Young E O, Ross D S
Onandaga County Soil and Water Conservation District, LaFayette, NY 13084, USA.
J Environ Qual. 2001 Jan-Feb;30(1):91-101. doi: 10.2134/jeq2001.30191x.
Phosphorus derived from agricultural practices has been targeted as a leading cause of water quality degradation in Lake Champlain. Mobilization of P from seasonally flooded agricultural soils is a concern. Using 14 soils from a research farm in New York's Champlain Valley, we characterized the available P status, extractable Fe and Al, P sorption capacities, and soluble phosphate release in flooded laboratory microcosms. Quantities of NH4-acetate available P ranged from 3 to 100 mg kg(-1) and fluoride-extractable P from 10 to 211 mg kg(-1). Flooding soils induced significant release of phosphate to the porewater over a 60- to 90-d period in 13 of the 14 soils studied. Porewater phosphate increases ranged from 2.2 to 27.0 times the initial phosphate concentrations. However, floodwater phosphate increases were much lower, with a maximum of 3.6 times the initial concentration. Average porewater phosphate concentrations over the flooding period ranged from 0.046 to 7.0 mg L(-1) and average floodwater P from 0.032 to 3.70 mg L(-1). Ammonium-acetate P and the degree of phosphorus saturation (DPS) were highly correlated with the average porewater and floodwater phosphate concentration. Average ratio of porewater to floodwater phosphate concentrations ranged from 1.0 to 3.3. Five soils that were lower in fluoride-extractable P had increasing porewater phosphate accompanied by increasing porewater Fe2+ and decreasing floodwater phosphate. Results suggest that P solubility and mobility were a function of both the available P status and redox cycling.
农业活动产生的磷已被视为尚普兰湖水质恶化的主要原因。季节性淹没的农业土壤中磷的迁移是一个令人担忧的问题。我们使用纽约尚普兰山谷一个研究农场的14种土壤，对其有效磷状况、可提取铁和铝、磷吸附能力以及淹水实验室微观环境中可溶性磷酸盐的释放进行了表征。醋酸铵有效磷含量范围为3至100 mg kg⁻¹，氟化物可提取磷含量范围为10至211 mg kg⁻¹。在所研究的14种土壤中，有13种土壤在60至90天的时间里，淹水导致孔隙水中磷酸盐大量释放。孔隙水中磷酸盐的增加幅度为初始磷酸盐浓度的2.2至27.0倍。然而，洪水磷酸盐的增加幅度要低得多，最高为初始浓度的3.6倍。淹水期间孔隙水磷酸盐的平均浓度范围为0.046至7.0 mg L⁻¹，洪水磷酸盐平均浓度范围为0.032至3.70 mg L⁻¹。醋酸铵磷和磷饱和度（DPS）与孔隙水和洪水磷酸盐的平均浓度高度相关。孔隙水与洪水磷酸盐浓度的平均比值范围为1.0至3.3。五种氟化物可提取磷含量较低的土壤，孔隙水磷酸盐增加，同时孔隙水Fe²⁺增加，洪水磷酸盐减少。结果表明，磷的溶解度和迁移率是有效磷状况和氧化还原循环的函数。
