The linear accumulation of atmospheric mercury by vegetable and grass leaves: Potential biomonitors for atmospheric mercury pollution

One question in the use of plants as biomonitors for atmospheric mercury (Hg) is to confirm the linear relationships of Hg concentrations between air and leaves. To explore the origin of Hg in the vegetable and grass leaves, open top chambers (OTCs) experiment was conducted to study the relationships of Hg concentrations between air and leaves of lettuce (Lactuca sativa L.), radish (Raphanus sativus L.), alfalfa (Medicago sativa L.) and ryegrass (Lolium perenne L.). The influence of Hg in soil on Hg accumulation in leaves was studied simultaneously by soil Hg-enriched experiment. Hg concentrations in grass and vegetable leaves and roots were measured in both experiments. Results from OTCs experiment showed that Hg concentrations in leaves of the four species were significantly positively correlated with those in air during the growth time (p?<?0.05), while results from soil Hg-enriched experiment indicated that soil-borne Hg had significant influence on Hg accumulation in the roots of each plant (p?<?0.05), and some influence on vegetable leaves (p?<?0.05), but no significant influence on Hg accumulation in grass leaves (p?>?0.05). Thus, Hg in grass leaves is mainly originated from the atmosphere, and grass leaves are more suitable as potential biomonitors for atmospheric Hg pollution. The effect detection limits (EDLs) for the leaves of alfalfa and ryegrass were 15.1 and 22.2 ng g^–1, respectively, and the biological detection limit (BDL) for alfalfa and ryegrass was 3.4 ng m^–3.     

Removal of anionic azo dye from aqueous solution via an adsorption–photosensitized regeneration process on a TiO2 surface

Textile dye effluents are typically characterized by strong color and recalcitrance, even at very low concentration. The process of enrichment of anionic azo dye on the surface of TiO₂ fibers followed by photosensitization degradation under ambient air conditions was extensively investigated. Adsorption isotherms and zeta potentials were used to describe the “dye/TiO₂ surface” interface, taking into account the effects of pH on the nature and population of the surface groups on the TiO₂ fibers. The extent of the photocatalytic degradation of dye on TiO₂ surface was determined by FTIR. N₂ adsorption isotherms and optical spectra were employed to investigate the effect of photosensitization. The adsorption of dyes on the TiO₂ surface occurs via electrostatic attraction through the formation of single- or multidentate-coordinated surface complexes. Almost complete photobleaching of the absorption band at 534 nm is achieved in ~4 h. Dye-sensitized TiO₂ fiber could absorb part of the visible light spectrum (λ?<?600 nm). Interfacial electron transfer can potentially alter the degradation efficiency. The regenerated TiO₂ fiber could be reused for subsequent decolorization without a decline in adsorption efficiency compared with freshly prepared TiO₂ samples, which may be attributed to preservation of the hierarchical pore structure and restoration of the original surface properties. In summary, we propose an efficient “adsorption–photoregeneration–reuse” process applying TiO₂ fibers for the degradation of dyes in water.     

活性红BF-3BN脱色菌群的构建及特性研究

采用梯度压力式驯化法,从河南某印染厂的活性污泥中富集筛选一组活性红BF-3BN高效脱色菌群AR1。经菌株分离和16S rDNA测序分析,确定菌群内微生物分别归属Clostridium sp.、Pseudomonas sp.和Shewtnella sp.等3个属。染料脱色实验结果表明,在活性红BF-3BN起始浓度为200...     

Mg-Al水滑石对偶氮染料活性艳红X-3B的脱色性能研究

采用共沉淀法合成出一系列镁铝摩尔比不同的碳酸根型水滑石（LDHs）,经500℃高温煅烧制备出镁铝复合氧化物CLDH,并用X-射线、红外光谱对它们进行表征。考查了吸附剂投加量、反应时间、初始pH值等因素对LDHs和CLDH处理阴离子染料活性艳红X-3B模拟废水效果的影响,并对吸附机理进行探讨。实验结果表明：以镁铝摩尔比为3∶1时制得的水滑石对活性艳红X-3B溶液的脱色效果最好。水滑石LDHs及其焙烧产物CLDH对活性艳红X-3B染料均具有较好的吸附性能,最佳反应时间分别为60 min和30 min;在较宽的pH范围内二者的脱色性能稳定,且CLDH对该染料的吸附效果要优于LDHs。LDHs及CLDH对活性艳红X-3B的吸附结果符合Langmuir吸附等温式,25℃下饱和吸附量分别为263.77 mg/g和875.23 mg/g。LDHs及CLDH的吸附机理分别为离子交换和层状结构重建。饱和吸附后的CLDH用高温热解法再生,吸附性能良好,随再生次数增多,脱色率下降。     

