MERCURY CONTENT IN BOTTOM SEDIMENTS OF MID-FIELD PONDS

Abstract

Two mid-field ponds located in the agricultural catchment was chosen for the investigations. Total of 24 samples of bottom sediments were collected. The samples were taken from sediment layers: 0–5 (W1), 5–10 (W2), 10–20 (W3) and 20–30 (W4) cm, with three points at once during the 2014 winter period. Mercury content in the samples was determined by analyzer AMA 254. Higher pH (active acidity) was recorded in sediments in pond located in a rural park than pond located within agricultural crops. Bottom sediment in mid-field pond (No. 1) had higher values of organic carbon averaging 22.70% than in the pond located in a rural park (No. 2), where organic carbon content averaged 4.59%. The mercury content in bottom sediments ranged from 0.02 to 0.41 mg ⋅ kg-1. The examined sediments were classified (at points P1, P2, P3 and P4) as uncontaminated sediments (Class I) and at points S1 and S2 were classified as moderately polluted sediments (Class II). Bottom sediments classified as class I and II can be disposed in the aquatic and terrestrial environments. Mercury concentrations in samples collected from both banks of the pond No. 1 and 2 differ significantly (Tukey test p ≤ 0.05) than those in the samples collected from central part of the ponds. Chemical analysis of the individual layers of bottom sediments in ponds showed that the largest accumulation of mercury occurred in a layer W1 (0–5 cm) in pond No. 2 (at point S2).

Keywords

• mercury
• mid-field ponds
• farmlands
• bottom sediments