Single and joint stress of acetochlor and Pb on three agricultural crops in northeast China

In order to evaluate ecological risk of agrochemicals in agricultural environment, single and joint toxic effects of an important herbicide and a typical heavy metal on root elongation of crops were investigated. Seeds of the three crops including wheat （Triticum aestivum）, Chinese cabbage （Brassica pekimensis） and soybean （Glycine max） as the main crops in northeast China were exposed to acetochior as a herbicide and lead （Pb） as a heavy metal using the pot-culture method, and meadow brown soil as one of the main soils distributed in northeast China was applied in the investigation. The results indicated that the interactive effects of the two pollutants on root elongation of the three crops were very complicated although they had markedly significant （P〈0.01） linear interrelationships based on the regression analyses. When the concentration of added Pb^2＋ reached 200 mg/kg, acetochlor and Pb had an antagonistic effect on the inhibition of root elongation of the three crops. However, acetochlor and Pb had significantly （P〈0.05） synergic effects on the inhibition of root elongation when concentration of added Pb^2＋ was up to 1000 mg/kg. At the low concentration of added Pb, joint toxicity of acetochlor and Pb was more dependent on the concentration of Pb. Among the three crops, wheat was the most sensitive to the toxicity of Pb and Chinese cabbage was the most sensitive to the toxicity of acetochlor.     

济南大气臭氧浓度变化规律

利用近2a济南市区近地面大气O₃浓度的观测数据,分析了O₃浓度的分布特征及时间变化规律.结果表明,济南市区O₃浓度以1a为周期呈明显的波动变化特征,城市光化学污染较重;1d当中O₃浓度呈明显的单峰型变化,一般在午后达到最高值,而日出时分出现最低值;春季和夏季O₃浓度高于秋季和冬季,而夏季和秋季O₃浓度的日内变化幅度明显高于春季和冬季;受人们活动规律的影响,周末O₃浓度的日内变化规律与平日有所不同.     

Optimized coagulation pretreatment alleviates ultrafiltration membrane fouling: The role of floc properties and slow-mixing speed on mechanisms of chitosan-assisted coagulation

To alleviate ultrafiltration(UF) membrane fouling, the pre-coagulation of poly-aluminum chloride(PACl) with the aid of chitosan(CTS) was conducted for synthetic humic acid–kaolin water treatment. Pre-coagulation of three molecular weights(MW) CTSs(50–190 kDa(CTSL), 190–310 kDa(CTSM) and 310–375 kDa(CTSH)) was optimized with slow-mixing speeds of 30, 60 and 90 r/min, respectively. The removal efficiency and floc properties as well as membrane fouling were analyzed, and were compared to results obtained by conventional coagulation with PACl. Results showed that variations in floc properties could be ascribed to the coagulation mechanisms of CTS_L/CTS_M/CTS_H at different slow-mixing speeds, resulting in reduced UF membrane fouling. Specifically, at the low speed of 30 r/min, all three CTS types produced flocs with similar properties, while CTSLresulted in the lowest removal efficiency and aggravated irreversible fouling. At the appropriate speed of 60 r/min, CTSMgenerated the most compact flocs with the combined effects of bridging and path mechanisms. The compact cake layer formed could alleviate irreversible fouling,which was beneficial for prolonging the operation of the UF membrane. At the high speed of90 r/min, CTSHformed fragile flocs and aggravated irreversible membrane fouling. We considered membrane fouling to be affected by floc properties and the resultant removal efficiency, which was governed by the MW of the CTS used and the slow-mixing speed applied as well.     

Determination of hexabromocyclododecanes in sediments from the Haihe River in China by an optimized HPLC–MS–MS method

Hexabromocyclododecanes(HBCDs),a new type of persistent organic pollutants widely used as brominated flame retardants,have attracted wide attention due to their increasing level and toxicity. A method based on high-performance liquid chromatography mass spectrometry(HPLC–MS–MS)in electrospray ionization mode has been developed by optimization of various parameters,which effectively improved the separation degree and responsive intensity of α-,β-and γ-HBCD isomers. The concentrations and distribution profiles of three HBCD isomers were investigated in sediments from the Haihe River in China.It was observed that the concentrations of HBCDs varied in the range of 0.4–58.82 ng/g,showing a decreasing trend along the flow direction,possibly due to attenuation and biodegradation along the flow direction of the Haihe River. The distribution profile of α-,β-,γ-HBCD was 7.91%–88.6%,0–91.47%,and 0.62%–42.83%,respectively. Interestingly,α-HBCD dominated in most sample sites. This was different from the distribution profile in commercial industrial products,which might be attributed to the inter-transformation and different degradation rates of the three HBCD isomers. The potential ecological risk of HBCDs in sediment was characterized under the two-tiered procedure of the European Medicines Evaluation Agency for environmental risk assessment. Although the HBCDs in the selected section of the Haihe River presented "no risk" in the sediment compartment,its risk in sediment cannot be neglected since sediment is one of the important sinks and reservoirs of pollutants.     

