人工湿地基质氧化还原酶与净水效果的相关性

为研究氧化还原酶活性对人工湿地中污染物去除率的影响,探讨将基质酶活性作为评判人工湿地整体去除效能的指标,本研究以生物陶粒和鹅卵石为基质并搭配种植再力花(Thalia dealbata)、美人蕉(Canna indica)和梭鱼草(Pontederia cordata)的复合垂直流人工湿地为研究对象,2016年6月至11月每月采样1次,对基质中4种氧化还原酶(脱氢酶、多酚氧化酶、过氧化物酶和硝酸还原酶)的酶活性进行测定,并从酶学的角度探讨这4种氧化还原酶的活性与养殖尾水中总氮(TN)、硝态氮(NO_3~–-N)、总磷(TP)、正磷酸盐(PO_4~(3–)-P)、COD_(Mn)去除率之间的关系。结果表明,氧化还原酶活性在整个实验过程中发生了显著变化,脱氢酶和过氧化物酶活性先上升后下降,酶活性分别在植物生长高峰期的8月和9月达到最高;多酚氧化酶和硝酸还原酶活性夏季(6—8月)变化不大,植物生长末期达到最高。空间分布上,脱氢酶、多酚氧化酶和过氧化物酶活性沿垂直方向分布表现出相同趋势,即表层最高,中层次之,底层最低。硝酸还原酶活性则表现出相反的趋势。脱氢酶活性与COD_(Mn)的去除率显著正相关(R~2=0.6783,P0.05);硝酸还原酶活性与NO3–-N的去除率显著正相关(R~2=0.6768,P0.05);多酚氧化酶和过氧化物酶活性与TN、NO_3~–-N、TP、PO_4~(3–)-P以及COD_(Mn)的去除率无显著相关性(P0.05)。结论认为,脱氢酶可作为人工湿地中去除COD_(Mn)的效能指标,硝酸还原酶可作为人工湿地中去除NO_3~–-N的效能指标。

Correlation between substrate oxidoreductase and water purification in constructed wetlands

The present study sampled every month from June to November in 2016, aimed to assess the effect of oxidoreductase activity on the removal rate of pollutants from constructed wetlands and to determine whether matrix enzyme activity can be used to assess the effectiveness of overall removal rate. Integrated vertical-flow constructed wetlands that incorporated two substrates (bio-ceramics and pebbles) and three plant species (Thalia dealbata, Canna indica, and Pontederia cordata) were constructed to investigate the activity of four oxidoreductases (dehydrogenase, polyphenol oxidase, peroxidase, and nitrate reductase) and to explore the relationship between enzyme activity and removal rates of total nitrogen (TN), nitrate nitrogen (NO₃^--N), total phosphorus (TP), orthophosphate (PO₄^3--P), and COD_Mnfrom aquaculture wastewater. Oxidoreductase activities were significantly different in the experimental operation cycle. Dehydrogenase and peroxidase activities initially increased and then decreased, and the enzyme activities reached maximum levels during the peak of plant growth. Polyphenol oxidase and nitrate reductase activities were not significantly different from June to August and reached maximum levels when the plants stopped growing. Dehydrogenase, polyphenol oxidase, and peroxide activities exhibited similar vertical distributions (i.e., surface > middle > lowest), whereas nitrate reductase activity exhibited the opposite trend. There were significant positive correlations between nitrate reductase activity and the removal rate of NO₃^--N (R²=0.6783, P=0.0444) and between dehydrogenase activity and the removal rate of COD_Mn (R²=0.6768, P=0.0439). The activities of polyphenol oxidase and peroxidase were not significantly correlated with the removal rates of TN, NO₃^--N, TP, PO₄³-P, and COD_Mn. Accordingly, dehydrogenase can be used as an indicator of the effectiveness of COD_Mn removal in constructed wetlands, and nitrate reductase activity can be used as an indicator of the effectiveness of NO₃^--N removal.