Characteristic accumulation and soil penetration of polychlorinated biphenyls and polybrominated diphenyl ethers in wastewater irrigated farmlands

Abstract

a b s t r a c tThe impact of wastewater irrigation on the distribution of two groups of persistent organic pollutants (POPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), in farm soil was investigated in this study. The concentrations of total analyzed PCBs were in the range 256-2140 pg g À1 on dry weight basis in surface soils. There was a higher accumulation of PCBs in farms irrigated by wastewater, with decachlorobiphenyl (CB-209) as the predominant congener. The spatial distributions of PBDEs were similar although not as obvious as that of PCBs, and BDE-209 was the predominant congener at 2040-496 000 pg g À1 dw, accounting for >96% of the total analyzed PBDEs. However, no significant correlations could be found between PCB and PBDE concentrations in the topsoil samples, and also with soil organic content between the different sites. On the other hand, soil vertical profiles showed significant relationship with soil organic content in cores taken from farms irrigated with wastewater. The vertical distribution was quite uniform at the topsoil, corresponding to the plowed layer, and decreased thereafter exponentially. Furthermore, the soil vertical distribution was found to be congener specific for PCBs, where less chlorinated congeners were able to penetrate deeper into the soil while heavier congeners were more restricted in their movement. This fractionation process was however not found for PBDEs. Also, the prevalence and high relative concentrations of CB-11 and CB-209 suggests that these PCB congeners should more often be included in routine environmental analysis in order to identifying unusual contamination sources.

Distribution of polychlorinated biphenyls in an urban riparian zone affected by wastewater treatment plant effluent and the transfer to terrestrial compartment by invertebrates

“…The pretreatment and analysis of the different sample matrices is based on the isotope dilution quantification protocol outlined in the US EPA 1668 methods and has been described in our previous studies (Wang et al, 2007;Wang et al, 2010). Briefly, the solid samples were freeze dried, ground, spiked with labeled surrogate standards, extracted by accelerated solvent extraction (ASE), cleaned up by a multilayer silica column and further spiked with labeled internal standards before instrumental analysis.…”

“…PCB-209 is not usually found in technical mixtures but has recently been found at remarkably high levels in some sewage sludge samples from Beijing (Guo et al, 2009) and also in wastewater irrigated farm soils (Wang et al, 2010). The specific sources of PCB-209 are currently not well known but might be related to industrial activities and the use of certain commercial products.…”

Future threats to agricultural food production posed by environmental degradation, climate change, and animal and plant diseases – a risk analysis in three economic and climate settings

“…There is evidence that these substances (PCBs being a case in point) can be toxic to plants, but at levels several orders of magnitude higher than found in soils irrigated with water contaminated by these chemicals (Holoubek et al 2009;Wang et al 2010;Weber and Mrozek 1979). However, these substances are of real concern from the perspective of food safety, as they may reach humans via contaminated foodstuffs of animal origin, particularly seafood (Guo et al 2009;Zhao et al 2006).…”

Bursa’nin Zeyti̇nli̇k Arazi̇leri̇ndeki̇ Topraklarda Poli̇aromati̇k Hi̇drokarbon (Pah) Konsantrasyonlarinin Bölgesel Deği̇şi̇mi̇

“…Yedi örnekleme noktasında ∑4-halkalı PAH'ların oranı %58 ile %100 arasında değişim göstermiş olup PAH'ların ortalama %72'sini 4-halkalı türler teşkil etmiştir. Bunu, ortalama %22'lik oranla 3-halkalılar ve daha sonra %5 ile 5-ve 6- Yapılan çalışmalar PAH bileşiklerinin topraktan süzülerek alt katmanlara ilerlemesinin toprağın organik madde miktarı ve bileşiğin molekül ağırlığı ile ilişkili olduğunu ortaya koymaktadır [54]. Nispeten düşük moleküler ağırlıklı PAH'lar toprakta daha derinlere inebilirken yüksek moleküler ağırlıklı olanlar ise toprağın üst katmanlarında birikme eğilimi göstermektedir [55].…”