Effects of hydropeaking on drift,stranding and community composition of macroinvertebrates: A field experimental approach in three regulated Swiss rivers

Hydropeaking operation leads to fluctuations in wetted area between base and peak flow and increases discharge-related hydraulic forces (e.g. flow velocity). These processes promote macroinvertebrate drift and stranding, often affecting benthic abundance and biomass. Our field experimental study—conducted in three hydropeaking-regulated Swiss rivers—aimed to quantify (a) the short-term effects of the combined increase in flow amplitude and up-ramping rate based on macroinvertebrate drift and stranding, as well as (b) long-term effects based on the established community composition. Hydropeaking led to increased macroinvertebrate drift compared to base flow and to unaffected residual flow reaches. Moreover, stranding of macroinvertebrates was positively related to drift, especially during the up-ramping phase. Flow velocity and up-ramping rate were identified as major determinants for macroinvertebrate drift, while flow ratio and down-ramping rate for stranding. Particularly high sensitivity towards hydropeaking was found for Limnephilidae, whereas Heptageniidae seemed to be resistant in respect to short- and long-term hydropeaking effects. In the long-term, hydropeaking did not considerably reduce benthic density of most taxa, especially of some highly resistant and resilient taxa such as Chironomidae and Baetidae, which dominated the community composition even though they showed comparably high drift and stranding responses. Therefore, we argue that high drift and/or stranding, especially of individual-rich taxa, does not necessarily indicate strong hydropeaking sensitivity. Finally, our results demonstrate the necessity to consider the differences in river-specific morphological complexity and hydropeaking intensity, since these factors strongly influence the community composition and short-term drift and stranding response of macroinvertebrates to hydropower pressure.     

Seasonal effects of a hydropeaking dam on a downstream benthic macroinvertebrate community

As more hydroelectric dams regulate rivers to meet growing energy demands, there is ongoing concern about downstream effects, including impacts on downstream benthic macroinvertebrate (BMI) communities. Hydropeaking is a common hydroelectric practice where short‐term variation in power production leads to large and often rapid fluctuations in discharge and water level. There are key knowledge gaps on the ecosystem impacts of hydropeaking in large rivers, the seasonality of these impacts, and whether dams can be managed to lessen impacts. We assessed how patterns of hydropeaking affect abundance, taxonomic richness, and relative tolerance of BMIs in the Saskatchewan River (Saskatchewan, Canada). Reaches immediately (<2 km) downstream of the dam generally had high densities of BMIs and comparable taxonomic diversity relative to upstream locations but were characterized by lower ratios of sensitive (e.g., Ephemeroptera, Plecoptera, and Trichoptera) to tolerant (e.g., Chironomidae) taxa. The magnitude of effect varied with seasonal changes in discharge. Understanding the effects of river regulation on BMI biodiversity and river health has implications for mitigating the impacts of hydropeaking dams on downstream ecosystems. Although we demonstrated that a hydropeaking dam may contribute to a significantly different downstream BMI assemblage, we emphasize that seasonality is a key consideration. The greatest differences between upstream and downstream locations occurred in spring, suggesting standard methods of late summer and fall sampling may underestimate ecosystem‐scale impacts.     

Classification of hydropeaking impacts on Atlantic salmon populations in regulated rivers

This article proposes and demonstrates a new classification system of fish population level effects of hydropeaking operations in rivers. The classification of impacts is developed along two axes; first, the hydromorphological effect axis assesses the ecohydraulic alterations in rivers introduced by rapid and frequent variations in flow and water level, second the vulnerability axis assesses the site-specific vulnerability of the fish population. Finally, the population level impact is classified into four classes from small to very large by combining the two axes. The system was tested in four rivers in Norway exposed to hydropeaking, and they displayed a range of outcomes from small to very large impacts on the salmon populations. The river with a relatively high base flow and ramping restrictions scored better than rivers with the lower base flow or limited ramping restrictions, indicating that hydropeaking effects can be mitigated while maintaining high hydropower flexibility. Most effect factors could easily be calculated from timeseries of discharge and water level, whereas the use of hydraulic models to estimate potential stranding areas may require more work. The vulnerability factors are mainly qualitative and depend more heavily on expert judgments and are thus more uncertain. The system was deemed suitable for the purpose of supporting management decisions for rivers exposed to hydropeaking operations. It evaluates the severity of the additional pressures due to hydropeaking operations and proved useful to identify mitigating measures. While the system was developed for Atlantic salmon river systems, it could be adapted to other species or systems.     

