成都市及周边地区严重臭氧污染过程成因分析

结合天气形势,地面观测资料和WRF-CMAQ模式,分析了2017年7月8~15日成都市一次罕见持续O₃污染过程的特征及成因,量化了各个物理化学过程对此次污染过程的相对贡献,并通过敏感性实验分析了四川盆地内O₃及其前体物的区域传输和本地光化学反应对此次污染过程的影响.结果表明,此次O₃持续污染过程主要是因为四川盆地内盛行偏东风,导致盆地东部城市群的O₃及其前体物经区域输送到成都及周边地区,加之成都市出现小风、气温升高等气象条件进而形成,属于典型的传输性爆发污染.持续污染形成的主要物理化学机制体现为日间气相化学过程贡献为稳定的正值,加之输送过程贡献出现爆发式升高,进而导致近地面O₃小时净增量迅速上升且高达50μg/（m³·h）,随之O₃浓度迅速响应,产生爆发式增长.此外,敏感性实验结果显示此次成都市O₃持续污染的形成受区域输送影响较受本地光化学反应影响更为明显.O₃污染爆发前上游地区高浓度O₃及其前体物沿流场输送并在成都及周边地区不断积累,导致日间O₃浓度不断升高.     

Dynamic fate modeling of γ-hexachlorocyclohexane in the lower reaches of the Liao River

A QWASI model dependent on temperature is parameterized to describe the long-term fate of persistent organic pollutants (POPs) in the Liao River. The model parameters, namely fugacity capacity, degradation rate, and transfer coefficient, are profoundly affected by temperature. This model is used to simulate the fate of γ-hexachlorocyclohexane (γ-HCH) in the lower reaches of the Liao River from 1998 to 2008. Modeling results show that γ-HCH fugacity capacities in air, water, and sediment increase as temperature decreases, and the transfer and transformation rate coefficients increase as temperature increases. The variations of transfer and transformation parameter D values depend on fugacity capacities, and transfer and transformation coefficients simultaneously. The performance of the model is evaluated by comparing the predicted and observed concentrations in the water and sediment of the Liao River. The predicted values agree well with the observed value in the order of magnitude, in most cases within the factor of 3. It is believed that the model is appropriate for simulating the long term fate of POPs in the Liao River. Translated from Environmental Science, 2006, 27(1): 121–125 [译自: 环境科学]     

磺酰脲类除草剂的残留分析

磺酰脲类除草剂是一类新型超高效除草剂，大约包括２Ｖ化合物，已被广泛用于禾谷作物防除阔叶杂草以及某些禾本科杂草，该类除草剂在环境中的残留浓度〈１μｇ．ｋｇ＾－１水平。常规的分析方法包括生物鉴定，酶免疫分析，气相色谱法和高效液相色谱法（ＨＰＬＣ）、ＨＰＬＣ／ＭＳ联用后，可以准确测定复杂环境样中磺酰脲类除草剂的痕量残留。     

持久性有机污染物(POPs)及其生态毒性的研究现状与展望

持久性有机污染物(POPs)是一类具有持久性、易于生物富集、对人和生物具有毒性的有机污染物质。POPs已成为全球关注的热点问题，它们对人和生物具有免疫毒性、内分泌毒性、生殖发育影响、致癌性以及其它一些毒性效应。因此应加强POPs生态毒性的研究。     

磺酰脲类除草剂在硅胶G表面的光解

应用高效薄层析方法研究了苄嘧磺隆，甲磺隆，氯磺隆，氯嘧磺隆4种磺酰脲类除草剂在氙灯与太阳光下的光解动力学，以及8种有机色素对苄嘧磺隆光降解的影响。结果表明4种除草剂在硅胶G表面的降解呈一级动力学反应；有机色素对除草剂的降解均表现显著的猝灭效应。其中以姜黄素的猝灭作用最强，色素剂量与光解中的猝灭效应存在着显著的相关性。色素剂量加大，猝灭效应加强。     

Best Management Practices for Silvicultural Chemicals and the Science Behind Them

Silvicultural chemicals include fertilizers and pesticides applied for forest management. All states east of the Rockies have at least some form of silvicultural chemical best management practices (SCBMPs) and it is widely accepted that SCBMPs effect some protection of water quality. All SCBMPs recommend handling and application precautions and a minimum width streamside management zone (SMZ) on each side of streams for protection of water quality and aquatic ecosystems. Typically these zones increase in width as stream width increases. In areas where cold-water fish are present, additional widths are designated for their protection. Minimum SMZ widths range from 8 to 91 meters on each side of the stream bank for intermittent and perennial streams. Most SMZ recommendations do not cover ephemeral drainages, ditches or canals. SMZs are generally described as being site specific with width dependent on slope, soil type and other conditions as well as the stream's designation as perennial or intermittent. The science behind SCBMPs is often elusive. Spray drift can be controlled through proper selection and use of application technology while considering site specific conditions. SMZs greatly reduce the amount of herbicides reaching streams. Available toxicological data and research on aquatic ecosystem impacts from herbicide use suggest that additional protection from silvicultural chemicals may not be necessary. However, there is evidence to suggest that protection of ephemeral and intermittent channels can further reduce entry of silvicultural chemicals into streams and also reduce sedimentation. This may be the most fruitful area of research we can pursue in light of the knowledge gaps listed.     

