The role of herbicides in the erosion of salt marshes in eastern England

Laboratory studies and field trials were conducted to investigate the role of herbicides on saltmarsh vegetation, and their possible significance to saltmarsh erosion. Herbicide concentrations within the ranges present in the aquatic environment were found to reduce the photosynthetic efficiency and growth of both epipelic diatoms and higher saltmarsh plants in the laboratory and in situ. The addition of sublethal concentrations of herbicides resulted in decreased growth rates and photosynthetic efficiency of diatoms and photosynthetic efficiency of higher plants. Sediment stability also decreased due to a reduction in diatom EPS production. There was qualitative evidence that diatoms migrated deeper into the sediment when the surface was exposed to simazine, reducing surface sediment stability by the absence of a cohesive biofilm. Sediment loads on leaves severely reduced photosynthesis in Limonium vulgare. This, coupled with reduced carbon assimilation from the effects of herbicides, could have large negative consequences for plant productivity and over winter survival of saltmarsh plants. The data support the hypothesis that sublethal herbicide concentrations could be playing a role in the increased erosion of salt marshes that has occurred over the past 40 years.     

Copper and Zn uptake by radish and pakchoi as affected by application of livestock and poultry manures

Environmental safety of agricultural utilization of livestock and poultry manures from intensive farming is attracting great attention because the manures often contain high concentrations of heavy metals and organic pollutants. Pot experiments, in which a pig manure (PM), a chicken manure (CM) and a commercial organic manure (OM) with different concentrations of Cu and Zn to simulate soil metal accumulation by manure application for different times were utilized in a garden soil at a rate of 2% (W/W), were conducted to study the effect of application of these livestock and poultry manures on growth of radish (Raphanus sativus L.) and pakchoi (Brassica chinensis L.) as well as their Cu and Zn uptake. The results exhibit that the manures except the PM improved the growth of radish and pakchoi. The difference of biomass among the same manure treatments containing different concentrations of Cu and Zn, however, was insignificant. In addition, application of the livestock and poultry manures significantly increased soil pHs and electric conductivities (EC) compared with the control, which is ascribed that these manures had high pH and contained large amounts of inorganic ions. The available soil Zn concentrations in the PM were higher than that in the CM and OM, and the extractable soil Cu concentrations in the three manures were almost the same after radish growth in the garden soil but were different after pakchoi growth. Zinc and Cu concentrations in the radish and pakchoi tissues increased when the soil Zn and Cu concentrations increased by manures application, but were still within a safe value. An except is the treatment PM4 in which the Zn concentration of the above-ground part of radish was 28.7 mg kg-1, exceeding the Chinese Food Hygiene Standard of 20 mg kg-1 based on fresh weight. Good correlation was obtained between the extractable soil Zn (or Cu) concentrations extracted by 1.0 mol l-1 NH4NO3 and the Zn (or Cu) concentrations in radish and pakchoi tissues, which was expected to be effective in forecasting Cu and Zn availability to radish and pakchoi in manure agronomic utilization.     

Study of factors affecting on the extraction efficiency of polycyclic aromatic hydrocarbons from soils using open-vessel focused microwave-assisted extraction

As part of an evaluation of focused microwave-assisted extraction (FMAE) using an open-vessel system, the effects of matrix, moisture content, ageing, and solvent have been studied on the extraction efficiency of polycyclic aromatic hydrocarbons (PAHs) from spiked soils. PAHs were spiked onto three different uncontaminated air dried and originally wet soil matrices with 1- and 20-day ageing periods. Solvents used were hexane–acetone (1:1), cyclohexane–acetone (1:1) and dichloromethane. FMAE only required a small amount of solvent (20 ml) and short extraction time (10 min) in the open cell under 90 W of microwave power. The results revealed that the extraction efficiency strongly depends on the nature of soil matrix; moisture content may enhance the recoveries of PAHs for many cases; and, the influence of the type of solvent is not significant. A comparison between microwave extraction and 16-h Soxhlet extraction has been made on spiked soils. It evidenced that the microwave method under ambient pressure is a suitable alternative to Soxhlet method for the analysis of PAHs in soils. For the evaluation of the developed FMAE method, three reference materials were used. The PAHs recovered from three reference materials were in a good agreement with reference values.     

城市降雨径流水质污染分析

目前我国对一些小流域的农业区面源污染积累较多经验，对城市面源污染的研究比较少，这是因为随着城市化进程的加速，这是人类在城市上的活动能力较农业区大幅度地增加，从而导致城市地面污染种类繁多复杂。本文通过应用径流形成原理理论对其进行初步分析，提出现行适用的控制城市径流污染的方法为工程和非工程的两大类。     

污染土壤的修复技术研究进展

分析了当前我国严峻的土壤环境状况，并从重金属和有机污染物两个方面，全面介绍了当前污染土壤的各种修复技术，包括物理化学修复方法、植物修复方法和微生物修复方法等；对各种方法的修复原理、已取得的研究进展、存在的优缺点及其将来的发展趋势进行了较全面的综述和展望。文章认为，污染土壤修复将是一项非常具有挑战性同时又是一项非常有前途的修复技术，将会对人类健康和经济可持续发展发挥重要作用。     

大气可吸入颗粒物(PM10)中矿物组分的X射线衍射研究

利用X射线衍射技术对北京2002春季和夏季的可吸入颗粒物进行了研究.结果表明,北京春季和夏季可吸入颗粒物的矿物组成明显不同,春季可吸入颗粒物中的矿物以硅铝酸盐为主,同时存在碳酸盐、硫酸盐、硫化物、铁的氧化物、粘土矿物以及难以鉴定的矿物;在夏季的样品中,矿物的种类有所减少,却有新的物种出现,如氯化氨、硫酸氨等.XRD定量分析显示,在沙尘天气时,可吸入颗粒物中石英和粘土矿物以及非晶质分别占到24.1%、28.5%和2 0%,斜长石和方解石分别占到10.4%和8.1%,其他矿物总共不到10%.矿物组分的确定对可吸入颗粒物来源的识别有一定的指导作用.     