东部平原不同类型湖泊沉积物中有机磷的特征

以选自东部平原3种不同类型8个浅水湖泊的18个表层沉积物样品为研究对象,运用分级提取法,研究了沉积物中有机磷（OP）质量分数、形态及其分布状况,并探讨了OP组分与湖泊富营养化的关系. 结果表明:东部平原湖泊沉积物中w（OP）为65.2～539.2 mg/kg,占w（TP）的19.9%～40.6%,污染程度高的沉积物w（OP）高于污染程度较轻的沉积物. 沉积物中各形态有机磷主要以中活性有机磷（MLOP）与非活性有机磷（NLOP）为主,不同类型湖泊沉积物中各形态w（OP）顺序均为城市湖泊>大型养殖型湖泊>大型自然湖泊. 城市湖泊与养殖型湖泊以NLOP为主,其相对含量达到50%以上;而大型自然湖泊以生物有效性有机磷（LOP+MLOP）为主,其相对含量为54.6%～61.6%,表明沉积物中有机磷分布状况与湖泊污染程度和人类活动紧密相关. 酸提取有机磷质量分数〔w（HCl-P_o）〕为10.5～200.9 mg/kg,在不同污染程度湖泊沉积物中差异明显,其和总有机磷（P_o）的比值〔w（HCl-P_o）/w（P_o）〕与湖泊水质指标呈显著正相关（P<0.01）,与沉积物w（TP）,w（OP）,w（LOP）及w（MLOP）也均呈显著正相关（P<0.01）,即沉积物中的HCl-P_o可能是湖泊水体磷的重要来源,沉积物中w（HCl-P_o）/w（P_o）可以反映湖泊的富营养化程度.      

二氧化硫在大气液相中的氧化

评述了二氧化硫在大气液相中的非催化氧化、催化氧化及光参与催化氧化,讨论了各种氧化机理的相对重要性。     

秦岭穆家庄铜矿地球化学特征

位于秦岭造山带东部柞山热水盆地中南部的穆家庄铜矿床由 7个矿体组成 ,赋矿地层为中泥盆统一套浅变质的具韵律特征的复理石沉积建造 ,矿床产出与地层层位、区域构造和NWW向断裂破碎带密切相关。矿石及其围岩的矿物组成、结构构造、化学成分、流体包裹体和氧、碳同位素地球化学研究表明 ,成矿温度为15 0～ 330℃ ,盐度 5 .8～ 2 3% ,矿石及围岩均以富SiO2 、TFe、Cu、Mn、Ba、Ca、Zn、Pb、Mg、As、Sb、S、C、B、K等元素为特征 ,成矿元素Cu、Zn、Pb等主要来源于前泥盆纪地层 ,成矿流体的O、C主要来自海水 ,铜矿床成因属于弱改造的海底喷流沉积型     

浅析喀斯特生态系统健康影响因子及评价指标——以毕节地区为例

从喀斯特生态系统以及喀斯特生态系统健康评价的概念出发,以毕节地区为例,分析了影响喀斯特生态系统健康的各类因子,如水土流失及石漠化、水资源、生物多样性、地貌、人类活动强度与方式、人-社会-生态健康可持续性等,利用因子载荷分析方法,从生态系统的结构功能、可持续利用能力、动态变化等三个方面筛选出26个因子构建了喀斯特生态系统健康评价的指标体系。     

Single and joint effects of pesticides and mercury on soil urease

The influence of two pesticides including chlorimuron-ethyl and furadan and mercury （Hg） on urease activity in 4 soils （meadow burozem and phaeozem） was investigated. The soils were exposed to various concentrations of the two pesticides and Hg individually and simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in soil. Chlorimuron-ethyl and furadan could both activate urease in the 4 soils. The maximum increment of urease activity by chlorimuronethyl was up to 14%-18%. There was almost an equal increase （up to 13%-21%） in the urease activity by furadan. On the contrary, Hg markedly inhibited soil urease activity. A logarithmic equation was used to describe the relationship （P〈0.05） between the concentration of Hg and the activity of soil urease in the 4 tested soils. Semi-effect dose （ED50） values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the calculation of the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with metal Hg on soil urease was mainly synergic at the highest tested concentrations.     

太原市冬季PM2.5化学组分特征与来源解析

为研究太原市城区冬季PM_2.5污染特征及来源,于2017年1月对PM_2.5及其化学组分（水溶性离子、碳组分和微量元素）、气态污染物（SO₂、NO₂）进行在线观测,结合气象数据,分析了清洁天和污染天PM_2.5及其化学组分特征,并利用正定矩阵因子分析法（positive matrix factorization,PMF）对PM_2.5进行来源解析.结果表明,2017年1月太原市城区污染天PM_2.5质量浓度（239.92 μg·m^-3）为清洁天的5.70倍,污染天PM_2.5主要化学组分SO₄^2-、NO₃^-、NH₄⁺、Cl^-、OC和EC分别为清洁天的7.04、5.76、6.51、5.62、4.06和4.70倍;污染天硫的氧化速率（SOR）和氮的氧化速率（NOR）分别为0.12和0.19,明显高于清洁天,说明污染天二次转化程度更高;PMF解析结果显示,污染天二次源（35.06%）、燃煤源（30.19%）和机动车源（24.25%）较清洁天分别增长18.03%、7.39%和2.10%,说明太原市城区污染天在管控机动车和燃煤等一次排放源的基础上,更应该注意对二次源前体物的控制.