Sodium hydrogensulphate

Endpoint summary

Additional information

Sodium hydrogensulfate:

The aquatic effect and risk assessment only deal with the effect on organisms/ecosystems due to possible pHchanges related to H⁺discharges, being the toxicity of Na⁺and SO₄^2-are expected to be negligible compared to the (potential) pHeffect.The high water solubility and very low vapour pressure indicate that NaHSO₄will be found predominantly in water. Significant emissions or exposure to air are not expected due to the low vapour pressure of NaHSO₄. Significant emissions or exposure to the terrestrial environment are not expected either for the industrial uses.

Environmental fate:

When NaHSO₄is emitted to wastewater or surface water, sorption to particulate matter and sediment will be negligible. The pHmay decrease, depending on the buffer capacity of the water. The higher the buffer capacity of the water, the lower the effect on pH will be. In general the buffer capacity preventing shifts in acidity or alkalinity in natural waters is regulated by the equilibrium between carbon dioxide (CO₂), the bicarbonate ion (HCO₃^-) and the carbonate ion (CO₃^2-):

 

 CO₂+ H₂O <-> HCO₃^-+ H⁺ (pKa1 = 6.35)

 

 HCO₃^-<-> CO₃^2-+ H⁺ (pKa2 = 10.33)

 

If the pHis < 6, un-ionised CO₂is the predominant species and the first equilibrium reaction is most important for the buffer capacity.

At pHvalues of 6-10, the bicarbonate ion (HCO₃^-) is the predominant species and at pHvalues > 10 the carbonate ion (CO₃^2-) is the predominant species. In the majority of natural waters the pH values are between 6 and 10, thus theNaHSO₄concentration and the second equilibrium reaction are most important for the buffer capacity.

From Source: SODIUM SULPHATE CAS N°: 7757-82-6 OECD SIDS April 2005

In the last 100 years sulfate concentrations have greatly increased in some rivers because of increased industrial and agricultural activities. In rivers the concentration has increased as well due to human activities, from 50 mg/L (natural background) to 60 mg/L since the 1950's. The sulfate ion concentration is highly variable in surface waters where it is linked to sulfur-bearing minerals. Sulfate concentrations range from 2 to 30 mg/l for most rivers and lakes in the US. However, some lakes in the Cariboo region and in Richter pass near Osoyoos have particularly high natural sulfate levels of the thousands of mg/l (Ministry of water, land and air protection,2000). Most freshwaters contain at least a few parts per million of sulfate, but 20 to 50 ppm or more are common in the easternand most of. Seawater contains levels of about 2700 ppm (Hitchcock, 1975).

Sea salt aerosols are produced in large quantities but do not appear to be a significant source of atmospheric sulfate, except near the place where they are produced due to the fact that they are too large to remain in the air. Hitchcock (1975) also states that levels of sulfate in air samples in plumes from fossil fuel power-generating plants decline very rapidly with distance from the source even when atmospheric conditions produce minimal dispersion of the plume.

The author measured the following concentrations in the air in:

·        Non-urban sites: 4.9-8.6 µg/m³

·        Coastal urban sites in: 8.1-11.3 µg/m³

·        Other coastal sites: 10.7-12.2 µg/m³

·        Inlandcities: 6.0-10.3 µg/m³

Urbanisation does not appear to influence the sulfate levels in. Most of the sulfate observed in the non-urban sites appears to be of local origin.

Hydrogen sulfide derived from the energy metabolism of bacterial sulfate reducers is the principal source of the 100 to 200 million ton of sulfur annually contributed to the global atmosphere. 

 

Since sodium sulfate is soluble in water itis expected to infiltrate the soil. Most of the ions will migrate downwards through the soil with the penetrating water, for it does not interact with soil given the very low log K_ow. Sodium sulfate may run off with surface water when the soil is saturated with moisture e.g. after a rainfall (Environment Canada, 1985).