Distribution of Persistent Organic Pollutants in Soil and Grasses Around Mt. Qomolangma, China

Abstract

Previous literature has reported the fate of persistent organic pollutants (POPs) in mountainous regions, but the Himalayas have received little attention, and few results from this region have been published. The present study collected soil and grass samples from the Mt. Qomolangma (Everest) area, central Himalayas, China, from the elevation range 4700 to 5620 m. We analyzed all samples for organochlorine pesticides (OCPs) to determine the level of OCP contamination in the Qomolangma region. The soil samples contained 0.385 to 6.06 ng g(-1) of DDT only, and these concentrations were lower than those from Europe and mountains close to industrial emissions. Our study detected a number of OCPs in the grass samples, such as hexachlorocyclohexane (HCH) (0.354 to 7.82 ng g(-1)), hexachlorobenzene (HCB) (0.0156 to 1.25 ng g(-1)), endosulfan (0.105 to 3.14 ng g(-1)), and DDT components (1.08 to 6.99 ng g(-1)). Their concentrations were higher than those in pine needles from Alberta, Canada. Our measurements of HCH and DDT in grass samples showed the same or slightly higher concentration levels than reported in moss from Mt. Qomolangma 15 years ago. This result and the analysis of isomer ratios (alpha/gamma-HCH and p-p'-DDE/p-p'-DDT) indicate recent releases of OCPs from a nearby region, possibly from dicofol use in India. We also investigated the elevation distribution of OCPs and found that HCH and HCB were progressively concentrated in colder, higher elevation sites. A bioconcentration factor (BCF) of grass was calculated, and the BCF values increased with the increasing elevation, indicating that the cold condensation of POPs at high-elevation sites may increase the potential threat to vegetation and the food chain in the mountain ecosystem.

Levels and distribution of organochlorine pesticides and hexachlorobutadiene in soils and terrestrial organisms from a former pesticide-producing area in Southwest China

“…The OCP concentrations found in plants from different regions Table 3. In general, the concentrations of both HCHs and DDTs in plants were one order of magnitude higher in the present contaminated site than in other areas (Wang et al 2007;Lin et al 2008;Yi et al 2012;Tarcau et al 2013;Pan et al 2014). These findings confirm that the contaminated sites are significant sources of pollution if left untreated, resulting in local and regional plant contamination.…”

“…However, large interspecies differences were observed in the OCP concentrations of plants, and all chemicals were found at higher concentrations in wolfsbane than in other species, indicating different OCP accumulative capacities. There is currently little information available regarding OCP concentrations in plants around other former pesticide factories, however, contamination with OCPs has been reported in various plants, including vegetables, grass, and trees from farms and industrial regions (Wang et al 2007;Lin et al 2008;Pan et al 2014). Inconsistencies in species, growth, and development of plants have made it difficult to draw comparisons, so simple comparisons were made using the levels of RHCHs and RDDTs when possible.…”

Hexachlorobenzene sources, levels and human exposure in the environment of China

“…HCB was not detected in soil samples of Mt. Qomolangma area with the elevation from 4700 m to 5620 m (Wang et al, 2007d), much lower than HCB levels (0.13-0.80 ng/g dry wt.) in European Pyrenees mountain soils (Grimalt et al, 2004).…”

“…in grasses were detected. The significant correlation between HCB levels and the altitude suggests that cold condensation was occurring in elevated areas (Wang et al, 2007d). In remote area of southeast Tibet, HCB could also be detected in conifer needles (Yang et al, 2008).…”

Polychlorinated biphenyls (PCBs) in air and soil from a high-altitude pasture in the Italian Alps: evidence of CB-209 contamination

“…Many studies have been conducted worldwide to assess POP levels and distribution in mountain areas (e.g. Grimalt et al 2001;Barra et al 2005;Wang et al 2006Wang et al , 2007Nizzetto et al 2008;Moeckel et al 2008;Tremolada et al 2009a).…”