Assessing ecological impairments in Neotropical rivers of Mexico: calibration and validation of the Biomonitoring Working Party Index

Freshwater ecosystems are one of the most endangered and threatened ecosystems worldwide, particularly in developing countries, where population growth, industrialization, urbanization, and changes in land use are increasing. In Mexico, water ecosystems are severely impacted and an easy-to-use tool is needed for monitoring freshwater ecosystems. This study presents the development of a calibration and validation procedure for the Biological Monitoring Working Party Index using physical–chemical and biological data from Neotropical rivers in Mexico (Apatlaco and Chalma-Tembembe). Water quality and macroinvertebrates were monitored in four campaigns including the dry and rainy seasons (2012–2013). Calibration of the index was performed in the following steps: determination of a physicochemical quality index, identification of the abundance class for each family of macroinvertebrates, incorporation of abundances in the corresponding physicochemical quality index interval, and determination of bioindication values for each macroinvertebrate family. With the calibrated values, the index was assessed for each study site and period. The calibrated index was validated by a statistical test. Ranges for water quality categories were defined by three statistical procedures. The range of the Biological Monitoring Working Party Index was tested with study sites from adjacent sub-basins. The Chalma-Tembembe River in agricultural areas comprised the categories “Bad polluted” to “regular and moderately polluted,” whereas the largest portion of the Apatlaco River in urban zones comprised “Bad, very polluted” to “Bad, extremely polluted.” Thus, the calibrated index is a suitable biomonitoring tool, allowing the detection of zones that need urgent management and a recovery plan.     

锦州市近岸海域水质特征分析及污染防治措施

应用综合污染指数法对锦州市近岸海域8个监测点位以及全海域2004年和2005年水质特征进行了分析,其结果表明全海域污染比较严重,且中度污染范围较广,近90%.除4#监测点属轻度污染,其余均属中度污染,且5#和7#监测点污染程度有加重趋势,应予以重视,最后就锦州市海水污染特征提出了相关防治措施.     

Assessment of heavy metal pollution in the urban stream sediments and its tributaries

Globally, aquatic ecosystems are highly polluted with heavy metals arising from anthropogenic and terrigenous sources. The objective of this study was to investigate the pollution of stream sediments and possible sources of pollutants in Nakivubo Channel Kampala, Uganda. Stream sediments were collected and analysed for heavy metal concentration using flame atomic absorption spectrophotometer. The degree of pollution in Nakivubo channelized stream sediments for lead, cadmium, copper, zinc, manganese and iron was assessed using enrichment factor, geo-accumulation index and pollution load index. The results indicated that (1) the sediments have been polluted with lead, cadmium and zinc and have high anthropogenic influences; (2) the calculation of geo-accumulation index suggest that Nakivubo stream sediments have background concentration for copper, manganese and Fe (I _geo ≤ 0); (3) factor analysis results reveal three sources of pollutants as explained by three factors (75.0 %); (i) mixed origin or retention phenomena of industrial and vehicular emissions; (ii) terrigenous and (iii) dual origin of zinc (vehicular and industrial). In conclusion, the co-precipitation (inclusion, occlusion and adsorption) of lead, cadmium and zinc with manganese and iron hydroxides, scavenging ability of other metals, very low dissolved oxygen and slightly acidic to slightly alkaline pH in stream water could account for the active accumulation of heavy metals in Nakivubo stream sediments. These phenomena may pose a risk of secondary water pollution under sediment disturbance and/or changes in the geo-chemistry of sediments.     

Spatial characteristics of surface water quality in the Haicheng River (Liao River basin) in Northeast China

Spatial variations of the water quality in the Haicheng River during April and October 2009 were evaluated for the national monitoring program on water pollution control and treatment in China. The spatial autocorrelation analysis with lower Moran’s I values displayed the spatial heterogeneity of the 12 physicochemical parameters among all the sampling sites of the river. The one-way ANOVA showed that all variables at different sampling sites had significant spatial differences (p < 0.01). Based on the similarity of water quality characteristics, cluster analysis grouped the 20 sampling sites into three clusters, related with less polluted, moderately polluted and highly polluted sites. The factor analysis extracted three major factors explaining 76.4 % of the total variance in the water quality data set, i.e., integrated pollution factor, nitrogen pollution factor and physical factor. The results revealed that the river has been severely polluted by organic matter and nitrogen. The major sources leading to water quality deterioration are complex and ascribed to anthropogenic activities, e.g., domestic and industrial wastewater discharges, agricultural runoff, and animal rearing practices.     

