Longitudinal distribution of macronutrients in the sediments of Jegricka watercourse in Vojvodina, Serbia

Abstract

Sediment matrices, as integral organo-mineral parts of aquatic bodies, can effectively bind and accumulate nutrients and potentially hazardous substances from diffuse and/or point sources of contamination. In this study, we analysed the longitudinal distribution of macronutrients (total N and available P and K) and the mechanical composition of the sediments of Jegricka watercourse (a part of the multi-functional Danube-Tisa-Danube canal network) known for its exposure to anthropogenic loads. The results showed that the nutrient pollution index was mostly above 1.0 (in 76%, 86% and 93% of the analysed samples for K, N and P, respectively), and the mean values for N, P and K were 2.69, 1.92 and 1.24, respectively. The average content of all nutrients and the sand fraction were significantly higher, whereas the clay fraction was considerably lower, in the sediment samples than in the adjacent arable Chernozem soil used as a benchmark. The differences in the nutrient contents and mechanical properties in the sediments were measured longitudinally (at upstream vs. downstream stations) and assessed using correlation, cluster analysis, and principal component analysis. The results suggest that the nutrient sources in the sediments as well as their transport and loading mechanisms along Jegricka watercourse are diverse and complex, likely driven by a combination of untreated industrial/urban wastewater discharges, erosion and surface runoff from the surrounding agricultural land. As a majority of the analysed watercourse banks belong to areas of special ecological value, the obtained results may be useful: i) indicators for designing and implementation of sustainable land/water policies and measures for the protection and rehabilitation of these valuable ecosystems, ii) inputs for testing/calibrating the sediment transport models and iii) the basis for sediment management.