engleski

IC and zeolites as tools for protection of agroecosystems

Facing the challenges of many global trends (overpopulation, climate changes, hunger, natural disasters, etc.) agriculturists have two important tasks: to insure a food security and to preserve natural resources. In order to achieve increase yield of cereals, all efforts are insignificant without nitrogen application, which is now, in modern agriculture an indispensable practice. That practice leads to many environmental problems (surface and ground water eutrophication, acidification of soils, air quality degradation) which require new remediation approaches for soils and waters. Zeolites, natural or synthetic hydrated aluminum silicates, due to their ion-exchange properties are recognized as effective tool for binding of hazardous inorganic components in soil and water systems. The aim of this research was to determine the influence of increased rates of natural zeolite (Clinoptilolite) on ionic composition of water contaminated by nitrogen fertilizers. The research included three laboratory experiments (with two different nitrogen fertilizers in three different production formulas: NPK 7-20-30, NPK 15-15-15, and KAN) which were consisted of five treatments in three repetitions, a total of 45 water samples. Each experiment involved: control treatment (water of Bliznec stream), artificially contaminated water (water of Bliznec with addition of certain nitrogen fertilizer) and three treatments of contaminated water treated with different amounts of zeolite (5, 10, 15 g / 200 ml water). Water, fertilizers and zeolites were in contact two weeks. After two weeks samples were filtrated in two steps: firstly through filter paper and then through cartridge (OnGuard IIP, 1cc, Dionex, Sep-Pak Vac and OASIS HLM, Waters). Anions separation and detection were performed on Doinex ICS-1000 system: separator column [Ion Pac AS 17 (4×250 mm) Dionex] ; KOH eluent with gradient elution: (A) 10 mmol L-1 KOH from 0-5.5 min, (B) 10-35-10 mmol L-1 KOH from 5.5-16.6-18 min, respectively, and (C) 10 mmol L-1 KOH from 18-30 min (total separation time 30 min) ; flow rate: 1.0 mL min-1 ; detection: suppressed conductivity. Cation separation and detection were performed on Doinex ICS-1000 system as well: separator column [Ion Pac CS 16 (5×250 mm) Dionex] ; MSA eluent (30 mM) constant during analysis (total separation time 30 min) ; flow rate: 1.5 mL min-1 ; detection: suppressed conductivity. Statistical analyses of differences in ion concentrations according to zeolite application were computed by analysis of variance (ANOVA) using SAS Institute 9.1.3 and mean values were separated by Fisher’s LSD test at P ≤ 0.05. Results indicate the capability of Clinoptilolite to ion exchange and its applications in remediation of contaminated water but also that ion chromatography method is suitable method for determination of ion contamination in water. Concentrations of N-NH4, N-NO3, and SO42- significantly increased compared to control application of all nitrogen fertilizers. Additionally application of NPK fertilizers contributed to significant increment of Cl- and PO43- ions. Compared to the concentrations in contaminated water samples, which were 68.9 mg N-NH4/L (in treatment with NPK 7-20-30), 99.0 mg N-NH4/L (in treatment with NPK 15-15-15), and 183.3 mg N-NH4/L (in treatment with KAN), applications of different doses of Clinoptilolite significantly decreased N-NH4 presence in water in range from 19.6 to 25.0 %. Also, significant decrement of PO43-, SO42- and Cl- ions in water was recorded just in treatment with the highest dose of zeolite. Only concentrations of N-NO3 were not significantly changed after Clinoptilolite applications. Further detail investigations can be focused on determination of sufficient zeolite dose which will lead to decrement of ions concentration on level present in natural and non-contaminated conditions.

Clinoptilolite, Ion chromatography ; Nitrogen fertilizers ; Remediation ; Water

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