Hidrológiai Közlöny 1999 (79. évfolyam)
4. szám - A Magyar Hidrológiai Társaság XVII. Országos Vándorgyűlése, Miskolc, 1999. július 7–8.
382 HIDROLÓGIA I KÖZLÖNY 1999. 79. ÉVF. 6. SZ. l/a. Results of laboratory microcosm experiment, when soil from a salt marsh was equilibrated under controlled redox level ranging from + 220 mV to - 240 mV, have shown that hydrogen sulfide, carbonyl sulfide, methanethiol, dimethyl sulfide and carbon disulfide are produced in salt marsh sediment during incubation. 1/b. Hydrogen sulfide was the dominate species under strongly anaerobic condition (Eh < -70 raV). 1/c. The other reduced volatile sulfur compounds were more important when soil redox potential was aerobic or in the upper part of the negatíve redox scale (Eh > - 70 mV). Moreover, hydrogen sulfide was not detectable above + 40 mV. 1/d. The results have alsó shown that the production of every measured reduced sulfur gas increased as the soil redox potential decreased from + 220 mV to - 240 mV. l/e. It was estabüshed that intensity of marsh soil reduction or degree of anaerobiosis is important in the production and emission of these reduced gaseous sulfur compounds 2/a. The results of our field measurements have shown that there are considerable seasonal and diumal changes in sulfur emission from wetlands along a salinity gradient in Gulf Coast (salt, brackish and freshwater marshes) 2/b. The dominant component was dimethyl sulfide in salt marsh, hydrogen sulfide in brackish marsh and numerous sulfur species in freshwater marsh. 2/c. We measured the highest emission in sah marsh and the lowest emission in freshwater marsh. 2/d Our studies and the previous investigations suggest that Spartina alterniflora be responsible for high dimethyl sulfide emission rates of salt marshes, the volatile reduced sulfur compounds produced at Eh > - 70 mV are mainly the result of the biodegradation of organic matter, the high quantity of hydrogen sulfide produced by Eh < -70 mV is the result of the dissimilatory sulfate reduction 3/a. The results of our field measurements have shown that a variety of odor causing reduced gases can be produced and emitted from wastewater treatment plants in each step of the treatment process. 3/b. Hydrogen sulfide, which is malodorous, corrosive and potenlially toxic gas was the most dominant volatile reduced sulfur compound measured (concentration rangé: 0.017-446.9 pg S/liter). Concentrations were not only above the odor detection threshold of hydrogen sulfide but above levels that may affect the health during long term exposure. 3/c. The concentration of methanethiol, dimethyl sulfide, carbon disulfide and carbonyl sulfide was significantly lower than hydrogen sulfide. However, even though emissions of these reduced sulfur gases were low as compared to hydrogen sulfide studies in the literature suggested that long term exposure and such levels can possible cause respiratory problems and other symptoms. 3/d. Methanethiol was the second or third most abundant reduced gaseous sulfiir compound found in gas samples collected at all locations. This fact is very important concerning odor nuisances since methanethiol has the lowest odor detection threshold concentration (0.0003 pg/m 3) which is more than 300 times higher than the odor detection threshold of hydrogen sulfide. 4/a. Results of our laboratory microcosms experiments demonstrated that oxidation-reduction processes play a major role in the composition and quantity of reduced malodorous gaseous sulfur compounds produced by wastewater sludge. 4/b. Hydrogen sulfide was the dominant volatile reduced sulfur compound measured under highly reduced redox conditions produced by sewage sludge. Maximum level of hydrogen sulfide production (283.9 ± 52.8 ng S/g dry sludge/hour) was measured in the most reduced (Eh = - 219 mV) microcosms In contrast, in gas samples from slightly oxidized (Eh = + 374 mV) microcosms hydrogen sulfide was not detectable. 4/c. Considerable methanethiol (350.9 ± 38.4 ng S/g dry sludge/hour) and dimethyl sulfide production (310 5 ± 46.2 ng S/g dry sludge/hour) were measured in moderately reduced microcosms. 4/d. Low level (less than 20.0 ng S/g dry sludge/hour) carbonyl sulfide and carbon disulfide production were observed at all redox levels studied. Acknowledgement The research was supported by National Science Foundation (Grant # BSR-9107555 and BES 9508728). A gáz halmazállapotú, redukált kénvegyületek emmissziójának természetes és antropogén forrásai István Dévai, Ronald D. DeLaune, William H. Patrick, Jr. and György Dévai Kivonat: A gáz halmazállapotú, redukált kénvegyületek iránti nagyfokú, s az utóbbi évtizedben egyre növekvő érdeklődés elsősorban a környezetszennyezéssel függ össze, hiszen ezek a vegyületek jelentős hatással vannak a levegő és a csapadék minőségére, sőt az időjárási viszonyokra is. A kén emisszióra vonatkozó legújabb becslések hangsúlyozzák a gázhalmazállapotú, redukált kénvegyület kibocsátás biogén forrásainak fontosságát, s megállapítják, hogy az antropogén emisszió azonos nagyságrendű, s csak valamivel magasabb, mint a természetes kén emisszió. Jelen közleményünkben a következő laboratóriumi és terep kísérleteink fontosabb eredményeit összegezzük (1) gázhalmazállapotú, redukált lénvegyületek, (hidrogén-szulfid, karbonilszulfid, metantiol, dimetil-szulfid, szén-diszulfid) keletkezése sós mocsári üledékben, laboratóriumi körülmények között (ún. mikrokozmoszban), a redoxpotenciál függvényében (2) évszakos és napszakos változások Louisiana állam (USA) öbölparti sós, brakvizi és édesvízi mocsarainak kén emissziójában (3) Baton Rouge város (Louisiana, USA) szennyvíztelepei kén emiszsziójának minőségi és mennyiségi jellemzése, a szennyvíztisztítás különböző lépcsőiben (4) gázhalmazállapotú, redukált és kellemetlen szagú kénvegyület keletkezése szennyvíziszapokban, minőségi és mennyiségi megoszlásuk a redoxpotenciál függvényében. Kulcsszavak: kén emisszió, vizes élőhelyek, szennyvíztisztító telepek, redox viszonyok, kellemetlen szagú kénvegyületek
