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H2S is very common in groundwater. It is usually created by the action of sulphate reducing bacteria in the aquifer/groundwater. It is common in groundwater where there is either a lot of sulphate from say evaporite deposits/gypsum, or rocks that contain pyrite or other metal sulphides (limestones, shales, metamorphic rocks), or in areas of volcanic activity/sulphur fumaroles etc. The metal sulphides in sediments and metamorphic rocks are broken down (weathered) by groundwater containing oxygen in the recharge zone. The sulphides become soluble sulphates. The groundwater subsequently moves deeper into, or along, the flow system and the redox potential changes. It becomes anoxic. The sulphate reducing bacteria, which are common and harmless members of the biofilms found in aquifers, then, under these reducing conditions, use the oxygen in the sulphate ion, as a part of their metabolism, and dissolved H2S is the by-product.

The most sensitive test equipment is the human nose. We can smell H2S down to very low levels of less than 0.1ppm.

Hach ( https://www.hach.com ) produce simple field testing kits that use a silver nitrate reagent on a filter paper and Alka-Seltzer tablets to drive off the H2S from the water sample in a small bottle. These test kits are quite accurate and very robust and have been around for over 35 years. However the human nose can still smell H2S when the test kits give a zero reading.

The golden rule with H2S is that if you can smell it you are probably alright. Our noses can smell H2S up to about 6-8 ppm. Above these levels the H2S cauterises, or overloads the sensors in our noses. H2S is more poisonous than hydrogen cyanide. Higher levels of H2S in a confined space can kill you, but if you can continue to smell it you are probably safe. You might feel a bit sick or woozy.

I once fell over and just managed to crawl out of a depression on a still night in the desert in Arabia. H2S had been de-gassing from the discharge water from a long pump test on a deep borehole, pumped into the depression. I smelled the H2S as I approached the lip of the depression, but lost the smell as I went down into it to take a flow meter reading on the discharge pipe. After a few minutes I felt dizzy, fell over, and just had enough wit to realise what was happening, and crawl up to the fresh air outside the lip of the depression. I had a banging headache for the next few hours.

H2S in a water supply is usually not a problem if the water is pumped and splashed into an open topped tank or reservoir. Aeration is a standard treatment process for H2S. However the water may still be unpleasant to drink because the H2S is often associated with high levels of manganese, iron and other metals. These may precipitate when the water is aerated. The water can be discoloured, and have a noticeable metallic taste. It is not the H2S that is the problem, but the metals dissolved in the water.

H2S is very common in groundwater. It is usually created by the action of sulphate reducing bacteria in the aquifer/groundwater. It is common in groundwater where there is either a lot of sulphate from say evaporite deposits/gypsum, or rocks that contain pyrite or other metal sulphides (limestones, shales, metamorphic rocks), or in areas of volcanic activity/sulphur fumaroles etc. The metal sulphides in sediments and metamorphic rocks are broken down (weathered) by groundwater containing oxygen in the recharge zone. The sulphides become soluble sulphates. The groundwater subsequently moves deeper into, or along, the flow system and the redox potential changes. It becomes anoxic. The sulphate reducing bacteria, which are common and harmless members of the biofilms found in aquifers, then, under these reducing conditions, use the oxygen in the sulphate ion, as a part of their metabolism, and dissolved H2S is the by-product.

The most sensitive test equipment is the human nose. We can smell H2S down to very low levels of less than 0.1ppm.

Hach ( https://www.hach.com ) produce simple field testing kits that use a silver nitrate reagent on a filter paper and Alka-Seltzer tablets to drive off the H2S from the water sample in a small bottle. These test kits are quite accurate and very robust and have been around for over 35 years. However the human nose can still smell H2S when the test kits give a zero reading.

The golden rule with H2S is that if you can smell it you are probably alright. Our noses can smell H2S up to about 6-8 ppm. Above these levels the H2S cauterises, or overloads the sensors in our noses. H2S is more poisonous than hydrogen cyanide. Higher levels of H2S in a confined space can kill you, but if you can continue to smell it you are probably safe. You might feel a bit sick or woozy.

I once fell over and just managed to crawl out of a depression on a still night in the desert in Arabia. H2S had been de-gassing from the discharge water from a long pump test on a deep borehole, pumped into the depression. I smelled the H2S as I approached the lip of the depression, but lost the smell as I went down into it to take a flow meter reading on the discharge pipe. After a few minutes I felt dizzy, fell over, and just had enough wit to realise what was happening, and crawl up to the fresh air outside the lip of the depression. I had a banging headache for the next few hours.

