Evaluation of environmental quality in Northern Estonia by the analysis of leachate
Date
2010-09-30
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Abstract
Töös käsitletakse prügilas, reostunud pinnases ja suletud kaevandustes tekkiva nõrgvee mõju ümbritsevale keskkonnale, kusjuures põhiline tähelepanu on pööratud nõrgvee kaudu tekkivale reostuskoormusele jõgede vee kvaliteedile. Analüüsiti nii nõrgvee kui ka pinnavee iseloomustavaid parameetreid. Reostunud pinnase puhul uuriti pindaktiivsete ainete bioloogilise lagunemise ja leostumise sõltuvust pinnase struktuurist. Kuna nõrgvees võib sageli sisalduda suures hulgas lahustunud sulfiide, siis uuriti ka divesiniksulfiidi lendumist vesikeskkonnast pH alandamise käigus. Pääsküla prügila sulgemise ajal (2003-2004) tehtud uuringud näitasid kõrge reoainete kontsentratsiooniga nõrgvee leostumist prügilast, mis lahjenes Pääsküla jõe vees, kuid sellele vaatamata jõudis üsna palju reoaineid Vääna jõkke. Reostunud pinnase bioloogilise tervendamise kiirendamiseks kasutatud pindaktiivsed ained lagunesid kiiremini poorses pinnases, kuhu difundeerus piisavalt hapnikku. Kuid ikkagi esines ka pindaktiivsete ainete ja naftasaaduste leostumist pinnasest, mis võib kujutada ohtu põhjaveele. Sulfiidilahusest lendus divesiniksulfiid aeglasemalt kui süsinikdioksiid karbonaadi lahusest, kuid reoveest lendus H2S isegi kiiremini kui CO2, aga lendunud H2S hulk oli väiksem kui teoreetiliselt arvutatud. Põlevkivikaevanduste sulgemise mõju uuriti Pühajõe veeproovide analüüside kaudu ning võrdluseks kasutati Kunda jõe vett. Pühajõe vees oli 1995. aastast kuni 2005. aastani vähenenud nii lämmastiku kui ka fosfori üldkontsentratsioon ligi 90%. Samuti oli Pühajõe vees vähenenud nitritlämmastiku sisaldus, mis kinnitas kaevanduste sulgemise positiivset mõju Pühajõe veele. Looduslikus keskkonnas võib nõrgvesi lahjeneda, kuid see ei pruugi olla piisav reoainete voogude oluliseks vähenemiseks
The influence of the leachate generated from the landfill, polluted soil and closed mines on the environmental quality was studied. The influence was evaluated through the analysis of fluxes of pollutants on the quality of river water. The characteristic parameters of the leachate and surface water were analyzed. Dependence of the structure of soil on the biodegradation and leaching of surfactants was studied for the oil-polluted soil. The leachate can contain the higher concentration of dissolved sulfide and because the emission of gaseous H2S from the water phase due to the lowering of pH was also studied. The analysis of leachate sampled during the close of Pääsküla landfill showed the high concentration of contaminants and it was decreased due to the dilution in the Pääsküla River, but the flux of contaminants was quite high into the Vääna River. The surfactants used to enhance the bioremediation of oil-polluted soil were degraded in the porous soil, because the diffusion of oxygen was enough fast. The measurements showed that the biodegradation of surfactants was not enough complete and the leaching of surfactants (and petroleum hydrocarbons) was occurred, what can generate the pollution of groundwater. The rate of emission of gaseous H2S from the solution of sodium bisulfide was lower than rate of CO2 emission from solution of sodium bicarbonate. The emission of H2S from the wastewater was faster, but the volumes of emitted H2S were lower than the theoretically calculated volumes. The influence of closing of the oil shale mines were studied by water sampled from the Pühajõgi River and the water samples of Kunda River were analyzed in comparison. During the ten years (1995 – 2005) the concentrations of total nitrogen and phosphorus were lowered on the average by ca 90% in the water samples of Pühajõgi River indicating the positive effect of closing of mines. That effect was also confirmed by the lowering of concentration of nitrite nitrogen. The dilution of leachate occurs in the natural environment, but the dilution is not enough to decrease significantly the flux of pollutants.
The influence of the leachate generated from the landfill, polluted soil and closed mines on the environmental quality was studied. The influence was evaluated through the analysis of fluxes of pollutants on the quality of river water. The characteristic parameters of the leachate and surface water were analyzed. Dependence of the structure of soil on the biodegradation and leaching of surfactants was studied for the oil-polluted soil. The leachate can contain the higher concentration of dissolved sulfide and because the emission of gaseous H2S from the water phase due to the lowering of pH was also studied. The analysis of leachate sampled during the close of Pääsküla landfill showed the high concentration of contaminants and it was decreased due to the dilution in the Pääsküla River, but the flux of contaminants was quite high into the Vääna River. The surfactants used to enhance the bioremediation of oil-polluted soil were degraded in the porous soil, because the diffusion of oxygen was enough fast. The measurements showed that the biodegradation of surfactants was not enough complete and the leaching of surfactants (and petroleum hydrocarbons) was occurred, what can generate the pollution of groundwater. The rate of emission of gaseous H2S from the solution of sodium bisulfide was lower than rate of CO2 emission from solution of sodium bicarbonate. The emission of H2S from the wastewater was faster, but the volumes of emitted H2S were lower than the theoretically calculated volumes. The influence of closing of the oil shale mines were studied by water sampled from the Pühajõgi River and the water samples of Kunda River were analyzed in comparison. During the ten years (1995 – 2005) the concentrations of total nitrogen and phosphorus were lowered on the average by ca 90% in the water samples of Pühajõgi River indicating the positive effect of closing of mines. That effect was also confirmed by the lowering of concentration of nitrite nitrogen. The dilution of leachate occurs in the natural environment, but the dilution is not enough to decrease significantly the flux of pollutants.
Description
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Keywords
dissertatsioonid, keemia, keskkonnamõjud, pinnase saastamine, keskkonnakontroll, prügilad, saasteained, leostumine, vee kvaliteet, veereostus, biolagunemine, hindamine, Põhja-Eesti