Polybrominated diphenyl ethers (PBDEs) in soil and dust from plastic production and surrounding areas in eastern of China

Polybrominated diphenyl ethers (PBDEs) are a class of organic pollutants. They are used as flame retardants that caused worldwide environmental concern. This study investigated the occurrence of PBDEs in soils and dusts from three plastic manufacture plants and surrounding areas in Eastern China. A total of 13 PBDE congeners were detected using gas chromatography-mass spectrometer (electron impact ionization). The total concentrations of PBDEs range from 2.21 to 558, 19.7–4916, and 8.70–18,451 ng/g dry weight in the soils of three sampling areas, with mean of 1004 ng/g d w; in dusts, the concentrations range from 7240 to 10,469, 684–4482, and 193–3989 ng/g d w, with an overall mean of 3619 ng/g d w. The most abundant congener is the BDE-209, followed by BDE-153 and BDE-85. This indicates that the brominated flame retardant added in the plastic manufacture is mainly the commodity decabromodiphenyl ether. In comparison with other polluted areas around the world, the PBDE concentrations in the soils of the plastic manufacture plants are similar to those in soils of waste plastic disposal areas and PBDEs production sites, but orders of magnitude higher than those in agricultural soils, mountain soils and rural soils. Daily exposure was estimated using the average concentrations of the pollution sites. The hazard quotient shows that the PBDEs pose considerable human health risks, especially to children, to which attention should be paid.

     

Effect of chemical dose on phosphorus removal and membrane fouling control in a UCT-MBR

Phosphorus removal was enhanced effectively by dosing aluminum sulfate and effluent phosphorus concentration was lower than 0.5 mg/L. Sludge activity was not inhibited but improved slightly with addition of aluminum sulfate. EPS concentrations both in mixed liquid and on membrane surface were decreased, contributing to the effective mitigation of membrane fouling. To enhance phosphorus removal and make the effluent meet the strict discharge level of total phosphorus (TP, 0.5 mg/L), flocculant dosing is frequently applied. In this study, the performance of aluminum sulfate dosing in a University of Cape Town Membrane Bioreactor (UCT-MBR) was investigated, in terms of the nutrients removal performance, sludge characteristics and membrane fouling. The results indicated that the addition of aluminum sulfate into the aerobic reactor continuously had significantly enhanced phosphorus removal. Moreover, COD, NH₄⁺-N and TN removal were not affected and effluent all met the first level A criteria of GB18918-2002. In addition, the addition of aluminum sulfate had improved the sludge activity slightly and reduced trans-membrane pressure (TMP) increase rate from 1.13 KPa/d to 0.57 KPa/d effectively. The membrane fouling was alleviated attributed to the increased average particle sizes and the decreased accumulation of the small sludge particles on membrane surface. Furthermore, the decline of extracellular polymeric substance (EPS) concentration in mixed sludge liquid decreased its accumulation on membrane surface, resulting in the mitigation of membrane fouling directly.     

PPCPs in a drinking water treatment plant in the Yangtze River Delta of China: Occurrence,removal and risk assessment

• 39 PPCPs were investigated at a DWTP using the Yangtze River as its water source. • Grab and continuous sampling were conducted for the comparison of data consistency. • Ketoprofen & carbamazepine can be risk management indicators because of the high RQ. The occurrence and removal of 39 targeted pharmaceuticals and personal care products (PPCPs) from source water, through a drinking water treatment plant (DWTP) to the water supply station, were investigated around the central part of Yangtze River Delta in China using both grab sampling and continuous sampling. Totally 24 of the 39 targeted PPCPs were detected in raw water, and 12 PPCPs were detected in the finished water. The highest observed concentration was enrofloxacin (85.623 ng/L) in raw water. Removal efficiencies were remarkably negative correlated with log K_ow (r = -0.777, p<0.01) after calibration control of concentration, indicating that more soluble PPCPs are easier to remove by the combined process (prechlorination and flocculation/precipitation), the concentration level also had a great impact on the removal efficiency. The normal process in the pilot DWTP seems to be ineffective for PPCPs control, with the limited removal efficiency of less than 30% for each step: pre-chlorination, flocculation and precipitation, post-chlorination and filter. There were notable differences between the data from continuous sampling and grab sampling, which should be considered for different monitoring purposes. The chlorination and the hydrolytic decomposition of PPCPs in the water supply pipe may attenuate PPCPs concentration in the pipeline network. The PPCPs examined in the effluent of DWTP do not impose a potential health risk to the local consumers due to their RQ value lower than 0.00067.     

