EBF) (0.4, 28.1 W/m2) sites, and the UMD-SEMI algorithm has high performance over both deciduous needleleaf forest (DNF) (0.78, 17.1 W/m2) and evergreen needleleaf forest (ENF) (0.51, 28.1 W/m2) sites. Perhaps the lower uncertainties in the required forcing data for the MS-PT algorithm, the complicated algorithm structure for the RRS-PM algorithm, and the calibrated coefficients of the UMD-SEMI algorithm based on ground-measured data may explain these differences.  相似文献   

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