EFFECT OF PHYSICO-CHEMICAL SOIL CHARACTERISTICS ON THE SORPTION BEHAVIOR OF DIMETHOATE

Konvencionalna poljoprivreda u svrhu visokog prinosa koristi pesticide i druge škodljive supstance čime se zagađuje okoliš, remeti se prirodna ravnoteža, dolazi do klimatskih promjena, eutrofikacije (cvjetanja mora), erozije, onečišćenja vode, ispuštanja tzv. stakleničkih plinova, smanjuje se plodnost tla. Pesticidi, njihovi derivati i druge štetne tvari dolaze do podzemnih voda te konačno dovode do zdravstvenih posljedica za ljude. Ciljevi istraživanja bili su proučiti mehanizme sorpcije dimetoata te utvrditi utjecaj pojedinih karakteristika tla na sorpcijsko ponašanje dimetoata. Analizirana su tri uzorka tla na području Primorsko-goranske županije: Jelenje (BJ) gdje prevladava bukova šuma, Plasa (PB) i vrt (VRT) u kojima raste primorski bor. Četvrti uzorak tla, crnica, je iz Slavonije (SC). Nakon sušenja i prosijavanja kroz 2 mm sito, određeni su teksturni sastav, reakcije tla te sadržaj organske tvari. Prilikom određivanja sorpcijskog kapaciteta tla za dimetoat korištena je tekućinska kromatografija visoke djelotvornosti (HPLC). Prema teksturnom sastavu uzorak SC spada u tešku glinu (preko 75%), PB i BJ u pjeskovitu ilovaču (30 – 45%), a VRT u glinastu ilovaču (63%). Analizirana tla svrstavaju se u slabo kisela tla (pH= 6,22- 6,39). U jako humozna tla (% C= 8,72- 13,25) spadaju VRT, SC i PB, a BJ (% C = 2,31) pripada skupini slabo humoznih tla. Freundlich-ovim modelom pomoću sorpcijskih izotermi za dimetoat dobivene su izoterme L-tipa za sva tri uzorka, SC, PB i BJ i VRT. Koeficijent raspodjele organskog mikrozagađivala između organskog ugljika i vode, udio organske tvari, ali i frakcija praha i krupnog pijeska utječu na pokretljivost dimetoata. Dimetoat ima visoku pokretljivost, brže prodire kroz pore tla do podzemnih voda koje se često koriste kao izvor vode za piće. Vrlo je važno primjenjivanje dimetoata na propisan način, poštivanje karence, a prilikom rukovanja s njim obavezno je korištenje zaštitne opreme.Conventional agriculture uses high-yield pesticides and other harmful substances to pollute the environment. Therefore, the natural balance is disturbed, climate change is occurring, eutrophi-cation (flowering of the sea), erosion, water pollution, discharging of the so-called greenhouse gases and soil fertility is reduced. Pesticides, its derivatives and other harmful substances reach groundwater and ultimately lead to health consequences for humans. The purpose of this reasrch was to study the mechanisms of sorption of dimethoate and to de-termine the influence of particular soil characteristics on the sorption behavior of dimethoate. Three soil samples were analyzed in the area of „Primorsko-goranska županija“: Jelenje (BJ), where beech forests prevail, Plasa (PB) and garden (VRT), where coastal pine grows. The fo-urth soil sample is from Slavonia (SC). After drying and sieving through a 2 mm sieve, the texture composition, soil reactions and organic matter content were determined. High perfor-mance liquid chromatography (HPLC) was used to determine the soil sorption capacity for di-methoate. According to the textured composition of use, SCs are heavy clay (over 75%), PB and BJ in sandy loam (30 - 45%), and VRT in clayey loam (63%). The analyzed soils are classified as poorly acidic soils (pH = 6.22-6.39). Very humic soils (% C = 8.72-13.25) include VRT, SC and PB, but BJ (% C = 2.31) belongs to the group of poorly humus soils. Using the Freundlich model, L-type isotherms for four samples, SC, PB, BJ, and VRT were obtained using the sorption isotherms for dimethoate.. The KOC value, the content of organic matter and also the powder and coarse sand fraction affect the mobility of dimethoate