Preliminary assessment of agriculture influence on heavy metal content in bottom sediments of small water reservoirs and in rushes

The main purpose of the paper was to determine the influence of catchment management on the bottom sediments quality of small water reservoirs as well as to determine toxic metal content in rushes. Samples of bottom sediments were collected in winter 2013 year, form 4 sediment layers (0-5, 5-10, 10-20 and 20-30 cm) at three points along the body of water. The 48 samples were collected. Soil material was prepared according to the procedures used in soil science, the analysis was performed for the fraction with a particle diameter of less than 1 mm. Plant samples from single species aggregations were randomly cut from 5 to 10 locations of 20-50 m2 area. From these samples the average composite sample was prepared. The total content of such elements as Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn was determined by atomic absorption spectrometry (using the Thermo Scientific iCE 3000 series spectrometer) after prior digestion in the mixture (5:1) of concentrated acids HNO3 (65%) and HClO4 (60%). Total Hg content was determined by the AMA 254 analyzer. Between the small water reservoirs adjacent to the areas where organic farming is used, and the reservoirs adjacent to the areas with mineral fertilization there are statistically significant differences in the concentrations of such metals as nickel (layers: 0-5, 5-10, 10-20 and 0-30 cm), as well as cobalt, chromium and iron (in a layer 5-10 cm). It has been found that some plants accumulate higher amounts of heavy metals (average values). Based on obtained results it can be stated that rushes actively captures large amounts of elements reaching studied objects and thereby protect the surface water of the reservoirs from contamination.

---

Opracowanie ze środków MNiSW w ramach umowy 812/P-DUN/2016 na działalność upowszechniającą naukę (zadania 2017).