利用差分光学吸收光谱技术,对北京市北郊的大气氨进行了近2个月的观测.结果显示,在秋冬季节,北京大气氨的浓度为(12.89±10.12)×10-9(part per billion),观测期间的小时浓度最大值为49.71×10-9.氨浓度的日变化呈现出白天低、夜晚高的特征,在早高峰时间,氨有明显的一个峰值浓度.另外,氨与NO2、CO、PM2.5和PM10之间相关性分别为0.845、0.824、0.821和0.598,明显高于春季,说明秋冬季北京大气氨受机动车排放影响明显.气象要素对氨 浓度明显影响,风速、气压和相对湿度与氨的关联性较高,相比而言,氨与气温关联性较低,说明秋冬季低温环境下,土壤排放、垃圾存储堆场和人体排泄物等排放对大气氨浓度影响较小. 相似文献
Herein, we found that anthraquinone (AQ) acted as a catalyst for the rapid and effective removal of triphenylmethane dye containing tertiary amino group (TDAG). Results showed that AQ had an enhanced catalytic reactivity towards the removal of TDAG compared to hydro-quinone, which was further proved and explained using density functional theory (DFT) calculations. AQs could achieve a TDAG removal efficiency and rate of approximately 100% and 0.3583 min−1, respectively, within 20 min. Quenching experiments and electron paramagnetic resonance (EPR) tests indicated that the superoxide radical (O2•−) generated through the catalytic reduction of an oxygen molecule (O2) by AQ contributed to the effective removal of the TDAG. In addition, it was found that the electrophilic attack of the O2•− radical on the TDAG was the driving force for the dye degradation process. Decreasing the pH led to protonation of the substituted group of AG, which resulted in formation of an electron deficient center in the TDAG molecule (TDAG-EDC+) through delocalization of the π electron. Therefore, the possibility of the electrophilic attack for the dye by the negative O2•- radical was significantly enhanced. This study revealed that the H+ and the O2•− generated by the catalytic reduction of O2 have synergistic effects that led to a significant increase in the dye removal rate and efficiency, which were higher than those obtained through persulfate oxidation. 相似文献
Soil formation and ecological rehabilitation is the most promising strategy to eliminate environmental risks of bauxite residue disposal areas. Its poor physical structure is nevertheless a major limitation to plant growth. Organic materials were demonstrated as effective ameliorants to improve the physical conditions of bauxite residue. In this study, three different organic materials including straw (5% W/W), humic acid (5% W/W), and humic acid-acrylamide polymer (0.2% and 0.4%, W/W) were selected to evaluate their effects on physical conditions of bauxite residue pretreated by phosphogypsum following a 120-day incubation experiment. The proportion of 2-1 mm macro-aggregates, mean weight diameter (MWD) and geometric mean diameter (GWD) increased following organic materials addition, which indicated that organic materials could enhance aggregate stability. Compared with straw, and humic acid, humic acid-acrylamide polymer application had improved effects on the formation of water-stable aggregates in the residues. Furthermore, organic materials increased the total porosity, total pore volume and average pore diameter, and reduced the micropore content according to nitrogen gas adsorption (NA) and mercury intrusion porosimetry (MIP) analysis, whilst enhancing water retention of the residues based on water characteristic curves. Compared with traditional organic wastes, humic acid-acrylamide polymer could be regarded as a candidate according to the comprehensive consideration of the additive amount and the effects on physical conditions of bauxite residue. These findings could provide a novel application to both Ca-contained acid solid waste and high-molecular polymers on ecological rehabilitation at disposal areas. 相似文献
Freshwater lakes are important reservoirs for antibiotic resistance genes (ARGs). In this study, we determined the ARG profiles in water samples from Ying Lake, China, using high-throughput quantitative PCR. The high prevalence of ARGs suggested significant pollution with ARGs in the study area, where the ARG diversity and abundance were greater in an area with box-type fish farming than an area with fenced fish farming. Network analysis indicated the widespread co-occurrence of ARGs and mobile genetic elements. cphA-01, blalMP02, and blaCMY202 were identified as adequate indicator genes for estimating the total ARG abundances. Redundancy analysis indicated that changes in the microbial communities caused by variations in the physicochemical parameters with different fish culture methods mainly determined the ARGs in the lake system. Thus, analyzing the factors that affect ARGs provided novel insights into the mechanisms responsible for the maintenance and propagation of ARGs in a lake.
Environmental Chemistry Letters - Worldwide arsenic (As) contamination in soils induces pollution of surface and ground waters, reduces crop quality and yield, and threatens human health.... 相似文献