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Impact of heavy metal on activity of some microbial enzymes in the riverbed sediments: Ecotoxicological implications in the Ganga River (India)
Ecotoxicology and Environmental Safety ( IF 6.8 ) Pub Date : 2017-12-19 , DOI: 10.1016/j.ecoenv.2017.12.015
Deepa Jaiswal , Jitendra Pandey

We studied the extracellular enzyme activity (EEA) in the riverbed sediment along a 518 km gradient of the Ganga River receiving carbon and nutrient load from varied human sources. Also, we tested, together with substrate-driven stimulation, if the heavy metal accumulated in the sediment inhibits enzyme activities. Because pristine values are not available, we considered Dev Prayag, a least polluted site located 624 km upstream to main study stretch, as a reference site. There were distinct increases in enzyme activities in the sediment along the study gradient from Dev Prayag, however, between-site differences were in concordance with sediment carbon(C), nitrogen (N) and phosphorus (P). Fluorescein diacetate hydrolysis (FDAase), β-glucosidase (Glu) and protease activities showed positive correlation with C, N and P while alkaline phosphatase was found negatively correlated with P. Enzyme activities were found negatively correlated with heavy metal, although ecological risk index (ERi) varied with site and metal species. Dynamic fit curves showed significant positive correlation between heavy metal and microbial metabolic quotient (qCO2) indicating a decrease in microbial activity in response to increasing heavy metal concentrations. This study forms the first report linking microbial enzyme activities to regional scale sediment heavy metal accumulation in the Ganga River, suggests that the microbial enzyme activities in the riverbed sediment were well associated with the proportion of C, N and P and appeared to be a sensitive indicator of C, N and P accumulation in the river. Heavy metal accumulated in the sediment inhibits enzyme activities, although C rich sediment showed relatively low toxicity due probably to reduced bioavailability of the metal. The study has relevance from ecotoxicological as well as from biomonitoring perspectives.



中文翻译:

重金属对河床沉积物中某些微生物酶活性的影响:恒河的生态毒理学意义(印度)

我们研究了恒河518公里处沿河床沉积物的河床沉积物的细胞外酶活性(EEA),该河床接受了来自各种人类来源的碳和养分负荷。此外,我们还与底物驱动的刺激一起测试了沉积物中积累的重金属是否抑制了酶的活性。由于没有原始值,因此我们将Dev Prayag(一个污染最小的地点,位于主要研究范围上游624公里处)作为参考地点。Dev Prayag沿研究梯度使沉积物中的酶活性明显增加,但是,位点间的差异与沉积物的碳(C),氮(N)和磷(P)一致。荧光素二乙酸酯水解(FDAase),β-葡萄糖苷酶(Glu)和蛋白酶活性与C呈正相关,E[R一世)随地点和金属种类的不同而不同。动态拟合曲线显示,重金属与微生物代谢商(qCO 2)表明微生物活性随着重金属浓度的增加而降低。这项研究形成了将微生物酶活性与恒河区域规模沉积物重金属积累联系起来的第一份报告,表明河床沉积物中的微生物酶活性与C,N和P的比例密切相关,并且似乎是敏感的。河流中碳,氮和磷的积累指标。沉积物中积累的重金属抑制了酶的活性,尽管富含C的沉积物显示出较低的毒性,这可能是由于金属的生物利用度降低所致。这项研究从生态毒理学和生物监测的角度都具有相关性。

更新日期:2017-12-19
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