Study of Maracaibo Lake water-coal interaction

in order to evaluate formally the potential changes produced in the coal due to its interaction with maracaibo lake water and determine the characteristics of environmental risk and toxicity of coal from miraflores pit of mina norte coalfield, guasare basin, zulia state, venezuela. two coal samples were subjected to mandatory epa toxicity leaching procedure with extracting solution #1, beside leaching procedure with maracaibo lake water adl, during 4, 6, 18, 48 and 72 hours, finally acute toxicity bioassays were done; coals and fluids were chemically characterized before and after leaching processes, those include: total sulphur, proximate analysis (fixed carbon cf, humidity hum, volatile matter mv and ash cz) of coal, sulphates, oil and grease, ph, aluminum interchangeable, chloride, base saturation, conductivity, sodium absortion ratio sar and as, ba, cd, hg, se, ag, cr, ni, zn y pb. the results indicate that the studied coals are thermally immature and they are classified as high volatile bituminous. during the process of leaching, fixed carbon (cf), humidity (hum), volatile matter (mv) and ash (cz) parameters stay essentially constant; while total sulfur concentration (st) varies along the leaching process. in one of the samples (high concentration of ash cz) the sulfur is leached while in the sample of low ash content the mass of sulfur in the coal increases. results obtained do not show evidence of short and long term pollution potential by bioavailable toxic elements. according to the characteristics observed in the present study, the risk condition of the guasare coal is class 1. the studied samples have a relatively low toxicity, and the coal 1 sample seem to be relatively more toxic than the coal 2 sample.