Effects of eggshell addition on calcium-deficient acid soils contaminated with heavy metals

The eggshell was used to remediate the contaminated soil by heavy metals. The eggshell addition decreased the available state of the heavy metals. The available calcium in the soil increased due to eggshell addition. The efficiency was investigated in different moisture conditions. In this study, effects of water conditions (flooded, wet, or dry) and eggshell dosages (0, 0.1, 1.0, and 10.0 g/kg soil, respectively) on pH variation, content of unavailable state of heavy metals, form of heavy metals, and available nutritious element calcium (Ca) in acid soils contaminated with heavy metals were investigated, respectively. The soil samples were continuously cultivated indoors and analyzed by toxicity characteristic leaching procedure and community bureau of reference (BCR) sequential extraction procedure. The results showed that the addition of eggshell could effectively improve the pH of acid soil and increase it to neutral level. Moreover, the contents of unavailable state of heavy metals Cu, Zn, and Cd increased significantly. Furthermore, when the soil was cultivated under the flooded condition with 1.0 g/kg eggshell, the unavailable state of Cu, Zn, and Cd increased the most, and these heavy metals were transformed into residual state. On the other hand, the amount of available state of Ca increased to 432.19 from 73.34 mg/kg with the addition of 1.0 g/kg eggshell, which indicated that the addition of eggshell dramatically improved the available state of Ca. Therefore, eggshell could ameliorate the soil environment as it led to the decrease of available heavy metals and improvement of fertilization effectively. In a word, this study indicates that the addition of eggshell would be a new potential method for remediation of acid field soils contaminated with heavy metals.     

Ethylene,xylene, toluene and hexane are major contributors of atmospheric ozone in Hangzhou,China, prior to the 2022 Asian Games

Environmental Chemistry Letters - The occurrence of volatile organic compounds (VOCs) in the atmosphere is a major health issue, notably in China, because those compounds are the precursors of...     

Bioaccumulation of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in wild aquatic species from an electronic waste (e-waste) recycling site in South China

Water and several wild aquatic species including Chinese mysterysnail, prawn, fish, and water snake were collected from a reservoir surrounded by several e-waste recycling workshops in South China. The samples were examined to investigate the levels and bioaccumulation extent of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) released from electronic waste (e-waste) which was processed by crude recycling method. Elevated levels of PBDEs [52.7 to 1702 ng/g wet weight (ww)] and PCBs (20.2-25958 ng/g ww) were found in the collected biota species compared to that in the reference samples (13.0-20.5 ng/g ww for PBDEs and 75.4-82.8 ng/g ww for PCBs). log BAF (bioaccumulation factor) ranged from 2.9 to 5.3 for PBDEs and from 1.2 to 8.4 for PCBs, depending on congeners and species. The relationship between log BAFs and log K(OW) (octanol-water partition coefficient) can be adequately described by species-specific parabolic models wherein log BAFs generally increased at log K(OW)<7 then decreased with further increasing log K(OW) both for PBDEs and PCBs. The exceptions were for Chinese mysterysnail and prawn, in which the log BAFs showed a positive linear correlation with log K(OW) for PBDEs. Some PBDE and PCB congeners showed BAF values declining from the general trend predicted by K(OW), largely attributing to metabolism of these congeners in species sampled.     

Design of single vertical tube falling-film evaporation basing on experiment

An experimental study for fluid hydrodynamic characteristics in thin water films falling down the outside of a vertical tube was performed with the analysis of several factors about the uniformity and stability of the film. Liquid evaporation is of major interest for many fields in process engineering. One of these is chemical process engineering, where evaporation of liquids and generation of super heated steam is mandatory for numerous processes. Generally, this is performed by the use of classical pool boiling and evaporation process equipment, providing relatively limited performance. The performance of the film distributor will affect the production capacity and service life of the evaporator. In this publication a novel falling-film distributor which is used annular gap and inlet tube rotated tangentially 270° to guarantee the film uniformity is presented. Experimental data suggested that there is optimum annular gap distance is between 1.5 and 2.0 mm and the spray density should be controlled between 250 and 700 kg m⁻¹ h⁻¹. Several suggestions for evaporator design are proposed.     

