河滨缓冲带植物根系和根际微生物特征及其对农业面源污染物去除效果

对河滨缓冲带常见的3种水生植物根系形态特点、活力特征及其土壤微生物群落多样性进行了研究,并对其农业面源污染物的去除效果进行了调查。结果表明,3种水生植物根系形态和活力特征具有显著差异。根系活力表现为水生鸢尾菖蒲千屈菜,与根尖数呈显著相关。同时,3种水生植物具有显著的根际效益,根际土壤微生物生物量显著高于非根际土壤;根际土壤微生物群落数量为细菌放线菌真菌;土壤微生物群落多样性指数为水生鸢尾菖蒲千屈菜,这与3种水生植物根系活力特征表现一致。3种水生植物河滨缓冲区对农业面源污染物TN、TP和CODCr的去除效果表现为水生鸢尾菖蒲千屈菜。说明不同水生植物根系结构导致根系活力不同,由此引起的土壤微生物群落多样性差异对水生植物农业面源污染物去除效果有一定影响。

Characteristics of aquatic plant roots, soil microbes and agricultural non-point source pollutant mitigation in riparian buffer zones

An experiment was conducted on the characteristics of root morphology and vitality, and soil microbial community diversity of three typical aquatic plants to determine their mitigation efficiency of agricultural non-point source pollutants in riparian buffer zones. All the aquatic plants used have significantly differences in the characteristics of root morphology and vitality. Root vitality values of the aquatic plants are in the following order: Iris pseudacorus > Acorus calamus > Lythrum salicaria. Root vitality has a significant correlation with root tip number. The aquatic plants show significant rhizosphere effect, soil microbial biomass in rhizosphere is markedly higher than that in bulk soils. Furthermore, microbial community in rhizosphere soils of the riparian buffer zone has the composition sequence as: bacteria > actinomycetes > fungi. Soil microbial community diversity index is as follows: I. pseudacorus > A. calamus > L. salicaria, having the same tendency as that of root vitality. The order of removal efficiency of TN, TP and COD_cr by the aquatic plants in the riparian buffer zone is I. pseudacorus > A. calamus > L. salicaria. The results suggest that variations in root vitality caused by differences in root structure of aquatic plants influence soil microbial community structure and diversity. This results in the differences in removal efficiencies of agricultural non-point source pollutants in riparian buffer zones.