Spatial variability of dissolved organic matter in the water-sediment systems in the Baiyangdian Lake

Dissolved organic matter (DOM) is widespread in natural water bodies and plays an essential role in ecological processes of aquatic ecosystems. However, spatial variability of DOM in shallow lakes is still kept unclear. Surface water, overlaying water and sediment samples were collected at 61 sampling sites in the whole Baiyangdian Lake to investigate spatial heterogeneity and distribution patterns of the DOM contents in three environmental compartments using geostatistical analysis. Results showed that DOM contents in sediments were higher than in waters, and the lowest DOM content occurred in surface water, with medium variability in overlying waters and sediments and high variability in surface waters. The highest DOM contents in waters and sediments appeared in Zaolinzhuang (ZLZ) and Zaozhadian (ZZD), respectively, while a relatively low contents appeared in ZLZ sediments. DOM in surface water and overlying water were negatively correlated with DOM in sediments. Semi-variance functions showed that a strong spatial autocorrelation for DOM in waters, while DOM in sediments had a medium spatial correlation. The autocorrelation distance of DOM in waters was between 1.16 km and 11.70 km, and in sediments was 4.25 km. The findings of this work can contribute to better understanding spatial variability of DOM, which would provide a guidance for the sampling optimization of waters and sediments in the Baiyangdian Lake and lake sustainable management.