The influence of fluctuating ramping rates on the food web of boreal rivers

A BACI (before‐after‐control‐impact) sampling design was applied to determine the possible effects of ramping rate (RR) regulation on food webs structure and function in a regulated boreal river. We used carbon and nitrogen stable isotope signatures of primary producers, macroinvertebrates and fish to determine variations in the source of carbon fuelling the food web as well as changes in the food web structure under variable RR flow regime. We hypothesized that unrestricted RR would (1) increase the connectivity between terrestrial and aquatic environments allowing for a higher contribution of terrestrial carbon to support the food web and (2) decrease food web length because of frequent disturbances. Unrestricted RR had little influence on δ¹³C values for the overall food web with most of the differences found between impacted sites compared and control sites, indicating that the proportion of various carbon sources entering the diet of consumers remained unchanged under unrestricted RR. In contrast, significantly higher δ¹⁵N values were measured in impacted sites (invertebrates and fish) and as well as under unrestricted ramping flow regime (invertebrates). Further, unrestricted RR was associated to a significant decrease in the difference between macroinvertebrates and fish δ¹⁵N signatures, equivalent to a reduction of the length of the food web by at least one trophic level. Results from this study indicate that RR should be taken into consideration in the regulation of operating regimes on rivers. Copyright © 2008 John Wiley & Sons, Ltd.     

The effect of a headwater dam on the use of leaf bags by invertebrate communities

Breakdown rates and colonisation of leaves from four tree or scrub species differing in quality are studied upstream and downstream of the Canales reservoir, a dam located in the headwater of the River Genil, Sierra Nevada, in southern Spain. This dam, with hypolimnetic release, displays short‐term fluctuations of discharge and nutrient enrichment in the tailwater during the study period. Breakdown rates of the four leaf species studied do not differ between sites, despite the higher dissolved nutrient concentration in the tailwater. This lack of differences is attributed to the potentially high physical breakage of leaves during peak flows that are of higher magnitude at the upstream site. The invertebrate density in leaf bags does not differ between sites, and Chironomidae and Ephemeroptera are the numerically dominant taxa at both sites. With regard to functional feeding groups, the scarcity and lack of significant differences between sites for shredders do not match the trend predicted by the Serial Discontinuity Concept in relation to the effect of a headwater dam. Possibly, the discharge fluctuations at both sites causes excessive instability of the natural substrate (leaf litter) for the shredder guild. However, as expected, the biomass of collectors colonising leaf bags is significantly higher at the tailwater, which might be explained not in terms of quantity, but as a consequence of the higher nutritional quality of the fine particulate organic matter (FPOM) accumulated in leaf bags at this site, owing to the eutrophication caused by the dam. Despite the scarcity of functional shredders at both sites, at the community level, the leaf material is significantly more ingested at the upstream site, suggesting the importance of this source of nutrition for the trophic web at this site in contrast with the tailwater, as predicted by the Serial Discontinuity Concept. This also suggests that caution is needed in using functional feeding groups as trophic guilds to infer system‐level trophic dynamics in streams, given the prevalence of generalist feeders among benthic macroinvertebrates in these environments. Copyright © 2000 John Wiley & Sons, Ltd.     

Effects of cold and warm thermopeaking on drift and stranding of juvenile European grayling (Thymallus thymallus)

Intermittent water releases from hydropower plants, called hydropeaking, negatively affect river biota. The impacts mainly depend on hydrological alterations, but changes in physical habitat conditions are suspected to be co-responsible. For example, hydropeaking accompanied by a sudden change of water temperature in the downstream river—called thermopeaking—is also presumed to impair aquatic ecosystems. Still, knowledge about these thermopeaking impacts on aquatic species and life-stages is limited. We performed flume experiments under semi-natural conditions to fill this knowledge gap, simulating single hydropeaking events with a change in water temperature. As response parameters, we quantified the drift and stranding of early life-stages of European grayling (Thymallus thymallus L.), a key fish species of Alpine hydropeaking rivers. Hydropeaking events with a decrease in water temperature (“cold thermopeaking”) led to significantly higher downstream drift (mean = 51%) than events with increasing water temperature (“warm thermopeaking”, mean = 27%). Moreover, during cold thermopeaking, a comparably high fish drift was recorded up to 45 min after the start of peak flows. In contrast, drift rates quickly decreased after 15 min during warm thermopeaking. Remarkably, the spatial distribution of downstream drift along gravel bars during cold thermopeaking showed the opposite pattern compared to those triggered by warm thermopeaking events indicating different behavioral responses. Furthermore, the stranding rates of the cold thermopeaking trials were twice as high (mean = 31%) as those of the warm thermopeaking experiments (mean = 14%). The outcomes present vital information for improving mitigation measures and adapting environmental guidelines.     

