tailieunhanh - Applications of Environmental Aquatic Chemistry: A Practical Guide - Chapter 2

Hành vi gây ô nhiễm trong môi trường: Nguyên tắc cơ bản 2,1 HÀNH VI CỦA WATERS tạp chất trong thiên nhiên Mỗi bàn tay của Thế giới của chúng tôi là Liên tục thay đổi, cũng như các chất gây ô nhiễm hệ sinh thái thiết yếu không mong muốn. Một số thay đổi xảy ra không ngờ chúng tôi khoảng thời gian địa chất; Những người khác nhanh chóng, xảy ra trong ngày, phút, hoặc ít hơn. Dầu và than đá được Thành lập từ động vật và thực vật quan trọng trên hàng triệu năm. Khi dầu và than. | 2 Contaminant Behavior in the Environment Basic Principles BEHAVIOR OF CONTAMINANTS IN NATURAL WATERS Every part of our world is continually changing essential ecosystems as well as unwelcome contaminants. Some changes occur imperceptibly on a geological timescale others are rapid occurring within days minutes or less. Oil and coal are formed from animal and vegetable matter over millions of years. When oil and coal are burned they can release their stored energy in fractions of a second. Control of environmental contamination depends on learning how to bring about desired changes within a useful timescale a task that requires an understanding of how pollutants are affected by environmental conditions. For example metals that are dangerous to our health such as lead are often more soluble in water under acidic conditions than under basic conditions. Knowing this one can plan to remove dissolved lead from drinking water by raising the pH and making the water basic. Under basic conditions a large part of dissolved lead can be made to precipitate as a solid and can be removed from drinking water by settling out or filtering. Contaminants in the environment are driven to change by Physical forces that move contaminants to new locations often without significant change in their chemical properties. Contaminants released into the soil and water can move into regions far from their origin under the forces of wind gravity and water flow. An increase in temperature will cause an increase in the rate at which gases and volatile substances evaporate from water or soil into the atmosphere. Electrostatic attractions can cause dissolved substances and small particles to adsorb to solid surfaces where they may leave the water flow and become immobilized in soils or filters. Water flow can erode soils and transport sediments carrying sorbed pollutants over long distances. Chemical changes such as oxidation and reduction which break and make chemical bonds allowing atoms to .