嗜热四膜虫在东江东莞段水质评价中的应用

Application of Tetrahymena thermophila in evaluation on water quality of Dongguan-section of Dongjiang

目的应用水质理化指标和嗜热四膜虫(Tetrahymena thermophila)生物指标检测水质,探讨嗜热四膜虫在水环境质量监测中的应用。方法于2016年4月至8月,在东江东莞段依上游到下游选取4处采样点(A^D)采集水面下约0.5m处表层水体。用化学检测法测定各采样点水体的五日生化需氧量、溶解氧(DO)、高锰酸盐指数、氨氮,用电感耦合等离子体质谱法测定六价铬、铅(Pb)、锰(Mn)和铁(Fe)含量。采用细胞计数仪测定各采样点水体培养下嗜热四膜虫种群数量和世代时间的变化,并采用Pearson相关分析对嗜热四膜虫生物指标与水质理化指标间的相关性进行检验。结果各采样点中五日生化需氧量仅上游1处采样点未超标;高锰酸盐指数均超标;氨氮在中下游两处采样点最高,约为标准值的6倍;铁在下游采样点超过标准限值的1.3倍;其余指标未超标。综合污染指数评价显示,下游受有机物和重金属污染严重,水质较差。与对照比较,各采样点培养下嗜热四膜虫种群生长数量均降低,差异具有统计学意义(P<0.05);种群生长数量自上游到下游呈降低的趋势。自上游到下游各采样点培养的嗜热四膜虫世代时间呈增加的趋势(P<0.05)。生化需氧量、氨氮是影响嗜热四膜虫种群数量和世代时间的关键环境因子(P<0.01)。结论东莞段水体对嗜热四膜虫生长有一定的抑制作用,上游水质相对较好,下游水质较差,与非生物环境因子综合评价结果一致。

Objective To investigate the application of Tetrahymena thermophila in environmental quality monitoring , T.thermophila's biological indicators and physicochemical factors of water were used to study the water quality.Methods The samples were collected at about 0.5 meters under the water surface from four different sites of the Dongguan -section of Dongjiang River,from April to August of 2016.The levels of BOD5,DO,CODMn,NH3-N were determined by chemical method, and the contents of Cr^6+,Pb ,Mn and Fe were determined by ICP-MS.The population growth and generation time of T.thermophila were determined by automated cell counter.Water physicochemical parameters were analyzed to study their correlations with the biological indicators.Results Among all the sites being sampled,only the site in upstream met the standards in terms of BOD5,CODMn exceeded limits in all sites,concentrations of NH3-N were the hightest in middle and downstream,reaching about six times as high as the limit value,concentration of Fe in downstream was 1.3 times as high as the limit value,other physicochemical factors of water met the related standards.Heavier pollution by organic pollutants and heavy metals was found in downstream.Compared with the control group,the amount of T.thermophila growing in the samples decreased from upstream to downstream (P<0.05).All sites showed significant influence on the generation time of T.thermophila (P<0.05) and the generation time increased from upstream to downstream.BOD5 and NH3-N were the main influencing factors for population growth rate and generation time of T.thermophila (P <0.01).Conclusion The investigated water samples of Dongguan -section inhibit the growth of T.thermophila,water pollution in middle and downstream is more serious,which is consistent with the comprehensive evaluation based on non-biologic environmental factors.