Mao, Shuduan, Liu, Shuren, Zhou, Yuting, An, Qi, Zhou, Xuji, Mao, Zhouying, Wu, Yiting, and Liu, Weiping
In addition to being historically intentionally manufactured as commercial products, polychlorinated biphenyls (PCBs) can be unintentionally released as by-products from industrial processes. Recent studies have emphasized the importance of unintentionally produced PCBs (UP-PCBs) and have even identified them as major contributors to atmospheric PCBs. However, little is known about contributions of UP-PCBs in current soils. In this study, all 209 PCB congeners were analyzed in agricultural soils on a national scale to investigate the influence of unintentional sources on Chinese soil. The concentration of Σ 209 PCBs in soils across China was in the range of 64.3–4358 pg/g. Four non-Aroclor congeners, i.e., PCB11, PCB44 + 47+65, PCB68, and PCB209, were dominant among all PCBs, averagely accounting for 26.3%, 8.83%, 3.03%, and 2.80% of total PCBs, respectively. PCB11 and PCB209 were found to be higher in East China, while PCB44 + 47+65 and PCB68 were higher in South China. Their spatial distributions were largely dependent on local sources. The results of source apportionment indicated that the legacy of historically produced and used commercial PCB mixtures was the dominant contributor to seven indicator PCBs in Chinese agricultural soils, especially high-chlorinated congeners. However, unintentional sources (i.e., pigment/paint, combustion-related sources, and polymer sealant), which contributed 57.4% of the total PCBs, are controlling PCB burdens in agricultural soils across China. Image 1 • A complete analysis of 209 PCBs were conducted in agricultural soils across China. • PCB11, PCB44 + 47+65, PCB68, and PCB209 were dominant congeners among all 209 PCBs. • The spatial distributions of non-Aroclor congeners were dependent on local sources. • The 7 indicator PCBs were dominated (52%) by the legacy commercial products. • Unintentional sources were the dominant contributor (57%) of the total PCBs in soils. The main finding of this work : PCBs in Chinese agricultural soils were dominated by non-Aroclor congeners. Unintentional sources contributed 57% of the total PCBs in soils. [ABSTRACT FROM AUTHOR]