Southeast Univ, Sch Energy & Environment, 2 Sipailou Rd, Nanjing 210096, Jiangsu, PR China; ERC Taihu Lake Water Environment Wuxi, 99 Linghu Rd, Wuxi 214135, PR China.
Southeast Univ, Sch Energy & Environment, 2 Sipailou Rd, Nanjing 210096, Jiangsu, PR China; ERC Taihu Lake Water Environment Wuxi, 99 Linghu Rd, Wuxi 214135, PR China.
Sci Total Environ. 2022 Apr 1;815:152896. doi: 10.1016/j.scitotenv.2021.152896. Epub 2022 Jan 6.
Excess phosphorus (P) in surface runoff has significant deleterious impacts on water quality through eutrophication. Commonly, P is transported via non-point pollution and the proportion of easily plant-available reactive P (RP) among other P forms may vary significantly. Non-reactive P (NRP) can potentially contribute to the eutrophication of waterbodies, however the cleavage into bio-available P forms and eventually their biological uptake remains uncertain. This holds also true for floating treatment wetlands (FTWs) which became established as nutrient mitigation measures for surface waters in recent years. However, little information is available about the conversion and removal of NRP in FTWs. In this study, the conversion and removal of different forms of P in FTWs were investigated. Experiments were operated in batch mode and treatments consisted of (1) two concentration levels: a high P concentration of 3.0 mg/L and a low P concentration of 1.0 mg/L, and (2) four mesocosm treatments: (a) artificial roots only, (b) substrates only, (c) plants only, (d) plants and substrates. The results showed that RP removal mainly depended on sedimentation, substrate sorption, and biological assimilation. The removal of NRP mainly depended on hydrolysis, microbial-mediated conversion, and biological absorption. The combination of plant and substrate provided stable and efficient phosphorus removal performance in high P conditions, while plants were important for P removal in low P conditions. Living plants were indispensable and greatly affected the performance of FTWs. The specific enrichment and culling of microorganisms by plants resulted in the formation of specific rhizosphere microbial communities and promoted the removal of NRP. Pseudomonas, Enterobacter, Acidovorax might be responsible for P mineralization in the FTWs. Comprehensive analysis indicated that the conversion and removal pathways of P in the FTWs were not mutually independent, and the plant-microbe-substrate interactions cannot be underestimated.
地表径流中过量的磷（P）通过富营养化对水质有重大的有害影响。通常，P 通过非点源污染传输，而其他 P 形态中易于被植物利用的反应性 P（RP）的比例可能有很大差异。非反应性 P（NRP）可能会导致水体富营养化，然而，将其转化为生物可利用的 P 形态并最终被生物吸收仍然不确定。这对于近年来作为地表水营养物质缓解措施而建立的浮式处理湿地（FTWs）也是如此。然而，关于 FTWs 中 NRP 的转化和去除，相关信息却很少。在本研究中，考察了 FTWs 中不同形态 P 的转化和去除。实验采用分批模式进行，处理方法包括：（1）两个浓度水平：高 P 浓度 3.0mg/L 和低 P 浓度 1.0mg/L；（2）四个中观处理：（a）仅人工根，（b）仅基质，（c）仅植物，（d）植物和基质。结果表明，RP 的去除主要取决于沉淀、基质吸附和生物同化。NRP 的去除主要取决于水解、微生物介导的转化和生物吸收。植物和基质的结合在高 P 条件下提供了稳定和高效的磷去除性能，而植物在低 P 条件下对 P 的去除至关重要。活的植物是不可或缺的，极大地影响了 FTWs 的性能。植物对微生物的特异性富集和选择导致了特定根际微生物群落的形成，并促进了 NRP 的去除。假单胞菌、肠杆菌、食酸菌可能是 FTWs 中 P 矿化的原因。综合分析表明，FTWs 中 P 的转化和去除途径不是相互独立的，植物-微生物-基质的相互作用不可低估。
