Toxic Metals, Non-Metals and Metalloids in Bottom Sediments as a Geoecological Indicator of a Water Body's Suitability for Recreational Use

Abstract

The study of bottom sediments was conducted within the basins of water bodies used for recreational purposes (e.g., bathing, fishing and diving) in the Silesian Upland and its periphery in southern Poland. Various concentrations of trace elements were found in bottom sediments, reflected by the following levels: Pb (30-3020 mg/kg), Zn (142-35,300 mg/kg), Cd (0.7-286 mg/kg), Ni (10-115 mg/kg), Cu (11-298 mg/kg), Co (3-40 mg/kg), Cr (22-203 mg/kg), As (8-178 mg/kg), Ba (263-19,300 mg/kg), Sb (0.9-52.5 mg/kg), Br (1-31 mg/kg), Sr (63-510 mg/kg) and S (0.001-4.590%). These trace elements are present in amounts that usually exceed those found in other bodies of water or are sometimes even unprecedented among bodies of water in the world (e.g., cadmium-286 mg/kg, zinc-35,300 mg/kg, lead-3020 mg/kg, arsenic-178 mg/kg). It was found that bottom sediments were contaminated to varying degrees with toxic metals, metalloids and non-metals, as evidenced by the values of geoecological indicators, i.e., the geoaccumulation index (-6.31 < I_geo < 10.90), the sediment contamination factor (0.0 ≤ Cfi < 286.0), the sediment contamination degree (4.6 < C_d < 513.1) and the ratios of the concentrations found to the regional geochemical background (0.5 < I_RE < 196.9). It was concluded that the presence of toxic elements (e.g., lead, zinc, cadmium, chromium, strontium and arsenic) in bottom sediments should be taken into account when classifying water bodies as suitable for recreational use. A maximum ratio of the concentrations found to the regional geochemical background of I_RE ≤ 5.0 was proposed as the threshold for the permissibility of recreational use of water bodies. The water bodies used for recreational purposes in the Silesian Upland and its periphery do not meet the geoecological conditions for safe use in terms of recreation and leisure activities. Forms of their recreational use that directly affect the participants' health (e.g., fishing and the consumption of fish and other aquatic organisms) should be abandoned.

Keywords: Silesian Upland; bottom sediments; heavy metals; recreation; toxic metals; trace elements; water bodies.

Figure 1

Locations of the water bodies used for recreational purposes covered by the study in the Silesian Upland and its periphery: 1—Dzierżno Małe, 2—Pogoria I, 3—Pogoria III, 4—Chechło, 5—Stawiki, 6—Morawa, 7—Gliniak, 8—Sosina, 9—Pławniowice, 10—Mały Zalew, 11—Rogoźnik II, 12—Rogoźnik I, 13—Balaton, 14—Koparki, 15—Paprocany.

Figure 2

Degree of contamination of bottom sediments of water bodies used for recreational purposes in the Silesian Upland and its periphery (numbering of water bodies—see Figure 1).

Figure 3

Land use forms in catchments of water bodies in the Silesian Upland and its periphery as catchment-area percentages. Land use forms: F—forest, ALW—agricultural land and wasteland, UIA—urban and industrial areas, W—water. Water body catchments (with outlets specified): a—Dzierżno Małe catchment area, b—Pogoria III catchment area (including the Pogoria I reservoir), c—Chechło catchment area 1, d—catchment areas of water bodies (including the Stawiki, Morawa and Gliniak), e—Sosina catchment area, f—Pławniowice catchment area (including the Mały Zalew reservoir), g—Rogoźnik I catchment area (including the Rogoźnik II reservoir), h—Balaton catchment area, i—Koparki catchment area, j—Paprocany catchment area.