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61.
Threshold concentrations for biological impairment by nutrients are difficult to quantify in lotic systems, yet States and
Tribes in the United States are charged with developing water quality criteria to protect these ecosystems from excessive
enrichment. The analysis described in this article explores the use of the ecosystem model AQUATOX to investigate impairment
thresholds keyed to biological indexes that can be simulated. The indexes selected for this exercise include percentage cyanobacterial
biomass of sestonic algae, and benthic chlorophyll a. The calibrated model was used to analyze responses of these indexes
to concurrent reductions in phosphorus, nitrogen, and suspended sediment in an enriched upper Midwestern river. Results suggest
that the indexes would respond strongly to changes in phosphorus and suspended sediment, and less strongly to changes in nitrogen
concentration. Using simulated concurrent reductions in all three water quality constituents, a total phosphorus concentration
of 0.1 mg/l was identified as a threshold concentration, and therefore a hypothetical water quality criterion, for prevention
of both excessive periphyton growth and sestonic cyanobacterial blooms. This kind of analysis is suggested as a way to evaluate
multiple contrasting impacts of hypothetical nutrient and sediment reductions and to define nutrient criteria or target concentrations
that balance multiple management objectives concurrently.
Any opinions, findings, conclusions, or recommendations expressed in this article are those of the authors alone, and do not
necessarily reflect the views of the U.S. Environmental Protection Agency or of the U.S. Government. 相似文献
62.
北京减河-潮白河水系的浮游植物与水质分析 总被引:2,自引:1,他引:1
2009年的调查结果显示,在北京减河-潮白河(顺义段)水系的10个监测断面中共检出浮游植物6门72种,其中蓝藻、绿藻、硅藻种数分别占20.8%、38.9%、27.8%。Shannon-Weaver多样性指数为1.45~2.42, 属中度污染。浮游植物平均密度为2991.17×104cells/L, 其中蓝藻、绿藻、硅藻分别占73.6%、8.1%、13.9%,群落中的优势种群均为耐有机污染的富营养型水体指示种。该水系6项理化指标(SD、TN、TP、CODCr、BOD5、 Chla )的TSIM值为86.02~89.66,属于富营养型水体,主要污染物是TP、TN、CODCr。在物理、化学和生物因素的综合作用下TN、TP含量在该水系中的降低率分别为79.36%,74.29%。浮游植物密度与CODCr、Chla呈极显著正相关(P<0.01)。 相似文献
63.
Inland water bodies are considered as integrated parts of the landscape and the monitoring of water quality and aquatic resources need to be addressed on a regional basis for optimal assessment and management. In this study, a simple stratified sampling scheme was applied to a mesoscale survey of western and northwestern Irish lakes, which was carried out to identify, based on the distribution patterns of phytoplankton biomass, potential associations between lake trophic state and land cover attributes. Phytoplankton community analysis was also performed to determine whether taxa associations reflected meteorology-linked aestival succession or specific spatial distributions. The assessment was based on the typology of hydrogeomorphological and land cover attributes of river catchments through ArcGIS analysis. Sampling was carried out in 50 lakes and during a 15-week period in summer 2009. Results showed a general longitudinal gradient in the trophic status of the lakes sampled, with a greater frequency of mesotrophic lakes in the eastern part of the study area where land cover is dominated by agricultural surfaces. Significant relationships (p < 0.010) were found between chlorophyll-a concentration and the proportion of river catchment surface covered by agriculture land and wetlands, findings which might be considered further as proxies for developing an eutrophication risk index. Multivariate analysis of phytoplankton community data clustered the sampled lakes into three assemblages, with ordination along axis 1 being significantly correlated to time and temperature (p < 0.006). There was greater frequency of occurrence of diatoms in lakes from cluster III (Kruskal–Wallis, p < 0.05, H = 6.34, df = 2, n = 49), concomitant to lower chlorophyll-a concentrations, lake surface temperatures and Secchi depths, reflecting meteorological conditions dominated by precipitations. Those results support the potential of mesoscale surveys to assess water quality variables and detect environmental patterns at regional scales. 相似文献
64.
基于2010年7月、10月两次对滦河流域的上游高原、中游山区以及下游平原河段21个典型断面水生生物调查,并采用Shannon-Wiener多样性指数、Pielou群落均匀度指数和Simpon指数对各区域的浮游生物与底栖动物的群落组成、生物多样性以及空间异质性进行生物多样性评价。结果表明:滦河流域浮游植物的优势种整体上以绿藻门和硅藻门为主,浮游动物以轮虫和桡足类为主要类群,底栖动物的主要类群为水生昆虫和软体动物;滦河流域浮游植物生态群落结构较稳定;浮游动物生态群落结构较不稳定;底栖动物种类以摇蚊科居多,生态结构较单一;滦河流域的水生生物类群组成及分布与水流、泥沙、水质等河流水文特征及河床底质类型密切相关,并可在一定程度上反映河流水环境状况。 相似文献
65.
66.
汉江下游河段水质生态模型及数值模拟 总被引:22,自引:1,他引:21
基于包含浮游动物作用的一维水质生态数学模型,考虑了长江水位的顶托作用,采用有限体积法,建立了汉江水质生态数值模型,用1992年的实测资料进行参数识别,对汉江1995年至1998年的水动力、氨氮、硝氮、凯氏氮、总磷、溶解氧(DO)生化需氧量(BOD),以及浮游植物的迁移转化规律进行了数值模拟,模拟结果与实测资料吻合较好,说明所建的模型符合汉江下游河段的实际情况。数值模拟结果表明:当汉江下游水体机物含量较高,水温6℃以上和光照充足时,汉江下游河段适宜藻类生长,易发生“水华”现象。特别在枯水季节,在流量较小和流速低的情况下,水体中藻类会过快生长。藻类的生长速度因各断面的流速、水深和水面宽的不同而不同。 相似文献
67.