梯级引水式水电站对底栖动物群落结构的影响

为研究梯级引水式水电站对底栖动物群落结构的影响,对云南景谷河3座梯级电站影响下河流底栖动物的群落结构进行了调查研究。研究结果表明,水电站的修建显著改变了河流的流速及水深;减水段和混合段水体底栖动物的物种丰度和多样性指数存在一定差异;不同级电站混合段底栖动物密度和生物量均高于减水段;功能摄食类群上混合段的滤食者、撕食者和捕食者相对丰度均显著高于减水段;丰度/生物量比较曲线表明,相对于混合段,水电站影响下减水段底栖动物群落受到了一定程度的干扰。故修建梯级小水电站时,应关注其对底栖动物的群落结构的影响。     

Role of discharge and temperature variation in determining invertebrate community structure in a regulated river

This paper quantifies patterns of discharge and temperature variation in the regulated river Lyon and the adjacent, unregulated river Lochay (Scotland) and assesses the importance of these patterns for benthic invertebrate community structure. Invertebrates were sampled at sites in each catchment in autumn, winter and spring during the 2002–2003 hydrological year. Metrics were used to characterize the discharge and temperature regimes in the period immediately preceding invertebrate sample collection. Metric values were then used in a canonical correspondence analysis (CCA) of the invertebrate sample data, in order to assess the significance of individual metrics and the overall importance of flow and temperature variability for community structure. The variance in the invertebrate data explained by this CCA was compared to that from a CCA using a range of environmental data from the sites (stream‐bed algal cover, channel hydraulic, sedimentary and water quality characteristics). This comparison allowed assessment of the relative importance of environmental variables versus hydrologic and thermal regimes. Invertebrate communities in the Lyon were relatively poor and uneven, with Ephemeroptera, Plecoptera and Coleoptera poorly represented. Distinct site and seasonal clusters were evident in the CCA ordination biplots, with Lyon and Lochay sites separated in dimensions represented by geometric mean sediment size, water temperature and algal cover. The cumulative variance values from ordinations using the discharge and temperature metrics were consistently highest, suggesting that differences in invertebrate communities showed a stronger relation to patterns of discharge and temperature variability than to the broader suite of environmental conditions. Although there were marked thermal differences between sites, temperature metrics appeared no more important than discharge metrics in explaining differences in invertebrate community structure. A number of the temperature and discharge metrics appeared similarly important, suggesting that no one aspect of the hydrothermal regime was any more important than others in helping to understand differences in invertebrate community between the study sites. Copyright © 2007 John Wiley & Sons, Ltd.     

Small hydropower dam alters the taxonomic composition of benthic macroinvertebrate assemblages in a neotropical river

Hydropower dams substantially modify lotic ecosystems. Most studies regarding their ecological impacts are based on large dams and provide little information about the far more abundant effects of small hydropower dams. Our aim was to characterize the ecological effects of a small hydropower dam and run‐of‐the‐river reservoir on the structure of benthic macroinvertebrate assemblages in the Pandeiros River located in the neotropical savanna of Brazil. We tested the hypothesis that benthic macroinvertebrate assemblages in sites directly affected by the dam and reservoir would show a different taxonomic structure compared with those in free‐flowing sites. We expected to find sensitive native species associated with the free‐flowing sites, whereas resistant and non‐native invasive taxa were expected in impounded sites. We also explored associations between the presence of native and non‐native invasive taxa to each habitat type. We found that the structure of benthic macroinvertebrate assemblages was significantly different between free‐flowing and impounded sites. Also, we found that the dam and reservoir facilitated colonization of non‐native invasive species (Corbicula fluminea and Melanoides tuberculata) because only in those sites they were found in high abundance, in contrast to the free‐flowing sites. Although the environmental conditions imposed by the impoundment altered the structure of benthic macroinvertebrate assemblages, the effects were limited to sites closest to the dam. Our results highlight the necessity of understanding physical habitat changes caused by the presence and management of run‐of‐the‐river dams and reservoirs.     

