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 variability and distribution patterns of organic matter contents in three environmental compartments using geostatistical analysis. Results showed that organic matter (OM) contents in sediments were higher with medium variability, and lower DOM content occurred in surface water, with medium variability in overlying waters and high variability in surface waters. The highest DOM contents in waters and OM in sediments appeared in Zaolinzhung (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 OM in sediments. Semi-variance functions showed that a strong spatial autocorrelation for DOM in waters, while OM in sediments had a medium spatial correlation. The autocorrelation distance of DOM in waters was between 1.16 km and 11.70 km, and OM in sediments was 4.25 km. The findings of this work can contribute to better understanding spatial variability of OM, which would provide a guidance for the sampling optimization of waters and sediments in the Baiyangdian Lake and lake sustainable management.