Photolysis of Enrofloxacin in aqueous systems under simulated sunlight irradiation: Kinetics, mechanism and toxicity of photolysis products

Photolysis of Enro in water was investigated under simulated sunlight irradiation using a Xenon lamp. The results showed that Enro photolysis followed apparent first-order kinetics. Increasing Enro concentration from 5.0 to 40.0 mg L⁻¹ led to the decrease of the photolysis rate constant from 1.6 × 10⁻² to 3.0 × 10⁻³ min⁻¹. Compared with the acidic and basic conditions, the photolysis rate was faster at neutral condition. Both of nitrate and humic acid can markedly decrease the photolysis rate of Enro because they can competitively absorb photons with Enro. The electron spin resonance and reactive oxygen species scavenging experiments indicated that Enro underwent self-sensitized photooxidation via OH and ¹O₂. After irradiation for 90 min, only 13.1% reduction of TOC occurred in spite of fast photolysis of 58.9% of Enro, indicating that Enro was transformed into intermediates without complete mineralization. The photolysis of Enro involved three main pathways: decarboxylation, defluorination, and piperazinyl N⁴-dealkylation. The bioluminescence inhibition rate using Vibrio fischeri increased to 67.2% at 60 min and then decreased to 56.9% at 90 min, indicative of the generation of some more toxic intermediates than Enro and then the degradation of the intermediates. The results will help us understand fundamental mechanisms of Enro photolysis and provide insight into the potential fate and transformation of Enro in surface waters.     

Quantification of net carbon flux from plastic greenhouse vegetable cultivation: a full carbon cycle analysis

Plastic greenhouse vegetable cultivation (PGVC) has played a vital role in increasing incomes of farmers and expanded dramatically in last several decades. However, carbon budget after conversion from conventional vegetable cultivation (CVC) to PGVC has been poorly quantified. A full carbon cycle analysis was used to estimate the net carbon flux from PGVC systems based on the combination of data from both field observations and literatures. Carbon fixation was evaluated at two pre-selected locations in China. Results suggest that: (1) the carbon sink of PGVC is 1.21 and 1.23 Mg C ha⁻¹ yr⁻¹ for temperate and subtropical area, respectively; (2) the conversion from CVC to PGVC could substantially enhance carbon sink potential by 8.6 times in the temperate area and by 1.3 times in the subtropical area; (3) the expansion of PGVC usage could enhance the potential carbon sink of arable land in China overall.     

低温对MBBR、SBR深度处理废水出水水质的影响

比较了低温和常温下移动床生物膜反应器(MBBR)与 SBR 深度处理低浓度废水的出水水质,研究了低温对反应器出水 COD、运行温度、DO、出水 pH、出水蛋白质质量浓度的影响.实验结果表明:相同曝气和环境温度条件下,MBBR 比 SBR 的运行温度高 0.5-1.5 ℃,受环境温度影响更小;与常温相比,低温反应器内 D...     

Unanswered questions on the airborne transmission of COVID-19

Environmental Chemistry Letters - Policies and measures to control pandemics are often failing. While biological factors controlling transmission are usually well explored, little is known about...     

林业资源开发与利用的现状与对策分析

在生态系统中,森林是重要的组成成分之一,在社会、经济以及人类不断发展的时代背景下,林业资源因过度的开发而受到了破坏。从现下的实际情况看来,这种现象对人们的生活并没有带来太大的影响,但是,对子孙后代却造成了无法挽回的损失,因此,需要林业部门加大对林业资源的保护以及开发利用力度,以此来确保林业资源的最大化使用,严禁出现过度开采以及浪费资源的现象。鉴于此,本文就林业资源开发与利用的现状与对策展开探讨,以期为相关工作起到参考作用。     

雾霾天气背景下大气环境监测质量的提升路径研究

本文主要针对雾霾天气背景下大气环境监测质量的提升路径展开深入研究,先阐述了大气环境监测质量的提升重要性,比如有利于提高环境污染的防治水平、有利于不断提高城市环境规划水平等,然后重点提出了几点可行的提升路径,主要包括制定大气环境监测质量保障体系、加强环境质量监测网络建设、加强大气环境监测采样管理、加强3S技术的应用、加强监测监察联动协调机制、扩大大气环境质量评价范围等,确保监测数据与完整性和准确性相符,确保大气环境监测质量的稳步提升,以创建节能减排、生态环保的节约型社会。