DDT and Its Metabolites in Fresh Water Fish Samples

Twenty two fresh water fish samples namely Puntius sarana （Shawrputi）, Cyprinus carpio （Karp）, Oreochromis niloticos （Telapia）, Channa punctatus （Taki）, Wallogonia attu （Boal）, Eutropiichthys vacha （Bacha）, Macrognathus aculiatus （Baim）, Ailia coila （Kajoli）, Mystus cavasisus（Gulsa）, Ompok pabda （Pabdha）, Corica soborna （Kachki）, Mystus vittatus （Tengra）, Glossogobius giuris （Baila）, Macrobrachium malcolmsli （Chingri）, Amblypharyngodon microlepis （Mola）, Anabas testudineus （Koi）, Macrognathus aculiatus （Baim）, Channa striatus （Shole）, Heteropnueste fossilis （Shing）, Puntius sophore （Small Puti） and Pseudambassis ranga （Telapia） were collected from two rivers and one cultured fish pond. The samples were extracted by QuEChERS method, cleaned up with conc. H2SO4 treatment and cleaned extracts were analyzed by GC-ECD. Small size cultured rui fish sample which did show detectable amount of DDT and its metabohtes was used for the recovery experiments. Percent recovery was found to be in the range of 70%-113%. Amount of total DDTs were found to be 54.34, 48.81, 62.09, 54.72,78.81, 60.07, 47.0, 42.7, 26.31, 10.36, 25.32, 12.96, 20.10, 12.78, 17.65, and 4.71, 8.58, 11.3 and 19.01 ng/g in gulsa, pabhda, baila, bacha, baim, small purl, tengra, chanda, kachki, boal, taki, chingri, mola, shole, shing, koi, swarpurl, karp and telapia fish samples, respectively. However, the residual amounts of DDTs in all the fish samples were below maximum residue limit （MRL of DDTs in fish 5.0 mg/kg） according to Codex Alimentarius Commission. The ratios of 4,4＇-DDT/DDTs were in the range of 0.03-0.44 which indicated that exposure to DDT is not due to recent use.

Addressing global change challenges for Central Asian socio-ecosystems

Central Asia is one of the most vulnerable regions on the planet earth to global climate change, depending on very fragile natural resources. The Soviet legacy has left the five countries （Kazakhstan, Tajikistan, Kyrgyzstan, Turkmenistan, and Uzbekistan） with a highly integrated system but they are facing great challenges with tensions that hinder regional coordination of food and water resources. With increasing climate variability and warming trend in the region, food and water security issues become even more crucial now and, if not addressed properly, could affect the regional stability. The long-term drivers of these two most critical elements, food and water, are climate change; the immediate and probably more drastic factors affecting the food and water security are land uses driven by institutional change and economic incentives. As a feedback, changes in land use and land cover have directly implications on water uses, food production, and lifestyles of the rural community in the region. Regional and international efforts have been made to holistically understand the cause, extent, rate and societal implications of land use changes in the region. Much of these have been understood, or under investiga- tion by various projects, but solutions or research effort to develop solutions, to these urgent regional issues are lacking. This article, serves as an introduction to the special issue, provides a brief overview of the challenges facing the Central Asian countries and various interna- tional efforts in place that resulted in the publications of this special issue.