Toprak ve bitkide kadmiyum ve kurşun kontaminasyonu ve etkileri.

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Çukurova Üniversitesi, Ziraat Fakültesi, Toprak Bilimi ve Bitki Besleme, Türkiye

Tezin Onay Tarihi: 1996

Tezin Dili: Türkçe

Öğrenci: KUTBETTİN YAPICI

Danışman: Kemal Yalçın Gülüt

Özet:

46 SUMMARY Based on examination of several reports/studies published before, this thesis has been prepared to give an overview information about the heavy metal problems, particularly on Cadmium (Cd) and lead (Pb). Increases in world population and thus industrial and technological developments results in environmental pollution. There are various sources for heavy metal contamination in the atmosphere or soil, such as several industrial sources, enhanced traffic density-exhaust gases and further anthroponic sources. Heavy metals are phytotoxic elements, but most of them are needed by plants at very low concentrations. Plant differ greatly in their tolerance against heavy metal toxicity. Plants differ not only in accumulation of heavy metals but also in compartementation of metals. Absorbtion and accumulation of heavy metals by plants are dependent on solubility, concentrations and mobility of metals in soils. Cadmium (Cd) is a particularly toxic metal to plants, animals and humans. One of the major toxic action of Cd is its binding affinity to thiol (-SH) group on proteins and enzymes. The typical symptoms of Cd toxicity in plants are inhibition of growth, discoloration of leaves and occurrence of chlorotic patches on leaves. Cadmium- dependent necrosis appears on older leaves, and at very high concentrations of Cd in tissues plants can be died. There is no any positive effect Cd on plant growth. The normal levels of Cd range between 0.01-0.02 ppm (in dry matter) in plants and 0.2-3.0 ppm in soils. The primary source of lead (Pb) contamination is petrol and petrol products. Lead at relatively high amounts is directly responsible for death of humans, animals and plants. Normal levels of Pb in soils without lead contamination range between 1 0 to 20 ppm. Under normal conditions plants contain Pb concentrations between 2 to 7 ppm (in dry matter). Heavy metals are toxic not only for plants T>ut also lor Tîumaas via feeds contaminated by metals. If foods are contaminated by heavy metals at high amounts, their consumption may result in serious impairments in human health.47 Mobility of heavy metals in soils is definetely dependent on pH of soils. Usually, heavy metals are soluble in acid soils. Enhancements in SO2, NOx, HC1 and HF emissions causes acid rain and in turn acidifîcatîurr öf sous*. Under such conditions, solubility of heavy metals increases leading to higher uptake of metals by plants. In soils with high pH or alkalinity, heavy metals are either very low soluble or are not soluble or immobilized. Therefore, to decrease the toxic action of metals, pH of soils can be increased by several ways, such as by liming. However, if pH is enoug high, then an additional increase in pH can not have a positive effect on the present heavy metal toxicity. For a better healthy environment and for protection of human and animals against toxic action of heavy metals, all possible measures should be operated to avoid or minimize the heavy metal inputs in the environment via sewage sludge or atmospheric emissions from all kinds of industrial sources or dust storm.