Environ Monit Assess (2011) 173:325–341 DOI 10.1007/s10661-010-1390-y Organochlorine residual concentrations in cattle egret from the Punjab Province, Pakistan Riffat Naseem Malik · Sidra Rauf ·Ashiq Mohammad · Syed-Ali-Musstjab-Akber Shah Eqani · Karam Ahad Received: 27 July 2009 / Accepted: 11 February 2010 / Published online: 7 March 2010 © Springer Science+Business Media B.V. 2010 Abstract In this study, residual concentration of organochlorine pesticides (OCPs) in the sediments, prey, and eggs of Bubulcus ibis were measured from three breeding heronries from the Punjab province of Pakistan. Pattern of contamination in eggs followed the order: DDTs > HCHs > heptachlor > aldrin. Overall, pesticide residual concentrations were greater in eggs of cattle egrets collected from heronry on the River Ravi. Among HCHs, γ-HCH was more prevalent in eggs, whereas DDTs followed the order: DDD > DDE > p, p ′ -DDT > o, p ′ -DDT. Eggshell thinning was detected which showed neg- ative relationship with residual concentration of DDE. In prey samples, residual concentration of POPs followed the order: DDTs > HCHs > di- cofol > heptachlor; however, contamination pat- tern in sediments followed a slightly different order: DDTs > heptachlor > dicofol > HCHs > dieldrin > aldrin. Concentration of β-HCH was R. N. Malik (B ) · S. Rauf · S.-A.-M.-A. S. Eqani Environmental Biology Laboratory, Department of Plant Sciences, Quaid-i-Azam University, Islamabad, 46000, Pakistan e-mail: r_n_malik2000@yahoo.co.uk A. Mohammad · K. Ahad Ecotoxicology Research Program, National Agricultural Research Center, Park Road, Islamabad, 45500, Pakistan more prevalent in sediments and comparatively greater concentrations of POPs were measured in sediments collected from the River Ravi. Dicofol was found for the very first time in the biological samples from Pakistan, and its concentration was measured as relatively high in eggs from heronry from the River Chenab. Residual concentrations measured in eggs were below the levels that could affect egret populations. Biomagnification of the total OCPs through the food chain was evident in three breeding heronries. The concentration of DDE measured in eggs of the cattle egret suggests the need for monitoring this contaminant in other bird species at different trophic levels. Keywords Persistent organic pollutants · Biomonitoring · Colonial water birds · Contamination · Biomagnifications · DDTs Introduction Multilateral environmental agreements (MEAs) address the environmental problems being faced by the international community and vouch for common responsibility among nations for the en- vironmental protection. Pakistan is the signatory to several MEAs aiming at sustainable develop- ment of natural resources and has ratified all three conventions related to chemicals and hazardous waste such as Basel, Rotterdam, and Stockholm.