Which method is known to indicate the presence of saltwater drowning?

The presence of chloride ions (Cl-) in the blood is a crucial indicator of saltwater drowning. When an individual drowns in saltwater, they inhale water that contains a high concentration of salt. This results in the absorption of chloride ions and other solutes from the seawater into the bloodstream. The detection of elevated chloride levels can serve as a forensic indicator that helps differentiate saltwater drowning from freshwater drowning, where such high levels of chloride ions would not be present.

In contrast, while increased blood sodium levels could also suggest exposure to saltwater, the specific measurement of chloride ions provides a more direct and reliable indication of saltwater drowning. The other options, such as a rise in potassium levels or a decrease in blood pH, may occur in various pathological states but are less definitive in confirming the nature of drowning. Therefore, the presence of chloride ions is the most accurate method for identifying saltwater drowning.