High cadmium adsorption on nanoscale zero-valent iron coated Eichhornia crassipes biochar

Environmental Chemistry Letters - Overgrowth of Eichhornia crassipes, or water hyacinth, in local waters is a major concern, which has caused severe ecological disasters. Moreover, once the E....     

冷冻胁迫对芦荟叶肉细胞原生质体中Ca2+、Na+分布的影响

低温和冻害是造成巨大农业损失和植物死亡的主要逆境因子。为揭示冷冻胁迫对植物细胞中离子分布的影响,选择芦荟细胞原生质体为受试材料,使用离子选择性微电极检测了经冷冻处理后的芦荟原生质体在低渗液中破裂时产生的Ca~(2+)浓度脉冲信号,并同时检测Na~+浓度脉冲信号作为对比。研究了冷冻温度、解冻时间和ZnO NPs处理等因素对冷冻胁迫下芦荟原生质体中Ca~(2+)分布的影响。结果表明,与未经冷冻处理的原生质体相对比,经过冷冻处理的原生质体破裂后,其Ca~(2+)脉冲信号前沿处发生明显的"凹陷",这说明,原生质体中Ca~(2+)分布出现分层现象,靠近细胞中心浓度较高而细胞膜附近浓度较低。这一分层现象在温度为-7℃时开始出现,原生质体解冻5 h后仍未消失。经过ZnO NPs预处理后再进行冷冻的原生质体,其Ca~(2+)脉冲凹陷深度明显减小。而当用ZnO NPs处理解冻后的原生质体时,其Ca~(2+)分层现象消失。冷冻胁迫下芦荟原生质体内Ca~(2+)分布发生显著变化,表明原生质体内Ca~(2+)分布变化与其抗寒反应存在一定关系。与Ca~(2+)相反,Na~+的分布几乎不受冷冻因素的影响。ZnO NPs处理对冷冻芦荟原生质体中Ca~(2+)浓度分布分层有明显的缓解作用,表明一定浓度范围的ZnO NPs在缓解冷冻造成的Ca~(2+)流动性下降,维持细胞Ca~(2+)分布的调控能力方面,具有一定的积极影响。     

自复位耗能摇摆框架的抗震性能参数分析

自复位耗能摇摆框架结构是在原RC框架结构基础上用自复位耗能摇摆柱(SCEDRC)对其中的普通柱进行改造而来。利用OpenSees有限元软件建立各结构的有限元模型,并进行动力弹塑性分析。对比了自复位耗能摇摆框架结构与RC框架结构的抗震性能;考察了自复位耗能支撑(SCEDB)安装角度、设计参数及SCEDRC位置等变化对结构抗震性能的影响。结果表明:自复位耗能摇摆框架结构的抗震性能优于RC框架结构,可实现改善结构变形模式、减小损伤和残余变形的目标。各参数变化对结构性能影响显著,SCEDB安装角度为30°～40°时,结构抗震性能最佳;增大SCEDB的第一刚度K1、第二刚度K2、初始预拉力P0和摩擦力F,均有利于提升结构的抗震性能;当SCEDRC布置为结构的中柱时,对提升整体抗震性能最为有利。     

16种农药对东亚小花蝽的生态风险评估

东亚小花蝽是我国北方林木、果园和农田的优势天敌昆虫。为评估常用化学农药对东亚小花蝽的毒害作用,首次测定了16种田间常用化学农药对东亚小花蝽的24 h急性接触毒性,并进行了生态风险评估。结果表明所试除草剂、杀菌剂和杀虫剂中的吡蚜酮对东亚小花蝽较为安全,3倍田间最高推荐剂量下的校正死亡率低于33.33%。阿维菌素、甲氨基阿维菌素苯甲酸盐、吡虫啉和啶虫脒对东亚小花蝽的半数致死浓度LC0分别为36.567、15.798、4.992和4.487 mg a.i.·L~(-1)5,农田内风险可接受。噻虫嗪、联苯菊酯和呋虫胺对东亚小花蝽的LC_(50)分别为0. 002、0. 080和0. 968 mg a. i.·L~(-1),农田内危害商值分别为3 976.36、69.03和16.93,在农田内对东亚小花蝽造成的风险均不可接受。本研究的结果有助于合理施用化学农药以保护和利用东亚小花蝽。     

