Kirish. Ekologiya kursi, maqsadi, vazifasi, tuzilmasi va tarixi. Reja

Suvning ifloslanishi

Ifloslanish suvga ham ta’sir o’tkazmoqda. Havodagi ifloslanish yomg’ir orqali yerga tushadi. Amerika Qo’shma Shtatlari va boshqa ko’plab mamlakatlarda ifloslanishning oldini olish uchun ifloslangan suvlarni taqdim etishdan avval qayta ishlash qonunan talab qilinmoqda. Ammo dunyoning ko’plab hududlarida ularni qayta ishlashning iloji yo’q. Ifloslanishning yana bir sababi, bu insonlar dengizlar, ko’llar va okeanlarga chiqindilar va ishlatilgan materiallarni tashlashlari hamdir.

Yer usti suvlari

Ba’zi suv ifloslanishlari baliqlar va boshqa tirik organizmlarni zaharlamoqda va bu suvda suzadigan va shu suvni iste’mol qiladigan insonlarga ham zarar yetkazish mumkin. Misol uchun ferma yerlaridagi kimyoviy pestitsid parchalari ariqlar va ko’llarga oqiziladi. Bu kimyoviy moddalar baliqlar, toshbaqa va qurbaqalar uchun ozuqa vazifasini bajaradigan hashoratlarga zarar yetkazmoqda. Ozuqani yetishmasligi esa suv ostida yashovchi hayvonlarning o’limiga olib kelmoqda. Ba’zi ifloslanishlar xususan simob va boshqa metallarni ozuqa orqali baliqlar tanasiga o’tkazmoqda. Zararlangan baliqlar va qisqichbaqalar bu metallarni insonlar, qushlar va boshqa hayvonlarga o’tkazishlari mumkin bo’ladi. Bu zararlangan hududlarda insonlar ifloslangan suv yo’llaridan keltirilgan baliqlar va qisqichbaqalarni yemasliklari haqida ogohlantiriladi. Dengiz suv o’tlarining gullashi boshqa bir suv ifloslanish muammosi sanaladi. Ortiqcha o’g’itlangan va ishlov berilmagan oqar suvlarda katta miqdorda azot mavjud. Agar ular ko’l yoki hovuzlarga oqizilsa, dengiz o’tlarining jadal o’sishiga sabab bo’ladi. Qachonki, suv o’tlari halok bo’lsa, ulardan suvda ko’p kisloroddan foydalanadigan bakteriyalar parchalanadi. Baliqlar va boshqa organizmlar esa suvda kislorodning kamligi sababli nobud bo’ladi.

Okean suvi

Dengizlar va ariqlar o’zi bilan chiqindilarni olib oxiri okeanlarga quyiladi. Har yili taxminan 4 mln kg moylar okean suvlariga quyiladi. Ko’plab moylar esa okean suvidan oz yoqilg’i sisternasini yuvish uchun foydalanadigan kemalardan kelib chiqmoqda.¹

¹Peter Rillero, Dinah ZikeEcology, 2005 (107-108-bet)

Water

Water is essential to life on Earth. It is a major ingredient of the fluid inside the cells of allorganisms. In fact, most organisms are 50 percent to 95 percent water. Respiration, digestion, photosynthesis, and many other important life processes can take place only in the presence of water. As Figure 2 shows, environments that have plenty of water usually support a greater diversity of and a larger number of organisms than environments that have little water.

Water Pollution Human activities can harm freshwater environments. Fertilizer-filled runoff from farms and lawns, as well as sewage dumped into the water, can lead to excessive growth of algae and plants in lakes and ponds. The growth and decay of these organisms reduces the oxygen level in the water, which makes it difficult for some organisms to survive. To prevent problems, sewage is treated before it is released. People

also are being educated about problems associated with polluting lakes and ponds. Fines and penalties are issued to people caught polluting waterways. These controls have led to the recovery of many freshwater ecosystems.

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