H2S in a water supply is usually not a problem if the water is pumped and splashed into an open topped tank or reservoir. Aeration is a standard treatment process for H2S. However the water may still be unpleasant to drink because the H2S is often associated with high levels of manganese, iron and other metals. These may precipitate when the water is aerated. The water can be discoloured, and have a noticeable metallic taste. It is not the H2S that is the problem, but the metals dissolved in the water. water. Regards, Martin Ager

H2S is very common in groundwater. It is usually created by the action of sulphate reducing bacteria in the aquifer/groundwater. It is common in groundwater where there is either a lot of sulphate from say evaporite deposits/gypsum, or rocks that contain pyrite or other metal sulphides (limestones, shales, metamorphic rocks), or in areas of volcanic activity/sulphur fumaroles etc. The metal sulphides in sediments and metamorphic rocks are broken down (weathered) by groundwater containing oxygen in the recharge zone. The sulphides become soluble sulphates. The groundwater subsequently moves deeper into, or along, the flow system and the redox potential changes. It becomes anoxic. The sulphate reducing bacteria, which are common and harmless members of the biofilms found in aquifers, then, under these reducing conditions, use the oxygen in the sulphate ion, as a part of their metabolism, and dissolved H2S is the by-product.

The most sensitive test equipment is the human nose. We can smell H2S down to very low levels of less than 0.1ppm.

Hach ( https://www.hach.com ) produce simple field testing kits that use a silver nitrate reagent on a filter paper and Alka-Seltzer tablets to drive off the H2S from the water sample in a small bottle. These test kits are quite accurate and very robust and have been around for over 35 years. However the human nose can still smell H2S when the test kits give a zero reading.

The golden rule with H2S is that if you can smell it you are probably alright. Our noses can smell H2S up to about 6-8 ppm. Above these levels the H2S cauterises, or overloads the sensors in our noses. H2S is more poisonous than hydrogen cyanide. Higher levels of H2S in a confined space can kill you, but if you can continue to smell it you are probably safe. You might feel a bit sick or woozy.

I once fell over and just managed to crawl out of a depression on a still night in the desert in Arabia. H2S had been de-gassing from the discharge water from a long pump test on a deep borehole, pumped into the depression. I smelled the H2S as I approached the lip of the depression, but lost the smell as I went down into it to take a flow meter reading on the discharge pipe. After a few minutes I felt dizzy, fell over, and just had enough wit to realise what was happening, and crawl up to the fresh air outside the lip of the depression. I had a banging headache for the next few hours.

H2S in a water supply is usually not a problem if the water is pumped and splashed into an open topped tank or reservoir. Aeration is a standard treatment process for H2S. However the water may still be unpleasant to drink because the H2S is often associated with high levels of manganese, iron and other metals. These may precipitate when the water is aerated. The water can be discoloured, and have a noticeable metallic taste. It is not the H2S that is the problem, but the metals dissolved in the water. Regards, Martin Ager David Ball

H2S is very common in groundwater. It is usually created by the action of sulphate reducing bacteria in the aquifer/groundwater. It is common in groundwater where there is either a lot of sulphate from say evaporite deposits/gypsum, or rocks that contain pyrite or other metal sulphides (limestones, shales, metamorphic rocks), or in areas of volcanic activity/sulphur fumaroles etc. The metal sulphides in sediments and metamorphic rocks are broken down (weathered) by groundwater containing oxygen in the recharge zone. The sulphides become soluble sulphates. The groundwater subsequently moves deeper into, or along, the flow system and the redox potential changes. It becomes anoxic. The sulphate reducing bacteria, which are common and harmless members of the biofilms found in aquifers, then, under these reducing conditions, use the oxygen in the sulphate ion, as a part of their metabolism, and dissolved H2S is the by-product.

The most sensitive test equipment is the human nose. We can smell H2S down to very low levels of less than 0.1ppm.

Hach ( https://www.hach.com ) produce simple field testing kits that use a silver nitrate reagent on a filter paper and Alka-Seltzer tablets to drive off the H2S from the water sample in a small bottle. These test kits are quite accurate and very robust and have been around for over 35 years. However the human nose can still smell H2S when the test kits give a zero reading.

The golden rule with H2S is that if you can smell it you are probably alright. Our noses can smell H2S up to about 6-8 ppm. Above these levels the H2S cauterises, or overloads the sensors in our noses. H2S is more poisonous than hydrogen cyanide. Higher levels of H2S in a confined space can kill you, but if you can continue to smell it you are probably safe. You might feel a bit sick or woozy.

I once fell over and just managed to crawl out of a depression on a still night in the desert in Arabia. H2S had been de-gassing from the discharge water from a long pump test on a deep borehole, pumped into the depression. I smelled the H2S as I approached the lip of the depression, but lost the smell as I went down into it to take a flow meter reading on the discharge pipe. After a few minutes I felt dizzy, fell over, and just had enough wit to realise what was happening, and crawl up to the fresh air outside the lip of the depression. I had a banging headache for the next few hours.

H2S in a water supply is usually not a problem if the water is pumped and splashed into an open topped tank or reservoir. Aeration is a standard treatment process for H2S. However the water may still be unpleasant to drink because the H2S is often associated with high levels of manganese, iron and other metals. These may precipitate when the water is aerated. The water can be discoloured, and have a noticeable metallic taste. It is not the H2S that is the problem, but the metals dissolved in the water. Regards, David Ball David