Sorption-desorption behavior of imidacloprid in western Slavonian soils

Tlo je važan dio ekosustava, kojeg čovjek iskorištava za poljoprivredu, život, industriju, itd. Stoga je vrlo važno proučiti i saznati sve karakteristike tla kako bi što manje utjecali na okolinu koja nas okružuje. Istraživanjem je proučavan utjecaj karakteristika tla na sorpcijsko-desorpcijsko ponašanje imidakloprida u tlima. Četiri analizirana tla (Š, J, O i Kt) uzeta su s područja zapadne Slavonije, dok je jedan uzorak s visokim udjelom organske tvari kupljen u trgovini (Ku). Svim uzorcima određene su fizikalno-kemijske karakteristike tla (mehanički sastav tla, aktualna, izmjenjiva i hidrolitička kiselost, količina humusa, sastav humusa i omjer apsorbancija huminskih kiselina pri 465 i 665 nm). Uzorcima tla dodavane određene koncentracije imidakloprida (1, 2.5, 5, 7.5, 15 i 25 mg/L) te je nakon vremena uravnoteženja od 48 h za sorpciju, odnosno 96 h za desorpciju, analizirana sorbirana odnosno desorbirana količina imidakloprida pomoću tekućinske kromatografije visoke djelotvornosti (HPLC). Mehanička analiza tla ukazuje da se sva tla mogu klasificirati kao glinaste ilovače, osim uzorka Ku koji se ubraja u pjeskulje. Nadalje, sva tla su kisela (pH u rasponu od 5,59 do 6,04) i slabo humozna (1,78-2,89%humusa), osim Ku koji je vrlo jako humozno tlo (62,37% humusa). Tla Š, Kt i Ku imaju veći udio ugljika u huminskim kiselinama, dok tla s oznakama J i O u fulvinskim kiselinama. Omjer apsorbancije je izrazito visok što ukazuje da se huminske kiseline većinom sastoje od cikličkih spojeva. Sorpcijske izoterme su L-oblika i konveksne za sve uzorke osim uzorka J čiji oblik je konkavan. Desorpcijske izoterme su sve konkavnog oblika. Koeficijenti raspodjele normalizirani su na udio organskog ugljika (KOC) kako bi tla s različitim udjelima organske tvari mogla biti uspoređivana te je određena pokretnost organskog mikrozagađivala. Pokretnost kod svih uzoraka klasificirana je kao izrazito visoka, osim kod uzorka oznake Ku gdje je ona srednja. Statistička analiza pomoću neparametrijskog testa Kendall-Tau ukazuje na utjecaj organske tvari na KF-sor. Nadalje, višestrukom linearnom regresijom utvrđen je utjecaj huminskih kiselina i ukupnog udjela organske tvari na sorpcijski kapacitet imidakloprida, dok su to kod procesa desorpcije huminske i fulvinske kiseline. Za poljoprivredno iskorištavana područja, ovakav tip istraživanja je potreban kako bi saznali karakteristike tla i kako one utječu na ponašanje pesticida u samom tlu. Današnje društvo mora težiti uspostavi održivog razvoja uporabe pesticida kako bi prirodni izvori ostali u što boljem stanju za buduće generacije.Soil is an important part of the ecosystem, which is exploited by man for agriculture, living, industry, etc. Therefore, it is very important to study and find out all the characteristics of the soil in order to minimize the impact on the environment that surrounds us. The effect of soil characteristics on the sorption-desorption behavior of imidacloprid in soils was investigated. Four analyzed soils (Š, J, O and Kt) were taken from the area of western Slavonia, while one sample with a high organic matter content was purchased from a shop (Ku). All samples determined the physicochemical characteristics of the soil (mechanical soil composition, current, changeable and hydrolytic acidity, humus content, humus composition and humic acid absorbance ratio at 465 and 665 nm). Specific concentrations of imidacloprid (1, 2.5, 5, 7.5, 15, and 25 mg / L) were added to soil samples and, after a balancing time of 48 h for sorption and 96 h for desorption, the adsorbed or desorbed amount of imidacloprid was analyzed by high performance liquid chromatography (HPLC) ). Mechanical soil analysis indicates that all soils can be classified as clayey loam, except for the Ku sample, which is sand. Furthermore, all soils are acidic (pH ranging from 5,59 to 6,04) and poorly humic (1,78-2,89% humus) except Ku which is a very strong humus soil (62,37% humus). Soils Š, Kt and Ku have a higher carbon content in humic acids, while soils labeled J and O in fulvic acids. The absorbance ratio is extremely high indicating that humic acids are mostly composed of cyclic compounds. The sorption isotherms are L-shaped and convex for all specimens except specimen J whose shape is concave. Desorption isotherms are all concave. The partition coefficients were normalized to the organic carbon content (KOC) so that soils with different organic matter contents could be compared and the mobility of the organic micro pollutant determined. Mobility in all specimens was classified as extremely high, except for the specimen Ku, where it is medium. Statistical analysis using the Kendall-Tau nonparametric test indicates the influence of organic matter on the KF-sor. Furthermore, a multiple linear regression determined the effect of humic acids and the total organic matter content on the sorption capacity of imidacloprid, while those of the desorption process of humic and fulvic acid. For agricultural areas, this type of research is needed to find out the characteristics of the soil and how they affect the behavior of pesticides in the soil itself. Today's society must strive for the sustainable development of pesticide use in order to keep natural resources in the best possible condition for future generations