Risk assessment of heavy metals in topsoil along the banks of theYangtze River in Huangshi,China

High concentrations of heavy metal in farmland threatens food production and human health. Our study assesses soil quality and the distribution of Cd, Cr, Cu, Zn, Pb and Ni, to identify possible sources of heavy metals along the banks of the Yangtze River in Huangshi. Heavy metal concentrations of 22 topsoil samples were measured using the inductively coupled plasma mass spectrometry instrument and data was analyzed by multivariate statistic approaches. Heavy metal contamination risk assessment was performed using a combination of the Nemerow multi-factor index method, the Hakanson potential ecological risk index method and the Muller index of geo-accumulation method. These methods determined similar results indicating that cadmium (Cd) poses a health risk to residents at the study site while Cr, Cu, Zn, Pb and Ni do not. The Nemerow multi-factor index method demonstrated that 18 samples were heavily polluted, three moderately polluted and one lightly polluted. The Muller index of geo-accumulation method found ten samples were moderately to strongly polluted by Cd, five were moderately polluted, six were lightly to moderately polluted and one was lightly polluted. The Hakanson potential ecological risk index method proved six samples were strongly polluted, seven were moderately polluted and nine were lightly polluted. Since our sampling sites were all in agricultural lands, we recommend the potential ecological risk index method as the most effective given it not only considers the range of pollutants contributing to soil pollution but factors in heavy metals toxicity. We are apt that the source of the high concentrations of Cd found in topsoil is derived from alluvial sediments upstream of the Yangtze River with a high percentage of residual speciation and a low percentage of exchangeable speciation distribution of Cd. This in turns indicates that a high concentration of Cd in soil had little impact on the natural environment. However, 31.9% of the iron-manganese oxides bound speciation indicating that such levels of Cd in soil would be potentially hazardous to the crops, particularly if exposed to a reductive condition.     

Assessment of water quality and identification of pollution sources of three lakes in Kashmir, India, using multivariate analysis

Multivariate statistical techniques, such as cluster analysis, principal component analysis (PCA) and factor analysis (FA) were applied to evaluate and interpret the water quality data set for 13 parameters at 10 different sites of the three lakes in Kashmir, India. Physicochemical parameters varied significantly (p?<?0.05) among the sampling sites. Hierarchical cluster analysis grouped 10 sampling sites into three clusters of less polluted, moderately polluted and highly polluted sites, based on similarity of water quality characteristics. FA/PCA applied to data sets resulted in three principal components accounting for a cumulative variance of 69.84, 65.05 and 71.76% for Anchar Lake, Khushalsar Lake and Dal Lake, respectively. Factor analysis obtained from principal components (PCs) indicated that factors responsible for accelerated eutrophication of the three lakes are domestic waste waters, agricultural runoff and to some extent catchment geology. This study assesses water quality of three lakes through multivariate statistical analysis of data sets for effective management of these lakes.     

The ecological condition of dead-end canals of the Delaware and Maryland coastal bays

Manmade, dead-end canals are common in residential developments along the coastal bays of Delaware and Maryland. The close proximity of housing to the water and the concentration of boating activities enhances the potential for anthropogenic stress to living resources in these poorly flushed aquatic systems. Measurements of water quality, sediment contaminants, and benthic macroinvertebrate assemblages were taken in 25 randomly selected canals and compared to 175 non-canal sites located throughout the coastal bays. The mean bottom dissolved oxygen concentrations in canals was half that found in non-canal sites. Mean water-column and benthic chlorophyll concentrations were, respectively, two times and four times higher in the canals. Sediment contaminant concentrations were significantly higher in the canals compared to the coastal bays, and exceeded published guideline values indicating possible adverse ecological effects. The contaminants of greatest concern in the canals included arsenic, copper, polyaromatic hydrocarbons, polychlorinated biphenyls, and several banned, persistent pesticides (DDT, dieldrin, endrin, and chlordane). Benthic macroinvertebrate assemblages in canals were severely degraded; mean species richness, abundance, and biomass were 1/7, 1/10, and 1/20, respectively, of the values for the remaining coastal bays. A single pollution-tolerant polychaete species (Streblospio benedicti) comprised approximately three-fourths (70%) of the community in the canals. Deep (>1 m) and muddy canals were in poorer condition than shallow and sandy ones.     

