Dostopnost Pb, Cd in Zn ter številčnost mikrobnih združb dušikovega cikla v tleh po remediaciji

Pintarič, Sara (author), Suhadolc, Marjetka (mentor), Maček, Irena (co-mentor)

Preučili smo vpliv remediacije z EDTA na kakovost tal, dostopnost potencialno toksičnih kovin (PTK) Pb, Cd in Zn v tleh in številčnost skupnih mikrobnih združb (bakterije, arheje, glive) ter mikrobnih združb dušikovega (N) cikla, v povezavi z lastnostmi tal. Zasnovali smo lončni poskus, v katerega smo vključili dva vzorca dolgoletno onesnaženih tal iz Mežiške doline (SLO) in kraja Arnoldstain (AT), ter kontrolna neonesnažena tla iz okolice Savelj (KONT). Vsi trije vzorci originalnih (`orig´) tal so se med seboj razlikovali v lastnostih tal, zlasti v pH in organski snovi, ter v skupni vsebnosti kovin. Polovica `orig´ tal vseh treh lokacij je bila pred postavitvijo poskusa remediirana z EDTA. V obravnavanja smo vključili tudi rastline (Lolium perenne) in dodali inokulum (rizoferna tla). Postopek remediacije je zmanjšal odstotek peska (za 9,2 %, 17,4 %, 8 %, v zaporedju AT, SLO, KONT) in vsebnost organske snovi. Povečal pa se je pH in vsebnost rastlinam dostopnih hranil (Nmin, P2O5, K2O), kar lahko razloži tudi večjo biomaso rastlin na remediranih (`rem´) tleh. V `rem´ tleh se je značilno zmanjšala vsebnost vseh kovin v vodotopni in izmenljivi frakciji, zlasti v tleh z višjim pH (SLO tla). Mikrobna biomasa je bila v `rem´ tleh značilno manjša kakor v `orig´ tleh, tudi štiri mesece po remediaciji (za 33 %, 49 %, v zaporedju AT, SLO tla). Remediacija je za 28 % zmanjšala število arhejskih 16S rRNA genov v SLO tleh. Poleg tega so se spremenjene razmere v tleh po remediaciji odrazile tudi na manjši številčnosti združbe fiksatorjev N, nitrifikatorjev in denitrifikatorjev, zlasti v tleh z višjim pH in večjo vsebnostjo organske snovi. Prisotnost rastline na `rem´ tleh je povečala mikrobno biomaso, številčnost bakterijskih 16S rRNA in glivnih ITS genov ter mikrobnih genov vključenih v N cikel, medtem ko je dodatek inokuluma vplival negativno na številčnost preučevanih mikrobnih združb v tleh. Zaključimo lahko, da remediacija preko spremenjenih razmer v tleh negativno vpliva na mikrobne združbe v tleh, vendar v močni odvisnosti od lastnosti tal. Rastline imajo pomembno vlogo v revitalizaciji `rem´ tal, medtem ko je potrebno dodatek inokulumov še dodatno preučiti.

• Language: Slovenian
• Keywords: potencialno toksične kovine, dostopnost, tla, bakterije, arheje, glive, dušikov cikel, fiksatorji, oksidatorji amonijaka, denitrifikatorji, revitalizacija, rastlina, inokulum
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [S. Pintarič]
• Year: 2018
• PID: 20.500.12556/RUL-103378
• UDC: 631.427.2:631.46(043.2)
• COBISS.SI-ID: 9039225
• Publication date in RUL: 16.09.2018

Secondary language

• Language: English
• Title: Pb, Cd and Zn availability and abundance of nitrogen cycle microbial community in remediated soil

Abstract

In this study we examined the impact of EDTA remediation on soil quality, the availability of potentially toxic metal (PTM) Pb, Cd and Zn in soil and the abundance of the total bacterial, archaeal and fungal community, as well as abundance of nitrogen (N) cycle microbial guilds in dependance of soil properties. We designed a pot experiment in which we included two samples of long-term contaminated soil from Meža Valley (SLO) and Arnoldstein (AT), and control non-contaminated soil from Savlje (KONT). All three samples of the original (`orig´) soils differed in soil properties, especially in the pH and soil organic matter content, and total metal concentration. `Orig´ soils were remediated by washing with EDTA. We also included plants (Lolium perenne) and added inoculum (rhizosphere soil) as treatments. Remediation with EDTA decreased the percentage of sand (by 9,2 %, 17,4 %, 8 %, in the order of AT, SLO, KONT) and the organic matter content. The pH and the available plant nutrients (Nmin, P2O5, K2O) increased, which can explain the larger plant biomass in remediated (`rem´) soil. The metal concentrations in soluble and exchangeable soil fraction, especially in the soil with the higher pH (SLO), were significantly decreased. In comparison to `orig´ soil, microbial biomass in `rem´ soil was significantly lower even four months after remediation (by 33 %, 49 %, in AT, SLO soil). Remediation reduced abundance of archaeal 16S rRNA genes in SLO for 28 %. Altered soil conditions after remediation have also reflected in lower abundance of microbial functional genes in the N-fixation, nitrification and denitrification pathways, especially in soils with the higher pH and higher organic matter content. The presence of plant increased microbial biomass, the abundance of bacterial 16S rRNA and fungal ITS genes, and functional microbial genes involved in N cycle in `rem´ soil, whereas the addition of inoculum negatively affected the abundance of all studied soil microbial communities. It can be concluded that remediation have, through changed soil conditions, a negative impact on soil microbial communities, however in strong dependance of soil properties. Plants play an important role in the revitalization of `rem´ soil, while the addition of inoculums needs to be further investigated.

• Keywords: potentially toxic metals, availability, soil, bacteria, archaea, fungi, nitrogen cycle, fixators, amonia oxidizers, denitrifiers, revitalization, plant, inoculum