Circulation of Heavy Metals in Soil-Plant-Animal Metabolic System with Special Reference to Cadmium

Yıl 1999, Cilt: 13 Sayı: 18, 42 - 58, 15.12.1999

Yalçin Bozkurt Eumorfia Zachou

Öz

Environmental pollution with heavy metals draws widespread concern due to the potentially toxic effect on humans. Cadmium is present naturally in the air mainly as a result of volcanic emissions and release by vegetation. Furthermore, extensive use of phosphate fertilisers has accumulated cadmium in agricultural land especially in countries where they are used for many years. Cadmium (Cd) is a nonessential trace element and is considered as a pollutant. Cadmium pollution in the environment occurs from smelting industries, attrition of automobile tyres, and burning of diesel and heating oil. Cadmium is added to soils with phosphatic fertilisers and with sewage sludge application to agricultural land. Soil and the aboveground parts of plants also receive additions through the atmosphere, particularly in areas near metal smelters. Several factors affect the activity of cadmium in soils and its availability for plant uptake such as soil pH; the amount of Cd present; the metal sorption capacity of the soil; the presence of micro-elements and of macronutrients; soil temperature, moisture content and soil aeration. Certain skin penetration of soluble cadmium compounds can take place when they are applied as a solution to the skin. Skin is not though the main route of cadmium uptake. The respiratory and gastrointestinal tracts are the two main routes of absorption in man and animals. Airborne cadmium is a potential danger for animals through its deposition to grassland which is grazed by them and not through direct inhalation. Cadmium is translocated through the food chain of soil, roots, vegetation and animals to man and is an accumulative poison and in daily life large populations of animals and man are exposed to low levels of cadmium in the environment and in food

Anahtar Kelimeler

Heavy Metals, Cadmium, soil, plant, animal

Destekleyen Kurum

SELÇUK ÜNİVERSİTESİ

Ağır Metallerin Toprak-Bitki-Hayvan Metabolik Sisteminde Sirkülasyonu: Kadmium Örneği

Öz

Ağır metallerin neden olduğu çevre kirliliği, insanlar üzerindeki potansiyel toksik etkilerinden dolayı geniş çapta ilgi çekmektedir. Kadmiyum, volkanik emisyonlar sonucunda havada doğal olarak bulunur. Fosfatlı gübreler, özellikle uzun yıllar aşırı derecede kullanıldığı ülkelerde tarım topraklarında kadmiyum birikimine neden olmuştur. Kadmiyum esansiyel olmayan zehirli bir iz elementtir. Çevrede kadmiyum kirliliğine, fabrika bacaları, otomobil lastikleri ve petrol ürünlerinin yakılması neden olmaktadır. Kadmiyum topraklara fosfat ve hayvan gübreleri yoluyla karışmaktadır. Toprak ve bitkilerin toprak üstü aksamları özellikle maden arıtma tesislerinin olduğu alanlarda ayrıca atmosferden de ilave kadmiyum alırlar. Topraklarda kadmiyum aktivitesini ve bitkiler tarafından alınabilirliğini etkileyen faktörler olarak; toprak pH' sı, toprakta mevcut kadmiyum miktarı, toprağın metal tutma kapasitesi, toprakta mikro besinlerin ve mikro elementlerin mevcudiyeti ile toprak sıcaklığı, nem oranı ve toprak havalandırması sayılabilir. Ayrıca, suda çözülebilir kadmiyum bileşikleri deriye uygulandıklarında deriye nüfuz edebilmeleri minimal da olsa mümkündür, ancak vücuda kadmiyum alımının asıl şekli deri yolu ile değildir. Solunum ve sindirim sistemleri hayvan ve insanlarda kadmiyum absorbsiyonunun temel yollarıdır. Havadaki kadmiyum hayvanlar için solunum yoluyla değil, otladıkları meralarda birikmesi yoluyla potansiyel bir tehlike oluşturınaktadır. Kadmiyum toprak, bitki ve hayvanlar yoluyla insanlara transfer edilen kümülatif bir zehir olup insan ve hayvan populasyonları günlük hayatta çevre ve gıdalardan düşük seviyelerde bile olsa kadmiyuma maruz kalmaktadırlar.

Anahtar Kelimeler

Ağır metaller, kadmiyum, toprak, bitki, hayvan, absorbsiyon

Kaynakça

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