Toxicological effects involved in risk assessment of rare earth lanthanum on roots of Vicia faba L. seedlings

Combined chemical analyses and biological measurements were utilized to investigate potential toxicological effects and possible mechanisms involved in risk assessment of rare earth elements (REEs) on Vicia faba L. seedlings, which were hydroponically cultivated and exposed to various concentrations of lanthanum (La) for 15 days. The results showed that La contents in both the solution and roots increased with the increase of extraneous La, contributing to hormetic dose responses of superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX), ascorbate peroxidase (APX) and endoprotease (EP) isozymes activities, and HSP 70 production enhanced at low doses but suppressed at higher doses of La. These physiological responses constituted antioxidant and detoxification systems against La-induced oxidative stress. The elevated La levels also contributed to oxidatively modified proteins, which were most responsible for subsequent cell death and growth retardation of the roots. By combination of hormetic and traditional threshold dose levels, the threshold dose range was deduced to be 108-195 μg La/g dry weight in the roots, corresponding to 0.90-3.12 mg/L of soluble La in the culture solution. It suggests that persistent applications of REEs may lead to potential ecological risk in the environment.     

填料投加对玉米深加工废水处理效果的影响

向单一活性污泥池内投加填料,分析了填料填充率对玉米深加工废水处理效果的影响。结果显示,随着填料填充率的增加,系统的抗CODCr冲击能力有所增强,当填充率为30%时,进水CODCr平均值为832.7mg/L,相邻2天CODCr变化的平均值为779.6mg/L,即CODCr变化均值超过进水CODCr的94%,CODCr去除率仍稳定在80%以上。填料投加对NH4+-N的去除效果改善较大,当填充率为20%时,NH4+-N去除率较无填料投加提高近50%,达90%;当填充率为30%时,去除率可基本稳定在90%。在试验研究的填料填充率下,填料投加对TN的去除改善不大。另外试验还观察到,污泥膨胀期间填料挂膜速率有加快趋势。     

大石围天坑群地下河沉积物中PAHs的污染特征

为探索喀斯特地下河沉积物中多环芳烃(PAHs)的污染特征、来源,研究选择典型的广西乐业大石围天坑群地下河进行,沿途采集7个断面的沉积物样品,利用气相色谱-质谱(GC-MS)对16种优控PAHs进行定量分析.结果表明,大石围天坑群地下河上层沉积物中总PAHs浓度为37.75～1 662.72 ng/g,下层沉积物为43....     

AERMOD用于沿海石化企业卫生防护距离计算的分析

我国趋向于在沿海地区建新大型石化企业,由于该地区气象和地形的特殊性,目前石化企业卫生防护距离计算的方法和标准不适舍于沿海地区.根据沿海地区石化企业的特点,提出使用新大气导则推荐的进一步预测模式AERMOD模型计算沿海石化企业卫生防护距离.以我国南方沿海某大型石化企业为例,分别使用不同的方法计算其卫生防护距离,并对结果进行分析比较.可以得出AERMOD模型计算结果更科学合理,可用于计算沿海地区石化企业的卫生防护距离.     

毛家村水库径流区生态环境状况与建设途径

毛家村水库是会泽县城居民主要的饮用水源,其水质经会泽县环境监测站监测,符合饮用水标准,但存在许多不容忽视的污染问题。其水质污染是点源和面源污染,水体趋于富营养化和粪大肠菌群超标。认为应从饮用水源保护、水环境整治、控制污染源、实施水土保持工程4个方面来加强生态环境建设,确保县城居民饮用水安全。     

不同温度下酚醛塑料释放甲醇的规律研究

为了预防和控制航天器、飞机、潜艇等密闭环境中挥发性有机物的污染,将有机硅改性酚醛塑料作为实验样品密封于Tedlar气体采样袋中,在不同的温度下试验,应用气相色谱-质谱联用仪在30 d的时间内对释放的甲醇进行连续测试,并进行曲线拟合回归.结果表明,40C时,甲醇释放量随试验时间的延长呈先增加后减少的趋势;50℃和65℃时...     

