Nanoparticles (NPs) have attractive properties that have received impressive consideration in the last few decades. Polylactic acid nanoparticles (PLA-NPs) stand out as a biodegradable polyester with excellent biocompatibility. This investigation introduces PLA-NPs prepared by using the emulsification-solvent volatilization (O/W) method. The effects of ultrasonication time, organic-to-aqueous phase volume ratio, surfactant Tween-20, and PLA on particle size as well as the polydispersity index (PDI) were investigated using a one-factor combination with Response Surface Methodology (RSM). The result indicates that, on the one hand, PLA was the key factor affecting particle size, which gradually increased as the amount of PLA increased from 0.01 to 0.1 g. The particle size of NPs gradually decreased as the surfactant Tween-20 increased from 0.25 mL to 1 mL in the aqueous phase. The volume ratio of the organic phase to the aqueous phase increased from 1:10 to 1:1, with the particle size initially decreasing (from 1:10 to 1:5) and subsequently increasing (from 1:5 to 1:1). As the ultrasonication time increased from 20 min to 40 min, the particle size initially increased (from 25 to 30 min) and then decreased (from 30 to 40 min). On the other hand, Tween-20 was the main factor of PDI, and with the increase of Tween-20, PDI changed significantly and increased rapidly. The volume ratio of the organic phase to the aqueous phase increased from 1:10 to 1:1, resulting in the stabilization and subsequent gradual decrease of the PDI. With the increase of ultrasonication time (20–40 min), PDI tended to be stable after the increase. The effect of PLA on PDI was not significant, and the change of PLA concentration did not cause a significant change in the size of PDI.

Riparian vegetated filter strips (RVFS) can effectively intercept agricultural non-point source pollution (ANSP) into a water body and reduce the risk of water body pollution. The present study evaluates the long-term effectiveness of different types and lengths (5 m, 9 m, 13 m) of RVFS in reducing the suspended solids (SS) and nutrients from agricultural runoff. Three field experimental plots (T1-T2-T3) planted with weeds, sweet clover (Melilotus suaveolens L.) and sweet clover/Chinese wingnut (Pterocarya stenoptera C. DC.) were established adjacent to the agricultural edge from 2011 to 2018. The runoff volumes, SS, and nutrients concentrations were determined at each effective runoff event during the study periods. The results indicated that all RVFS (T1, T2, and T3) reduced the mass of the nutrients rather than the concentration in all runoff events. In the rainfall events, the pollutants were reduced significantly in the presence of RVFS. The removal efficiency of T2 and T3 amounted to 79% and 84% for SS within the first 5 m, which was significantly higher than T1(61%). The 9 m-long T3 caused a significant reduction in the mean total phosphorus (TP) and dissolved phosphorus (DP) by 84% and 82%, respectively. More than 70% of the pollutants from rainfall runoff could be controlled by a 13 m RVFS. The snow-melt events increased the risk of ANSP migrating to streams, especially for the DP. However, the Chinese wingnut strip increased the filtering capacity of the DP as compared to the other two RVFS. Results from this study confirmed that the RVFS is a very effective mitigation system to reduce the sediment and nutrient loads in the agricultural runoff.

The objectives of this study were to identify the sources and concentrations of heavy metals in soils from typical industrial areas in Fuxin, China and assess potential ecological and health risks. A total of 52 surface soil samples from sites A and B were collected and analyzed for Cd, Pb, Cr, Cu, Ni, Zn, As, and Hg. Results showed that all concentrations of heavy metals exceeded background values to varying degrees, especially for Cd. The mean concentrations for Cd, Pb, Cr, Cu, Ni, Zn, As, and Hg in sites A and site B were 1.31±0.97 and 1.23±0.65 mg·kg−1, 12.54±12.45 and 8.51±8.85 mg·kg−1, 48.26±26.62 and 33.20±31.67 mg·kg−1, 23.29±27.40 and 23.98±28.71 mg·kg−1, 63.01±34.44 and 50.21±10.99 mg·kg−1, 114.07±52.26 and 108.60±41.75 mg·kg−1, 10.45±0.80 and 9.80±1.17 mg·kg−1, and 0.045±0.072 and 0.06±0.05 mg·kg−1, respectively, indicating that these metals were enriched in the surface soil of the study areas. Site A only reaches a low risk degree, and site B is of medium risk degree. This difference is due to the diverse industry distributions and pollution emissions. Related control and measure should be drawn up from noncancer and cancer risks for children and adults.