Uporaba bioloških indeksov kakovosti tal za vrednotenje učinka revitalizacije onesnaženih tal, opranih s kelatnim ligandom EDTA

Hribar, Tjaša (author), Leštan, Domen (mentor), Kaurin, Anela (comentor)

Dolgoletna rudarska in železarska industrija v Mežiški dolini je vodila v onesnaženje tal s potencialno strupenimi kovinami (PSK), kot so Cd, Zn in Pb. Skozi leta so se tla na onesnaženje prilagodila, koncentracija kovin v tleh pa se je kopičila. Del mobilnih kovin se je akumuliral v vrtninah, ki so del človekove prehranjevalne verige. Ex situ remediacija s kelatnim ligandom EDTA je zmanjšala delež PSK v tleh, a je zaradi fizičnega in kemijskega posega v tla vplivala na pedološke in biološke lastnosti tal. Remediacija je znižala koncentracijo Pb za 71 %, Cd za 53 % in Zn za 28 %. Najvišjo mobilnosti v tleh ima Zn, Pb in Cd pa nižjo, a primerljivo mobilnost. V sklopu pedološke analize tal se je znižala vrednost N, Corg in rastlinam dostopen P v tleh, zvišal pa se je pH in rastlinam dostopen K. Struktura remediiranih tal je v primerjavi z originalnimi tlemi vsebovala višji delež delcev nad velikostjo 1 mm in nižji delež delcev pod velikostjo 0,5 mm. Z encimskimi testi, ki temeljijo na pretvorbi substrata in detekcijo nastalega produkta s spekrofotometrom, smo preverili aktivnost petih encimov; β-glukozidaze, kisle in alkalne fosfataze, dehidrogenaze in ureaze. Encimska aktivnost remediiranih tal se je obnovila na aktivnost osnovnih tal pri alkalni fosfatazi, ureazi in dehidrogenazi. Največje razlike v aktivnosti med originalnimi in remediiranimi tlemi imamo pri dehidrogenazi in β-glukozidazi, kar pomeni, da je imela remediacija večji vpliv na kroženje C in manjši vpliv na kroženje N. Remediacija je v začetnem stanju povečala bazalno respiracijo mikroorganizmov, v nadaljevanju pa ni bilo razlik v respiraciji med originalnimi in remediiranimi tlemi. Najnižje vrednosti mikrobne biomase (Cmik) in mikrobnega koeficienta (qmik) imamo v začetnem stanju, vedno z nižjimi vrednostmi za remediirana tla. Zmanjšanje koncentracije PSK v tleh smo primerjali z akumulacijo mobilnega dela PSK v nadzemni in koreninski del radiča (Cichorium intybus L). Ugotovili smo, da je nadzemni del radiča iz remediiranih tal akumuliral 16-krat manj Cd, 5,4-krat manj Pb in 4,9-krat manj Zn, korenine radiča pa 6,6-krat manj Cd, 14,5-krat manj Pb in 4,2-krat manj Zn. Z remediacijo je radič akumuliral koncentracije Pb, Zn in Cd pod zakonsko določene meje v listnati zelenjavi, zato je primeren za uživanje.

• Language: Slovenian
• Keywords: potencialno strupene kovine (PSK), etilendiamintetraocetna kislina (EDTA), remediacija tal, encimska aktivnost
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [T. Hribar]
• Year: 2020
• PID: 20.500.12556/RUL-121496
• UDC: 60:502.175:631.45:546.81:546.47/.48(043.2)
• COBISS.SI-ID: 32342275
• Publication date in RUL: 13.10.2020

Secondary language

• Language: English
• Title: Usage of biological soil quality indices for evaluation of revitalized contaminated soil washed with chelant EDTA

Abstract

Long-lived mining industry in Mezica Valley lead to soil pollution by potentially toxic metals (PTM) such as Cd, Zn and Pb. Through the years the soil has adapted to the contamination, metal concentrations in soil have increased and part of mobile metals have accumulated in vegetables which are part of human food chain. Ex situ remediation of chelating ligand EDTA reduced the share of PTM in soil but its physical and chemical interference influenced soil's pedological and biological properties. Remediation reduced Pb concentration by 71%, Cd by 53% and Zn by 28% with the highest mobility of Zn in soil and comparable mobility of Pb and Cd. Values of soil's N, Corg and plant accessible P reduced but in the contrarily, values of pH and plant accessible K increased. Soil structure of remediated soil had higher share of soil particles above 1 mm in size and lower share of soil particles below 0,5 mm in size, in comparison with original soil. With enzyme tests based on the conversion of substrate and spectrophotometric detection of formed product, we had analysed the activity of five enzymes; β-glucosidase, acidic and alkaline phosphatase, dehydrogenase and urease. Enzyme activity of remediated soil such as the activity of alkaline phosphatase, urease and dehydrogenase restored at the level of original soil. The highest differences in the activity of original and remediated soils are in the enzyme activity of dehydrogenase and β-glucosidase. Remediation had bigger effect on C cycling and lesser effect on N cycling. Remediation also increased bazal respiration of microbes in the initial state. Further on, there were no differences in respiration between original and remediated soil which coincides with dehidrogenase activity and qCO2 values. The lowest values of microbe biomass (Cmik) and microbe coefficient (qmik) were in initial state, always lower in remediated soil. We also measured the accumulation of the mobile part of PSK in the above ground part and in the roots of chicory (Cichorium intybus L.). After soil remediation leaves of chicory accumulated 16-times less Cd, 5,4-times less Pb and 4,9-times less Zn. Roots accumulated 6,6-times less Cd, 14,5- times less Pb in 4,2- times less Zn then chicory grown on original soil. Given concentrations of accumulated Pb, Zn and Cd after remediation were under legal limits which makes these plant suitable for human consumption.

• Keywords: potentially toxic metals (PTM), ethylenediaminetetraacetic acid (EDTA), soil remediation, enzyme activity