环境监测中如何提高水污染环境监测质量的分析

随着经济的不断发展,人类对于资源的消耗速度越来越快,使得环境正在逐渐的恶化。针对这种情况,保护环境成为了当前社会发展的重要手段。环境监测就是定期对环境中所含有的污染物进行分析,通过不断收集数据,来分析环境污染的变化,进而找出影响环境的原因。环境监测的内容包括空气、土壤等多个方面,水体监测是其中重要的工作内容,直接影响到对环境的正确评价。鉴于此,本文首先分析了水污染监测工作的重要性,然后提出了提高水污染监测质量的方法,希望能够为相关工作提供借鉴。     

改性累托石对镉离子吸附性能的研究

将天然累托石进行处理制备改性累托石.在静态条件下,研究了改性累托石对重金属离子Cd2 的吸附容量、等温吸附等吸附性能,同时探讨了影响吸附的因素和吸附机理.结果表明,改性累托石对Cd2 的吸附容量高.在20℃,pH=5.0～7.0、Cd2 浓度0～100 mg/L范围内,按镉与改性累托石质量比为1∶20投加改性累托石进行处理,吸附时间为90min,Cd2 去除率可达96%以上,改性累托石对Cd2 的吸附在实验浓度范围内符合符合Freundlich方程.     

工程项目大气环境影响评价中污染物浓度叠加方法研究

本文对工程项目大气环境影响评价中污染物浓度叠加方法进行了研究。在叠加方法研究中,提出用判别指数判别筛选叠加方法。通过叠加方法筛选,选取了瞬时浓度,日均浓度叠加方法。经实例验证,证明方法是合理可行的,适用于大气污染物浓度叠加计算。     

土壤环境质量分级评价

利用土壤环境背景值和土壤临界值两个主要参数,将土壤质量状况分为背景区、安全区、过渡区、警戒区和控制区等5级;结合上海地区的状况,分析其物理特征和含量范围,井提出应采取的措施。     

生物反应器填埋场的发展及应用研究

缩短垃圾稳定化时间,并有效地收集和处理渗滤液及填埋气体,是促使传统卫生填埋法向生物反应器填埋场发展的主要因素。生物反应器填埋场通过回灌渗滤液等控制手段,改善填埋场内部微生化环境,加速填埋场稳定化进程。生物反应器填埋场的关键在于渗滤液收集系统、防渗系统、气体收集系统和渗滤液回灌系统。一些在运行的全规模生物反应器填埋场证明了这种操作方式能加快垃圾降解和填埋气体的产生,减少渗滤液处理量。然而还有一些经济和技术上的不确定性,包括持久有效性、压实度和氧化-还原环境等因素都需要进一步研究。     

塔克什肯口岸土壤放射核素含量调查研究

利用高分辨半导体能谱分析方法分析了新疆塔克什肯口岸土壤天然放射性核素铀238、镭226、钍232、钾40和人工放射性核素铯137的含量,共选取8个采样点16个土壤样品及4个煤炭及废旧金属样点。结果表明:进口货物道路各采样点其铀238、钾40及铯137均比非进口货物道路各点高,镭226、钍232含量则相反,而煤炭和废金属的各样品的铀238、镭226、钍232、钾40都高于进出口道路和非进口道路,Cs137则相反,表明进口煤炭和非金属对天然放射性核素产生了较大影响,而对人工放射性核素影响较小。和新疆及全国背景值比,进口道路和非进口道路土壤中各放射性核素含量均未超过天然本底值范围,进口煤炭和废金属虽然各放射性核素含量则略高于背景值,表明试验点没有受到放射性污染,对当地居民和进出境人员不会产生辐射伤害。