Faculty of Agriculture and Life Sciences, Lincoln Univ., P.O. Box 84, Lincoln, Christchurch, 7647, New Zealand.
AgResearch, Lincoln Science Centre, Private Bag 4749, Christchurch, 8140, New Zealand.
J Environ Qual. 2021 Mar;50(2):287-311. doi: 10.1002/jeq2.20202. Epub 2021 Mar 5.
Phosphorus (P) pollution of surface waters remains a challenge for protecting and improving water quality. Central to the challenge is understanding what regulates P concentrations in streams. This quantitative review synthesizes the literature on a major control of P concentrations in streams at baseflow-the sediment P buffer-to better understand streamwater-sediment P interactions. We conducted a global meta-analysis of sediment equilibrium phosphate concentrations at net zero sorption (EPC ), which is the dissolved reactive P (DRP) concentration toward which sediments buffer solution DRP. Our analysis of 45 studies and >900 paired observations of DRP and EPC showed that sediments often have potential to remove or release P to the streamwater (83% of observations), meaning that "equilibrium" between sediment and streamwater is rare. This potential for P exchange is moderated by sediment and stream characteristics, including sorption affinity, stream pH, exchangeable P concentration, and particle sizes. The potential for sediments to modify streamwater DRP concentrations is often not realized owing to other factors (e.g., hydrologic interactions). Sediment surface chemistry, hyporheic exchange, and biota can also influence the potential exchange of P between sediments and the streamwater. Methodological choices significantly influenced EPC determination and thus the estimated potential for P exchange; we therefore discuss how to measure and report EPC to best suit research objectives and aid in interstudy comparison. Our results enhance understanding of the sediment P buffer and inform how EPC can be effectively applied to improve management of aquatic P pollution and eutrophication.
水体中的磷（P）污染仍然是保护和改善水质的一个挑战。解决这一挑战的关键是要了解是什么因素控制了溪流中 P 的浓度。本定量综述综合了有关基流条件下溪流中 P 浓度主要控制因素（即沉积物磷缓冲作用）的文献，以更好地理解地表水-沉积物 P 相互作用。我们对净零吸附条件下的沉积物平衡磷酸盐浓度（EPC）进行了全球荟萃分析，EPC 是沉积物缓冲溶液中可溶解反应性磷（DRP）的浓度。我们对 45 项研究和 900 多次以上 DRP 和 EPC 配对观测的分析表明，沉积物通常具有向溪流释放或去除 P 的潜力（83%的观测值），这意味着沉积物与地表水之间的“平衡”很少见。这种 P 交换的潜力受到沉积物和溪流特征的调节，包括吸附亲和力、溪流 pH 值、可交换磷浓度和颗粒大小。由于其他因素（例如水文相互作用），沉积物改变溪流中 DRP 浓度的潜力通常无法实现。沉积物表面化学、底层水交换和生物群也会影响沉积物与地表水之间 P 的潜在交换。方法选择对 EPC 的确定有很大影响，从而影响 P 交换的估计潜力；因此，我们讨论了如何测量和报告 EPC，以最适合研究目标并有助于研究间的比较。我们的研究结果增强了对沉积物 P 缓冲作用的理解，并为如何有效地应用 EPC 来改善水生生境的磷污染和富营养化管理提供了信息。
