Gradient distribution of persistent organic contaminants along northern slope of central-Himalayas, China.

High mountains may serve as condenser for persistent organic pollutants (POPs) and the vegetation in remote areas has been used as a means to characterized atmospheric concentrations of air pollutants. In this study, organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs) in Himalayan spruce needle samples from Zhangmu-Nyalam region (central-Himalayas) were analyzed and the altitudinal gradient of these pollutants was investigated. Total HCHs and DDTs concentration in needles were in the range of 1.3-2.9 ng g(-1) dry weight and 1.7-11 ng g(-1) dry weight, which were lower than concentrations reported in spruce needles from Alps, however higher than concentrations in conifer needles from mountain areas of Alberta. Total Himalayan spruce needle PAHs was below 600 ng g(-1) and fluorene, phenanthrene and acenaphthene were abundant individual compounds measured. The ratios of alpha-HCH/gamma-HCH in pine needles were similar with the usual values for technical HCH, implying technical HCHs might be used in this region. The high ratios of o-p'-DDT/p-p'-DDT and no p-p'-DDE measured in this study led to the suspicion that a new source of o-p'-DDT and/or p-p'-DDT existed in this region. In addition, higher ratios of low molecular weight-/high molecular weight-PAHs in this region indicated that petroleum combustion, vehicle emission and low-temperature combustion might be the major contributions of PAH source. To examine the POPs distillation, the analyte concentrations were correlated with altitude. The more volatile OCPs, alpha-HCH, gamma-HCH, aldrin and alpha-endosulfan positively correlated with altitude, however, less volatile OCPs (DDT and DDD) inversely related with elevation. Almost all PAHs detected in this area showed positive correlations with altitude. It is worthy to note that heavy PAHs (Benzo[k] fluoranthene and Benzo[a]anthracene) displayed positive correlation, which implied the sources of PAHs were near the sampling sites. The distillation of POPs was strongly affected by the proximity between sampling sites and contaminant sources. If the contaminant sources are close to the mountains, it may be the dominant factor that controls the concentration gradient.

[1]  T. Zhu,et al.  Observation of organochlorine pesticides in the air of the Mt. Everest region. , 2006, Ecotoxicology and environmental safety.

[2]  B. Jansson,et al.  Organochlorine pesticides and polychlorinated biphenyls in the atmosphere of Southern Sweden , 1987 .

[3]  S. Eisenreich,et al.  Atmospheric deposition of toxaphene to eastern north America derived from peat accumulation , 1986 .

[4]  G Stern,et al.  Temporal trends of organochlorine pesticides in the Canadian Arctic atmosphere. , 2002, Environmental science & technology.

[5]  J. Aislabie,et al.  Polycyclic aromatic hydrocarbons in nearshore marine sediments of Australia. , 1992, The Science of the total environment.

[6]  Ronald A. Hites,et al.  The global distribution of polycyclic aromatic hydrocarbons in recent sediments , 1978 .

[7]  Richard W. Battarbee,et al.  Influence of altitude and age in the accumulation of organochlorine compounds in fish from high mountain lakes. , 2004, Environmental science & technology.

[8]  Shihua Qi,et al.  Distribution of polycyclic aromatic hydrocarbons in the coastal region off Macao, China: assessment of input sources and transport pathways using compositional analysis. , 2003, Environmental science & technology.

[9]  P. Bergqvist,et al.  Polycyclic aromatic hydrocarbons in a semiaquatic plant and semipermeable membrane devices exposed to air in Thailand. , 2003, Environmental science & technology.

[10]  T. Zhu,et al.  Organochlorine pesticides in the air around the Taihu Lake, China. , 2004, Environmental science & technology.

[11]  J. Grimalt,et al.  Temperature dependence of the distribution of organochlorine compounds in the mosses of the Andean mountains. , 2004, Environmental science & technology.

[12]  R. Metcalf.  Organic Insecticides: Their Chemistry And Mode Of Action , 1955 .

[13]  D. Calamari,et al.  Spatial Distribution of PAHs in the U.K. Atmosphere Using Pine Needles , 1996 .

[14]  Shinsuke Tanabe,et al.  PCBs and chlorinated hydrocarbon pesticides in Antarctic atmosphere and hydrosphere , 1983 .

[15]  F. Wania,et al.  Organic contaminants in mountains. , 2005, Environmental science & technology.

[16]  S. Tanabe,et al.  Geographical distribution of persistent organochlorines in air, water and sediments from Asia and Oceania, and their implications for global redistribution from lower latitudes. , 1994, Environmental pollution.

[17]  Marco Vighi,et al.  Role of plant biomass in the global environmental partitioning of chlorinated hydrocarbons , 1991 .

[18]  M. Diamond,et al.  Factors affecting the occurrence and enantiomeric degradation of hexachlorocyclohexane isomers in northern and temperate aquatic systems , 2001, Environmental toxicology and chemistry.

[19]  C. Dimock,et al.  Origins of polycyclic aromatic hydrocarbons in estuarine sediments , 1979 .

[20]  P. Gschwend,et al.  Fluxes of polycyclic aromatic hydrocarbons to marine and lacustrine sediments in the northeastern United States , 1981 .

[21]  M. Vighi,et al.  Distribution of Organochlorine Pesticides in Pine Needles of an Oceanic Island: The Case of Tenerife (Canary Islands, Spain) , 2003 .

[22]  Gan Zhang,et al.  Compositional fractionation of polycyclic aromatic hydrocarbons (PAHs) in mosses (Hypnum plumaeformae WILS.) from the northern slope of Nanling Mountains, South China , 2005 .

[23]  S. Bhargava,et al.  Exposure risk to carcinogenic PAHs in indoor-air during biomass combustion whilst cooking in rural India , 2004 .

[24]  S. Scharf,et al.  Regional aspects and statistical characterisation of the load with semivolatile organic compounds at remote Austrian forest sites. , 2000, Chemosphere.

[25]  D. Schindler,et al.  Orographic cold-trapping of persistent organic pollutants by vegetation in mountains of western Canada. , 2003, Environmental science & technology.

[26]  J. Seiber,et al.  Fate of Summertime Airborne Organophosphate Pesticide Residues in the Sierra Nevada Mountains , 1997 .

[27]  Z. Migaszewski.  Determining Organic Compound Ratios in Soils and Vegetation of the Holy Cross MTS, Poland , 1999 .

[28]  J. Grimalt,et al.  Aliphatic and aromatic hydrocarbons in different sized aerosols over the Mediterranean Sea: Occurrence and origin , 1987 .

[29]  F. Wania.  Global fractionation and cold condensation of low volatility organochlorine compounds in polar regions , 1993 .

[30]  R. Harrison,et al.  Concentrations of particulate airborne polycyclic aromatic hydrocarbons and metals collected in Lahore, Pakistan , 1996 .

[31]  J. Froines,et al.  Seasonal variation of the particle size distribution of polycyclic aromatic hydrocarbons and of major aerosol species in Claremont, California , 2004 .

[32]  M. Lee,et al.  Source identification of urban airborne polycyclic aromatic hydrocarbons by gas chromatographic mass spectrometry and high resolution mass spectrometry. , 1977, Biomedical mass spectrometry.

[33]  Subodh Sharma,et al.  Persistent organic pollutants and mercury in the Himalaya , 2005 .