CRBCZO -- Climate, Stable Isotopes, Well Water Levels -- White Clay Creek Transect A floodplain, Transect C -- (2012-2012)

Diana Karwan, Olesya Lazareva, Donald L. Sparks, Anthony Aufdenkampe

The Christina River Basin-Critical Zone Observatory (CRB-CZO), located in the Piedmont region of Southeastern Pennsylvania and northern Delaware, is a partnership between the University of Delaware and the Stroud Water Research Center. At Transect A of the White Clay Creek Watershed (WCCW) of the CRB-CZO, the composition of soil pore-waters and stream was investigated to understand how the geochemical dynamics of Fe- and Mn- along redox gradients affect the C cycle within a floodplain aquifer.

Soil pore-water was collected with in-situ borosilicate glass samplers (50 mm long, 20 mm diameter, 1 μm pore size, Ecotech, Germany) with the attached PTFE (Teflon) tubes (3/1.5 mm i.d./o.d) to sampling bottle. Six samplers were deployed on both sides of the floodplain within a 10-40 cm thick dark organic-rich silty soil that represents a buried pre-settlement wetland soil, underlain gravel, and stream. No pore-water was extracted from the pre-settlement deposits due to unsaturated conditions. Water sampling was carried out for about 14 months (July, 2011 - September, 2012) on biweekly basis except last 2 months in order to evaluate temporal and spatial biogeochemical dynamics of floodplain aquifer under a variety of meteorological and hydrologic conditions. In total, 103 soil pore-water samples were collected and analyzed for DOC, Fe and Mn, pH, temperature, alkalinity, conductivity, major anions, major cations, δD, and δ18O.

戴安娜·卡万（Diana Karwan）、奥列西娅·拉扎列娃（Olesya Lazareva）、唐纳德·L·斯帕克斯（Donald L. Sparks）、安东尼·奥夫登坎佩（Anthony Aufdenkampe）

克里斯蒂娜河流域关键带观测站（Christina River Basin-Critical Zone Observatory，简称CRB-CZO）坐落于宾夕法尼亚州东南部皮埃蒙特地区与特拉华州北部，是特拉华大学与斯特劳德水研究中心的合作项目。在该观测站的白粘土溪流域（White Clay Creek Watershed，简称WCCW）样带A处，研究团队对土壤孔隙水与溪流的组成展开调查，以探明氧化还原梯度下铁（Fe）、锰（Mn）的地球化学动力学如何影响泛滥平原含水层内的碳循环。

土壤孔隙水采用原位硼硅酸盐玻璃采样器（长50 mm、直径20 mm、孔径1 μm，德国Ecotech公司生产）采集，配套聚四氟乙烯（PTFE，又称特氟龙Teflon）管（内径/外径3/1.5 mm）连接至采样瓶。研究团队在泛滥平原两侧的10~40 cm厚深色富有机质粉质土壤中布设了6个采样器，该土层为埋藏的前殖民时期湿地土壤，其下伏为砾石层与溪流。由于前殖民时期沉积物处于非饱和状态，未从中提取孔隙水。采样工作持续约14个月（2011年7月至2012年9月），除最后两个月外，每两周开展一次采样，以评估不同气象与水文条件下泛滥平原含水层的时空生物地球化学动态。本次研究共采集并分析了103个土壤孔隙水样品，检测指标包括溶解性有机碳（Dissolved Organic Carbon，DOC）、铁、锰、pH、温度、碱度、电导率、主要阴离子、主要阳离子、δD及δ18O。