A probability-based model to quantify the impact of hydropeaking on habitat suitability in rivers

A negative effect of hydropower on river environment includes rapid changes in flow and habitat conditions. Any sudden flow change could force fish to move towards a refuge area in a short period of time, causing serious disturbances in the life cycle of the fish. A probability-based model was developed to quantify the impact of hydropeaking on habitat suitability for two fish species, brown trout (Salamo trutta) and Grayling (Thymallus thymallus). The model used habitat preference curves, river velocity and depth to develop the suitability maps. The suitability maps reveal that habitat suitability deteriorates as flow increases in the studied part of the river. The probability model showed that, on average, suitability indices are higher for adult grayling than juvenile trout in hydropeaking events in this part of the river. The method developed shows the potential to be used in river management and the evaluation of hydropeaking impacts in river systems affected by hydropower.     

Effects of plant community composition and exposure to wave action on invertebrate habitat use of Lake Huron coastal wetlands

Invertebrate communities from different coastal marsh‐plant communities were compared along wave‐exposure gradients using data from 1994, 1998 and 1999. Data were subjected to correspondence analyses to search for patterns in invertebrate communities in relation to plant‐community structure and wave exposure. In 1994, quantitative plant‐ and sediment‐invertebrate samples were taken from nine habitats: four from inland, subsurface‐connected marshes and five from littoral, emergent marshes. In 1998, sweep‐net samples were taken from 13 plant communities: six on the exposed and seven on the protected side of an island. In 1999, 2–3 plant communities/sites were sampled with sweep nets from four sites around the Bay so that intersite differences between inner, less‐exposed and outer, more‐exposed habitats could be examined. In all three studies, correspondence analyses separated inland, protected or inner sites from littoral, exposed or outer sites, suggesting differences in invertebrate‐community structure. For example, Hydracarina and Asellidae occurred in large numbers in inland sites, but were less common or absent from exposed, littoral sites. Littoral marshes also separated along an exposure gradient with Tanytarsini and Orthocladiinae collectors of organic particles occurring in very high numbers in outer, exposed areas where organic particles from the pelagic zone entered the marsh. Certain plant‐community types clustered together (e.g. wet meadow and Scirpus) while others, such as Typha, stands clustered according to exposure to waves suggesting the importance of both plant‐community structure and wave exposure in determining invertebrate‐community structure. We present a conceptual model that suggests that invertebrates in Great Lakes' marshes are distributed along gradients of decreased mixing of pelagic water and increases in sediment organic matter from outer to inner marsh and between littoral and adjacent inland marshes. Some invertebrates do best on one end of these gradients, while the majority are generalists found across habitat types.     

Interactive effects of basin features and land‐use change on macroinvertebrate communities of headwater streams in the Patagonian Andes

Composition and structure of macroinvertebrate communities were documented in relation to hydrochemical variables over a 10‐month period in four headwater tributaries of the Futaleufú River, northwestern Chubut, Argentina. The streams are located along the strong rainfall gradient that decreases from west to east and they have different basin features. At Blanco and Baggilt streams, riparian vegetation consisted primarily of native Nothofagus forest, while in the Nant y Fall and Rifleros, basins with a long legacy of domestic grazing, the introduced Salix fragilis was the dominant riparian species. Macroinvertebrate species richness, density, and biomass were similar among rivers; however, biomass of shredders was highest in the Nothofagus forested streams and collector‐filterers were significantly higher in Salix fragilis‐bordered rivers. Water temperatures were higher in non‐native Salix sites than in the native or mixed forested sites. Canonical community analysis indicated community composition was related to geomorphic attributes of the rivers, especially slope, basin height (elevation change), distance to the source, substratum size, and Salix coverage. Moreover, seasonally dynamic variables, rainfall and water temperature were good community predictors. Land‐use change (conversion from Nothofagus to pastures and the Salix fragilis invasion in the riverbanks of pasture‐dominated catchments) was interactive with natural stream attributes as determinants of macroinvertebrate distribution and abundance. Copyright © 2004 John Wiley & Sons, Ltd.     

