Most surface water is low in minerals, gases, and ________.

The correct answer is "Dissolved solids." Surface water typically contains a lower concentration of minerals and dissolved solids compared to groundwater sources. This characteristic is primarily due to the natural filtering effects of soil and rocks that groundwater passes through, which can add additional minerals and dissolved substances.

In contrast, surface water bodies such as rivers, lakes, and streams are often influenced by surface runoff, precipitation, and limited interaction with mineral-rich geological formations, resulting in lower levels of these dissolved solids. The clarity and quality of surface water is relevant in the context of water treatment and environmental health, making the concentration of dissolved solids an important factor when assessing water quality.

Other options, while they may relate to characteristics of water quality, do not fit the context of being universally low in most surface water compared to dissolved solids. For example, turbidity refers to how clear the water is based on the presence of particles, which can vary greatly depending on conditions like rainfall. Algae populations can fluctuate based on nutrient levels, and bacteria levels can be influenced by a variety of environmental factors, making them less predictable in terms of consistent comparison to dissolved solids.