Heavy metal (Pb) bioaccumulation and distribution in aquatic and terrestial ecosystems and its impact on sustainable agriculture

The human population worldwide (about 6 billion) is increasing at 2% per year. There is a need to increase the global food production which necessitates the improvement of agricultural practices such as massive use of fertilizers and pesticides, soil amendments, etc. The industrialization program of the government converted many agricultural and forest lands into industrial sites and housing projects. This leads to some environmental problems such as an increase in domestic and industrial wastes, sewages and solid wastes as well as land disturbances which led solid erosion and possible contamination of groundwater resources. Hence, the atmosphere, water and terrasphere may be contaminated with all sorts of pollutants. Thus, environmental sustainability must go hand in hand with sustainable agriculture. Some basic and general information on heavy metal contamination was provided particularly, on the lead content of some freshwater and marine fishes, bivalves, snails, freshwater shrimps, some aquatic plants and some vegetables grown near the shores of Laguna de Bay and in some urban farms which are utilizing water from nearby river, creek or small pond for irrigation. Further, the fate and distribution of cadmium and lead in Philippine Mallard (Itik), including its fresh eggs, balut and penoy were also discussed. The chemical pollutants may exist temporarily or permanently in the soils or sediments, water, atmosphere, plants and in animals. Since the main mode of entry of contaminants into an organism is through food, water and air, ingested heavy metals may move into a food-chain and goes into a higher tropic level via a food web where bioaccumulation and biomagnification can occur along the pathway. The critical concentration of a potential toxic metal like lead (Pb) may become toxic to the body fluids, tissues or an organ. Lead has been reported to have adverse impacts in the brain and nervous systems, reproductive system, circulatory system and the kidneys; impaired mental development and hearing loss in children and adults. There is no known beneficial effect of lead in humans