Why is rain sometimes black in color and what chemical parameters should be tested?
Case ID : 00203
1) Why is rain sometimes in black color? 2) What chemical parameters should be tested for rain that appears to be black?
From :
Safoora, Fathimath
Thailand
Last viewed : 20 April 2024 10:42 Viewed : 5465 (times)
Answers
Answer from expert #1
The most likely cause of rain that looks black is elemental carbon. Chemicals can be adsorbed onto the surface of carbon particles but it would depend on the situation as to what chemicals should be monitored.
Answer from expert #2
Rain becomes black in colour if it contains carbon particles from incomplete combustion of carbon compounds, usually those in fossil fuels but also from incineration of waste. Apart from carbon particles, such rain may contain products of incomplete combustion. Some of these may be very toxic but there is no way of knowing what to look for without knowledge of the material being burnt. It should be assumed that there will be associated toxicity and the source of the black particles should be sought and brought under control.
Answer from expert #3
The origin of black soot is normally incomplete combustion of fossil fuel and burning of biomass. The major component is black soot, but Polycyclic compounds as well as inorganic ions and metals could be associated with are being part of the black soot (particulates). The analysis to be performed should include carbon and perhaps PAHs and depending on the local source of pollution also sulphate, nitrate as well as selected metals.
Compound specific information can be obtained from the ATSDR webpage.
Answer from expert #4
The origin of black soot is normally incomplete combustion of fossil fuel and burning of biomass. The major component is black soot, but Polycyclic compounds as well as inorganic ions and metals could be associated with are being part of the black soot (particulates). The analysis to be performed should include carbon and perhaps PAHs and depending on the local source of pollution also sulphate, nitrate as well as selected metals.
Answer from expert #5
1. Most likely black rain is caused by soot in the atmosphere. Soot particles are emitted by combustion of fossil fuels, biofuels, and biomass. Black carbon particles are removed from atmosphere mainly through wash-out in rainfall or snow.
2. Chemical parameters to be tested include black carbon.
Answer from expert #6
Rain is black if there is soot in the atmosphere due to incomplete combustion. Collect the soot particles and analyse in the lab.
Answer from expert #7
The 'blackness" is most likely caused by unburnt carbon particles -- black carbon , from combustion processes.
Besides testing for carbon, sulfates and mercury contents should also be tested.
