Comprehensive analysis of the fates and risks of veterinary antibiotics in a small ecosystem comprising a pig farm and its surroundings in Northeast China.

This study investigated the behavior of veterinary antibiotics (VAs) in a small farm ecosystem. Manure and environmental samples were collected around a large pig farm in northeast China. Thirty-four VAs in six categories were analyzed. Then, a multimedia fugacity model was used to estimate the fates of VAs in the environment. The results showed that VAs were prevalent in manure, soil, water, and sediment, but not in crops. Compared with fresh manure, VA levels were significantly lower in surface manure piles left in the open air for 3-6 months. The main VAs, tetracyclines and quinolones, decreased by 427.12 and 158.45 µg/kg, respectively. VAs from manure piles were transported to the surroundings and migrated vertically into deep soil. The concentrations of ∑VAs detected in agricultural soils were 0.03-4.60 µg/kg; > 94% of the mass inventory of the VAs was retained in soil organic matter (SOM), suggesting that SOM is the main reservoir for antibiotics in soil. Risk assessment and model analysis indicated that the negative impact of mixed antibiotics at low concentrations in farmland on crops may be mediated by indirect effects, rather than direct effects. Our findings highlight the environmental fates and risks of antibiotics from livestock farms.

Occurrence, seasonal variation, potential sources, and risks of organophosphate esters in a cold rural area in Northeast China.

Organophosphate esters (OPEs) in the environment have been the focus of increasing attention due to their ubiquity and potential toxicity. However, there is little information on the occurrence and characteristics of OPEs in rural areas, especially those with cold year-round temperatures and frozen soil in winter. In this study, environmental samples were collected, in summer and winter, from villages and towns in Northeast China differing in the types and intensities of their anthropogenic activities. The samples were analyzed for 12 OPEs. The results showed the widespread presence of alkyl-OPEs, Cl-OPEs, and aryl-OPEs in the water, soil, snow, and ice of the study sites. In summer, tris(1-chloro-2-propyl) phosphate (TCPP) and tris(2-chloroethyl) phosphate (TCEP) were the primary compounds in water and soil, respectively. The ∑12OPE concentration in three villages varied from 46.26 to 257.37 ng/L in water, and from 6.62 to 19.46 ng/g in soils. The ∑12OPE concentrations in water were lower in winter than summer, but conversely, ∑12OPE concentrations in frozen soils in winter were higher than those in soils in summer. In winter, there was a shift in the predominant OPEs in water and frozen soils, with dominance of TCEP and complex compounds, respectively. Obvious seasonal characteristics of the potential sources and ecological risks of OPEs in these areas were also determined, with more complex sources of OPEs seen in summer than winter. In summer, only 2-ethylhexyl diphenyl phosphate (EHDPP) in water posed a potential risk, while in summer and, especially, in winter, EHDPP and tris(2-ethylhexyl) phosphate posed potential risks in soils. The high ∑12OPE concentration in snow (56.77 ng/L) implied that wet deposition can amplify OPEs in other environmental compartments. This is the first systematic report on OPEs in a cold rural area. Our findings highlight the need for seasonal monitoring of OPEs in similar areas.