Effects of human activities on benthic macroinvertebrate community composition and water quality in the upper catchment of the Mara River Basin,Kenya

Land‐use changes in the upper reaches of the Mara River Basin have modified their biophysical and hydrological processes, resulting in water quality degradation in streams. This study was conducted to investigate the effects of human activities on water quality and macroinvertebrates along the Nyangores River, one of the main tributaries of the Mara River, Kenya. Seven sampling sites were chosen to correspond to the loss of riparian cover, livestock watering and human activities (e.g. laundry washing, bathing, cultivation, wastewater inputs, dumping of solid wastes from urban areas and settlements along the river). Physical–chemical variables and water samples for nutrient analyses were collected monthly from February to July 2012. Benthic macroinvertebrates also were collected at the same sites as for the water quality samples. Two‐way analysis of variance tested the significant differences for each variable among the sites. Similarity percentages (SIMPER) analysis was used to identify the key taxa contributing to differences between minimally disturbed and most disturbed conditions in the study area. The results indicated increased nutrient concentrations in agricultural and settlement areas. Significant (P < 0.05) spatial–temporal variations in water quality variables were observed. A total of 42 macroinvertebrate genera were encountered, with Ephemeroptera, Plecoptera and Trichoptera orders dominating the minimally disturbed areas, and Diptera dominating the disturbed areas receiving point and no‐point solid and liquid wastes, including nutrients, from urban areas and settlements. Canonical correspondence analysis (CCA) revealed significant relationships between macroinvertebrate communities and measured physicochemical variables. The results of this study indicate the need for protection of riparian zones and treatment of sewerage wastes before their release into waterways. The dumping of solid wastes near streams and rivers also is discouraged, to maintain the quality of surface waters and aquatic organisms.     

多种修复技术对城市内河水质及微生物群落的影响

采集城市内河水样,分别采用曝气增氧、碳源添加、生物投菌和综合修复等技术,在实验室进行水质修复模拟实验,并以水质参数、微生物多样性及丰度为鉴定指标,分析不同修复技术对城市河流水质的修复效果及其对河流微生物群落结构的影响。结果表明,曝气、生物投菌和综合修复技术可以提高河流微生物群落结构多样性,水体微生物群落以变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)、放线菌门(Actinobacteria)和疣微菌门(Verrucomicrobia)为主;而使用碳源添加技术的水样,河流微生物的多样性下降明显,变形菌门(Proteobacteria)的相对丰度达到了93%;水质修复方面,曝气增氧技术和生物投菌技术都仅能降低水体COD质量浓度,无法降低水体TN及NH+4-N质量浓度;碳源添加和综合修复技术,对水体TN和NH+4-N的去除效果明显,但投加碳源的河流水体中的COD质量浓度显著上升;相关性分析结果表明,影响水体微生物群落结构的主要环境因子为COD和DO。     

感潮河道桥梁和码头工程群对行洪累积影响

以宁波甬江流域感潮河段所建工程群为研究对象,基于Delft3 D数学模型开展了典型洪潮条件下桥梁和码头群对河道行洪的累积影响研究,对比分析单类工程群和两类工程群对河道洪水位和流速的影响.结果表明:桥梁和码头群对河道行洪存在累积影响,位置集中在宁波大学上游的甬江、奉化江和姚江河段;在两类工程群单独作用下均存在水位(流速)...     

Hyporheic invertebrate community composition in streams of varying salinity in south‐western Australia: diversity peaks at intermediate thresholds

Many streams of southwestern Australia have become secondarily saline through land clearance and other human activities in their catchments. Elevated salinities impact on aquatic biota and ecological processes of surface streams but little is known of the effects on the diversity and community composition of hyporheic (subsurface) invertebrates occupying the saturated sediments where surface and groundwaters exchange. We hypothesized that biodiversity of hyporheic invertebrates would decline with increasing salinity, especially where saline groundwater upwelled into the surface stream. We also predicted changes in community composition associated with salinity and direction of vertical hydrological exchange. Water and hyporheic invertebrates were sampled from downwelling and upwelling zones of 13 streams in southwestern Australia ranging in median surface water salinity from 0.27 to 17.86 g L⁻¹. Overall, taxa richness of hyporheic invertebrates was uncorrelated with salinity but, surprisingly, correlated positively with the salinity of upwelling water. However, when the sites were divided into ‘fresh’ (<3 g L⁻¹) and ‘mesosaline’ (>3 g L⁻¹) groups, this relationship became non‐significant. Instead, taxa richness and total abundance were correlated positively with salinity of downwelling water in fresh sites and negatively in mesosaline sites, resulting in a peak in richness at intermediate salinities. Community composition was unrelated to direction of hydrological exchange but was strongly associated with hyporheic salinity. Hyporheic assemblages of ‘fresh’ rivers were typified by harpacticoid copepods and candoniid ostracods, whereas the amphipod Austrochiltonia and several dipteran groups were more common below ‘mesosaline’ rivers. Although many hyporheic taxa collected in this study apparently have broad tolerances to salinity, secondary salinization due to human activities potentially changed community composition, possibly altering rates of ecological processes such as organic matter breakdown occurring within the sediments of streams undergoing salinization. Copyright © 2007 John Wiley & Sons, Ltd.     

