Thursday, October 25, 2012

Testing Nitrate Levels in the Municipal Wetlands

What is Nitrate?

Nitrate (NO3) is a compound that is comprised of nitrogen and oxygen. Nitrogen comes from decomposing organic materials like manure, plants, and human wastes. Often the nitrogen (N) is derived from ammonia (NH3) or ammonium (NH4).

Plant species need nitrogen to form amino acids and proteins, which are essential for plant cell growth, but plants cannot use organic nitrogen directly. Microorganisms in the soil convert the nitrogen locked in crop residues, human and animal wastes, and compost to ammonium (NH4). