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V dvanajstih vzorcih tal iz okolice vrtcev, šol, zelenjavnih vrtov in dvorišč v Mežiški dolini, s koncentracijami Pb od 469 do 4333 mg kg-1 in Zn od 313 do 8670 mg kg-1, smo določili mobilnost in biodostopnost Pb in Zn. Koncentracija Pb je v enajstih vzorcih presegla kritično vrednost, koncentracija Zn pa v devetih (glede na uredbo v Ur.l.RS št. 68, 1996). Mobilnost Pb in Zn določena s TCLP metodo (Toxicity Characteristic Leaching Procedure) je pokazala, da nobeden od vzorcev ni presegal vrednosti, ki bi tla po metodologiji EPA (US Environmental Protection Agency) uvrščala med nevarne odpadke. Koncentacije Pb in Zn v testni rastlini solati (Lactuca sativa L.) so bile pod mejo detekcije instrumenta (atomski absorpcijski spektrofotometer). S fiziološko osnovanim PBET ekstrakcijskim testom (Physiologically Based Extraction Test) smo vzorcem in talnim prašnim delcem določili delež Pb, ki je biodostopen v človeškem prebavnem sistemu. Iz simulirane želodčne faze je bilo dostopnega 2,8 - 22,8 %, iz črevesne pa 1,2 - 9,0 % celokupnega Pb v tleh. Koncentracije biodostopnega Pb so bile v prašnih delcih manjše kot v vzorcih tal.

Pet reprezentančnih vzorcev močno onesnažene zemljine z območja stare cinkarne v Celju (Slovenija), ki so vsebovali od 7300 do 17200 mg kg-1 celokupnega Pb, od 6000 do 63600 mg kg-1 celokupnega Zn in od 24 do 250 mg kg-1 celokupnega Cd, smo remedirali z metodo stabilizacije s 15 ut.% portland cementa. Po 4 mesecih stabilizacije se je mobilnost Pb, Zn in Cd določena s TCLP metodo ("Toxicity Characteristic Leaching Procedure") 5,8 - 17,4, 8,1 - 35,8 oz. 4,3 - 7,3-krat zmanjšala. Potencialna dostopnost Pb, Zn in Cd za rastline, določena z ekstrakcijo z dietilentriaminpentaocetno kislino (DTPA), se je po stabilizaciji 1,6 - 9,8, 1,1 - 2,1 oz. 1,3 - 4,1-krat zmanjšala. Biodostopni delež Pb določen s fiziološko osnovanim ekstrakcijskim testom ("Physiologically Based Extraction Test"; PBET) se je v črevesni frakciji po stabilizaciji 5,9 - 11,3-krat zmanjšal.

A knowledge of the total amount of heavy metals in soil is not enough to assess the environmental impact and decide on suitability of polluted soils for agronomic use. Six-step sequential extraction procedure was used to determine the distribution of Pb, Zn and Cd among various fractions of soils from six locations in Mežica valley. Phyto-available heavy metals: water soluble heavy metal species and fraction exchangeable from colloids to soil solution, accounted in average for 0.23-1.14% of Pb, 0.36-3.88% of Zn and 0-8.2% of Cd. The majority of heavy metal species was found to reside in non phyto-available carbonate fraction, fraction bound to Fe and Mn oxides, fraction bound to organic matter and residual fraction. Among soils tested the significant variations in distribution of heavy metals among different soil fractions were observed, presumably due to differences in soils characteristics.

Odpadno blato iz čistilnih naprav (ČN) ima zaradi velike hranilne vrednosti potencial za uporabo v kmetijstvu, vendar je pogosto onesnaženo s potencialno strupenimi kovinami (PSK). V raziskavi smo preverili ali ReSoil® tehnologija, ki temelji na uporabi EDTA (50, 70 in 100 mmol l-1), omogoča učinkovito odstranjevanje PSK iz odpadnega blata, vzetega po aerobni (blato1) in anaerobni (blato2) biološki obdelavi. Največji delež odstranitve Pb smo dosegli v blatu1 (do 60 %), največji delež odstranitve Zn in Cu pa v blatu2 (do 55 in 29 %). Vsebnost hranil se po remediaciji ni bistveno spremenila, le vsebnost dostopnega fosforja se je v blatu2 po remediaciji do 1,7-krat zmanjšala, vendar je še vedno ostala velika (489-510 mg 100-1 g-1). Po remediaciji so bile koncentracije v izpirkih za vse kovine, razen za Zn, pod mejo za nenevarne snovi. Za dokazovanje možnosti recikliranja procesnih raztopin in EDTA smo blato2 oprali s 50 mmol l-1 pralno raztopino v seriji 5 zaporednih remediacij in pri tem v povprečju odstranili 28 % Pb, 48 % Zn, 35 % Cu, 30 % Mn in 10 % Fe. ReSoil® tehnologija sicer omogoča odstranjevanje PSK iz blata in pri tem ohrani njegovo hranilno vrednost, vendar je učinkovitost tehnologije odvisna od postopkov obdelave blata na ČN.

In this study, we investigated the importance of plant cover for secondary succession and soil fungal community development in remediated substrates after EDTA washing of metal-contaminated soils. The abundance of the total fungal community, determined by ITS fungal marker genes (Internal Transcribed Spacer region), and root colonisation by arbuscular mycorrhizal (AM) fungi were monitored in two types of soil material (calcareous and acidic) sown with perennial ryegrass (Lolium perenne L.) and without plant cover (bulk soil). Four months after the start of the experiment, the abundance of ITS genes in the soil clearly showed that the presence of plants was the main factor affecting the total fungal community, which increased in the rhizosphere soil in most treatments, while it remained at a low level in the bulk soil (without plants). Interestingly, the addition of environmental inoculum, i.e., rhizosphere soil from a semi-natural meadow, did not have a positive effect on the abundance of the total fungal community. While fungal ITS genes were detected in soils at the end of the first growing season, arbuscular mycorrhizal (AM) structures were scarce in Lolium roots in all treatments throughout the first season. However, in the second season, more than a year after the start of the experiment, AM fungal colonisation was detected in Lolium roots in virtually all treatments, with the frequency of colonised root length ranging from 30% to >75% in some treatments, the latter also in remediated soil. This study demonstrates the importance of plants and rhizosphere in the development and secondary succession of fungal communities in soil, which has important implications for the revitalisation of remediated soils and regenerative agriculture.