Fawen Zhang

Slag-based cementitious material was synthesized from blast furnace slag, clinker, gypsum, and activator to replace cement in cemented paste backfill (CPB). We researched the influence of slag-based cementitious material dosages and curing times on the properties of CPB, including unconfined compressive strength tests, leachate toxicity and chemical speciation of heavy metal as well as microstructural tests and analyses. The results indicated that the addition of slag-based cementitious material improved the compressive strength of the CPB, which attained the compressive strength requirements (≥1.0 MPa) at 28 days. The leachate concentrations of Pb, Cr, Cu, and Cd in CPB decreased as the slag-based cementitious material dosage and curing period increased, which met the standard (GB 5085.3-2007). The dosage of 10% slag-based cementitious material could effectively immobilize the heavy metals in the tailings, and the immobilization performance was similar to that of 20% cement, which indicated the amount of slag-based cementitious material was only half the quantity of cement in CPB. Microstructural analysis showed the hydration products included calcium silicate hydrate, ettringite, and portlandite, which could enhance the bonding force between the tailing grains.

Arsenic (As) is considered to be a carcinogen that tends to be accumulated in rice. However, the molecular mechanism of crop response to As is not sufficiently understood. In the study, M2 and L5 were screened out from 16 experimental cultivars as sensitive and tolerant ones based on the phenotypic changes between As(III) treated and control group, respectively. A total of 11052 significant differential expression genes (DEGs) and 918 significantly differentially accumulated metabolites (DAMs) were identified by using the comparative transcriptomic and metabolomic analysis. The KEGG pathway analysis suggesting that As(III) stress could effectively induce the production of DEGs related to rice defense function to improve plant tolerance responses to As(III) toxicity. The variation of DEGs metabolic pathways between two comparison groups was mainly concerning plant growth. The metabolomic analysis demonstrated that DAMs detected in M2 and L5 were principally enriched in the pathway related to plant growth, development and stress tolerance. The dermatan L-iduronate was the largest contributors of the two pairwise groups to separating metabolites in As(III) treated to control group. The combined transcriptome and metabolome analysis revealed that changes of the DAMs in M2 and L5 comparison groups regulated by DEGs resulted in variation in phenotype and arsenic accumulation between the two cultivars. This study provides insight into the molecular mechanisms related to the response and processes involved in toxic effects and adaptive strategies to As(III) stress.

With the widespread applications of manufactured nanoparticles (NPs), there are increasing concerns about their potential adverse effects on the environment and living systems. Many studies demonstrated that NPs could significantly affect the growth and development of crop plants. However, knowledge regarding the impacts of NPs on crop quality is rather limited. In this study, the effects of CeO2 NPs (25, 75, and 225 mg Ce/kg) and CeCl3 (25 mg Ce/kg) on the nutritional components of soil-cultivated corn and soybean plants were evaluated. Both treatments tended to decrease the dry weight of grain per plant, while only 225 mg/kg CeO2 NPs on soybean and CeCl3 on corn showed statistical significance compared with the respective control. CeO2 NPs at 225 mg/kg significantly decreased the content of starch in the corn kernels by 18.2% but increased total phenols in soybean seeds by 18.4%. Neither CeO2 NPs nor CeCl3 significantly affected the contents of minerals in corn kernels except for Zn. However, in the case of soybean, the two treatments tended to decrease the contents of P, Zn, Mn, and Mo but increase the content of S. Overall, the results suggest that CeO2 NPs and Ce3+ ions showed similar but not identical effects on corn and soybean plants. CeO2 NPs affect the nutritional quality of crop plants in a species-dependent manner.

In order to enhance efficiency of the nitrogen and phosphorus removal of sewage treatment plant, Taking Wu Longkou sewage treatment plant project in Zhengzhou as an example, this article introduces the structure, the working principle, the craft character, as well as the problems existed in the practical application of the improved oxidation ditch, and raises some corresponding processing countermeasures. Looked from the running situation of Wu Longkou sewage treatment plant, the improved oxidation ditch have certain advantages in city sewage treatment, such as high organic removing efficiency, good removing effect of nitrogen and phosphorus, low investing expenses and operating cost and so on. It is a craft that is worth promoting in urban sewage treatment.