Bioassay of baltimore harbor sediments

Baltimore Harbor, a tributary area of the northern Chesapeake Bay, has recelved and is receiving large quantities of chemical pollutants. As part of a cooperative study to explore possible corrective treatment for existing pollution burdens, gross bioassay analyses were performed for sediments from nine representative stations, employing two species of fish, mummichogs (Fundulus heteroclitus) and spot (Leiostomus xanthurus), and one mollusc, the soft-shell clam (Mya arenaria). Acclimated organisms were exposed in static systems to a series of concentrations of suspended sediment from each station, to fuller's earth in suspension, and in control tanks for 48 hours. Parallel analysis of the sediment was performed for the metals, Pb, Cr, Zn, Ca, As, for PCB's and for hexane extracts. The sediments were all substantially polluted with low correlations among components. Twenty-four hour TLm and 48-hour TLm increased proportionately with sediment concentration but display species specificity. The relationships observed permit use of mummichog data to index gross toxicity of sediments throughout the harbor. Further comparison of mummichog 24-hour TLm value with benthie species diversity determined in a previous study permitted zoning of the entire harbor into highly toxic, moderately toxic, low toxic and slightly toxic zones. Gross toxicity of sediments determined by bioassay can therefore be used as an index of the suitability of the sediments for benthic macroinvertebrate communities.     

Statistical approaches to evaluate the aquatic ecosystem qualities of a significant mining area: Emet stream basin (Turkey)

Emet Stream is one of the most important branches of Uluabat Lake (Ramsar area) and also one of Turkey’s most important river systems. In addition to the geologic structure of the basin, Harmancik Chromium Mines are one of the most important inorganic pollution sources for the basin and also for Uluabat Lake. In the present study, water, sediment and fish (Squalius cii, Capoeta tinca and Barbus oligolepis) samples were collected seasonally from eight stations (one of them was on the Kinik Stream where the Harmancik Chromium Mines is located on and one of them was on the Dursunbey Stream) on the Emet Stream Basin. Some limnological parameters (pH, conductivity and total hardness) in water and Cr, Ca, Mg, Ni and Mn levels in biotic (muscle, gill, liver and kidney tissues of fishes) and abiotic (water and sediment) components of basin were determined to evaluate the effects of Harmancik Chromium Mines on the system. Cluster Analysis, Factor Analysis, Pearson Correlation Index, One Way Anova Tests, Scatter dot Comparing and Matrix plot Distribution Diagrams were applied to the results in order to estimate the data properly. Water samples were evaluated according to the water quality criteria for Turkey and sediment samples were evaluated according to the sediment quality criteria. According to data obtained, statistically significance differences were identified between Kinik and Emet Streams according to Cr and Ni accumulations in water and sediment. Chromium levels of Kinik Stream were extremely higher an average of 153 times for water and 10 times for sediment than uncontaminated stations. Water and sediment quality of Emet Stream were decreasing after falling the Kinik Stream and increasing after falling the Dursunbey Stream. It was also determined that, the amount of chromium in muscle tissues of three fish species were much higher than the limit value of 0.15 mg kg^?1 that FAO identified.     

Invertebrate Communities of Low-Salinity Wetlands: Overview and Comparison between Phragmites and Typha Marshes Within the Hudson River Estuary

Benthic macroinvertebrate abundance, taxonomic composition, and surface flooding dynamics were compared among high and low elevation stands of narrow-leaved cattail (Typha angustifolia) and invasive common reed (Phragmites australis) at Iona Island Marsh, an oligohaline wetland, and Piermont Marsh, a mesohaline wetland, within the Hudson River National Estuarine Research Reserve during 1999 and 2000. Overall, the benthic macroinvertebrate community at both sites was similar in composition and abundance to those documented from other low-salinity systems. Macroinvertebrate taxa richness was lowest in mesohaline common reed, but similar among common reed and cattail habitats in oligohaline wetlands. Total macroinvertebrate densities were greater at high-elevation compared to low-elevation reed stands at the mesohaline site during summer 1999 and spring 2000. Total macroinvertebrate densities were similar among both oligohaline vegetation types during all seasons, except for spring 2000, when lower densities were observed in low-elevation common reed. A weak positive relationship between macroinvertebrate density and depth of flooding suggests that surface hydrology may be influencing the observed patterns of macroinvertebrate density among the vegetation stands. These results suggest that benthic macroinvertebrate abundance and diversity may not necessarily be impaired in low-salinity wetlands experiencing invasion by common reed unless the change in vegetation is accompanied by a measurable alteration to physical conditions on the marsh surface (i.e., elevation and flooding dynamics).     

