《环境污染和监测》魔法香蕉nanb

3、Organic Contaminants

　　1.List three main reasons why organochlorine (OC) pesticides are persistent in the environment. Describe some of the consequences of this persistence.
　　列出有机氯农药在环境中持续存在的三个主要原因。描述这种坚持的一些后果
　　（1）Reason
　　①DO NOT readily degrade in the environment:
　　Resistant to photolytic and biological degradation耐光解和生物降解；Carbon-halogen bonds are resistant to hydrolysis；抗水解Aromatic rings are also resistant to degradation；More Cl atoms in a compound = more resistant氯越多耐受性越强；Half-life > 1 month, sometimes much greater
　　② Lipophilic:亲脂性的
　　? More soluble in octanol辛醇 than water (Log KOW)
　　③ Accumulate in the environment and organisms
　　（2）Result：
　　①Persistence leads to potential for:
　　? Bioconcentration、? Bioaccumulation、? Toxicity (Environmental and Human)
　　②POPs have been linked to adverse health effects in both health and animals including:
　　cancer,?damage to the nervous system,?reproductive disorders, and?disruption of the immune system.免疫

　　2.Describe the mode of action of DDT that makes it an effective insecticide. Explain why DDT was eventually phased out by many governments
　　描述使滴滴涕成为有效杀虫剂的作用方式。解释为什么DDT最终被许多政府淘汰
　　（1）action
　　? Binds to Na+ ion channels in insect neurons and prevents closing of the channel
　　? Neurons fire spontaneously leading to exhaustion and death
　　? Shape: two tetrahedral C and two flat benzene rings
　　（2）why be phased out
　　①Persistence
　　? Soil half life: Estimated between 2 – 15 years
　　? C-Cl bonds and aromatic structures very resistant to degradation
　　? Semi-volatile = transported to poles via global distillation
　　②Bioaccumulation and Biomagnification
　　? Both DDT and DDE are very lipophilic
　　? Long half-lives
　　③Human Toxicity
　　? Potential chronic toxicity in humans:
　　? Reduced fertility,? Birth defects,? Breast cancer,? Diabetes,? Pre-term birth,? Decreased lactation,? Sperm impairment,? Currently, Indoor Residual Spraying (IRS) in developing countries is increasing exposure intensity.
　　– Ecological Toxicity
　　? Bioaccumulation and Biomagnification of DDT may lead to ecological toxicity in a number of species, but is mostly commonly associated with effects on predatory birds as characterized by:? Eggshell thinning in predatory birds、? Decline of the American Bald Eagle
　　3.Explain what the term Kow means. Describe the relationship between the log Kow values of organic pollutants and bio-magnification.
　　解释Kow一词的含义。描述有机污染物的logkow值与生物放大倍数之间的关系。
　　①Kow：
　　正辛醇-水分配系数(Octanol-Water Partition Coefficient, Kow，或称辛醇-水分配系数)为讨论有机污染物在环境介质（水、土壤或沉积物）中分配平衡的极其重要的参数。Kow定义为某一有机物在某一个温度下，在正辛醇相和水相达到分配平衡之后，在两相的浓度的比值。Kow,i=有机物i 在正辛醇相中的浓度/在水相中的浓度
　　Octanol-Water Partition Coefficient (Kow, or octanol-water partition coefficient) is an extremely important parameter to discuss the distribution balance of organic pollutants in environmental media (water, soil or sediment). Kow is defined as the ratio of the concentration of an organic matter at a certain temperature after the distribution equilibrium between the n-octanol phase and the water phase is reached. Kow,i= concentration of organic matter i in the n-octanol phase/concentration in the water phase
　　②Since POPs are relatively fat soluble they:
　　? Accumulate in the fat or organisms、? Have high potential to biomagnify in the food-chain.
　　4.Explain why POPs tend to present a greater environmental concern in colder climates.
　　解释为什么在较冷的气候条件下持久性有机污染物会对环境造成更大的影响。
　　①Colder climates present a number of challenges for the degradation of POPs
　　②Colder climates mean – slower degradation rates
　　③Ecosystems have animals with a higher percentage of body body fat (seals, bears, whales) – tend to bioaccumulate more POPs
　　④ Humans tend to rely on theses animals as a food source – and hence also accumulate more POPs

　　5. Classify the following compounds as either organic, inorganic or organometallic.
　　将下列化合物分为有机化合物、无机化合物或有机金属化合物。
　　有机物：含C有机物，有机酸（羧酸），非金属元素
　　无机物：酸碱盐
　　①organometalic:a
　　②inorganic:b,e,c
　　③organic:d