原子荧光光谱法测定环境水样中的锡

AFS-9700双道原子荧光光度计测定环境水样中的锡,选择最佳的仪器条件:负高压300V,原子化器高度8mm,灯电流80mA,载气流量400ml/min,屏蔽气流量900ml/min。在最佳酸碱比例-体积分数为4.0%的硝酸介质与20g/L硼氢化钾中,锡荧光强度与其质量浓度在1.00~10.0ug/L成线性关系,方法检出限为0.010ug/L,加标回收率为94.4%~105%,RSD(n=7)<2.3%。此方法更为简便,快速,灵敏度高,适用于环境水样中锡的测定。     

Preliminary study of groundwater denitrification using a composite membrane bioreactor

A composite membrane bioreactor (CMBR) integrating the immobilized cell technique and the membrane separation technology was developed for groundwater denitrification. The CMBR had two well mixed compartments with one filled with the nitrate-containing influent and the other with a dilute ethanol solution; the compartments were separated by the composite membrane consisting of a microporous membrane facing the influent and an immobilized cell membrane facing the ethanol solution. Nitrate and ethanol molecules diffused from the respective compartments into the immobilized cell membrane where nitrate was reduced to gaseous nitrogen by the denitrifying bacteria present there with ethanol as the carbon source. The microporous membrane was attached to one side of the immobilized cell membrane for retention of the disaggregated bacteria. Relative to the single dose of external ethanol, the two-dose supplementation produced better treatment results as evidenced by the lower concentrations of NO₃⁻-N and ethanol (as measured by total organic carbon) of the effluent. The batch treatment in CMBR removed most of the nitrate in the influent and attained a stable denitrification rate of 0.1 g·m⁻²·h⁻¹ for most of the 96-h cycles during the 30-cycle study. The effluent was essentially free of ethanol and nitrite nitrogen.     

黄土高原水蚀风蚀交错区典型植被下土壤呼吸季节变化特征与影响因素

运用红外气体分析仪测定了黄土高原水蚀风蚀交错区典型植被下土壤呼吸,分析了不同土地利用方式下土壤呼吸与土壤温度、水分和土壤养分的关系.结果表明,不同植被下土壤呼吸季节变化特征区别明显,主要受水分和温度的影响.裸地、农地、苜蓿地、柠条地、撂荒地、长芒草地、荒草地、退化苜蓿地、坡地苜蓿地、坡地撂荒地、坡地农地、梯田农地的土壤呼吸季节变化范围分别为0.32～0.82、0.41～2.83、0.74～2.81、0.76～3.07、0.67～2.79、0.51～2.12、0.56～2.05、0.59～1.66、0.42～2.09、0.31～1.86、0.32～1.93和0.41～3.17μmol.(m2.s)-1,土壤呼吸速率的季节变化幅度以农地(167%～203%)最大,依次为撂荒地(117%～154%)、柠条地(134%)、长芒草地(129%)、苜蓿地(119%～120%)、裸地(94%),最小是退化苜蓿地(92%).裸地和退化苜蓿地的土壤呼吸季节变化幅度不大,苜蓿地和柠条地月平均土壤呼吸强度显著高于其他土地利用方式,农地在7、8月土壤呼吸强度显著高于其它土地利用方式,且其温度敏感性(Q10)也最大,达1.86.不同植被下,土壤呼吸和土壤有机质及速效钾含量呈显著正相关关系,有机质和全氮主要在水热条件好的7、8月影响土壤呼吸,而在温度与水分条件不优越的条件下,土壤铵态氮的含量与土壤呼吸强度呈负相关.     

温州城市不同下垫面径流中无机氮的含量及初期冲刷效应

在温州两个采样区分别监测了4场降雨事件,选取交通干道、停车场、小区屋面、小区路面、城市排水系统汇流口、草地等6种下垫面,测定地表降雨径流中溶解铵态氮（NH＋4-N）、溶解硝态氮（NO-3-N）、溶解亚硝态氮（NO-2-N）的含量及基本理化指标.结果表明,温州城市降雨径流中NH＋4-N、NO-3-N和NO-2-N的降雨事件平均浓度（EMC）值分别介于0.40～5.55、0.01～4.70、0～0.87mg·L-1（以N计）之间,九山外河区域氮污染比山下河区域严重,交通干道、居民生活区是氮污染严重的地方,应加以重视.多数下垫面径流中溶解态无机氮以NH＋4-N为主,比例可达50%以上,九山外河区域各下垫面径流中NH＋4-N普遍超过了地表水环境V类水标准.除小区路面以外,各下垫面径流多次出现NH＋4-N的初期冲刷效应,仅小区屋面和汇流口径流中出现过NO--N初期冲刷效应.