3.4.1 National Standards

National standards on soil quality have not yet been developed. The National Agricultural Laboratories (later The Kenya Agricultural Research Institute, KARI) published a directory of methods of analysis of soil - Physical and Chemical Methods of Soil Analysis, 1980 Edition. This directory constitutes the first attempt to develop standardised methods of Soil Analysis in Kenya, but their use has been limited to analysis for agricultural purposes. In this directory methods of soil analysis have been classified into 4 categories.

(a) Physical Analysis, consisting of:

(i) Particle size analysis (mechanical analysis)
(ii) Soil Moisture Retention - the pF
(iii) Bulk density and porosity
(iv) Hydraulic conductivity
(v) Structure stability

(b) Mineralogical Analysis, consisting of:

(i) Clay mineralogy
(ii) X-ray diffractometry
(iii) Differential thermal analysis
(iv) Preparation of sand and mineral slides
(v) Free iron oxides

(c) Chemical Analysis, consisting of:

(i) pH: pH - Water
pH - KCl
pH - CaCl 2
(ii) Exchangeable acidity
(iii) Total nitrogen
(iv) Available phosphorus
(v) Available nutrients
(vi) Cation exchangeable capacity and exchangeable cations at pH 8.2 and pH 7
(vii) Soluble salts by electrical conductivity
(viii)Saturation extract

d) Special Analysis, consisting of:

(i) Available Fe, Mn, Zn and Cu
(ii) Total nutrients K, Ca, Mg and P
(iii) Total Si, Al and Fe
(iv) Calcium carbonate equivalent
(v) Gypsum (CaSO 4 )

3.4.2 International and other National Standards
International Standards which have been developed and published that deal with soil quality are given in the ISO catalogue 1996. These standards have been adopted by many countries. For example, the British Standards
Institution has developed and published a Standard on Soil Quality, namely, the BS 7755: 1990 - Soil Quality, Parts 3 and 4 on Chemical and Biological Methods. This standard is a direct adoption of the ISO Standards.

The Bureau of Indian Standards has also developed a number of standards on soil, the most significant of which is IS 2720 - Methods of Test for Soils. This testing is for engineering purposes although some of the methods would
remain the same if the testing were for agricultural and other uses. The chemical methods of test in this standard are similar to those in use at KARI.

Chemical industries are essential for the formation of a strong and sustainable industrial base. They are also vital in forging the necessary linkages between industry and the agricultural, transport and communication sectors. Those that are likely to have significant gaseous emissions are as listed below:

- Metallurgical industries relted to iron and steel production which provide a wide range of materials required by the engineering industry. This industry is
important in recycling metal chemical containers which release highly volatile compounds.
- Chemical and bio-technological industries that provide fertilizers, pesticides, industrial process chemicals and packaging materials relevant especially to agriculture and food production. The industries release persistent organic products in gaseous form.
- Pharmaceutical industries for the production of medicinal drugs and vaccines which release complex chemical formulations.
- Agro-industries such as power alcohol generation.

(ii) Rubber and Plastics Industry

Rubber and plastics industries are major sources of VOCs. There are about 100 manufacturers of plastic products in the country. Almost all the raw materials are imported; however, there are also two plants that recycle plastic wastes. These generate many organo-chlorine compounds such as vinyl chloride which are carcinogenic.

The top ten chemicals released by the rubber and miscellaneous plastic industries are 1,1,1 trichloromethane; acetone; carbon disulphide; dichloromethane; methanol; methylethylketone; styrene and xylene. They are suspect in areas where chemicals are heated to vaporisation temperature during operations or during open air burning.
(iii) Paper Mills Industry

Pulp mills processes emit gaseous wastes as part of the manufacturing process. The typical odour of Kraft pulp mill is due to the presence of sulphur in the boiling liquor which is responsible for the production of hydrogen sulphide, methyl mercaptan, methyl disulphide, and sulphur dioxide gases. In some mills, other additional emission types may come from auxiliary operations. At the Pan Paper Mills in Webuye, for example, chlorine is released from chlorine washer tower as well as from the caustic soda/chlorine generation plant. The sources of these gases are as follows:
- blow tank vents of the batch digester plant;
- seal tank vents of brown stock washing plant;
- recovery boiler and lime mud reburning kiln stack;
- smelt dissolving tank vent stack;
- vent from hot well (foul condensate tank) in evaporation plant;
- vent from bleach plant (washers and bleach towers); and,
- leakages from caustic soda/chlorine plant.

