Haack Elizabeth, Warren Lesley A
School of Geography and Geology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4K1.
Environ Sci Technol. 2003 Sep 15;37(18):4138-47. doi: 10.1021/es026274z.
Biofilms in shallow, tailings-associated acid rock drainage (ARD) accumulated metals from May to September, indicating scavenging is stable within these biological solids over seasonal time frames. Results indicate a doubling (Mn, Cr) to over a 6-fold increase (Ni, Co) in biofilm metal concentrations. Biofilm oxygen and pH gradients measured over diel time scales with microelectrodes were observed to be both spatially and temporally variable, indicating that biofilms are highly dynamic geochemical environments. Biofilm metal retention and affinities were element specific indicating different processes control their sequestration. Metals were specifically scavenged by the organic constituents of the biofilm itself (Ni, Co) and associated biominerals of amorphous Mn oxyhydroxides (HMO; Ni, Co, and Cr). Results are consistent with sorption and coprecipitation processes controlling Ni and Co biofilm association, while Cr dynamics appear linked to those of Mn through redox processes. Biofilm HMO concentrations increased seasonally but showed significant diel fluctuations, indicating that both formation and dissolution processes occurred over rapid time scales in these biofilms. Biofilm HMO concentrations increased nocturnally but decreased during daylight hours to late afternoon minima. Under the geochemical conditions of the streams, observed HMO formation rates can only be explained by microbial catalysis. These results are the first to quantitatively examine microbial biofilm metal dynamics using microscale, geochemical techniques at both diel and seasonal time scales. They provide strong evidence for the significant role that microbial activity can play in metal geochemistry in natural environments.
浅部尾矿伴生酸性岩排水（ARD）中的生物膜在5月至9月间积累金属，这表明在季节性时间尺度上，这些生物固体中的清除作用是稳定的。结果表明生物膜中金属浓度翻倍（锰、铬）至增加6倍以上（镍、钴）。用微电极在昼夜时间尺度上测量的生物膜氧气和pH梯度在空间和时间上都是可变的，这表明生物膜是高度动态的地球化学环境。生物膜对金属的保留和亲和力具有元素特异性，表明不同过程控制着它们的螯合。金属被生物膜本身的有机成分（镍、钴）以及无定形羟基氧化锰（HMO；镍、钴和铬）的相关生物矿物特异性清除。结果与控制镍和钴与生物膜结合的吸附和共沉淀过程一致，而铬的动态变化似乎通过氧化还原过程与锰的动态变化相关联。生物膜中HMO浓度呈季节性增加，但显示出显著的昼夜波动，这表明在这些生物膜中，形成和溶解过程都在快速的时间尺度上发生。生物膜中HMO浓度在夜间增加，但在白天至下午晚些时候降至最低。在溪流的地球化学条件下，观察到的HMO形成速率只能用微生物催化来解释。这些结果首次使用微观地球化学技术在昼夜和季节性时间尺度上对微生物生物膜金属动态进行了定量研究。它们为微生物活动在自然环境中金属地球化学中可能发挥的重要作用提供了有力证据。
