IMPACT OF WATERSHED URBANIZATION ON STREAM INSECT COMMUNITIES1

ABSTRACT: The impact of urbanization on stream insect communities was determined by sampling 22 sites in northern Virginia representing a range of human population densities. Watershed development had little effect on the total insect numbers (no./m²), but shifted the taxonomic composition markedly. Relative abundance of Diptera (mainly chironomids) increased at more highly urbanized sites, while most other insect orders including Ephemeroptera (mayflies), Coleoptera (bettles), Megaloptera (dobsonflies), and Plecoptera (stone-flies) decreased. Trichoptera (caddisfiles) exhibited a variable response. Genus diversity and richness (number of genera) were significantly higher in less urbanized streams. Two genera of chironomids were positively correlated with increased urbanization, while 14 other genera (scattered through several orders) were negatively related to human population density. Principal components analysis demonstrated a gradient from more urbanized to less urbanized stations based on generic and order level biological data. Results of this study indicate that watershed urbanization has a major impact on benthic insect communities even in the absence of point source discharges.     

BENTHIC INVERTEBRATE RESPONSE TO POLLUTION ABATEMENT: STRUCTURAL CHANGES AND FUNCTIONAL IMPLICATIONS1

We examined changes in certain structural and functional aspects of the benthic invertebrate community in the Penobscot River, Maine, between 1974 and 1981. During this period, two pulp and paper manufacturers and three municipalities spent an estimated $33 million to reduce point source effluents harmful to aquatic life. We developed a biotic index based on objectively derived pollution tolerance values for resident taxa. Analysis of the benthic invertebrate community indicated that substantial improvement in water quality had resulted from pollution abatement. We established a four-group water quality classification scheme based on biotic index ranges, and showed that every site that was not in the best water quality classification in 1974 improved its classification to a better water quality group in 1981, and that the sites in the best group did not change. Relative abundances of functional feeding groups also changed, as were predicted by the river continuum theory. The effluents had acted as a “reset mechanism” that shifted polluted areas from autotrophic to more heterotrophic conditions. The direction of the shift was reversed in response to abatement efforts. Functional analyses of energy dynamics could lead to a more ecologically sound classification of water quality.     

家用小型汽车室内多溴联苯醚(PBDEs)的检测

为了研究家用小型汽车室内多溴联苯醚(PBDEs)的存在状态,对上海市7辆使用2 a以上的不同型号家用轿车进行了调查。采集形成于车窗玻璃内表面的有机膜,采用气相色谱-质谱联用仪(GCMS)对有机模样品进行了定性及定量分析,并根据表面膜-空气分配模型计算汽车室内空气中PBDEs的质量浓度。结果表明:13种待测多溴联苯醚(PBDEs)目标化合物均被检出;在车窗玻璃内表面有机膜中,Σ13PBDEs含量为19.63~26.13 ng/m2;家用小型汽车室内空气中Σ13PBDEs质量浓度为376.61~961.24 pg/m3;由于PBDEs的正辛醇-空气分配系数KOA与PBDEs的溴代度正相关,高溴代PBDEs在有机膜中的含量较高(实测BDE-209是其最主要的污染物),而低溴代PBDEs在空气中的含量较高(BDE-28是其最主要的污染物);与家庭、办公场所、公共场所等室内环境相比,家用小型汽车室内空气中PBDEs质量浓度处于较高水平。     

Derivation and Use of Sediment Quality Guidelines for Ecological Risk Assessment of Metals and Radionuclides Released to the Environment from Uranium Mining and Milling Activities in Canada

