Biosfera. Tabiiy resurslar, ulardan oqilona foydalanish va atmosfera muhofazasi. Suv

Tuproq zararlanishi

Hosildor yerlar o‘simlik unib chiqishi uchun zarur hisoblanadi. Hosildor yerlar shakllanishi yuz ming yillarga borib taqaladi. Yomg‘ir yog‘ib, yerni bo‘shatib, uning ustki qismini oqizib ketadi, shamol ham uning ustki qismini ozi bilan uchirib ketadi. Tuproqning bir joydan ikkinchi joyga ko‘chib harakatlanishi- Eroziya deb ataladi. Eroziyaga uchragan yerlar daryo va kichik daryolar tomonidan yuvilib turiladi va quyosh nuriga to‘sqinlik qilib fotosintez jarayoniini sekinlashtiradi. Bu esa baliqlar, molyuskalarga va boshqa organizmlarga talofat keltiradi. Eroziya tabiiy jarayon, lekin u insoniyat tasiri ostida kuchayib boradi, ekinzorlar haydalib, o‘rmonlar kesilishi oqibatida
yerlar ochiq holga kelib qolmoqda. Ochiq holdagi yerlarni esa shamol va yomg‘ir osonlik bilan yuvib oqizib ketadi.¹

Soil Loss

Fertile topsoil is important to plant growth. Newtopsoil takes hundreds or thousands of years to form.The Launch Lab at the beginning of this chapter showsthat rain washes away loose topsoil.Wind also blows itaway. The movement of soil from one place to anotheris called erosion (ih ROH zhun). Eroded soil thatwashes into a river or stream can block sunlight andslow photosynthesis. It also can harm fish, clams, andother organisms. Erosion is a natural process, buthuman activities increase it. When a farmer plows afield or a forest is cut down, soil is left bare. Bare soil ismore easily carried away by rain and wind. Figure 19shows some methods farmers use to reduce soil erosion.

Soil Pollution

Soil can become polluted when air pollutants driftto the ground or when water leaves pollutants behindas it flows through the soil. Soil also can be pollutedwhen people toss litter on the ground or dispose oftrash in landfills.
Solid Wastes What happens to the trash you throwout every week? What do people do with old refrigerators,TVs, and toys? Most of this solid waste isdumped in landfills.Most landfills are designed to sealout air and water. This helps prevent pollutants fromseeping into surrounding soil, but it slows normaldecay processes. Even food scraps and paper, whichusually break down quickly, can last for decades in a
landfill. In populated areas, landfills fill up quickly.Reducing the amount of trash people generate canreduce the need for new landfills.
¹Peter Rillero, Dinah ZikeEcology, 2005 (109- bet)