Historical trends of organochlorine pesticides (OCPs) recorded in sediments across the Tibetan Plateau

Sediment cores from four lakes across the Tibetan Plateau were used as natural archives to study the time trends of organochlorine pesticides (OCPs). The total concentrations of dichlorodiphenyltrichloroethane (ΣDDT) and hexachlorocyclohexane isomers (ΣHCH) were in the range of 0.04–1.61 and 0.08–1.88 ng/g based on dry weight (dw), while the input fluxes were in the range of 0.3–236 and 0.7–295 pg/cm²/y in the core sediments, respectively. The input fluxes of ΣDDT and ΣHCH generally peaked in sediment layers corresponding to the 1970s–1990s and peaked in top sediment layers. The ratio of α/γ-HCH decreased in the top layer sediments, implying that the contribution of lindane (pure γ-HCH) has been increasing in recent years. In addition, the ratio of o,p′-DDT/p,p′-DDT increased significantly over the last 15–20 years, suggesting that dicofol (characterized by high ratio of o,p′-DDT/p,p′-DDT about 7.0) has recently become a relatively more important source of DDT compared to technical DDT itself. The time trends of OCPs recorded in lake sediments examined the impact on such remote alpine regions by human activities.     

Evaluation of fast atmospheric dispersion models in a regular street network

Environmental Fluid Mechanics - The need to balance computational speed and simulation accuracy is a key challenge in designing atmospheric dispersion models that can be used in scenarios where...     

草甘膦与镉复合胁迫对玉米幼苗抗氧化酶活性及光合作用的影响

为了探讨草甘膦(PMG)与重金属镉(Cd)复合胁迫对作物(玉米幼苗)生长的影响作用机制。通过温室盆栽试验,分别进行了不同浓度的PMG单一处理(浓度分别设计为0、1.25、2.5、5、10、20 mg·kg~(-1))和不同浓度的PMG(浓度分别为0、1.25、2.5、5、10、20 mg·kg~(-1))与浓度5 mg·kg~(-1)Cd2+的复合处理。采用分光光度法和连续激发式荧光仪分别对玉米幼苗抗氧化酶(过氧化物酶POD、过氧化氢酶CAT、超氧化物歧化酶SOD)、丙二醛(MDA)、叶绿素含量、荧光动力学曲线及相关参数进行了测定。结果表明,单一和复合胁迫分别在PMG浓度为1.25~5 mg·kg~(-1)、1.25~2.5 mg·kg~(-1)时,玉米幼苗通过增大抗氧化酶(SOD、POD、CAT)活性,清除积累过多的活性氧自由基,提高叶绿素含量的合成,加大光合作用速率,促进玉米幼苗的生长;单一和复合胁迫分别在PMG浓度为5~20 mg·kg~(-1)、2.5~20 mg·kg~(-1)时,由于玉米幼苗积累了过多的膜脂过氧化物,导致抗氧化系统损坏,阻碍叶绿素含量的合成,同时也损害了PSII的功能(MO、φPO、ΨO、φEO、φDO、ABS/RC、TRO/RC、ETO/RC、DIO/RC、PIABS),导致玉米幼苗光合作用受到抑制,阻碍幼苗的生长。研究表明,草甘膦单一胁迫和与重金属镉复合胁迫,对玉米幼苗酶活性及光合作用的影响,均随处理浓度的升高表现为双阶段性,低浓度促进,高浓度抑制;与同浓度的PMG单一处理相比,Cd2+的存在,加大了PMG单独存在时的损害作用,使得玉米幼苗对PMG胁迫的敏感浓度点从5 mg·kg~(-1)降低到2.5 mg·kg~(-1)。     

Comparison of membrane fouling in ultrafiltration of down-flow and up-flow biological activated carbon effluents

The UF membrane fouling by down- and up-flow BAC effluents were compared. Up-flow BAC effluent fouled the membrane faster than down-flow BAC effluent. The combined effects dominated irreversible fouling. The extent of fouling exacerbated by inorganic particles was higher. The TMP, permeate flux, and normalized membrane flux during 21 days of UF of DBAC and UBAC effluents. Fouling during ultrafiltration of down- and up-flow biological activated carbon effluents was investigated to determine the roles of polysaccharides, proteins, and inorganic particles in ultrafiltration membrane fouling. During ultrafiltration of down- flow biological activated carbon effluent, the trans-membrane pressure was≤26 kPa and the permeate flux was steady at 46.7 L?m⁻²?h⁻¹. However, during ultrafiltration of up-flow biological activated carbon effluent, the highest trans-membrane pressure was almost 40 kPa and the permeate flux continuously decreased to 30 L?m⁻²?h⁻¹. At the end of the filtration period, the normalized membrane fluxes were 0.88 and 0.62 for down- and up-flow biological activated carbon effluents, respectively. The membrane removed the turbidity and polysaccharides content by 47.4% and 30.2% in down- flow biological activated effluent and 82.5% and 22.4% in up-flow biological activated carbon effluent, respectively, but retained few proteins. The retention of polysaccharides was higher on the membrane that filtered the down- flow biological activated effluent compared with that on the membrane that filtered the up-flow biological activated carbon effluent. The polysaccharides on the membranes fouled by up-flow biological activated carbon and down- flow biological activated effluents were spread continuously and clustered, respectively. These demonstrated that the up-flow biological activated carbon effluent fouled the membrane faster. Membrane fouling was associated with a portion of the polysaccharides (not the proteins) and inorganic particles in the feed water. When there was little difference in the polysaccharide concentrations between the feed waters, the fouling extent was exacerbated more by inorganic particles than by polysaccharides.     

