Kinner Nancy E, Harvey Ronald W, Shay David M, Metge David W, Warren Alan
Bedrock Bioremediation Center, University of New Hampshire, Durham 03824, USA.
Environ Sci Technol. 2002 Oct 15;36(20):4312-8. doi: 10.1021/es020611m.
The association between protists, bacteria, and dissolved organic carbon (DOC) in an oxygen-depleted, 6 km-long wastewater contaminant plume within a sandy aquifer (Cape Cod, MA) was investigated by comparing abundance patterns along longitudinal and vertical transects and at a control site. Strong linear correlations were observed between unattached bacterial abundance and DOC for much of the upgradient-half of the plume (0.1-2.5 km downgradient from the source) that is characterized by quasi-steady state chemistry. However, a logarithmic decrease was observed between the number of protists supported per mg of DOC and the estimated age of the DOC within the plume. The relatively labile dissolved organic contaminants that characterize the groundwater sampled from the plume < or = 0.1 km downgradient from the contaminant source appeared to indirectly support 3-4 times as many protists (per mg of DOC) as the older, more recalcitrant DOC in the alkylbenzene sulfonate (ABS)-contaminated zone at 3 km downgradient (approximately 30 years travel time). Substantive numbers of protists (>10(4)/cm3) were recovered from suboxic zones of the plume. The higher than expected ratios of protists to unattached bacteria (10 to 100:1) observed in much of the plume suggest that protists may be grazing upon both surface-associated and unattached bacterial communities to meet their nutritional requirements. In closed bottle incubation experiments, the presence of protists caused an increase in bacterial growth rate, which became more apparent at higher amendments of labile DOC (3-20 mgC/L). The presence of protists resulted in an increase in the apparent substrate saturation level for the unattached bacterial community, suggesting an important role for protists in the fate of more-labile aquifer organic contaminants.
通过比较沿纵向和垂直断面以及在一个对照点的丰度模式，对马萨诸塞州科德角一个沙质含水层中一条6公里长的缺氧废水污染羽流中的原生生物、细菌和溶解有机碳（DOC）之间的关联进行了研究。在羽流上半部分的大部分区域（从源头向下游0.1 - 2.5公里），未附着细菌丰度与DOC之间观察到强线性相关性，该区域以准稳态化学为特征。然而，每毫克DOC所支持原生生物的数量与羽流中DOC的估计年龄之间呈对数下降。从污染物源头向下游≤0.1公里处的羽流中采集的地下水中，相对不稳定的溶解有机污染物似乎间接支持的原生生物数量（每毫克DOC）是在下游3公里处烷基苯磺酸盐（ABS）污染区中较老、更难降解的DOC所支持原生生物数量的3 - 4倍（大约30年的运移时间）。从羽流的缺氧区回收了大量原生生物（>10⁴/cm³）。在羽流的大部分区域观察到的原生生物与未附着细菌的比例高于预期（10到100:1），这表明原生生物可能通过捕食表面相关和未附着的细菌群落来满足其营养需求。在密闭瓶培养实验中，原生生物的存在导致细菌生长速率增加，在添加较高水平的不稳定DOC（3 - 20 mgC/L）时这种增加更为明显。原生生物的存在导致未附着细菌群落的表观底物饱和水平增加，这表明原生生物在更不稳定的含水层有机污染物的归宿中起着重要作用。
