Distribution and migration of heavy metals in soil and crops affected by acid mine drainage: Public health implications in Guangdong Province, China.

Acid mine drainages (AMD) contain high concentrations of heavy metals, and their discharges into streams and rivers constitute serious environmental problems. This article examines the effects of AMD on soil, plant and human health at Dabaoshan mine in Guangdong Province, China. Although the large scale mining was stopped in 2011, the heavy metal pollution in soil continues to endanger crops and human health in that region. The objectives of this study were to elucidate distribution and migration of Cd, Cu, Zn, As and Pb and associated health implications to local inhabitants. We collected and analyzed 74 crop samples including 28 sugarcane, 30 vegetables, 16 paddy rice and the corresponding soil samples, used correlation and linear relationship for transformation process analysis, and applied carcinogenic and non-carcinogenic risk for hazard evaluation. Results showed that the local soils were heavily polluted with Cd, Cu and As (especially for Cd) and the mean Igeo value was as high as 3.77. Cadmium, Cu, and Zn in rice and vegetables were comparable with those found four years ago, while As and Pb in edible parts were 2 to 5 times lower than before. The root uptake of Cd and Zn contributed mainly to their high concentrations in crops due to high exchangeable fraction of soil, while leafy vegetables accumulated elevated As and Pb contents mainly due to the atmospheric deposition. Metal concentrations in sugarcane roots were higher than those in rice and vegetable roots. The risk assessment for crops consumption showed that the hazard quotients values were of 21 to 25 times higher than the threshold level for vegetables and rice, indicating a potential non-carcinogenic risk to the consumers. The estimated mean total cancer risk value of 0.0516 more than 100 times exceeded the USEPA accepted risk level of 1×10(-4), indicating unsuitability of the soil for cultivating the food crops. Therefore, the local agricultural and the land-use policies need to be reevaluated.

Water-Induced Surface Reconstruction of Co3O4 on the (111) Plane for High-Efficiency Li-O2 Batteries in a Hybrid Electrolyte.

The crystal plane effect of cobalt oxide has attracted much attention in Li-O2 batteries (LOBs) and other electrocatalytic fields. However, boosting the catalytic activity of a specific plane still faces significant challenges. Herein, a strategy of adding water into the electrolyte is developed to construct a LiOH-based Li-O2 battery system using the (111) plane-exposed Co3O4 as a cathode catalyst. The electrochemical performance shows that on the (111) plane, in the presence of water, the overpotential is largely reduced from 1.5 to 1.0 V and the cycling performance is enhanced. It is confirmed that during the discharge process, water reacts to form LiOH and induce the phase transformation of Co3O4 to amorphous CoOx(OH)y. At the recharge stage, LiOH is first decomposed and then CoOx(OH)y is reduced to Co3O4. Compared with pristine (111), the newly formed Co3O4 surface exhibits more active sites, which accelerates the following oxygen reduction and oxygen evolution processes. This work not only reveals the reaction mechanism of water-induced reaction on the (111) plane of Co3O4 but also provides a new perspective for further design of hybrid Li-O2 batteries with a low polarization and a longer cycle life.

Bias-dependent hole transport through a multi-channel silicon nanowire transistor with single-acceptor-induced quantum dots.

Quantum transport in multi-channel silicon nanowire transistors presents enhanced data capacity and driving ability by overlapping current, which are essential for constructing quantum logic platforms. However, the overlapping behavior of the quantum transport through multi-channels remains elusive. Herein, we demonstrated bias-dependent hole transport spectroscopy from zero-dimensional (0D) to one-dimensional (1D) features in a lightly boron-doped multi-channel silicon nanowire transistor. The evolution of the initial 0D conductance peak splitting with source/drain bias voltages reveals the statistically distributed positions of single dopant atoms in multi-channels relative to the source or drain side. Two sets of 1D subbands are determined separately for heavy and light holes with different effective masses by measuring the positions of transconductance valleys, which have a negative shift with increasing bias voltage. Our results will benefit the practical utilization of silicon-based devices with atomic-level functionality in the field of quantum computation.

Effect of water-in-oil-in-water (W/O/W) double emulsions to encapsulate nisin on the quality and storage stability of fresh noodles.

Rock-bean protein (RP) was extracted from wild rock beans by ultrasonic treatment and microwave extraction. The RP has a high content of 7S and 11S globulin components and good heat stability. Subsequently, water-oil-water double emulsions were prepared using a water core containing nisin, momordica charantia extract (MCE), and Lactobacillus plantarum as functional additives, corn oil as the intermediate wall, and RP/gum arabic (GA) as the outer wall material. For a ratio of corn oil to water of 5:1, the maximum encapsulation efficiency was 28.22%, and RP/GA had good dispersion characteristics, where the smallest average particle size was achieved for a 1:1 ratio. Finally, the microcapsules were used to study the effect of its addition to noodles. The addition of 2 wt% of the microcapsules to low-gluten flour resulted in a dough with suitable rheology, and can extend the shelf life of the fresh noodles prepared using this dough.

Preparation of corn starch/rock bean protein edible film loaded with d-limonene particles and their application in glutinous rice cake preservation.

Glycerol hydrogenated rosin (GEHR) and d-limonene were prepared for micro-particles by electrostatic spray method. When the GEHR/d-limonene ratio is 5.5:4.5 and the electrostatic spray extrusion speed is 1 mL/h, the best particle size (177.24 ± 17.09 µm) and embedding rate of d-limonene (41.74 ± 9.88%) are achieved. Then, rock bean protein (RP) was extracted from wild rock beans and combined with GEHR/d-limonene particles and corn starch (CS) to prepare a new type of edible film. The prepared film was characterized using Fourier transform infrared spectroscopy in terms of structural changes and physical, optical, mechanical, and thermal properties. The results show that the edible film with a ratio of 1:1 exhibited more optimized thermal (179.2 °C) and mechanical properties (TS 0.88 MPa, EAB 54.36%). Studies on freshly prepared glutinous rice cake as an object for preservation using edible film show that the films can prolong shelf life by ~2-4 d. Through this experiment, it can serve as a reference for the development of a new type of edible film.

Coking wastewater treatment plant as a sources of polycyclic aromatic hydrocarbons (PAHs) in sediments and ecological risk assessment.

The spatial and temporal distribution of polycyclic aromatic hydrocarbons (PAHs) was investigated in sediments of Maba River, a major tributary of Beijiang River (South China). A total of 13 samples from Maba River and its tributary, Meihua River, were analyzed for 16 PAHs. The total concentration of 16 PAHs (ΣPAH) in high and low water period ranged between 47.61 to 25480.98 ng g-1, with a mean concentration of 4382.98 ng g-1, and 60.30 to 15956.62 ng g-1 with a mean concentration of 3664.32 ng g-1, respectively. Three-ring and four-ring PAHs were the dominant species. It was concluded that a pattern of pyrolytic input as a major source of PAHs in sediments through the molecular ratio method for the source identification, such as HMW/LMW PAHs, Flu/(Flu+Pyr), IcdP/(IcdP+BghiP) and BaA/(BaA+Chr). It is suggested that the pollution emission from the iron and steel plant might be the most important sources of PAHs into Maba River water system. The threat of PAHs contamination to biota of the river was assessed using effect range low (ERL) and effect range median (ERM) values, which suggested that PAHs in Maba River and its tributary had already caused ecological risks.