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Nam Ton Watershed

Knowledge Platform

Sampling process

For future water quality and sediment monitoring program, it is recommended that water and sediment sampling should be considered for both low and high flow periods. Collecting sample at the beginning of rainy season (first few rains) or onset when the water level is low flow and bed sediment is still stable, is important to diagnose chemical concern and potential source of chemicals. The second sampling should be carried out in high flow (August-October). The site condition should be taken in account such as the safety issue.

The selection of parameters of water and sediment for analysis should be significant and can answer the needs of area. It is necessary to choose the parameters which relate to the type of development project or activities. For the Nam Ton water and sediment monitoring program, all parameters need to be continuously monitored concerning some activities as described below:

Mining activities

Currently, there is a gold mine operated along the Nam Ton and there is potential to have coal mine will be operated in the future in this area some parameters need to be more concerned:

Parameter

Reasons

Acidity

Where sulphidic materials such as pyrite (iron sulphide) are exposed to oxidising conditions, which can occur as a result of mining or other  disturbances, the sulphide will react and water can transport the reaction products (acidity, iron, copper and sulphate) into surface waters and groundwater.

Alkalinity

Elevated Alkalinity level is usually found in tailing.Refers to the quantitative capacity of water to neutralise a strong acid to a designated pH and is primarily a function of carbonate, hydrogen-carbonate and hydroxide content. It may significantly affect many uses and treatments of natural and wastewaters.

Cyanide

Sodium cyanide (NaCN) may be used in the metallurgical process to generate a copper-gold concentrate.Cyanide is also hazardous and toxic to fish and aquatic organisms. Fish can be killed both directly by the cyanide content and indirectly by food consumption.

Arsenic

Arsenic may be found in natural water. Health problem could occur when drinking arsenic rich water over long periods. Arsenic is introduced into water through the dissolution of minerals and ores, and concentrations in groundwater in some areas are elevated as a result of erosion from local rocks. Exposure at mining and industrial emissions may also be significant locally. According to the lab results, the level of arsenic in soil is slightly high. It is recommended this parameter should be continuously monitored.

Metals

During operations, oxidation of sulphideminerals in the waste rock dump may generate acidic drainage with elevated concentrations of metals that could potentially have downstream impacts if released to the environment.

TSS

Fine sediments transport adsorbed nutrients. Excess nutrients can impact water quality through eutrophication, a process whereby excess nitrogen and phosphorus causes unwanted biological growth. Sediment will be generated as a result of land disturbance at the Mine site during construction, operations and at closure. Sediment reduces water quality by making the water turbid (cloudy). Turbidity prevents sunlight from penetrating the water and thus reduces photosynthesis and underwater vegetation. Oxygen levels are reduced in turbid waters, further degrading habitat for fish and other aquatic organisms.

Agriculture activities

Fertilizer, herbicides and pesticides are expected to be used in the Nam Ton Watershed, mainly rainfed rice paddies and upland agriculture. It is highly recommended that agricultural runoff should be monitored and monitoring program should be continuously monitored.

In terms of health issue, groundwater quality monitoring is unavoidable.  Wastewater from mining and agricultural chemical could impact on groundwater quality and to people if they drink contaminated groundwater. Regarding to different activities described above, continuously groundwater monitoring should be taken in account of water quality monitoring program in cooperated with watershed management framework by involving the participation of different stakeholders.

Parameters

Reasons

Ammonia

Ammonia is rich in nitrogen and hence makes an excellent fertiliser. Ammonium salts are a key source of nitrogen for fertilisers and like nitrate, ammonia may speed the process of eutrophication in waterways. Ammonia is considered dangerous and toxic to fish and aquatic communities, even at very minimal concentrations.

Nitrate

Nitrate is one of the main ingredients in a farm fertiliser and is required for crop production. When it is raining, varying nitrate quantities are washed away from farmland into nearby watercourse. Nitrates also get into waterways from lawn fertiliser run off, leaking septic tanks and cesspools, manure from farm livestock and animal wastes. Nitrates stimulate the growth of plankton and water weeds that provide food for fish. This may increase the fish population. However, if algae grow too wildly, oxygen levels will be reduced and fish will die. Nitrates can be reduced to toxic nitrites in the human intestine, and many babies have been seriously poisoned by well water containing high levels of nitrate-nitrogen. The U.S. Public Health Service has established 10 mg/L of nitrate-nitrogen as the maximum concentration level allowed in public drinking water.

Calcium

Calcium is naturally present in water which may dissolve from rocks. Calcium is a determinant of water hardness because it can be found in water as Ca2+ ions. Magnesium is the other hardness determinant. Calcium is present in various construction materials, such as cement, brick lime and concrete, it is present in batteries, and is applied to Calcium may have beneficial effects when ingested. It may block the absorption of heavy metals in the body and is thought to increase bone mass and prevent certain types of cancer. Very high concentrations of calcium may adversely affect the absorption of other essential minerals in the body.