广州珠江西航道,流溪河有机污染特征与感潮作用

珠江西航道和流溪河在广州市区上游，为广州市主要水源区。由于感潮作用，受市区严重污染的水体因涨潮上溯而上游传输。严重影响上游水质。因此，弄清感潮作用对广州水源区水质的影响程度和范围，对水源保护与利用有重要意义。本研究从下游到上游，对水源区底泥中有机物特征进行了分析，结果表明：（１）从上游到上游，受感潮作用影响逐渐减小，污染程度逐渐减轻；（２）水源区有机物特征呈有规律变化。从靠近城市的下游到远离城市的     

铜陵矿区主要河流水质分析与污染评价

铜陵矿区是长江下游重要的铜铁资源基地,也是典型的含硫多金属矿区,矿山酸性废水是矿业开发活动不可避免的环境问题,对地表水体有很大影响。本文以铜陵矿区主要河流为研究对象,通过野外调查采样和室内测试分析,从常规理化性质、矿山酸性废水和重金属元素三方面分析了的水质现状,采用单因子指数和内梅罗水质指数法进行了污染评价。结果表明:(1)矿区河流污染成分以有机污染和矿山酸性废水污染为主,其次是重金属污染。(2)在检测的46个河段中, 按综合污染指数大小分级,共计有93.48%的河段受到不同程度的污染,其中,水质严重污染的河段占 4.35%,水质重污染的河段占13.04%,水质污染的河段占 65.22%,水质轻污染的河段占10.87%;共计有6.52%的河段水质较好,均为清洁状态。(3)3条河流按污染程度大小依次为新桥河>顺安河>红星河,除顺安河外,其他均受到了矿山酸性废水污染。今后应重点关注矿山酸性废水的污染机理与风险评估,加强矿区水环境保护与恢复治理工作。     

Risk characterization and surface water quality assessment of Manas River,Assam (India) with an emphasis on the TOPSIS method of multi-objective decision making

The present study centers on the investigation of surface water quality with the aid of quality indices and explores the application of a multi-objective decision-making method (TOPSIS) in arranging decisions for policy makers on the basis of overall ranking of the sampling locations. A case study has been performed on the Manas River, Assam (India). Water Quality Index (WQI) involving physico-chemical parameters, and heavy metal pollution index (HPI) and contamination index (CI) involving heavy metal influences were employed for water quality assessment. WQI graded two sampling locations “very poor” and all other locations “poor”. HPIs of all the locations were below the critical value of 100, but the CI depicted that two locations were “moderately contaminated”. Risk assessment to human health was done using hazard quotient and hazard index. Cluster analysis (CA) demonstrated site similarity by grouping the relatively more polluted and less polluted (LP) sites into two major clusters. However, there surfaced difficulty in discerning the overall water quality, as all the three quality indices included different parameters and contradicted each other. A multi-objective decision-making tool, TOPSIS was therefore employed for ranking the locations on the basis of their relative pollution levels. The novelty of the study reflects in the identification of the relatively more or relatively less polluted sites within the same cluster in CA by the application of TOPSIS. The study justifies the effectiveness of TOPSIS method in prioritizing decisions in complex scenarios for policy makers.     

Do Spartina maritima Plantations Enhance the Macroinvertebrate Community in European Salt Marshes?

