Zhou L X, Zhou S G, Zhan X H
College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
J Environ Qual. 2004 Jan-Feb;33(1):154-62. doi: 10.2134/jeq2004.1540.
Bacterial extracellular polymers (BEP) affect the translocation and fate of organic and inorganic pollutants in terrestrial and aquatic ecosystems. In this study, BEP from activated sludge was compared with sludge dissolved organic matter (DOM) in terms of behavior and effects on the mobilization and bioavailability of Cu in a well-aged Cu-contaminated orchard sandy loam. Addition of sludge BEP (10-200 mg dissolved organic carbon [DOC] L(-1)) to the soil resulted in 1.6- to 12.8-fold-higher soil soluble Cu concentration over the control and 1.3- to 2.2-fold over sludge DOM of the same concentration. Consequently, the Cu uptake by the ryegrass (Lolium perenne L., cv. Target) grown in the soil was increased by 31% due to interval watering of 100 mg DOC L(-1) of sludge BEP solution in a 35-d period. The influence of sludge BEP on mobilizing soil Cu could be maintained as long as 60 d or more, depending on BEP biodegradation status. The findings that sludge BEP promoted Cu mobilization and bioavailability could be attributed to less adsorption of BEP by soil, slow degradation, and higher affinity with Cu. For example, after 3 wk of aerobic incubation, the soluble Cu present in the sludge DOM-treated soil was reduced to about the level of the control, while the concentration of soluble Cu in BEP-treated soil was 6.2 times higher than that in the control. Therefore, sludge BEP could act as a facilitated-transport carrier of Cu. The environmental risk of Cu should receive much attention if BEP is incorporated into soils.
细菌胞外聚合物（BEP）会影响有机和无机污染物在陆地和水生生态系统中的迁移及归宿。在本研究中，将活性污泥中的BEP与污泥溶解有机物（DOM）在行为以及对一块长期受铜污染的果园砂壤土中铜的迁移和生物有效性的影响方面进行了比较。向土壤中添加污泥BEP（10 - 200毫克溶解有机碳[DOC] L⁻¹）后，土壤可溶性铜浓度比对照高出1.6至12.8倍，比相同浓度的污泥DOM高出1.3至2.2倍。因此，在35天的时间段内，由于间隔浇灌100毫克DOC L⁻¹的污泥BEP溶液，生长在该土壤中的黑麦草（Lolium perenne L.，品种Target）对铜的吸收增加了31%。污泥BEP对土壤中铜的迁移影响可持续长达60天或更长时间，这取决于BEP的生物降解状态。污泥BEP促进铜迁移和生物有效性的发现可归因于BEP被土壤吸附较少、降解缓慢以及与铜的亲和力较高。例如，经过3周的好氧培养后，污泥DOM处理土壤中存在的可溶性铜降至对照水平左右，而BEP处理土壤中的可溶性铜浓度比对照高6.2倍。因此，污泥BEP可作为铜的促进运输载体。如果将BEP引入土壤，铜的环境风险应受到更多关注。
