RESEARCH ARTICLE Cu 2+ and Fe 2+ mediated photodegradation studies of soil-incorporated chlorpyrifos Nazia Rafique 1 & Saadia R. Tariq 1 & Karam Ahad 2 & Touqeer Taj 2 Received: 11 June 2015 /Accepted: 20 October 2015 /Published online: 28 October 2015 # Springer-Verlag Berlin Heidelberg 2015 Abstract The influences of Cu 2+ and Fe 2+ on the photodegradation of soil-incorporated chlorpyrifos were in- vestigated in the present study. The soil samples spiked with chlorpyrifos and selected metal ions were irradiated with UV light for different intervals of time and analyzed by HPLC. The unsterile and sterile control soil samples amended with pesticides and selected metals were incubated in the dark at 25 °C for the same time intervals. The results of the study evidenced that photodegradation of chlorpyrifos followed the first-order kinetics. The dissipation t 0.5 of chlorpyrifos was found to decrease from 41 to 20 days under UV irradia- tion. The rate of chlorpyrifos photodegradation was increased in the presence of both metals, i.e., Cu 2+ and Fe 2+ . Thus, initially observed t 0.5 of 19.8 days was decreased to 4.39 days in the case of Cu +2 and 19.25 days for Fe +2 . Copper was found to increase the rate of photodegradation by 4.5 orders of mag- nitude while the microbial degradation of chlorpyrifos was increased only twofold. The microbial degradation of chlor- pyrifos was only negligibly affected by Fe 2+ amendment. The studied trace metals also affected the abiotic degradation of the pesticide in the order Cu 2+ >Fe 2+ . Keywords Photodegradation . Soil . Chlorpyrifos . Cu 2+ . Fe 2+ Introduction Intense and massive agricultural applications led to the accu- mulation of high concentrations of pesticides in the soil that may ultimately become hazardous to the various forms of life. In the soil, the accumulation and dissipation of pesticides de- pend on the nature of pesticides and the soil characteristics (Liu et al. 2007; Morillo et al. 2000). Chlorpyrifos (O,O-diethyl O-(3,5,6-trichloro-2- pyridyl)phosphorothioate) is one of the most frequently used organophosphorus insecticides that is effectively used against various pests and insects of important cash crops. It is also frequently used to control the termites, flies, mosquitoes, and various household and veterinary pests (Zhang et al., 2011). In soils, its t 0.5 usually ranges between 60 and 120 days, but differ- ent soil conditions such as pH, soil type, and temperature may extend it over 1 year. The frequent use of chlorpyrifos has been reported to contaminate the soils and water as well as destroy the non-target organisms (EC 2005; Mugni et al. 2012). Moreover, its abundant use in agriculture has been linked to various health problems that may emanate from dietary exposure to the resi- dues of chlorpyrifos present in the food (Mugni et al. 2012). Its high acute toxicity may affect the cardiovascular system, respi- ratory system, and the central nervous system (Dam et al. 2000). The environmental fate of chlorpyrifos is governed by both the biotic and abiotic processes, such as chemical hydrolysis, microbial degradation, and photolysis (Sreekumaran and Pradeep 1999; Zalat et al. 2014). Responsible editor: Philippe Garrigues * Nazia Rafique naziarafiqchem@gmail.com Saadia R. Tariq saadiartariq74@gmail.com Karam Ahad karam_ahad@yahoo.com Touqeer Taj touqeertaj@yahoo.com 1 Department of Chemistry, Lahore College for Women University, Lahore, Pakistan 2 Ecotoxicology Research Institute (ERI), Department of Plant and Environment Protection (DPEP), NARC, Islamabad, Pakistan Environ Sci Pollut Res (2016) 23:4473–4480 DOI 10.1007/s11356-015-5655-4