Apart from the odorous gases, the particulate matter are emitted from the stacks of bark boiler, recovery boiler, and lime-mud reburning plant. Dust carry-over in the flue gas from the recovery boiler is collected in three electrostatic precipitations and back to the system. Similarly, the dust carry-over from the kiln is scrubbed in a venturi scrubber with mill water and fed to clarifiers for the separation of sludge which is fed into the system. It, therefore, becomes difficult to pinpoint, in the factory, the actual stack that is emitting fugitive gases.

The pulp and paper industry releases 87% of its total toxic emissions into the atmosphere; approximately 10% to water, and 2% is transferred to site or disposed of on land.

Air releases can be traced to a variety of sources. Approximately 50% are methanol, a by-product of the pulp making process. The other major toxic chemicals emitted include chlorinated compounds, sulphuric acid and the chelator methylethylketone, originating from the bleaching stage.

The priority pollutants are particulate matter, total reduced sulphur (TRS) and NMVOC.

(iv) Cement and Excavations

There are three cement plants in Kenya whose combined production capacity is 1.55 million tonnes per year while actual production is about 1.4 million tonnes per year. Domestic consumption of cement is 1.1 million tonnes per
year leaving a surplus of 0.3 million tonnes for export. The main raw materials for cement production are limestone, pozzuolana, and gypsum and are available in adequate quantities in various parts of the country. The main
pollutants are dust particulates, grit and dust.

(v) Ceramic Tiles

There are three ceramic plants producing crockery, wall tiles, and sanitary ware. The basic raw materials such as silica sand, kaolin, Kisii soapstone, quartz, among others, are locally available. The main pollutants are dust
particulates, grit and dust.

(vi) Glass Factories
There are three glass container manufacturing plants in the country. The country imports the larger containers. The basic raw materials for glass manufacture such as soda ash, silica sand, sodium sulphate, and fluorspar are locally available.

The Central Glass Industries in Ruaraka is the largest container glass industry in Kenya, which is located in a heavily residential area and currently a major concern to residents in as far as air pollution is concerned. The main
pollutants are sulphur oxides, NMVOC, carbon monoxide, dust and particulates.

Working with the raw materials of the above industries exposes one to respiratory diseases, digestive disorders, skin diseases, rheumatic and nervous conditions, hearing, and vision disorders.

(vii) Excavations

The building and construction industry including harvestingand transport of building materials is a major source of particulate releases to the atmosphere.

Typical activities in this area include sand harvesting, transport and storage; stone crushing and dressing, quarry blasting and construction. Sand harvesting presents a peculiar source of pollutants since it depends on where the sand is mined. The sand from the coastal and Machakos areas has heavy grains which are not easily airborne .Volcanic sand used in the central region of Kenya and mined around Mt. Longonot, however, has got finer grains which are easily air-borne with possible negative impacts to the environment.

Particulate matter is emitted from sand and gravel operations and is made up principally of inert crystal material, for example, soil and rock particles. Dust
emissions in the form of fugitive dust occur during removal of over burden, sand and gravel from the deposit, wind- blown dust from storage piles, from transport, during material dumping from trucks, front and leaders, and conveyors from screening. The amount of moisture affects the amount of dust emissions that occur. In Kenya the deposit is dry and the material have high silt content and usually dust emissions are significant.

This is an area where standards are difficult to formulate. Emissions can be reduced by various technological innovations. They include: - using water sprays to keep materials wet;

- limiting drop heights of materials;
- covering lorries;
- using enclosures or holding materials at transfer and handling points; and,
- exhausting air from these points to air pollution control systems.

The priority pollutants are dust and particulate, carbon monoxide, and hydrogen sulphides.

(viii) Tanneries and Leather Industry

Leather tanning industry uses many types of chemicals which, when they react together, emit hazardous and offensive smells such as hydrogen sulphide in addition to generating other toxic chemicals and hazardous wastes.
The Government has put in place a number of programmes aimed at reducing chemical risks, strengthening management of hazardous wastes, and maximising environmentally sound waste re-use and recycling. Special
incentives were given in the national budget speech of 1994, to encourage tanneries to set up effective effluent disposal plants to overcome the present pollution problems. The Kenya Industrial Research and Development Institute is carrying out research in treatment of tannery waste which would reduce air pollution associated with tanneries.