The rise of glyphosate and new opportunities for biosentinel early‐warning studies

Glyphosate has become the most commonly used herbicide worldwide and is reputedly environmentally benign, nontoxic, and safe for use near wildlife and humans. However, studies indicate its toxicity is underestimated and its persistence in the environment is greater than once thought. Its actions as a neurotoxin and endocrine disruptor indicate its potential to act in similar ways to persistent organic pollutants such as the organochlorines dichlorodiphenyltrichloroethane (DDT) and dioxin. Exposure to glyphosate and glyphosate‐based herbicides for both wildlife and people is likely to be chronic and at sublethal levels, with multiple and ongoing exposure events occurring in urban and agricultural landscapes. Despite this, there has been little research on the impact of glyphosate on wildlife populations, and existing studies appear in the agricultural, toxicology, and water‐chemistry literature that may have limited visibility among wildlife biologists. These studies clearly demonstrate a link between chronic exposure and neurotoxicity, endocrine disruption, cell damage, and immune suppression. There is a strong case for the recognition of glyphosate as an emerging organic contaminant and substantial potential exists for collaborative research among ecologists, toxicologists, and chemists to quantify the impact of glyphosate on wildlife and to evaluate the role of biosentinel species in a preemptive move to mitigate downstream impacts on people. There is scope to develop a decision framework to aid the choice of species to biomonitor and analysis methods based on the target contaminant, spatial and temporal extent of contamination, and perceived risk. Birds in particular offer considerable potential in this role because they span agricultural and urban environments, coastal, inland, and wetland ecosystems where glyphosate residues are known to be present.     

Human milk contamination by nine organochlorine pesticide residues (OCPs)

Abstract

Organochlorine pesticides (OCPs) are widely used around the world as insecticides, herbicides, fungicides, nematicides, and rodenticides. Despite banned in Brazil, the usage remains occurring in many countries. The persistence and extreme mobility of OCPs contribute to the contamination of the environment and the human body. The OCPs bioaccumulation in adipose tissue triggers the excretion into human milk during breastfeeding. Hence, the present study determined eighteen OCPs residues in the breast milk of mothers from the Western Region of Bahia State, Brazil. Nine different residue species were found, including beta-Hexachlorocyclohexane (9.24?±?0.00?ng g^?1 fat), delta- Hexachlorocyclohexane (22.15?±?10.48?ng g^?1 fat), Heptachlor (58.08?±?74.13?ng g^?1 fat), Aldrin (142.65?±?50.65?ng g^?1 fat), Dieldrin (774.62?±?472.68?ng g^?1 fat), Endosulfan I (408.44?±?245.51?ng g^?1 fat), Dichloro-diphenyl-dichloro-ethylene (29.17?±?22.42?ng g^?1 fat), Dichloro-diphenyl-trichloro-ethane (28.87?±?0.00?ng g^?1 fat) and Methoxychlor (1699.67?±?797.43?ng g^?1 fat). The Methoxychlor presence in all samples may reveal a recent exposure, while Dieldrin and Endosulfan I analyses can point to distant past exposure.     

典型持久性有机污染物在翅碱蓬中的分布特征

碱蓬是潮间带的常见优势种群,为了解其在持久性有机污染物从陆域向海洋迁移中所起的作用,利用GC-MS研究了东营和营口潮间带盐沼植物翅碱蓬不同器官及根系土中有机氯农药(OCPs)、多环芳烃(PAHs)、十溴联苯醚(BDE209)和多氯联苯(PCBs)的含量和分布特征.结果表明,4类持久性有机污染物在翅碱蓬中的污染水平依次为ΣPAHsΣOCPsBDE209ΣPCBs(96～1506ng/g、14～577ng/g、1.8～33ng/g和399～2161pg/g).营口潮间带沉积物中OCPs、PAHs和PCBs的污染水平高于东营,但这3类污染物在两地潮间带翅碱蓬叶子中的含量水平相当.OCPs在两地翅碱蓬各器官中的分布相同,即茎根叶,PAHs和PCBs2种污染物受根系土中有机质含量的影响,在翅碱蓬器官中呈现不同的分布.BDE209在东营潮间带的污染水平(19.7ng/g)高于营口(2.36ng/g),在碱蓬器官中呈现不同分布.     

北京地区冬夏季持续性雾-霾发生的环境气象条件对比分析

在北京地区,除冬季供暖期外盛夏也是雾-霾天气的高发季节,与我国南方不同.使用微波辐射仪、风廓线和常规气象探测资料、NCEP再分析资料以及大气成分观测结果,通过对比分析揭示了冬、夏季持续6 d的2个雾-霾过程形成和维持机制的异同.冬季雾-霾过程出现在高空西北气流、低层多短波活动的背景下,其形成和维持的主要机制是边界层内始终有逆温层、地面弱风场、底层湿度逐渐增大.逆温层昼高夜低、湿度昼小夜大是影响PM2.5质量浓度和能见度日变化的重要环境因子.在雾-霾天气持续期间地面弱风场能够维持主要源于冷空气势力弱、常不能影响到地面.此外,入夜后地面迅速辐射降温、边界层上层有暖平流以及空气过山后下沉增温在逆温层的形成中起了关键作用.然而,对于夏季持续性雾-霾天气,气溶胶区域输送、环境大气保持对流性稳定、空气的高饱和度是其发生的重要条件.在副热带高压长时间控制下对流层低层盛行偏南风,北京的PM2.5质量浓度随着偏南风风速增大升高.对流层底层系统性偏南风与北京附近的山谷风共同构成了从北京以南气溶胶累积地向北输送的机制.夏季雾-霾过程低层没有逆温,但是北京上空一直维持超过200 J·kG-1的对流抑制能量,它同样限制了污染物的垂直扩散.夏季自由对流高度也存在昼夜变化,其对PM2.5浓度和能见度的作用与逆温层高度升降相同.因此,冬、夏个例分别代表了2种不同类型的持续性雾-霾过程,导致差异的根本原因在于大气环流型.