Ecological restoration of salt marshes using plantations may enhance the macroinvertebrate community, but little is known about the development of benthic macroinvertebrates after ecological engineering projects in European salt marshes. This study analyzed the environment and the macroinvertebrate community in European salt marshes 3 years after restoration using Spartina maritima plantations in comparison with non-restored and preserved marshes in Odiel Marshes (Southwest Iberian Peninsula). We hypothesized that planting Spartina maritima on intertidal mudflats would increase species richness and diversity (Shannon–Weaver index) of the benthic macroinvertebrate community by increasing environmental heterogeneity, providing feeding resources and improving sediments characteristics. Benthic macrofauna samples (composed mainly of annelids, crustaceans, and mollusks) were sampled in plots of 20 cm?×?25 cm to 5 cm depth between +1.8 and +3.0 m above Spanish Hydrographic Zero. Sediment organic matter content, bulk density, pH, and redox potential were the variables that best explained macroinvertebrate distribution. Restored marshes achieved similar diversity and even higher specific richness than preserved marshes, although with differences in species composition. Non-restored marshes showed the lowest diversity. Restored and preserved marshes did not differ in total abundance or biomass of macroinvertebrates, both being higher than in non-restored marshes. The macroinvertebrate communities in preserved and non-restored marshes showed the largest difference in taxa composition, with restored marshes occupying an intermediate position. Salt marsh restoration using S. maritima increased the complexity (ecological diversity and species richness) and abundance of the benthic macroinvertebrate community. Our study offers new information about the role of salt marsh plants in mediating faunal communities via ecological engineering projects.     

Shallow water agglutinated foraminiferal response to Late Cretaceous–Early Paleocene sea-level changes in the Dakhla Oasis,Western Desert,Egypt

The Late Cretaceous (Maastrichtian) to early Paleocene (Thanetian) shallow water (<100 m) agglutinated foraminifera from a section at Dakhla Oasis (Western Desert, Egypt) were analyzed for their assemblage, species and genera distribution, diversity, depositional environment, community structure and palaeobathymetry with respect to regional tectonics, climate and global eustasy. Data suggest an equitable benthic environment with low species dominance deposited in a brackish littoral and/or marsh setting. Sea level curves using characteristic benthic foraminiferal species, genera and assemblages corroborate quantitatively generated estimate and statistical analysis. Data suggests that in the absence of or of an impoverished benthic foraminiferal fauna, a high resolution agglutinated foraminiferal dataset can be as good a predictor of the benthic community structure and environment, as its calcareous counterpart, at least for shallow settings (<100 m). Present data also provides a good window in better understanding the distribution and interrelationship between the three dominant genera, Haplophragmoides, Trochammina and Ammobaculites. Faunal changes at boundaries (Cretaceous/Paleogene, Danian/Selandian and Selandian/Thanetian) are also evaluated.     

Chlorinated volatile organic compounds found near the water surface of heavily polluted rivers

The objectives of this study were to identify the chlorinated volatile organic compounds near the water surface of two heavily polluted rivers in the south of Taiwan and compare their concentration distributions. Air samples were collected seasonally at the upstream, midstream and downstream water surfaces of each river and the chlorinated volatile organic compounds were analyzed qualitatively and quantitatively by gas chromatography and electron capture detector. Totally, twelve kinds of chlorinated volatile organic compounds were found at the water surfaces of both rivers and many of them were reported to be carcinogenic or probably carcinogenic to human. The results showed that each chlorinated volatile organic compound had its own distribution pattern and no good correlation of chlorinated volatile organic compounds between both rivers was obtained. The chlorinated volatile organic compounds identified at the river water surface of Fong Shan Stream showed much higher concentration than those of Chuen-Tsen River. Several chlorinated volatile organic compounds, including chlorodibromomethane, hexachlorobutadiene, 1,1,2,2-tetrachloroethene and 1,2-dibromo-3-chloropropane were found with much higher concentration (mean concentrations of 124.5 μg/m³, 334.5 μg/m³, 92.2 μg/m³, 268.4 μg/m³, respectively) at the water surface of Fong Shan Stream in some seasons (especially spring and summer, summer and winter, spring and winter, spring and summer, respectively) and they were reported to be possibly carcinogenic to human. Therefore, it may be concluded that the people living close to Fong Shan Stream possibly had higher health risks due to the release of volatile organic compounds from the heavily polluted river.     

Geochemical reconnaissance survey and environmental assessment for stream sediments of Wadi Um Gier,Southeastern Desert,Egypt

