Sanja Grabar MSc, Hazardous Waste Management Agency Ltd., Environmental Services, Savska cesta 41/IV, HR-10000 Zagreb, Croatia, Tel: +385 1 6311 999, Fax: +385 6176 734, sanja.grabar@apo.hr
Natalija Koprivanac PhD and Dinko Vujević, MSc, University of Zagreb, Faculty of Chemical Engineering and Technology, Department of Polymer Engineering and Organic Chemical Technology, Marulićev trg 19, HR-10000 Zagreb, Croatia, Tel: +385-1-4597 124, Fax: +385-1-4597-143, nkopri@marie.fkit.hr, dvujev@marie.fkit.hr

Pesticides represent the group of organic synthetic compounds with the high risk to the environment and human health as well. Among herbicides, a type of pesticides, the most used one is atrazine, which can be often found in natural waters with concentration above maximum permissible level; 0.1 mg/dm³ according to EC Directives [1]. In order to decrease the amount of atrazine in wastewater on the level determined by regulatives, the adsorption of atrazine on chosen types of zeolites and activated carbon has been investigated in the samples prepared as simulated wastewaters. Also, degradation of atrazine by Advanced Oxidation Processes (AOPs), Fenton and Fenton “like” as well as combination of adsorption and AOPs with Fenton and Fenton “like” reagents have been studied. The efficiency of atrazine removal and degradation after the physical and/or chemical treatment has been estimated on the basis of TOC and HPLC analyses. Activated carbon has been shown as the most efficient adsorbent but also 76.2% of atrazine has been removed from simulated wastewater by using zeolite HY at the atmospheric conditions after 2 hours of contact and 96% after 72 hours respectively. These very good results obtained by HY zeolite preferable the application of the zeolites as adsorbents instead of activated carbon. The use of zeolites has advantage because of the cost efficiency and possibility of reusing. The kinetic of atrazine degradation in applied AOPs has been monitored simultaneously. A mathematical model, describing kinetic of atrazine degradation has been developed. Experimental data have been compared with those ones predicted by model. It has been estimated that degradation of atrazine can be described with kinetic of pseudo-first order rate. To achieve even better ecoefficiency, the adsorption with zeolites can be used as a pretreatment method for the removal of atrazine from wastewater and Fenton and Fenton “like” processes as polishing step in wastewater treatment.

[1] J.M. Sayre, J.Am.Water Works Assoc. 80 (1988) 53

Behavior and Fate of Chlorpyrifos Introduced into Soil-crop Systems by Irrigation

Ligang Wang, Ph.D., Institute of Subtropical Agriculture, Chinese Academy of Science (CAS), Changsha 410125, P.R.China, Tel: 86-13973195586, Email: lgwang0827@yahoo.com.cn
Xin Jiang, Institute of Soil Science, CAS, Nanjing 210008, P.R.China

The effect of chlorpyrifos introduced into red soil on the growth of wheat and oilseed-rape seedlings, together with their uptake of chlorpyrifos, was studied using pot cultivation. The results show that, if the initial concentration of chlorpyrifos introduced into red soil by irrigation water containing chlorpyrifos was 1–10 µg/g, absorption of chlorpyrifos residue from soil by wheat seedlings leads to a concentration of 0.257–4.50 µg/g 20 days later from irrigation day on; with the same initial concentration, oilseed-rape seedlings reach a concentration of 0.249–2.02 µg/g 20 days later from irrigation day on. An initial concentration of chlorpyrifos in red soil that is equivalent to or below 10 µg/g did not significantly influence the growth of wheat seedlings. Similarly, an initial concentration equivalent to or below 5 µg/g did not significantly influence the growth of oilseed-rape seedlings. The degradation rate of chlorpyrifos was 1.4–4.2 times more in oilseed-rape rhizosphere soil than in unvegetated soil. The amount of bacteria and fungi in oilseed-rape rhizosphere soil was 3.18 times and 1.84 times, respectively, as much as in unvegetated soil. However, there was no considerable difference in levels of actinomyces between the rhizosphere soil and the unvegetated soil. Compared with unvegetated soil, the pH in rhizosphere soil was lowered by 0.19–0.23 pH unit.

Key words: Red soil; Chlorpyrifos; Wheat; Oilseed-rape; Rhizosphere

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