Distribution Of Heavy Metals In Sediments Of Hun-tai River And The Impact On Macroinvertebrate

Based on the field survey data of macroinvertebrate communities and environmental elements in Hun-Tai River Basin, the macroinvertebrate community structures’response to human activities was carried out. The pollution conditions, distribution characteristics, source and environmental risks of heavy metal pollution in surface sediments of Hun-Tai River were studyed by applicating the background value comparative analysis and risk evaluation analysis. The community structure, spatial pattern and the impact factor of the macroinvertebrate were analised by the dominant species analysis, feeding functional group analysis, cluster analysis, indicator species analysis and ordering analysis, and the biological indicated factors to heavy metal contamination in the sediments were searched. The main findings are as follows:(1) Spatial distribution characteristics of different heavy metals were different. The spatial distribution characteristics of Cu, Zn, Cd and Pb were more similar, and there were highly significant positive correlation Between Cu, Zn, Cd and Pb (p<0.01), showing the four elements had the same sources. The concentration of Ni, Cd, Cu, Zn, Cr and Pb were influenced mainly by anthropogenic activities, and Fe and Mn were mainly originated from natural sources in surface sediments. Among the eight kinds of heavy metal elements, the content of Fe was in the highest as29550.65mg/kg, and the content of Cd was in the lowest as0.38mg/kg, the enrichment of Pb, Cd and Cu was identified,.(2) Among the risk evaluation analysis, the Pb was considered as the most serious polluted metal in surface sediments by applying the Index of Geoaccumulation (Igeo) and the consensus-based sediment quality guidelines (CB-SQGs), and Cd had the highest potential ecological toxicity by using the assessment of potential ecological risk index (Ei). The background value comparative analysis and risk evaluation analysis reflected the higher contamination and ecological risk of Pb, Cd and Cu in the Hun-Tai River.(3) Orthocladinae spp., Chironominae spp., Oligochaete spp. and Baetis thermicus in Hun-Tai River had a distribution of wide range and the large number. The functional feeding group is relatively simplex, and the collector-gatherers relative abundance up to89.44%. In the upper reaches of Hun-Tai River, sensitive species had a distribution of wide range and a high biodiversity, but in the middle and lower reaches, human disturbance enhanced resulting in serious degradation of community structure, a greatly reduce in number of species, and a increase in tolerance species individual numbers, and the downstream suffered from more and more serious non-point source pollution and organic contamination. The combined effect of the hydration factor (TP, CODMn and BOD5) and the heavy metal elements (Cu, Ni and Cr) in sediment was the main environmental factors affected the macroinvertebrate community structures in upstream sample of the Hun River. In downstream of the Hun-Tai River, the hydration factor such as EC, NH4-N and TP gradually become the dominant influence factors.(4) The different macroinvertebrate species richness had different responses to the different types of heavy metals, and Ephemeroptera (E), Plecoptera (P), and Trichoptera (T) species richness were more sensitive to heavy metals. E species richness was more sensitive to Cr, P species richness was more sensitive to Cu and T species richness was more sensitive to Pb. The different macroinvertebrate species percentage composition had different responses to the different types of heavy metals, EPT%was more sensitive to Zn and T%was more sensitive to Zn and Pb, but Chironomidae%was more tolerance to Mn and Pb, and Diptera%was more tolerance to Mn and Ni. The different macroinvertebrate functional feeding groups had different responses to the different types of heavy metals, collector-filterers (FC)%was more sensitive to Zn、Cd and Pb, but the Shredders (SH)%was more tolerance to Ni.(5) The different macroinvertebrate species had different responses to the different types of heavy metals. Trichoptera Hydropsyche nevae and Diptera Hybomitra montana were more tolerance to Cr, Ephemeroptera Paraleptophlebia westoni, Ephemera strigata, and Trichoptera Simulium yonagoense, Tanypodiinae spp., and Araneae Argyroneta aquatica were more sensitive to Cr; Ephemeroptera Serratella rufa and Trichoptera Tanypodiinae spp., Chironominae spp., Orthocladinae spp. and Antocha sp. were more tolerance to Mn; Diptera Hybomitra montana was more tolerance to Ni; Ephemeroptera Ephemera strigata and Diptera Hydrophorus sp. were more sensitive to Cu; Ephemeroptera Ephemera orientalis were more sensitive to Zn; Diptera Chironominae spp. was more tolerance to Cd, Trichoptera Hydropsyche nevae, Glossosoma sp., and Diptera Antocha sp. were more sensitive to Cd; Trichoptera Hydropsyche nevae, Glossosoma sp., Hydropsyche orientalis, and Diptera Hexatoma sp were more sensitive to Pb.