Ce-based catalysts used in advanced oxidation processes for organic wastewater treatment: A review

Refractory organic pollutants in water threaten human health and environmental safety, and advanced oxidation processes (AOPs) are effective for the degradation of these pollutants. Catalysts play vital role in AOPs, and Ce-based catalysts have exhibited excellent performance. Recently, the development and application of Ce-based catalysts in various AOPs have been reported. Our study conducts the first review in this rapid growing field. This paper clarifies the variety and properties of Ce-based catalysts. Their applications in different AOP systems (catalytic ozonation, photodegradation, Fenton-like reactions, sulfate radical-based AOPs, and catalytic sonochemistry) are discussed. Different Ce-based catalysts suit different reaction systems and produce different active radicals. Finally, future research directions of Ce-based catalysts in AOP systems are suggested.     

MnCeOx/diatomite catalyst for persulfate activation to degrade organic pollutants

Persulfate(PS)-based oxidation technologies are attracting increasing attentions in water treatment due to their high efficiency and stability.In this study,a novel diatomite supported MnCeO_x composite(MnCeO_x/diatomite) was prepared and characterized for activation of PS to degrade organic pollutants.Results indicated that diatomite not only dispersed MnCeO_x and increased the specific surface area of catalyst,but also improved the low-valence metal site(Mn~(2+)and Ce~(3+)) and reactive oxygen species site(-OH) of MnCeO_x,thus enhancing the activities of MnCeO_x.MnCeO_x/diatomite/PS showed high efficiency for multiple dyes and pharmaceutical pollutants.Constant rate(k) of MnCeO_x/diatomite(k_(MnCeOx/diatomite)) was three times higher than the sum of constant rate of MnCeOx(k_(MnCeO_x))and constant rate of diatomite(k_(diatomite)).In addition,MnCeO_x/diatomite showed wide pH application(5-9).Cl~- and NO_3~(2-) had no effect while SO_4~(2-) and humid acid had slightly negative effects on MnCeOx/diatomite/PS system.Moreover,MnCeOx/diatomite showed good reusability and stability.Mechanism analyses indicated that electron transfer of Mn and Ce attributed to the activation of PS and oxygen to produce free radicals.SO_4·~-,·OH and O_2·~-on the surface of catalyst were the main active free radicals to attack pollutants.     

作物重金属铜污染的HHT边际谱特征与污染预测模型

为了解读作物受重金属污染的光谱响应与光谱特征,以不同浓度梯度硫酸铜（CuSO₄·5H₂O）胁迫土壤的盆栽玉米培养胁迫实验为研究对象,依据不同胁迫梯度下玉米叶片反射光谱以及叶片中Cu²⁺含量的测定数据,采用希尔伯特-黄变换（HHT）方法,研究了玉米叶片在不同Cu²⁺胁迫梯度下光谱的Hilbert边际谱变化特征与污染程度预测方法.通过构建玉米叶片光谱的边际谱熵（MSE）,边际谱幅值（MSA）、边际谱陡坡斜率（MSSS）和边际谱包围面积（MSEA）等特征参量,分析叶片在不同Cu²⁺污染程度下的边际谱变化;同时基于边际谱特征参量值与叶片中Cu²⁺含量的相关性分析和逐步回归统计,提出了玉米叶片重金属污染的Cu²⁺含量预测指数模型.实验结果表明,不同Cu²⁺胁迫梯度下,玉米叶片光谱的边际谱为分布在100Hz频率以内的连续谱;MSE值表现出与叶片中Cu²⁺含量呈负相关的变化趋势,而MSA、MSSS和MSEA值都表现出与叶片中Cu²⁺含量呈正相关的变化趋势;由于MSEA值与叶片中Cu²⁺含量的相关性最好,可把MSEA作为监测作物重金属污染衡量或预测的最优指标;根据MSE、MSA、MSSS和MSEA值构建的Cu²⁺含量预计指数模型应用结果比较,证明MSEA指数模型具有最优的预测能力.     

京津冀对流层甲醛的时空演变特征及其影响因素

依据2009—2016年OMI卫星反演的逐日数据,结合遥感图像处理技术和克里金插值法,对京津冀地区对流层甲醛柱浓度的时空特征及影响因素进行了分析.结果发现,2009—2016年8年间京津冀地区甲醛柱浓度年际变化总体呈上升趋势,年均增长率为1.01%,最大增长率出现于2009—2010年,为12.91%.8年间,甲醛柱浓度值具有波动性,最低值和最高值分别出现于2009年和2013年.研究区甲醛柱浓度季节变化表现为夏季值秋季值冬季值春季值,甲醛柱浓度月均值在每年的6月达到最高.甲醛柱浓度空间分布的低值区大多处于地势较高的京津冀地区西北部,高值区主要分布在京津冀地区南部平原.甲醛柱浓度变化不仅与自然因素的温度呈显著正相关,与气压呈显著负相关,还与社会经济因素中的煤炭消耗量、原油消耗量及工业增加值等呈正相关.京津冀地区甲醛柱浓度时空特征总体受当地自然和社会经济因素的综合影响.