Sedimentary Records of DDT and HCH in the Pearl River Delta, South China

Abstract

Tropical regions in developing countries are thought to be significant sources of organochlorine pesticides in the global context, owing to high rate of use and only a recent production ban or restriction on application of these pesticides. In the present paper, DDT and HCH in eight 210Pb-dated sedimentary cores from the Pearl River Delta, South China, were analyzed in order to reconstruct the time trends of these persistent organic pollutants in this tropical region. The sedimentary inventories of sigmaDDT and sigmaHCH through the cores ranged from 36.6 to 1109.5 ng/cm2 and from 11.2 to 226.3 ng/cm2, respectively, and their spatial distribution implies that the water flows from the Humen, Jiaomen, Hongqili, and Hengmen outlets rather than the Xijiang flow from Modaomen outlet, supplied the major historical input of DDT to the estuary. Although a production ban of technical HCH and DDT was imposed in China in 1983, their sedimentary fluxes display increasing trends or strong rebounds in the 1990s as recorded in the core profiles, characteristic of the increasing ratios of (DDE + DDD)/DDT and DDE/DDT. It is suggested that an enhanced land soil runoff in the process of large-scale land transform, as well as a higher river water flow in early 1990s, had mobilized these pesticides from soil to the sedimentary system in the region.

Organochlorine pesticide contamination in marine organisms of Yantai coast, northern Yellow Sea of China

“…The reasons for the high percentage of β-HCH are that β-HCH is slow in biological and chemical degradation, has lowest water solubility and vapor pressure, is most stable, resistant to microbial degradation, and accumulated in organisms at high concentration (Simonich and Hites 1995;Willett et al 1998). In addition, α-HCH is transformed into β-HCH (Wu et al 1997); this is consistent with the fact that β-HCH is detected as a predominant isomer in mussel, sediments, and human tissues (Smeds and Saukko 2001;Zhang et al 2002;Rajendran et al 2005;Jin et al 2008).…”

China's water pollution by persistent organic pollutants

“…In addition, the concentrations of DDTs were higher in the Pearl River (with an annual water discharge of 3.4 Â 10 11 m 3 ) than those in the Yangtze River (with an annual water discharge of 9.2 Â 10 11 m 3 ) (Guan et al, 2009;Jiang et al, 2000;Tang et al, 2008). This is not surprising as the annual pesticide application in the Pearl River watershed (37 kg/ha) was five times the national average from 1980 to 1995 (Zhang et al, 2002). Globally, the levels of HCHs and DDTs detected in the Yangtze River (0.6e28.1 and nde16.7 ng/L, respectively), Yellow River (0.7e48.1 and 0.06e10.8 ng/L) and Pearl River (0.50e14.8 and 1.1e19.6 ng/L) were comparable to the concentrations obtained from Ebro River (0.2e28.6 and 2e6.8 ng/L) in Spain (Fernández et al, 1999) and Mumbai (0.2e15.9 and 3.0e33.2 ng/L) in India (Pandit et al, 2006) but were an order of magnitude lower than those in Red River (nde96.7 and ndÀ324 ng/L) in Vietnam (Hung and Thiemann, 2002) and Küçük Menderes River (187e337 and 72e120 ng/L) in Turkey (Turgut, 2003) (Table S1).…”

Organochlorine pesticides in seawater and the surrounding atmosphere of the marginal seas of China: Spatial distribution, sources and air–water exchange

“…In recent years, the production of OCPs was either eliminated or their release into the environment reduced under the Stockholm Convention on OCPs, which was adopted by many countries. However, in Southeast Asian countries, the late production ban as well as the current legal and illegal application for agricultural practices and for the control of certain diseases, such as malaria, typhus and cholera, have contributed to higher concentrations of OCPs in the environment (i.e., the atmosphere, water and sediment) (Hung and Thiemann, 2002;Iwata et al, 1994;Zhang et al, 2002), aquatic wildlife (e.g., mussels) (Ueno et al, 2003) and the human population (e.g., human breast milk) (UNEP, 2002;Wong et al, 2002). Oceanic waters are a receptor of land based pollutant sources, and coastal waters are particularly affected by inputs of OCPs via discharges of sewage, industrial effluents and significant rivers that drain into the marginal seas of China.…”