Water vapor in the air The volume of Water vapor is variable, depending on temperature, precipitation, rate of evaporation and other factors at a particular location The percentage of water vapor ranges from 0.1- 5%. Generally it is 1-3%(the 3rd most abundant constituents in the air)

2.1土壤胶体及其吸附性 2.2土壤的酸碱性 2.3土壤的氧化还原性

The atmosphere The atmosphere is a thin blanket of gas that envelops the earth The gases that make up the atmosphere are held close to the earth by the pull of gravity With increasing distance from the earth's surface, the temperature, density, and composition of the atmosphere gradually change

Air quality and particles Epidemiological(流行病学) evidence associates atmospheric particles with diseases and mortality Particles penetrate the lungs, blocking and irritating aIr passages. Particles themselves could exert toxic effects. ( toxic substances present in the particles [polycyclic Aromatic Hydrocarbons are examples of toxic substances in aerosols.]

3.污染物的生物迁移 3.1生物积累 3.2生物富集 3.3生物放大

Objectives of Water Treatment The objectives for water treatment derive from two concerns Human health and welfare The health of aquatic ecosystems

Pests and pesticides Pest: ANY UNWANTED organism that directly or indirectly interfere human activity is called a pest. Pesticides, or biocides are substances that can kill organisms that we consider to be undesirable The most widely used types of pesticides Insecticides Herbicides

Acute(急性) and chronic(慢性) toxicity Acute toxicity refers to a rapid and serious response to a high but short-lived dose Acute poisons interfere with essential physiological processes, leading to a variety symptoms of distress, even death Chronic toxicity refers to a time-lagged response to a relatively low but prolonged exposure

Plant nutrients Plant growth requires various nutrients Major nutrient elements: C,N, P trace elements: S, Si, Cl, I, and metallic elements(Fe, Mn, Cu, etc) The minor elements because of the low demand can Water y be supplied at adequate rates in natural

《环境化学 ENVIRONMENTAL CHEMISTRY》：大气气溶胶消光性质的研究进展（韦莲芳）