Distribution and source apportionment studies of heavy metals in soil of cotton/wheat fields Nazia Rafique & Saadia R. Tariq Received: 21 December 2015 /Accepted: 14 April 2016 # Springer International Publishing Switzerland 2016 Abstract Heavy metals enriched agricultural soils have been the subject of great concern because these metals have potential to be transferred to the soil solution and afterward accumulated in food chain. To study the trace metal persistence in crop soil, 90 representative soil samples were collected and analyzed for heavy metal (As, Cd, Cu, Fe, Mn, Ni, Pb, and Zn) and anions (chloride, nitrates, phosphates and sulfates). Cluster and factor analysis techniques were used for the source identification of these excessive heavy metal levels and ecological risk was determined with potential ecological risk assessment. The degree of enrichment of eight studied heavy metals in comparison with the corre- sponding background levels decreased in order: Cd > Pb > Fe > Ni > Mn > As > Cu ~ Zn. Arsenic and cadmium exhibited 1.30- and 1.64-fold exceeded levels than threshold limits set by National environment qual- ity standards, respectively. Cd in cotton field’ s soil may lead to higher potential risk than other heavy metals. On overall basis, the cumulative mean potential ecological risk for the district (207.75) corresponded to moderate risk level with higher contributions from As and Pb especially from Cd. Cadmium formed strong positive correlation with phosphate content of soil at p < 0.01. Cluster analysis indicated that Cluster 1 (extremely pol- luted) probably originated from anthropogenic inputs of phosphate fertilizer and past usage of arsenical pesticides. Keyword Heavy metals . cotton/wheat soil . potential ecological risk . Phosphate fertilizer . multivariate statistical methods Introduction There is an emergent public concern over the prospec- tive accumulation of heavy metals in the soils of cotton and wheat fields owing to rapid industrial development and increasing reliance on agrochemicals during the last several decades (Wong et al. 2002; Nicholson et al. 2003). The advance agricultural activities especially excessive use of fertilizers, pesticides, liming, sewage sludge and irrigation water contain heavy metals which accumulate in agricultural soil and, hence, pose a risk to humans and wildlife (M. Jamali et al. 2007; Atafar et al. 2010; Shan et al. 2013; Jiang et al. 2014; Tariq et al. 2016). Lime and superphosphate fertilizers used fre- quently in agriculture contain not only the major ele- ments necessary for plant nutrition and growth but also Environ Monit Assess (2016) 188:309 DOI 10.1007/s10661-016-5309-0 Electronic supplementary material The online version of this article (doi:10.1007/s10661-016-5309-0) contains supplementary material, which is available to authorized users. N. Rafique (*) Ecotoxicology Research Institute, Department of Plant and Environment Protection, National Agricultural Research Centre (NARC), Park Road, Islamabad, Pakistan e-mail: naziarafiqchem@gmail.com S. R. Tariq Department of Chemistry, Lahore College for Women University, Lahore, Pakistan e-mail: saadiartariq@yahoo.com