[Effects of Low-density Polyethylene Microplastics on the Growth and Physiology Characteristics of Ipomoea aquatica Forsk].

Microplastic pollution in soil and its toxicological effects have attracted increasing attention from researchers, but the mechanisms of microplastics affecting crop growth and physiology remain unclear. A pot experiment was conducted to evaluate the impacts of various mass concentrations (0%, 0.2%, 5%, and 10%) of low-density polyethylene microplastics (LDPE MPs) on the germination rate, photosynthetic pigment content, biomass, antioxidant enzyme activity, soluble protein, and soluble sugar content of water spinach (Ipomoea aquatica Forsk). The results showed that LDPE MPs significantly inhibited (P<0.05) the seed vigor of water spinach, and the inhibitory effect increased with increasing concentration of LDPE MPs. However, the 5% LDPE MPs significantly promoted the aboveground biomass of water spinach. The 0.2% and 10% LDPE MPs significantly improved the superoxide dismutase (SOD) activity and catalase (CAT) and peroxidase (POD) activities, respectively. Further, malondialdehyde (MDA) content decreased with increasing concentration of LDPE MPs, and the reductions reached 15.53%-27.39% in comparison to that in the control. The LDPE MPs also significantly increased the soluble sugar content of water spinach leaves. In summary, LDPE MPs could inhibit the seed vigor and promote biomass accumulation in water spinach. Water spinach could relieve the oxidative stress caused by LDPE MPs by regulating antioxidant enzyme activity and soluble protein content. Therefore, this study may provide basic information for assessing the influences of microplastics on vegetables.

Dynamic characteristics of the novel strobilurin fungicide SYP-3343 in aerobic soils.

SYP-3343, (E)-2-(2-((3-(4-chlorophenyl)-1-methyl-1H-pyrazole-5-yloxy)methyl)phenyl)-3-methoxyacrylate, is a newly developed strobilurin fungicide. However, the environmental behavior and fate of SYP-3343 in soil have not been well-documented. In this study, ¹4C-labeled SYP-3343 was employed to investigate the dynamic characteristics in three typical soils under aerobic conditions. Radioactivity analysis after high-performance liquid chromatography (HPLC) showed that SYP-3343 degraded rapidly in the coastal soil with a half-life of 43.8 days. After incubation of 100 days, its extractable residues were greater than 76.0% and bound residues were less than 12.4%, indicating that SYP-3343 was not easy to accumulate in soils. The mineralization to ¹4CO2 reached 5.4% for acidic soil, 2.8% for neutral soil, and 1.7% for alkaline soil, suggesting that it was difficult to cleave the pyrazole ring completely. In addition, dynamic characteristics of SYP-3343 in sterile and non-sterile loamy soil showed that soil microbes affected SYP-3343 residue in soil and could accelerate the process of degradation and mineralization.