The correct option is 35 ppt.
Explanation
Salinity refers to the total content of dissolved salts in seawater. It is calculated as the amount of salt (in grams) dissolved in 1,000 grams (1 kg) of seawater and is usually expressed as parts per thousand (ppt) or permille (‰). The average salinity of the world's oceans is generally considered to be 35 ppt.
Detailed Analysis
The average salinity of the Indian Ocean is 35 ppt.
- Regional Variations: The salinity distribution within the Indian Ocean shows distinct contrasts between its western and eastern parts.
- The Arabian Sea records higher salinity (typically 36 ppt to 37 ppt) due to high rates of evaporation and a relatively low influx of fresh water.
- The Bay of Bengal records lower salinity (typically 30 ppt to 33 ppt) due to the substantial influx of fresh water from major river systems such as the Ganga and the Brahmaputra.
- Overall Average: Despite these regional anomalies, the mean salinity for the Indian Ocean as a whole remains at the standard oceanic average of 35 ppt.
Key Takeaway: While the Arabian Sea is more saline and the Bay of Bengal is less saline due to freshwater influx, the overall average salinity of the Indian Ocean is 35 ppt.