Toxicity of engineered nanoparticles on organisms is of concern worldwide due to their extensive use and unique properties. The impacts of ZnO nanoparticles (ZnO NPs) on seed germination and root elongation of corn (Zea mays L.) and cucumber (Cucumis sativus L.) were investigated in this study. The role of seed coats of corn in the mitigation toxicity of nanoparticles was also evaluated. ZnO NPs (1,000 mg L⁻¹) reduced root length of corn and cucumber by 17 % (p < 0.05) and 51 % (p < 0.05), respectively, but exhibited no effects on germination. In comparison with Zn²⁺, toxicity of ZnO NPs on the root elongation of corn could be attributed to the nanoparticulate ZnO, while released Zn ion from ZnO could solely contribute to the inhibition of root elongation of cucumber. Zn uptake in corn exposed to ZnO NPs during germination was much higher than that in corn exposed to Zn²⁺, whereas Zn uptake in cucumber was significantly correlated with soluble Zn in suspension. It could be inferred that Zn was taken up by corn and cucumber mainly in the form of ZnO NPs and soluble Zn, respectively. Transmission electron microscope confirmed the uptake of ZnO NPs into root of corn. Although isolation of the seed coats might not be the principal factor that achieved avoidance from toxicity on germination, seed coats of corn were found to mitigate the toxicity of ZnO NPs on root elongation and prevent approximately half of the Zn from entering into root and endosperm.

The protected vegetable farming is a style of high frequent rotation farming which requires a huge amount of fertilizers to maintain soil fertility. A total of 125 surface soils covering from east to west of China were sampled for the analysis of 17 antibiotics in order to identify antibiotics contamination caused by long-term manures application. The results indicate that the agricultural land has accumulated a statistically significantly higher antibiotics concentration than conventional open croplands. The maximum oxytetracycline concentration was 8400 μg kg(-1), the highest level that has ever been reported for oxytetracycline in soils. The residual concentration is decided by both plant duration and manure type. Short-term (<5 years) planting shows the highest residues of tetracyclines and fluoroquinolones in the soils. The organic farming characteristic of applying commercial compost as a single fertilizer in planting shows the lowest antibiotics residue in the soils on the whole. Principal component analysis suggests that the various combinations of antibiotic compounds in the soil may be used to trace the manure source. The antibiotics in soil may threaten water quality through contamination by diffusion. Ciprofloxacin and sulfachinoxalin are calculated to be a higher migration risk to surface waters, hence their environmental fate requires further study.

The accumulation of phthalic acid esters (PAEs) in soil and plants in agricultural land near an electronic waste recycling site in east China has become a great threat to the neighboring environmental quality and human health. Soil and plant samples collected from land under different utilization, including fallow plots, vegetable plots, plots with alfalfa (Medicago sativa L.) as green manure, fallow plots under long-term flooding and fallow plots under alternating wet and dry periods, together with plant samples from relative plots were analyzed for six PAE compounds nominated as prior pollutants by USEPA. In the determined samples, the concentrations of six target PAE pollutants ranged from 0.31–2.39 mg/kg in soil to 1.81–5.77 mg/kg in various plants (dry weight/DW), and their bioconcentration factors (BCFs) ranged from 5.8 to 17.9. Health risk assessments were conducted on target PAEs, known as typical environmental estrogen analogs, based on their accumulation in the edible parts of vegetables. Preliminary risk assessment to human health from soil and daily vegetable intake indicated that DEHP may present a high-exposure risk on all ages of the population in the area by soil ingestion or vegetable consumption. The potential damage that the target PAE compounds may pose to human health should be taken into account in further comprehensive risk assessments in e-waste recycling sites areas. Moreover, alfalfa removed substantial amounts of PAEs from the soil, and its use can be considered a good strategy for in situ remediation of PAEs.

Veterinary antibiotics (VAs) are emerging contaminants and enter into soil principally by agricultural application of organic fertilizer. A total of 33 solid animal manures and 17 compost samples from protected vegetable farms in nine areas of China were analyzed for the antibiotic classes of tetracyclines, fluoroquinolones, sulfonamides, and macrolides (17 substances in total). Oxytetracycline was found as a dominant compound in the samples, and its highest concentration reached 416.8 mg kg⁻¹ in a chicken manure sample from Shouguang, Shandong Province. Among the samples, animal manures (especially pig manure) contained higher VA residues than composts. However, fluoroquinolones exhibited higher persistence in the compost samples than other antibiotic classes. This is particularly the case in the rice husk compost, which contained the highest level of ofloxacin and ciprofloxacin (1334.5 and 1717.4 μg kg⁻¹ on average, respectively). The veterinary antibiotic profile in the risk husk compost had a good relationship with that in the corresponding manures. The refined commercial compost had the lowest VA residues among the compost samples in general. This implied that composting process might be important to reduce the antibiotic residue. High residue of antibiotics in soil was assumed to be a hazard to ecosystem. This is especially noticeable under current application rates (150 t ha⁻¹ a⁻¹) in protected vegetable farming because over half of the samples exhibited a risk quotient (RQ) >1 for one or more antibiotics.