Can floor-area-ratio incentive promote low impact development in a highly urbanized area?—A case study in Changzhou City,China

As an environmental friendly measure for surface runoff reduction, low impact development (LID) has been applied successfully in urban areas. However, due to high price of land and additional expense for LID construction in highly urbanized areas, the developers of real estate would not like to proceed LID exploitation. Floor area ratio (FAR) refers to “the ratio of a building’s total floor area to the size of the piece of land upon which it is built.” Increasing FAR indicates that the developers can construct higher buildings and earn more money. By means of awarding FAR, the developers may be willing to practice LID construction. In this study, a new residential district is selected as a case study to analyze the tradeoff between the runoff reduction goal achieving by LID practices and the incentive of awarding FAR to promote LID construction. The System for Urban Stormwater Treatment and Analysis IntegratioN (SUSTAIN) model is applied to simulate the runoff reduction under various LID designs and then derive the Pareto-optimal solutions to achieve urban runoff reduction goals based on cost efficiency. The results indicates that the maximum surface runoff reduction is 20.5%. Under the extremity scenarios, the government has options to award FAR of 0.028, 0.038 and 0.047 and the net benefits developers gain are 0 CNY, one million CNYand two million CNY, respectively. The results provide a LID construction guideline related to awarding FAR, which supports incentive policy making for promoting LID practices in the highly urbanized areas.

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侧向辐射注浆技术引起地表隆起变形分析

侧向辐射注浆技术是用于处治现役高速公路沉降变形的新技术,可在通车条件下对高速公路进行加固。在通车条件下对高速公路进行加固需要对施工效应进行分析,确保施工过程中高速公路通车安全。根据土体中的球孔扩张理论,将侧向辐射注浆假设为半无限体多球孔扩张模型,将几何条件复杂的侧向辐射注浆简化为多球孔几何模型,并引入有限边界球孔扩张理论,建立注浆压力和扩孔半径的关系,得到了土体注浆过程存在极限注浆压力,在极限注浆压力后存在软化效应的结果;确定注浆球孔扩张压力和隆起变形的关系,最终给出了同时考虑注浆压力和注浆量两个注浆施工控制指标的地表隆起位移计算方法。结合工程实测参数,计算并对比分析了不同注浆压力、不同注浆步距对地表隆起位移的影响,给出了侧向辐射注浆施工隆起位移的计算方法,能够对注浆设计和施工提供指导作用。     

Field tests to study the dynamics of weed inhibition of allelopathic rice and microbial physiological traits of rice rhizospheric soils北大核心CSCD

The weed inhibition of allelopathic rice PI312777 and nonallelopathic rice Lemont, allelopathic potential of rice rhizospheric soils, as well as the microbial physiological traits of rice rhizospheric soils, were studied by field tests after weedremoving and weed treatments. The results showed that the inhibitory rate of PI312777 at the 7-leaf stage on paddy weeds was 85.82%. Results of the Soil-Agar Sandwich method revealed that the allelopathic potential of PI312777 rhizospheric soils on the inhibitory rate of plant dry weight of barnyard grass was significantly higher at the 5-leaf stage than that at the 3-leaf stage, and increased by 20.16% from the 3-leaf stage to the 5-leaf stage after weed treatment. When at the same leaf stage, the soil microbe biomass carbon and soil respiration, the number of soil bacteria, and activity of soil enzymes (urease, protease, and sucrase) were significantly higher in PI312777 rhizospheric soils than in Lemont rhizospheric soils; they were also higher after the weed-removing treatment than after weed treatment. The largest increase of soil allelopathic potentials and soil microbial physiological indexes in PI312777 rhizospheric soils appeared from the 3-leaf stage to the 5-leaf stage. In case of weed treatment, the allelopathic potential of PI312777 rhizospheric soils on the soil microbe biomass carbon, soil respiration, the number of soil bacteria, activity of urease, activity of protease, and activity of sucrase increased by 53.11%, 51.56%, 38.97%, 44.83%, 60.00%, and 41.92%, respectively, from the 3-leaf stage to the 5-leaf stage. These results indicated that rice allelopathy had a close relationship with the activity of rhizospheric soils. Rice allelochemicals lead to the change of soil microbes; rice allelopathy is a process based on plant-soil interaction. © 2018 Science Press. All rights reserved.