Spatial Profiling and Assessing Dominance of Sources to Water Phosphorus Burden in a Shallow Lake

摘要

Efficacy of phosphorus (P) mitigation strategies in lake basins could not be quantitatively evaluated due to a lack of assessment frameworks, confounding preferential management. The promiscuity in contributions of P sources to burden is a major cause. This study aimed to spatially profile water P burden with special emphasis on assessing dominance of P sources in a lake system. Exploratory data analysis with multivariate statistical techniques was applied to interpret raw data matrix of 21 variables employed in water and sediment samples collected from Baiyangdian Lake, the largest freshwater shallow lake in North China. Simple trend surface analysis was performed to estimate P distribution similarities. Multivariate exploratory analysis was conducted on variables and sites to accomplish pattern recognition and magnitude identification of sources. Linear regression model was applied to quantitatively determine importance of P regulators. Results revealed that P fractionation in sediments reflected the dominance of P sources and played a pivotal role in discriminating water P burden. Intensive P enrichment was highly associated with nitrogen levels and conductivity as response of exogenous input. Sedimentary sand fraction needed more concern due to its high risks of potential sink and preferential release. Metallic oxide bound P along with organic P served as main sediment contributions. Pertinent separate strategies were suggested to be implemented sub-regionally in mitigating effects of P downstream. The proposed framework enabled assessment on source-related P burden to evaluate profits of P reduction management options and provided an alternative framework of focal point determination for local government agencies.