Chemical properties of water in a flooded opencast sulphur mine

Abstract

The chemical properties of water in the only flooded sulphur opencast mine in the world have been analysed. The reservoir has a depth of 22 m and is still continuously pumped, which affects the deeper tertiary aquifer. Instead of quaternary water being pumped out, tertiary water flows into the reservoir. Mineralisation of the water in this reservoir varied from 2000 to 10,000 mg dm )3 near the bottom. Light penetrates to 8 -10 m and this photic layer is oxygenated. The hypolimnion is only partially oxygenated and contains H 2 S. The monimolimnion is salty and also poisoned by H 2 S. Discriminant analysis shows three layers: upper 0 -10 m, transitional 10 -15 m and bottom 15 -22 m. Variability of the chemical properties is negligible through the year, excluding special situations such as ice melting. The transitional layer is rich in SO 4 2) -about 1000 mg dm )3 and unionized H 2 S. S 2) oxidation is very intensive, excess CaSO 4 precipitates at a depth of 10 m resulting in opacity. Above and below, these concentrations diminish. For this zone a new name is proposed: the katalimnion. In the bottom layer, NO 3 ) does not occur -whereas there is a high concentration of NH 4 + . Discrimination on the basis of chemical parameters divides the vertical profile into three levels: epi-+ meta-+ upper half of the hypolimnion, lower half of the hypolimnion and monimolimnion. This indicates that for sampling, three levels might be sufficient. The same analysis used for time showed a low differentiation in the annual cycle. These results can help in optimizing the monitoring scheme for this pit lake and reducing its cost.

Acoustical estimates of fish and zooplankton distribution in the Piaseczno reservoir, Southern Poland

“…Two categories of acoustical targets were present in the water column. The most frequent type formed a thin layer at the depth corresponding roughly to the lowest limit of oxygen concentration ( _ Zurek 2006a). During spring these targets occupied the depths between 13 and 15 m (mean 14.2 ± 0.9) during the day, and between 10 and 12 m (mean 11.3 ± 0.7) at night (Figure 4).…”

“…This poverty of biological life is probably due to the presence of hydrogen sulfide and complete lack of oxygen in deeper layers. In 2001 all the environmental parameters of the Piaseczno reservoir were measured on a monthly basis ( _ Zurek 2006a). From the oxygen concentration distributions (Figure 1) it is clear that the depths below 12 m are unsuitable for fish throughout the year.…”

Phytoplankton and its relationships with chemical parameters and zooplankton in meromictic Piaseczno reservoir, Southern Poland

“…Details of water chemistry of this lake were elaborated by _ Zurek (2006a). The following physicochemical parameters were measured: temperature, light, pH, conductivity, Na, K, Ca, Mg, SO 4 , CO 3 , hardness (total, carbonate and noncarbonate), sulphide, hydrogenated sulphide, unionized sulphide.…”

“…Medium values of 1 mg dm -3 are low in the epi-, meta-and upper hypolimnion. Below the photic zone concentrations decrease to 0.05 mg, The pH is generally neutral or slightly basic: in the photic layer ranging from 8.6 to 7.0, neutral in the chemocline, and in the monimolimnion increasing to 7.2-7.4, ( _ Zurek 2006a).…”

“…Basic non-carbonate hardness, excluding the deepest layer, and some short periods in autumn and spring, had an almost constant value of 18-20 mval. The dominant anion in the water column is SO 4 but near the bottom, it is replaced by Cl À anions ( _ Zurek 2002( _ Zurek , 2006a. The photic layer is low in nitrate, usually its concentrations are below 0.5 mg N-NO 3 dm À3 .…”