预处理-气浮-氧化沟工艺处理再生纸废水

介绍了预处理-气浮-氧化沟工艺在再生纸废水处理工程中的应用。运行结果表明:该工艺处理效果稳定,耐冲击负荷能力强,进水ρ(COD)、ρ(BOD5)、ρ(SS)分别为1542,654,2254mg/L时,出水分别为77,38,22mg/L,系统出水水质达GB3544-2001《造纸工业水污染物排放标准》。     

汽车喷涂作业中连续送风式长管呼吸器应用的系统分析

本文讨论了汽车制造喷涂岗位作业常用两种呼吸防护方案:连续送风式长管呼吸器与自吸过滤式呼吸器。通过对比两种呼吸防护方案的特点,包括防护等级、组合防护功能、使用舒适性,以及员工接受度,发现连续送风式长管呼吸器在各方面都要优于自吸过滤式呼吸器。此外还重点介绍了连续送风式长管呼吸器在此种环境使用过程中所涉及到的系统组成、压缩空气质量、压力调节,流量及认证组件等部分的使用要求和要点。     

Hydrogeochemical and Isotopic Investigations on Groundwater Salinization in the Datong Basin,Northern China1

Abstract: Analyses of major elements, environmental isotope ratios (δ¹⁸O, δ²H), and PHREEQC inverse modeling investigations were conducted to understand the processes controlling the salinization of groundwater within the Datong Basin. The hydrochemical results showed that groundwater with high total dissolved solid (TDS) concentrations was dominated by sodium bicarbonate (Na‐HCO₃), sodium chlorite (Na‐Cl), and sodium sulfate (Na‐SO₄) type waters, whereas low‐TDS groundwater from near mountain areas was dominated by calcium bicarbonate (Ca‐HCO₃) and magnesium bicarbonate (Mg‐HCO₃) type waters. The characterization of the major components of groundwater and PHREEQC inverse modeling indicated that the aluminosilicate hydrolysis, cation exchange, and dissolution of evaporites (halite, mirabilite, and gypsum) governed the salinization of groundwater within the Datong Basin. The environmental isotope (δ¹⁸O, δ²H) and Cl^?/Br^? ratios revealed the impact of fast vertical recharge by irrigation returns and salt‐flushing water on the groundwater salinization. According to the analyses of major hydrochemical components and PHREEQC inverse modeling, evaporite dissolution associated with irrigation and salt‐flushing practice was probably the dominant controlling factor for the groundwater salinization, especially in the central part of the basin. Therefore, groundwater pumping for irrigation and salt‐flushing should be controlled to protect groundwater quality in this area.     

饭店绿色竞争力的关键要素与提升路径探讨

饭店的绿色竞争力是企业在提高了绿色化水平后在市场竞争中所表现出来的相对优势。绿色竞争力是企业竞争力的一部分,它主要由绿色技术、绿色管理、绿色产品、绿色人力、绿色营销等五个关键要素构成,并通过这些要素的改进和提高来实现饭店整体竞争力的提升。通过绿色竞争力的提高,可以使饭店在不牺牲环境利益的前提下获得更大、更持续的经营效益。     

高盐度采油废水生物处理影响因素

采用UASB+SBR法处理某海洋油田产生的采油废水。针对该废水难降解和高盐度的特性,探讨总盐度、Cl-浓度、处理负荷、曝气时间等因素对生物处理过程的影响,为工程设计及实际应用提供科学依据。     

几种阴阳离子对磷钨酸光催化降解甲基橙的影响

以磷钨酸为光催化剂,在紫外灯照射下,对甲基橙溶液进行光催化降解,考察了几种阴阳离子对磷钨酸光催化降解甲基橙溶液的影响。结果表明：Mg^2＋、Ca^2＋、NO3^-、SO4^2-和CO3^2-均对催化活性有促进作用,其中Mg^2＋和Ca^2＋仅有微弱的促进作用;NO3^-和SO4^2-随着浓度的增加促进作用也有所增加;CO3^2-则随着浓度的增加促进作用呈下降趋势;Mn^2＋、Al^3＋和Cl^-对光解反应存在较强的抑制作用,且Al^3＋和Cl^-随着其浓度的增加,抑制作用增强。