温度对两种固定化硝化菌硝化反应的影响

通过包埋固定化硝化菌颗粒和生物接触氧化法在不同温度条件下的硝化反应速率测定试验,发现在28℃时两个反应器均达到最大硝化速率,分别为40 mgN/(L.h)和31 mgN/(L.h);温度降至8℃时,硝化速率分别为18 mgN/(L.h)和8 mgN/(L.h),包埋固定化硝化菌在低温条件下显示出明显的优势。温度为20~32℃时,包埋硝化菌处理高氨氮废水很容易形成亚硝酸型硝化。     

Influence of habitat heterogeneity and bed surface complexity on benthic invertebrate diversity in a gravel‐bed river

Maintaining or restoring physical habitat diversity is a central tenet of sustainable river management, yet a link between habitat and ecological diversity in fluvial systems has long remained equivocal. The lack of consistent evidence partly reflects the problems of characterizing habitat in ways that are ecologically meaningful. This paper assesses the influence of habitat heterogeneity and complexity on macroinvertebrate assemblages in a mountain gravel‐bed river. With the use of 0.1‐m resolution data obtained from an acoustic Doppler current profiler, heterogeneity and complexity in hydraulic conditions and bed topography were characterized using 13 metrics applied to 30 areas, each 1 m², with an invertebrate sample collected from each area. Turnover of invertebrate taxa (i.e., β‐diversity) between sampled areas was rather limited, but observed differences in diversity were related significantly to several metrics of habitat heterogeneity. Invertebrate abundance was related to habitat diversity, patch size coefficient of variation, and patch size, whereas the Shannon diversity was related to the number of patches and patch size. None of the habitat complexity metrics accounted for a significant amount of observed variation in invertebrate communities between sampled areas. The paper demonstrates that high‐resolution data can help reveal relationships between habitat and benthic invertebrate diversity.     

长荡湖、滆湖、竺山湾藻类功能群结构组成与环境因子的关系

为研究太湖流域上游长荡湖、滆湖、竺山湾三大典型浅水湖泊藻类功能群结构组成与环境因子的关系,基于2019年2月至2020年10月水文、水质及浮游植物数据,采用Q指数、香农-维纳多样性指数、TLI综合富营养化指数分析了3个湖泊的水质状况,采用非度量多维尺度变换(NMDS)分析了浮游植物群落结构组成特征,采用冗余分析探讨了浮游植物功能群与环境因子的关系。结果表明：长荡湖和滆湖水质整体属于轻度富营养化,竺山湾除冬季外,均属于中度富营养化;长荡湖、滆湖、竺山湾分别有浮游植物7门61属96种、8门75属129种和6门53属124种,分别划分为9、10和11个优势功能群;3个湖泊藻类功能群变化的共同环境因子是水温、高锰酸盐指数和总磷,而总氮和氮磷比对3个湖泊功能群结构变化的作用并不明显。     

北京市中心城河流表层沉积物重金属污染评价

为了解北京市中心城河流表层沉积物中重金属污染现状,采用地累积指数法、主成分分析法、潜在生态风险指数法评价和分析了沉积物中汞、砷、铅、铬、镉、锰、铜7种重金属的污染程度、污染来源及潜在生态风险。结果表明,重金属平均含量为Hg 0.670 mg/kg,As 6.01 mg/kg,Pb 31.1 mg/kg,Cr 63 mg/kg,Cd 0.29 mg/kg,Mn 277mg/kg,Cu 45mg/kg;平均地累积指数排序为Hg(1.49)Cr(0.34)Cu(0.24)Cd(0.14)Pb(-0.77)As(-1.41)Mn(-2.30),沉积物主要受Hg、Cr、Cu、Cd的污染,Hg处于中等污染程度,Cr、Cu、Cd处于轻度-中等污染程度,污染主要来源于三方面:交通、汽配(修)及供暖燃煤。重金属平均潜在生态风险系数排序为Hg(357)Cd(80)Cu(13)As(9)Pb(7)Cr(4)Mn(2),中心城沉积物潜在生态风险指数平均值为472,总体上具有较强生态危害。