微生物对土壤环境中重金属的影响 微生物对重金属的影响主要体现在四个方面 生物吸附和富集作用 溶解和沉淀作用 氧化还原作用 菌根真菌与土壤重金属的生物有效性的关系

Chapter 1.a Fable for Tomorrow There was once a town in the heart of america where all life seemed to live in harmony with its surroundings The town lay in the midst of a checkerboard of prosperous farms, with fields of grains and hillsides of orchards where in spring white clouds of bloom drifted

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

Toxic metals Some metals are essential for the normal development and well-being of humans and other creatures They include Na, K, ca, Mg, cu, Cr, and Zn Other metals are toxic even when present in an organism at very low concentrations Examples: Antimony, Arsenic, Barium

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

What is the pH of natural rain water? pH of natural rain water is determined by acidic and basic species that are

Ozone in the atmosphere STRATOSPHERE TROPOSPHERE In this region, ozone protects In this region, ozone can us from the sun's harmful damage lung tissue and uitraviolet radiation

Whether and climate Weather is the condition of the atmosphere in terms of temperature, humidity, winds and precipitation Climate is defined as the average weather over various time periods ranging from a few weeks to decades to geological timescales Whether and climate are ultimately determined by location, topography, and the exchange of radiant energy between the Sun, Earth, and space

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.]

Good Ozone and Bad Ozone Stratospheric ozone protect lives on Earth from harmful effects of UV radiation. .Iropospheric ozone: Causing respiratory distress and eye irritation Destroying plants Producing cracks in rubber Ozone is a strong oxidant, reacts with molecules containing C=C double bonds, forming epoxides