Zastupljenost i specijacija žive u jadranskom planktonu, školjkašima i ribi – pregled

This article presents an overview of available research on mercury speciation in the most studied biota of the Adriatic Sea as a specific biogeochemical subunit of the Mediterranean. We present current knowledge about mercury concentration, speciation, spatial distribution and temporal changes in plankton, bivalves and fish from the Adriatic Sea. Results from mercury speciation studies in marine organisms are used to describe the extent of mercury bioaccumulation in the Adriatic Sea. Mercury biogeochemical cycle in the Adriatic is characterised by increased mercury concentrations from the water column, through plankton, bivalves and smaller fish to predator fish species. Although the Adriatic Sea has the highest mercury concentration in the whole Mediterranean Sea, fish species at the higher trophic levels have similar mercury concentrations everywhere in the Mediterranean, indicating incomplete understanding of the transfer mechanisms of mercury from seawater to upper trophic levels. As consumption of (contaminated) food is the main route of human exposure to mercury, it is of great importance to understand the influence of mercury contamination in the Adriatic Sea.Ovaj članak predstavlja pregled dostupnih istraživanja o specijaciji žive u najproučavanijoj bioti Jadranskog mora kao posebne biogeokemijske podjedinice Mediterana. Predstavljamo postojeće znanje o koncentraciji žive, specijaciji, prostornoj raspodjeli i vremenskim promjenama u planktonu, školjkašima i ribi Jadranskog mora. Rezultati studija o specijaciji žive u morskim organizmima su korišteni za opis razdiobe bioakumulacije žive u Jadranskom moru. Biogeokemijski ciklus žive u Jadranu karakterizira povećanje koncentracije žive od vodenog stupca, preko planktona, školjkaša i manjih riba do predatorskih ribljih vrsta. Iako Jadransko more sadrži najviše koncentracije žive u cijelom Mediteranu, riblje vrste na višim trofičkim razinama imaju slične koncentracije žive posvuda u Mediteranu, ukazujući na nepotpuno razumijevanje prijenosnih mehanizama žive iz morske vode na više trofičke razine. Budući da je konzumiranje (kontaminirane) hrane glavni put ljudske izloženosti živi, od iznimne je važnosti razumijevanje utjecaja kontaminacije živom u Jadranskom moru

Dober dan, znanost

Ste se kdaj vprašali kako znanstveniki ugotavljajo prisotnost strupenih oz. škodljivih snovi v vodi, zraku, v zemlji. Ste razmišljali kako ali na čem raziskovalci opravljajo poskuse? Vas zanima, kaj odkriva definicija »poskusni kunec« v ekotoksikologiji? Na to odgovarjamo v današnji rubriki Dober dan znanost. Gostja je doktorica znanosti Suzana Žižek, ki ima v Laboratoriju za raziskave v okolju Univerze v Novi Gorici svoj raziskovalni živalski vrtiček

Dober dan, znanost

Raziskave o škodljivih vplivih kemikalij na okolje in človeka je treba jemati resno. Od leta 1996 govorimo o posebej nevarnih okoljskih onesnaževalcih, hormonskih motilcih, ki povzročajo nepravilnosti v delovanju žlez z notranjim izločanjem. Med najbolj nevarnimi hormonskimi motilci so nekatere vrste plastike, zaščitna sredstva v kmetijstvu, številne industrijske kemikalije in nekatera sintetizirana zdravila. Motilci so pa tudi naravne spojine, ki jih proizvajajo organizmi. O motilcih endokrinega sistema in spremembah, ki jih povzročajo, se je Zdenka Tomulić pogovarjala z doc. dr. Suzano Žižek iz Laboratorija za raziskave v okolju Univerze v Novi Gorici

The possibility of occurrence of coccidiostats in the environment

Coccidiostats are veterinary pharmaceuticals used for prevention and treatment of coccidiosis. They pose a potential environmental risk because of their widespread use in veterinary medicine. In large quantities they are used as feed additives for poultry. They enter the environment mostly through the use of manure from treated animals, which is a substantial source of coccidiostats since up to 95 % of consumed coccidiostats are excreted unchanged. In Europe, 11 coccidiostats are permitted, which differ in their mechanism of action. Through soil fertilization on agricultural areas coccidiostats are transferred via manure into surface water and groundwater. They could be used as indicators of agricultural pollution. The presence, transport and concentration of coccidiostats in the environment are still largely unknown. This article provides an overview of coccidiostats, their use, efficiency and occurrence in the environment. It describes the factors influencing their occurrence in the environment. An overview of literature on the topic of coccidiostats in the environment is presented. In the case of the Drava field the potential environmental concentration of the coccidiostat monensin in the environment was established. The assessment took into account the number of chickens on a chosen farm, the related arable land and the properties of monensin. It was found that due to fertilization with chicken manure we can expect predicted environmental concentrations (PEC) of monensin in soil up to 0,30 mg/kg and in groundwater up to 80,4 µg/l

THE EFFECT OF SELENIUM ON MERCURY TRANSPORT ALONG THE FOOD CHAIN

More than 500 years of mercury (Hg) production in Idrija (Slovenia) resulted in aconsiderable pollution of Idrija region with Hg. Although the mine is closed formore than 20 years, the total soil concentration of Hg may still reach up to severalhundred mgkg-1dry weightin local gardens and more that thousand inother urbanregions. Hg in soil undergoesdifferent chemical transformations and in someformsit may enterplants and higher trophic levelsin food chains, also withbiomagnification pattern.The local population is, besides air and dust, thus exposedto mercury also via consumption of locally produced food.Several studies showedthat the increased level of selenium in soil may reduce the uptake of mercury inplants but very few include other trophic levels in a food chain as well.In our pilotstudy we followed an impact of Seon Hg transport from soil to plants(Lactucasativa) and further to soil dwelling animals (Porcellioscaber). Lettuce wasplanted in a contaminated soil from Idrija and in soil with added HgCl2. The leavesof half of the plants weresprayed with Sesolution (5μg L-1)threeand five weeksafter planting.After six weeks plants were analyzed for Hg and Se and offered asfood to terrestrial isopods for two weeks. Our preliminary results revealed thatfoliar treatment of plants with Se may affect Hg accumulation in plants andtherefore further transport of Hg across the food chain