The Screening Level Concentration (SLC) approach was used to derive Lowest Effect Level (LEL) and Severe Effect Level (SEL) concentrations for nine metals (As, Cr, Cu, Pb, Mo, Ni, Se, U and V) and three radionuclides (²²⁶Ra, ²¹⁰Pb, and ²¹⁰Po) released to the aquatic environment during the mining and milling of uranium ore. This method was chosen because it allowed for the best use of the considerable historical and current data collected for diverse purposes in the uranium mining and milling regions of Canada (20,606 data points used in the analysis). Except for Cr, all the LELs derived in this study using the weighted method and published sediment quality guidelines (SQGs) were highly reliable (> 85%) in predicting sites unimpacted by uranium mining/milling defined as sites where reductions in the abundance and species richness of benthic invertebrate communities were < 20%. The derived SEL values and corresponding published SQGs (with the exception of Ni) were not reliable predictors (≤60%) of severe impacts on benthic invertebrate communities when severe impacts are defined as a reduction in abundance and species richness ≥40%. Most of the severely impacted sites had sediment contaminant concentrations well below the SEL values. It is concluded that LELs derived using the weighted method can reliably be used in ecological risk assessments as concentrations below which adverse effects on benthic invertebrate communities are not expected. In contrast, it is recommended that SELs not be used in assessments of uranium mining/milling activities as concentrations above which adverse effects are anticipated.     

APPLICATION OF BIOLOGICAL MEASURES FOR STREAM INTEGRITY ASSESSMENT IN SOUTH-EAST BRAZIL

The sensitivity of eleven metrics using macroinvertebrate assemblages were evaluated in an environmental gradient in a tropical river in south-east Brazil. Eight sites were sampled in an altitudinal range of 160–650 m.a.s.l. during 1999 (April and August) and 2000 (February). Four substrates were sampled at each site: riffle litter, pool litter, stony substrates and sediment. Correspondence Analysis indicated that assemblages were primarily more influenced by physical changes (like deforestation and erosion processes) than the water chemistry. The sensitivity of each metric was evaluated through the application of box-and-whisker plot method by its power to assess impairment (metrics should be able to discriminate reference sites from impaired sites) and natural variability (metrics should not discriminate two reference sites). Metrics that failed in at least one of the above premises were not considered as sensitive. In this study, the most sensitive metrics were Shannon index, BMWP-ASPT, %_EPT, and relative abundance of EPT to Chironomidae.     

Testing Bioassessment Metrics: Macroinvertebrate, Sculpin, and Salmonid Responses to Stream Habitat, Sediment, and Metals

The purpose of this article is to report on the testing of responses of multimetric macroinvertebrate and habitat indices to common disturbances to streams: stream habitat alteration, excessive sediment, and elevated metals concentrations. Seven macroinvertebrate community metrics were combined into a macroinvertebrate biotic index (MBI), and 11 channel morphology, riparian, and substrate features were combined into a habitat index. Indices were evaluated by comparing the habitat results to fish population surveys and comparing the macroinvertebrate results to habitat ratings, percent fine sediments measured by Wolman pebble counts, and copper concentrations. Macroinvertebrate scores decreased with increasing percentages of fine sediments measured either across the bankfull or instream channel widths. Macroinvertebrate scores decreased with increasing copper. One metric, richness of Ephemeroptera, Plecoptera, and Trichoptera (EPT) taxa, was more responsive to both copper and sediment than was the multimetric MBI. Habitat scores corresponded well with the age class structure of salmonids, but not with that of benthic sculpins. Both salmonid and sculpin age classes declined with increasing percentages of fine sediments. The decline was graded with the sculpin age classes, whether fine sediments were measured across the instream or bankfull channel, whereas salmonids consistently responded only to the instream fine sediments.     

闽西南花岗质岩浆作用与成矿

重点讨论了闽西南地区花岗岩类的同位素年龄和演化，将其划分为五期七个阶段，初步确定各阶段花岗岩类的岩石系列和组合及其与区域构造演化的关系。讨论了推覆构造与岩浆作用的关系，并认为与本区成矿作用有关的岩浆岩主要为两类花岗质岩石。研究区良好的矿源层和有利的赋矿层位以及海西期以来幔源岩浆的多次活动，使研究区成为十分有远景的成矿集中区。     

Deformity frequencies of benthic marine diatoms associated with contaminated sediments in Hong Kong

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