The growth and alkaline phosphatase activity (APA) of two raphidophyceae species Chattonella marina and Heterosigma akashiwo were investigated in response to P-limitation and subsequent addition of dissolved inorganic phosphorus (DIP, NaH2PO4) and two dissolved organic phosphorus (DOP) compounds: guanosine 5-monophosphate (GMP) and triethyl phosphate (TEP). APA levels increased greatly after P-starvation as the decrease of the cellular phosphorus quotes (Qp). C. marina responded to P-limitation quickly and strongly, with 10-fold increase in APA within 24 hr after P-starvation. The larger difference between maximal and minimal QP values in C. marina indicated its high capacity in P storage. APA of H. akashiwo was maximally enlarged about 2.5 times at 48 hr of P-starvation. After the addition of nutrients, cell numbers of C. marina increased in all treatments including the P-free culture, demonstrating the higher endurance of C. marina to P-limitation. However, those of H. akashiwo increased only in DIP and GMP cultures. APA increased only after the addition of the monophosphate ester GMP. The results suggest that quick responses of C. marina to P-limitation, high capacity in P storage as well as endurance for P-depletion provide this species an ecological advantage in phytoplankton community competition under DIP-limited conditions. 相似文献
68.
The variation patterns of phytoplankton standing crop and productivity in the North Adriatic frontal region and the relative importance of pico-, nano-, micro-phytoplankton are shown. Data of standing crop (chlorophyll a - Chl a ) and productivity ( 14 C assimilation) and PAR radiation ( w Em m 2 r s m 1 ) were collected during the four oceanographic cruises of the PRISMA II project. Average standing crop and productivity in the study area were 1.41 - 0.42 r mg r m m 3 Chl a and 1.23 - 0.37 r mg r C r m m 3 r h m 1 ; average assimilation number (P/B) was 0.872 - 0.589 r mg r C (mg-Chl a ) m 1 h m 1 and average photosynthetic efficiency (PE) was 0.020 - 0.054 (mg r C(mg-Chl a ) m 1 r h m 1 ) [ w Em m 2 r s m 1 ] m 1 . Phytoplankton biomass and productivity showed significant patterns of variation with the distance from the coast, with increasing depth and decreasing light intensity. The same patterns were shown by the three phytoplankton size classes. The spatio-temporal variations were significantly larger within the microplankton than within the pico- and nano-plankton size classes. Planktonic guilds were dominated by picoplankton, both as standing crop and productivity, in the northern stations (0.539 - 0.21 r mg r m m 3 Chl a and 0.572 - 0.25 r mg r C r m m 3 r h m 1 ) and in those more offshore, while microplankton was more important in the coastal and southern stations (0.727 - 0.58 r mg r m m 3 Chl a and 0.63 - 0.28 r mg r C r m m 3 r h m 1 ). In relative terms, picoplankton accounts for the 53% and 46% of biomass and primary production, while the microplankton account for the 43.6% and 48%. Assimilation number and photosynthetic efficiency did not show spatio-temporal variations but PE was inversely related with PAR radiation for all the size classes. Data suggest that the spatio-temporal patterns observed in this study are affected by the competitive relationships among body size classes in the phytoplankton guilds. 相似文献
69.
Anabella Covazzi Harriague Giancarlo Albertelli Adrianna Bonomi Mauro Fabiano Tecla Zunini-Sertorio 《Chemistry and Ecology》2007,23(3):263-277
Suspended particulate matter, zooplankton, and macrobenthos dynamics were investigated in a shallow area of the Ligurian Sea (north-west Mediterranean) characterized by wide temporal variability over an annual cycle. As indicated by multivariate analyses, the seasonal dynamics can be summarized as follows: (1) a late winter-early spring phytoplankton bloom followed by high zooplankton and macrobenthos densities during the spring months; (2) low-quality particulate suspended matter in summer, and an increase in the importance of zooplankton taxa with a wide range of feeding strategies, a decrease in macrofaunal abundance, and an increase in deposit-feeders and predators; and (3) a second phytoplankton bloom in autumn, followed by an increase in copepod density and a low macrofaunal abundance. In conclusion, pelagic and benthic communities in the coastal area of the Ligurian Sea mainly seem to be controlled bottom-up. Our results suggest that the quality of the particulate organic matter may play an important role in determining the temporal changes of both plankton and benthic assemblages, while the direct influence of other environmental features (such as sediment grain size) is relevant only for some macrobenthic taxa (e.g. crustaceans). 相似文献
70.
Alessandra Pugnetti Francesco Acri Luisa Alberighi Donato Barletta Mauro Bastianini Fabrizio Bernardi-Aubry Andrea Berton Franco Bianchi Giorgio Socal Cecilia Totti 《Chemistry and Ecology》2004,20(6):399-409
Taxonomic composition, biomass, primary production and growth rates of the phytoplankton community were studied in two stations in the NW Adriatic Sea on a seasonal basis, in areas characterized by differing hydrological and trophic conditions. The main differences between the two stations were quantitative rather than qualitative, most phytoplankton species being common to both stations. The effects of differing nutrient concentrations and plume spreading were evident. Biomass and primary production rates were significantly higher in the coastal station (S1), and the phytoplankton distribution in the water column was markedly stratified in S1 and more even in the offshore station (S3). However, chlorophyll a specific production, potential growth rate and production efficiencies were very similar in both stations, even when phosphorus concentrations were limiting. A discrepancy between potential and actual growth rate was observed: as a feature common to both stations, comparisons between potential and actual growth rates revealed that little carbon produced by phytoplankton accumulated as algal biomass; therefore, very high loss rates were estimated. 相似文献