The purposes of this study were to assess the influence of old mining activities on the geochemistry and quality of sediments and to identify the sites of economic elements. Thirty sites of stream sediment were sampled in the study area covered by granitic, metarhyodacitic and meta-andesitic rocks and related tuffs-hosted abandoned Au mine. The suite of chemical elements, Ag, Bi, Cd, Cu, Fe, Ga, Hg, Mn, Nb, Pb, Rb, Sb, Se, Sn, Te, Th, U, Y, Zn and Zr, pH value and total organic carbon were determined, and univariate, bivariate and multivariate statistical methods were applied. The results show that the enrichment factor (EF) is very high in the case of Te and significant also with respect to Ag, Bi, Cu, Sb, Se, Sn and Zn. Likewise, geoaccumulation indices (Igeos) varied from very highly polluted with Sn and Te, strongly to very strongly polluted with Bi and Se, and moderately polluted with Sb. The polluted sites of Ag, Bi, Sb, Se, Sn and Te were outlined using Igeos maps, and economic sites of Ag and Sn were identified by geochemical maps leading to their sources, which are likely to be mining activities and lithogenic processes. The pollutant elements may cause toxicity in stream sediments, or surface or underground water, as well as plants and animals in the area. This investigation provides an environmental baseline for future monitoring of possible human/anthropogenic, industrial and agricultural impacts on the study area and considers an attempt at re-mining Ag and Sn.     

广州感潮河段底泥有机质特征

珠江广州河段水文水质特征受感潮作用影响很大，因感潮上溯作用，靠近市区河段的严重污染，不仅对下游水质造成影响，而且对上游珠江西航道和流溪河这一重要水源区的水质有影响。本研究分析了广州上游珠江西航道和流溪河这一河段底泥中有机质特征，从有机地球化学角度探讨感潮作用对广州市上游水质的影响范围和程度，指明鸦岗以上河段受感潮作用影响很小，而西村和石门则受较大程度影响，有机质呈明显人为污染特征。本研究同时表明有机地球化学原理方法可以应用于探讨河流水文水质。     

潮白河流域土壤重金属生态风险评价方法研究

为了研究潮白河流域某段土壤重金属环境质量现状及潜在生态风险评价,系统采集了42件土壤样品,对其7种重金属(Cu、Pb、Zn、Cr、Ni、Cd和As)进行了测试分析,利用《土壤环境质量标准》评价土壤重金属污染现状,并参考北京市土壤重金属背景值,采用环境质量指数与环境潜在生态危害指数、内梅罗综合指数法相结合的方法,探讨土壤中7种重金属的累积污染现状及潜在生态风险。研究表明,土壤样品中Cu、Zn、Cr含量超标分别为97.62%、100%、100%;Cu、Zn、Cr含量重度污染等级以上的分别占2.38%、2.38%、4.76%;潜在生态危害指数法评价表明,Cu、Zn、Cr含量处于轻微生态危害等级分别占97.62%、100%、100%,Cu含量2.38%处于强生态危害等级。内梅罗综合指数法评判表明,所有样点均已污染,其中达到轻度污染、中度污染、重度污染的样点分别占28.57%、42.86%、28.57%;而潜在生态危害指数法评价显示土壤样品点中97.62%处于轻微生态风险等级,根据悲观原则可以判断该段流域重金属污染均处于轻度污染以上。     

Tidal river sediments in the Washington,D.C. area. III. Biological effects associated with sediment contamination

Sediment toxicity and benthic macroinvertebrate community structure were measured as one component of a study cohceived to determine the distribution and effect of sediment contamination in tidal freshwater portions of the Potomac and Anacostia rivers in the Washington, D.C., area. Samples were collected at 15 sites. Analyses included a partial life cycle (28 d) whole sediment test using the amphipod Hyalella azteca (Talitridae) and an assessment of benthic community structure. Survival and growth (as estimated by amphipod length) were experimental endopoints for the toxicity test. Significant mortality was observed in 5 of 10 sites in the lower Anacostia River basin and at the main channel Potomac River site. Sublethal toxicity, as measured by inhibition of amphipod growth, was not observed. Toxicity test results were in general agreement with synoptically measured sediment contaminant concentrations. Porewater total ammonia (NH₃+NH₄ ⁺) appears to be responsible for the toxicity of sediments from the Potomac River, while correlation analysis and simultaneously extracted metals: acid volatile sulfide (SEM∶AVS) results suggest that the toxicity associated with Anacostia River sediments was due to organic compounds. Twenty-eight macroinvertebrate taxa were identified among all sites, with richness varying from 5 to 17 taxa per site. Groups of benthic assemblages identified by group-average cluster analysis exhibited variable agreement with sediment chemical and sediment toxicity results. Integration of toxicological, chemical, and ecological components suggests that adverse environmental effects manifest in the lower Anacostia River benthos result from chemical contamination of sediment.