Centre for Ecology and Hydrology, Lancaster Environment Centre, Lancaster LA1 4AP, UK.
School of Environmental Sciences, University of Liverpool, Liverpool L69 3GP, UK.
Sci Total Environ. 2016 Dec 1;572:1573-1585. doi: 10.1016/j.scitotenv.2015.09.129. Epub 2015 Oct 21.
We developed a model of the biogeochemical and sedimentation behaviour of carbon (C), nitrogen (N) and phosphorus (P) in lakes, designed to be used in long-term (decades to centuries) and large-scale (10-10km) macronutrient modelling, with a focus on human-induced changes. The model represents settling of inflow suspended particulate matter, production and settling of phytoplankton, decomposition of organic matter in surface sediment, denitrification, and DOM flocculation and decomposition. The model uses 19 parameters, 13 of which are fixed a priori. The remaining 6 were obtained by fitting data from 109 temperate lakes, together with other information from the literature, which between them characterised the stoichiometric incorporation of N and P into phytoplankton via photosynthesis, whole-lake retention of N and P, N removal by denitrification, and the sediment burial of C, N and P. To run the model over the long periods of time necessary to simulate sediment accumulation and properties, simple assumptions were made about increases in inflow concentrations and loads of dissolved N and P and of catchment-derived particulate matter (CPM) during the 20th century. Agreement between observations and calculations is only approximate, but the model is able to capture wide trends in the lakewater and sediment variables, while also making reasonable predictions of net primary production. Modelled results suggest that allochthonous sources of carbon (CPM and dissolved organic matter) contribute more to sediment carbon than the production and settling of algal biomass, but the relative contribution due to algal biomass has increased over time. Simulations for 8 UK lakes with sediment records suggest that during the 20th century average carbon fixation increased 6-fold and carbon burial in sediments by 70%, while the delivery of suspended sediment from the catchments increased by 40% and sediment burial rates of N and P by 131% and 185% respectively.
我们开发了一个湖泊碳（C）、氮（N）和磷（P）的生物地球化学和沉降行为模型，旨在用于长期（数十年至数百年）和大规模（10-10km）的主要营养物建模，重点关注人为引起的变化。该模型代表了入流水体悬浮颗粒物的沉降、浮游植物的生产和沉降、表层沉积物中有机物的分解、反硝化作用以及 DOM 的絮凝和分解。该模型使用 19 个参数，其中 13 个是先验固定的。其余 6 个参数通过拟合来自 109 个温带湖泊的数据以及来自文献的其他信息获得，这些信息共同描述了 N 和 P 通过光合作用被浮游植物同化的化学计量学，N 和 P 在全湖的保留，以及 N 通过反硝化作用的去除，以及 C、N 和 P 在沉积物中的埋藏。为了在模拟沉积物积累和特性所需的长时间内运行模型，对 20 世纪期间入流水体中溶解 N 和 P 以及流域来源的颗粒物（CPM）浓度和负荷的增加做出了简单的假设。观测值和计算值之间只有近似的一致性，但该模型能够捕捉到湖水和沉积物变量的广泛趋势，同时也对净初级生产力做出了合理的预测。模型结果表明，异源碳（CPM 和溶解有机碳）对沉积物碳的贡献大于藻类生物量的生产和沉降，但藻类生物量的相对贡献随着时间的推移而增加。对 8 个具有沉积物记录的英国湖泊的模拟表明，在 20 世纪，平均碳固定增加了 6 倍，沉积物中碳埋藏增加了 70%，而流域输送的悬浮沉积物增加了 40%，N 和 P 的沉积物埋藏率分别增加了 131%和 185%。
