[Spatio-temporal Distribution Characteristic and Risk Assessment of Heavy Metals in Soils Around Centralized Drinking Water Sources in Wuhan].

In the present study, the spatio-temporal distribution characteristics of heavy metals (Cd, Hg, As, Pb, Cr, Cu, Ni, and Zn) in soil around 19 centralized drinking water sources in Wuhan were investigated. Single-factor and comprehensive pollution indexes were used to determine soil pollution levels. The potential ecological hazard index was employed to evaluate soil potential ecological risks. The correlation and cluster analysis were conducted to identify pollution sources. The results showed that higher concentrations of heavy metals were present in soil from centralized drinking water source located in core area than suburb area of Wuhan. The concentrations of heavy metals in soil from centralized drinking water sources near the Yangtze River were higher than that in the sites near the tributaries of the Yangtze River. The average single potential ecological risk index of Hg, As, Pb, Cr, Cu, Ni, and Zn were lower than 40, which suggests a slight potential ecological risk. The average single potential ecological risk index of Cd was 80-160, which indicates a high potential ecological risk. The average comprehensive potential ecological risk index of heavy metals in soil around centralized drinking water sources in Wuhan was 142.12, which corresponded to a slight potential ecological risk. The correlation analysis showed that the sources of Cu, Pb, and Cr were similar and came from transport. The sources of Ni, As, Cr, and Cu were similar and could be attributed to metallurgical industries. The sources of Zn, Hg, and Cr were similar and could be related to antiseptic and catalytic industries. The long-term monitoring of Wuhan Dijiao and Baishazhou waterworks indicated that the concentrations of heavy metals around centralized drinking water sources in Wuhan were markedly decreased after 2017 and that ecological risk may be further reduced in the future.

Ascorbic acid induced activation of persulfate for pentachlorophenol degradation.

In the present study, ascorbic acid (AA) induced persulfate activation was investigated for the further exploration of organic pollutants oxidation by persulfate. We interestingly found that AA showed a significant catalytic activity to persulfate. Under neutral pH and room temperature condition, about 71.3% of pentachlorophenol (PCP, 10 mg L-1) was decomposed in 180 min with 40 mmol L-1 persulfate and 1.0 mmol L-1 AA, while only 15.4% and 3.2% of PCP was removed by alone persulfate and AA respectively. The result of EPR spectra identified sulfate radical (SO4•-) and hydroxyl radical (OH) were generated during the reaction between persulfate and AA. Quenching experiments confirmed that both SO4- and OH contributed to the decomposition of PCP. With the addition of AA augmented from 0 to 1 mmol L-1, the PCP degradation ratio continuously increased. However, excess AA could consume the generated reactive oxygen species (ROSs) that led to the inhibition of PCP degradation. Meanwhile, the PCP degradation by persulfate-AA was strongly pH dependent. The PCP degradation rate was declined as the initial pH increased from 3.5 to 10.5. At pH above 12.5, the base activation began to predominate over AA activation of persulfate. Furthermore, it was observed that the AA inducing persulfate activation was related to the extent of AA ionization, while C6H8O6 promoted the highest persulfate activation for the PCP degradation, and C6H6O62- induced the lowest persulfate activation. This study indicates the high potential of AA induced persulfate activation for treatment of organochlorine contaminated water.

Voltage-driven translocation behaviors of IgG molecule through nanopore arrays.

Nanopore-based biosensing has attracted more and more interests in the past years, which is also regarded as an emerging field with major impact on bio-analysis and fundamental understanding of nanoscale interactions down to single-molecule level. In this work, the voltage-driven translocation properties of goat antibody to human immunoglobulin G (IgG) are investigated using nanopore arrays in polycarbonate membranes. Obviously, the background ionic currents are modulated by IgG molecules for their physical place-holding effect. However, the detected ionic currents do 'not' continuously decrease as conceived; the currents first decrease, then increase, and finally stabilize with increasing IgG concentration. To understand this phenomenon, a simplified model is suggested, and the calculated results contribute to the understanding of the abnormal phenomenon in the actual ionic current changing tendency.