Spiteri Claudette, Slomp Caroline P, Regnier Pierre, Meile Christof, Van Cappellen Philippe
Department of Earth Sciences-Geochemistry, Faculty of Geosciences, Utrecht University, P.O. Box 80021, 3508 TA Utrecht, The Netherlands.
J Contam Hydrol. 2007 Jun 16;92(1-2):87-108. doi: 10.1016/j.jconhyd.2007.01.002. Epub 2007 Jan 10.
A 1D reactive transport model (RTM) is used to obtain a mechanistic understanding of the fate of phosphorus (P) in the saturated zone of two contrasting aquifer systems. We use the field data from two oxic, electron donor-poor, wastewater-impacted, sandy Canadian aquifers, (Cambridge and Muskoka sites) as an example of a calcareous and non-calcareous groundwater system, respectively, to validate our reaction network. After approximately 10 years of wastewater infiltration, P is effectively attenuated within the first 10 m down-gradient of the source mainly through fast sorption onto calcite and Fe oxides. Slow, kinetic sorption contributes further to P removal, while precipitation of phosphate minerals (strengite, hydroxyapatite) is quantitatively unimportant in the saturated zone. Nitrogen (N) dynamics are also considered, but nitrate behaves essentially as a conservative tracer in both systems. The model-predicted advancement of the P plume upon continued wastewater discharge at the calcareous site is in line with field observations. Model results suggest that, upon removal of the wastewater source, the P plume at both sites will persist for at least 20 years, owing to desorption of P from aquifer solids and the slow rate of P mineral precipitation. Sensitivity analyses for the non-calcareous scenario (Muskoka) illustrate the importance of the sorption capacity of the aquifer solids for P in modulating groundwater N:P ratios in oxic groundwater. The model simulations predict the breakthrough of groundwater with high P concentrations and low N:P ratios after 17 years at 20 m from the source for an aquifer with low sorption capacity (<0.02% w/w Fe(OH)(3)). In this type of system, denitrification plays a minor role in lowering the N:P ratios because it is limited by the availability of labile dissolved organic matter.
一维反应输运模型（RTM）用于从机理上理解磷（P）在两个截然不同的含水层系统饱和带中的归宿。我们以加拿大两个受废水影响的缺氧、电子供体贫乏的砂质含水层（剑桥和马斯卡科地点）的现场数据为例，分别作为钙质和非钙质地下水系统，来验证我们的反应网络。经过大约10年的废水入渗，磷在源地下游的前10米内主要通过快速吸附到方解石和铁氧化物上而有效衰减。缓慢的动力学吸附进一步有助于磷的去除，而磷酸盐矿物（磷铁矿、羟基磷灰石）的沉淀在饱和带中在数量上并不重要。还考虑了氮（N）的动态，但硝酸盐在这两个系统中基本上表现为保守示踪剂。钙质地点持续排放废水时模型预测的磷羽流推进情况与现场观测结果一致。模型结果表明，去除废水源后，两个地点的磷羽流将持续至少20年，这是由于磷从含水层固体中解吸以及磷矿物沉淀速率缓慢所致。非钙质情况（马斯卡科）的敏感性分析说明了含水层固体对磷的吸附能力在调节有氧地下水中地下水氮磷比方面的重要性。模型模拟预测，对于吸附能力低（<0.02% w/w Fe(OH)₃）的含水层，在距源20米处17年后会出现高磷浓度和低氮磷比的地下水突破。在这种类型的系统中，反硝化在降低氮磷比方面作用较小，因为它受到不稳定溶解有机物可用性的限制。
