Agricultural Catchments Programme, Johnstown Castle, Teagasc, Wexford, Co. Wexford, Ireland.
Water Res. 2012 May 1;46(7):2225-36. doi: 10.1016/j.watres.2012.01.048. Epub 2012 Feb 9.
Conduit and other karstic flows to aquifers, connecting agricultural soils and farming activities, are considered to be the main hydrological mechanisms that transfer phosphorus from the land surface to the groundwater body of a karstified aquifer. In this study, soil source and pathway components of the phosphorus (P) transfer continuum were defined at a high spatial resolution; field-by-field soil P status and mapping of all surface karst features was undertaken in a > 30 km(2) spring contributing zone. Additionally, P delivery and water discharge was monitored in the emergent spring at a sub-hourly basis for over 12 months. Despite moderate to intensive agriculture, varying soil P status with a high proportion of elevated soil P concentrations and a high karstic connectivity potential, background P concentrations in the emergent groundwater were low and indicative of being insufficient to increase the surface water P status of receiving surface waters. However, episodic P transfers via the conduit system increased the P concentrations in the spring during storm events (but not >0.035 mg total reactive P L(-1)) and this process is similar to other catchments where the predominant transfer is via episodic, surface flow pathways; but with high buffering potential over karst due to delayed and attenuated runoff. These data suggest that the current definitions of risk and vulnerability for P delivery to receiving surface waters should be re-evaluated as high source risk need not necessarily result in a water quality impact. Also, inclusion of conduit flows from sparse water quality data in these systems may over-emphasise their influence on the overall status of the groundwater body.
管道和其他岩溶水流向含水层，连接农业土壤和耕作活动，被认为是将磷从地表转移到岩溶含水层地下水体的主要水文机制。在本研究中，以高空间分辨率定义了磷转移连续体的土壤源和路径组成部分；在超过 30 平方公里的泉水补给区进行了田间土壤磷状况和所有地表岩溶特征的制图。此外，在超过 12 个月的时间里，以亚小时为基础监测了在出现泉水处的磷输送和水排放。尽管存在中度到强度的农业活动，但土壤磷状况变化较大，土壤磷浓度升高的比例较高，岩溶连通性潜力较高，但出现泉水中的背景磷浓度较低，表明不足以增加受纳地表水的地表水中的磷状况。然而，通过管道系统的间歇性磷转移在风暴事件期间增加了泉水中的磷浓度（但不超过 0.035 毫克总反应性磷/升），这一过程类似于其他以间歇性地表水流为主要转移途径的集水区；但由于延迟和衰减径流，岩溶具有较高的缓冲潜力。这些数据表明，应该重新评估将磷输送到受纳地表水的风险和脆弱性的现行定义，因为高源风险不一定会导致水质影响。此外，在这些系统中，从稀疏水质数据中包含管道水流可能会夸大它们对地下水体整体状况的影响。
