Health Assessment Of River Ecosystem In North Of Anhui Province

Huaihe River Basin has been an agriculturally-developed and densely populated region in eastern China since the ancient times. Wanbei rivers refer to the rivers located in the north of mainstream of Huaihe River in Anhui Province, including twenty-two tributaries such as Shaying River, Wohe River, Tuohe River and so on. The river ecosystem health of Huaihe River in northern Anhui Province has been destroyed to some extent with the regional economic development and population growth as well as the increasing pressure of water resources. In this paper, the indices of rivers in northern Anhui Province were research objects including the physicochemical properties of overlying waters and sediments, diversity of crustacean plankton and zoobenthos in rivers and microbial diversity in sediments. The relationships between physicochemical properties in overlying waters and biological diversity in rivers were analyzed, and then the main influencing factors of the river’s health were screened for the comprehensive assessment of river ecosystem health. The results indicated that:(1) TN and TP were the main pollution factors in overlying waters, which followed by CODMn. TN pollution was serious in Shayinghe River, Quanhe River, Zhaohe River. The range of TP overweight was wider and CODMn value exceeded seriously in Beituohe River, Laosuihe River, Qianhe River, Shayinghe River, Youhe River. According to correlation analyses of metals in overlying waters, Cd, K, Na and Ca might share the same source while Cr had an exceptional source.(2) 293 species and 79 families of vascular plants were identified in total and the dominant populations were Graminales, Compositae, Cyperaceae, Leguminosae and Polygonaceae. The Mollusca was the main zoobenthos in rivers of northern Anhui Province, and 16 benthic species belonging to 12 families of 3 classes were identified in total in the studied rivers with bellamya aeruginosa as the dominant species. Based on the results of multiple regression analyses, DO, Mg and Pb impacted significantly on the bacterial diversity of sediments, and EC, K, Mg, Cd and Pb had significant impacts on the archaeal diversity of sediments.(3) 98 species of planktonic crustaceans, including rotifers, cladoceras and copepods, belonging to 48 genera of 22 families, were identified in total and the dominant species were Brachionus calyciflorus and Keratella valga and Schizocerca diversicornis and Microcyclops varicans and Thermocyclops taihokuensis. Maximum of abundance was in Beituohe River while the manimum were in Beifeihe River and mainstream of the Huaihe River. The lower biomass was shown in Shayinghe River, Beifeihe River, mainstream of the Huaihe River, Zhaohe River and Runhe River whereas the largest biomass existed in Beituohe River. Diversity index of Shannon-Wiener (H) in the rivers of north Anhui was 2.81, which ranged from 0.99 to 3.90. Results of CCA showed that TW、TP、IP、CODMn、Cd had greater effect on the community structure of crustacean plankton in rivers of north Anhui Province.(4) Based on the comprehensive assessment of river ecosystem health,6 sites were assessed as "sick", meanwhile,56 sites were evaluated as "poor" with 70 "subhealthy" sites and 3 "healthy" sites, which indicated that rivers of northern Anhui Province have been suffering damages to a certain degree. In addition, the morphology and aquatic organisms of rivers presented as major factors that impacted on the health of river ecosystem.