[Effects of polystyrene microplastics (PS-MPs) on the growth, physiology, and biochemical characteristics of Hydrilla verticillata]. / 聚苯乙烯微塑料对黑藻生长及生理生化特征的影响.

In order to evaluate the effects of polystyrene microplastics (PS-MPs) on the growth, physiology, and biochemical characteristics of submerged plants, we exposed a typical submerged plant, Hydrilla verticillata, to a series of concentrations (i.e. 0, 5, 10, 30, 50, 100 mg·L-1) of 3 µm polystyrene microplastics (PS-MPs) and measured parameters including height, biomass, chlorophyll content, antioxidant enzyme activity, photosynthetic fluorescence. The results showed that the height of H. Verticillata significantly decreased at the high PS-MP concentrations (50 to 100 mg·L-1), while the fresh weight significantly increased at the low PS-MP concentration (5 mg·L-1). The fresh weight of H. verticillata gradually decreased with the increasing PS-MP concentration but the dry weight did not change. The total amount of chlorophyll, chlorophyll a, and chlorophyll a/b significantly decreased with the increases of the PS-MP concentrations, while the chlorophyll b did not change. PS-MPs affected the antioxidant enzyme activities of H. verticillata. The activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) were first increased and then decreased with the increasing PS-MP concentration. The chlorophyll fluorescence parameters (Fo, Fm, Fv/Fm) decreased with the increasing concentration of PS-MP and the 1-Qp-Lss value (reflective of the closing of PSⅡ reaction center) was increased under the stable state, probably due to the inhibited PSⅡ reaction center. The overall intensity of fluorescence imaging of H. verticillata decreased with the increasing concentration of PS-MPs. When the PS-MP concentration was lower than 10 mg·L-1, the photosynthetic activity of the leaves was normal. In contrast, when the PS-MP concentration was higher than 30 mg·L-1, it caused significant adverse effects on leaves, including weaker photosynthetic intensity and the presence of yellow or withered leaves. Our results suggested that H. verticillata could tolerate PS-MP pollution but its growth and photosynthesis would be inhibited at high concentrations (>30 mg·L-1). Our results provided basic information to better understand the eco-physiological effects of PS-MPs in the freshwater environment.

Bideposited silver nanocolloid arrays with strong plasmon-induced birefringence for SERS application.

Silver nano-rod, nano-zigzag, nano-saw, and nano-particle arrays are fabricated with glancing angle bideposition. The structure-dependent anisotropic optical properties of those bideposited nanostructured arrays are measured and investigated. The equivalent birefringence values of nano-rod and nano-zigzag arrays are much larger than crystals found in nature and liquid crystal used in display products. The fact that induced localized plasmon-magnetic field between nanorods dominates the strong phase retardation between p-polarized and s-polarized transmitted wave. For the nano-saw, the strong localized electric field induced between the saw teeth leads to strong SERS signals. Although the bideposited nanoparticles own weak morphological anisotropy, strong optical phase retardation is still detected at wavelengths near 400 nm.