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The extent of organochlorine pesticides (OCPs) contamination in coastal waters around LaiZhou Bay and JiaoZhou Bay in Shandong Peninsula, northern China, was investigated. The areas around the two bays are both densely populated, thrived with intensive agriculture and industrial activities. Multi-techniques including GC–MS, GC–μECD coupled with chemical peak confirmation and strict QC procedures were used for the quantitative determination of 15 OCPs including alpha, beta, gamma and delta isomers of hexachlorocyclohexane (HCH), pentachloronitrobenzene (PCNB), heptachlor, aldrin, endosulfan, p,p′-DDE, dieldrin, endrin, p,p′-DDD, o,p′-DDT, p,p′-DDT and methoxychlor. The survey results show that contaminations by OCP residues remain widespread in the areas, but the averaged concentration levels are all below the regulatory limits, e.g., CMC limits (acute criterion values) specified in US Environmental Protection Agency (USEPA) and China national standards. Average concentration of OCPs in water samples were from undetectable to 3. 8ngl−1 in LaiZhou Bay and from 0. 1 to 3. 9ngl−1 in JiaoZhou Bay, respectively. A comparison between the current and historical data shows a rapidly decreasing trend of OCPs over the past twenty years in the study areas. [Copyright &y& Elsevier]

Decreasing bioaccessible antibiotics, heavy metals, and antibiotic resistance genes (ARGs) in soil by adsorption is an attractive, but unrealized, approach for ARG risk reduction. This approach has the potential to reduce the (co)selection pressure from antibiotics and heavy metals on bacteria and ARG horizontal gene transformation to pathogens. Here, a wet-state silicon-rich biochar/ferrihydrite composite (SiC–Fe(W)) synthesized by loading ferrihydrite onto rice straw-derived biochar was examined for i) adsorption of oxytetracycline and Cu2+ to reduce (co)selection pressure and ii) adsorption of extracellular antibiotic resistance plasmid pBR322 (containing tet A and bla TEM-1) to inhibit ARG transformation. SiC–Fe(W) gained the adsorption priority of biochar (for Cu2+) and wet-state ferrihydrite (for oxytetracycline and pBR322) and showed adsorptive enhancement (for Cu2+ and oxytetracycline) from a more wrinkled and exposed surface from biochar silica-dispersed ferrihydrite and a more negatively charged biochar, and the adsorption capacity for SiC–Fe(W) was 17–135 times that of soil. Correspondingly, 10 g/kg SiC–Fe(W) amendment increased the soil adsorption coefficient K d by 31%–1417% and reduced the selection pressure from dissolved oxytetracycline, co-selection pressure from dissolved Cu2+, and transformation frequency of pBR322 (assessed with Escherichia coli). The development of Fe–O–Si bonds on silicon-rich biochar in alkaline enhanced ferrihydrite stability and adsorption capacity (for oxytetracycline), presenting a new potential strategy of biochar/ferrihydrite composite synthesis for adsorptive inhibition of ARG proliferation and transformation in ARG pollution control. [Display omitted] • SiC–Fe(W) containing silica-stabilized and high-surface ferrihydrite and sichar was synthesized. • SiC–Fe(W) held adsorption capacity exceeding biochar and wet-state ferrihydrite for Cu2+ and oxytetracycline. • Adsorptive inhibition of ARG proliferation and transmission in soil was realized by SiC–Fe(W). • SiC–Fe(W) promoted the persistence of soil sorption enhancement towards oxytetracycline and ARG in dry-wet cycle. [ABSTRACT FROM AUTHOR]