organic and inorganic pollutants in soil by abdul aleem memon

ORGANIC AND INORGANIC POLLUTANTS IN SOILS

Abdul Aleem MemonPh.D Student

Ph.D-2K15-SS-32

A substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource. A pollutant may cause long- or short-term damage by changing the growth rate of plant or animal species, or by interfering with human amenities, comfort, health, or property values

Pollutants

Inorganic Pollutants in soils

Heavy metals, such as cadmium, lead, chromium, copper, zinc, mercury and arsenic etc..

HEAVY METAL POLLUTANTS-

• Heavy metals in soil are basically due to industrial discharges.

• Certain heavy metals eg. Zn, Cu, Ni, Cd and Pb are also present in significant levels in sewage sludge and reach the soil where they become part of life cycle and affects adversly.

Soil contamination by heavy metals, such as cadmium, lead, chromium, copper, zinc, mercury and arsenic, is a matter of great concern.

Heavy metals are present naturally in the soil, but their levels are increased by:

HEAVY METALS

• industry (non-ferrous industries, power plants, iron, steel and chemical industries);

• agriculture (irrigation with polluted water, use of mineral fertilisers)

• waste incineration;

• combustion of fossil fuels; and

• road traffic.

HEAVY METALS

Pollution of agricultural soils by heavy metals may lead to reduced yields and elevated levels of these elements in agricultural products, and thus to their introduction into the food chain.

Heavy metal deposits on grassland soils remain predominantly in the top few centimetres and are directly ingested with soil by grazing animals.

HEAVY METALS

Heavy metals are toxic and inhibit the soil's microorganic activity. Their concentration in the soil can remain for decades or even centuries.

Reduction of heavy metal emissions is the most direct way to decrease the atmospheric deposition of these elements and their build-up in the soil. Despite the great increase in traffic, for example, a reduction in lead emissions has been achieved through incentives to use unleaded petrol.

HEAVY METALS

Implementing complex measures that reduce soil acidification could more efficiently reduce heavy metals. On agricultural land, heavy metal quantities can be decreased by using low-metal content resources for fertilisers, replacing inorganic pesticides with organic products, and other similar methods.

HEAVY METALS

Organic Pollutants in Soils• N and P derivatives• Pesticides• PAHs (polycyclic aromatic hydrocarbons)• BTEX (benzene, toluene, ethylbenzene and xylene)• PCPS • NAPL• Plastics, biopolymers• Dyes• Phenols, Chlorophenols• Choroanilines• Bleach Plant effluents• Nitro Compounds etc…

Nitrogen and phosphorus are elements essential to all forms of life and are therefore relevant to soil systems and food crops. Although they are important plant nutrients, excessive application may lead to nitrogen or phosphate saturation in the soil, and eventual contamination of the groundwater. The amount of leaching depends on the soil, the local climate and the style of crop management.

NITRATES AND PHOSPHORUS

Phosphorus

Phosphorus accumulates in the upper layer of soil in regions with high livestock densities. In soils saturated with phosphorus, especially those with shallow groundwater, high phosphorus concentration occurs in the upper groundwater layer and in surface water, resulting in eutrophication.


EUTROPHICATION

NitrogenThe problem of nitrate pollution is recognised internationally and is usually associated with intensive agriculture practices. Good agricultural practices that alleviate the problem are:


• the selection of crops that require fewer nutrients;

• a timely application of fertiliser (in the growing season);

• improved methods of manure application;

• shortening the length of the grazing season; and

• reducing the intensity of grassland use (by lowering cattle density).


Pesticides pollute the soil directly by affecting the organisms that reside in it. Soil, however, can act as a vector for the pollution of surface water and groundwater. Organic pollutants enter the soil via atmospheric deposition, direct spreading onto land, contamination by wastewater and waste disposal.

PESTICIDES AND ORGANIC CONTAMINANTS

In addition to pesticides, organic contaminants include many other components, such as oils, tars, chlorinated hydrocarbons, PCBs and dioxins. There is such a wide variety of organic substances that their detection and monitoring in the soil is practically impossible.


Pesticides (mainly fungicides, herbicides and insecticides) are used in agriculture to protect crops and to ensure a quality harvest. Persistent or mobile pesticides are especially dangerous, as are those that affect non-targeted organisms.


The use of pesticides may lead to:

• destruction of the soil's micro-flora and fauna, leading to both physical and chemical deterioration;

• severe yield reduction in crops; and

• leaching of toxic chemicals into groundwater and potentially threatening drinking water resources.


Some improvements in application and legislation may reduce the side effects of pesticides, such as:

• banning broad-spectrum and highly mobile pesticides;

• employing integrated pest-management;

• enforcing biological control; and

• developing biotechnologies.


THANK YOU….

organic and inorganic pollutants in soil by abdul aleem memon

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