Wong, M. H. | bioRxiv Science

bioRxiv2020

Pollutants in Hong Kong Soils: Organochlorine Pesticides and Polychlorinated Biphenyls

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were investigated in 138 soil samples collected in Hong Kong. Results showed that within the selected OCPs, only DDT and its metabolites (DDD and DDE) were frequently detected. Of 138 soil samples, 18% were non-detected for any DDT residues, while 25% were contaminated sporadically with DDT only (non-detected to 1090 {micro}g kg-1) and 57% contained various combinations of DDT, DDD and DDE (2.03 to 1118 {micro}g kg-1). In contrast, total PCBs ({sum}66 congeners) contamination was distributed more evenly (0.22 to 154 {micro}g kg-1) than DDTs, but serious contamination was found in industrial areas and soils collected near highways. Concentrations of 7 indicator PCBs ranged between non-detected to 34.5 {micro}g kg-1. The ratios of DDT/metabolites were typically greater than 1, thus suggesting recent application of DDT. Medium-range deposition from industrial areas within as well as away from the city is also suspected to be the origins of DDTs and PCBs found in Hong Kong soils. The concentrations of DDTs and PCBs in all soil samples did not exceed the recommended values in soil quality guidelines except 3 samples for DDT from locations far away from densely populated districts such as Tuen Mun and Tin Shui Wai. Therefore, DDTs and PCBs were not of significant concern in terms of their impacts on public health and environment.

pharmacology and toxicology↗

bioRxiv2020

Pollutants in Hong Kong Soil: As, Cd, Cr, Cu, Hg, Pb and Zn

Six heavy metals (Hg, Cu, Cd, Cr, Pb, Zn) and 1 metalloid (As) in surface soils of Hong Kong were investigated in 10 land use categories (urban park, greening area, country park, rural area, restored landfill, agricultural farmland, orchard farm, crematorium, industrial and near highway area). Edaphic Hg concentration in Hong Kong was firstly reported here. Clustering of land uses was observed based on total pollutants concentrations (sum of 7 metals). The most polluted cluster consisted of industrial and highway areas (median: 617 to 833 mg kg-1) and the runner-up cluster included urban park, greening area and restored landfill (median: 400 to 500 mg kg-1). However, this general finding was not observed for Hg, where higher concentration was found in agricultural farmland (median 109 g kg-1). The use of low quality fertilizers, together with the contribution from exhausts and wearable parts from automobiles were believed to be the major sources of Cr, Cu and Zn in Hong Kong, while the application of Hg-containing agrochemicals maybe the main mechanism of Hg contamination in agricultural soil. Based on the daily intake assumption of 0.2 g d-1 of soil particles by USEPA, direct ingestion of Hg-containing soils is not a major exposure pathway for population in Hong Kong. When comparing the edaphic heavy metal concentrations with Dutch soil quality guidelines demonstrated that Hg, Cd and Pb were not in level of health concerns, while Cu, Cr and Zn in less than 6% of total samples were found to exceed the Dutch intervention values sporadically. In contrast, suburban soils from northern and northeastern Hong Kong were mostly contaminated with As (10% of total samples) at concentration that could be potentially causing adverse health impacts to the nearby population. Pollutant in Hong Kong soils seriesO_LIChung, M. K., Hu, R., Cheung, K. C. & Wong, M. H. Pollutants in Hong Kong soils: Polycyclic aromatic hydrocarbons. Chemosphere 67, 464-473 (2007). http://doi.org/10.1016/j.chemosphere.2006.09.062 C_LIO_LIChung, M. K., Cheung, K. C. & Wong, M. H. Pollutants in Hong Kong Soil: As, Cd, Cr, Cu, Hg, Pb and Zn https://doi.org/10.1101/2020.02.16.951558 C_LIO_LIChung, M. K., Hu, R., Cheung, K. C. & Wong, M. H. Pollutants in Hong Kong Soils: Organochlorine Pesticides and Polychlorinated Biphenyls https://doi.org/10.1101/2020.02.16.951541 C_LI

pharmacology and toxicology↗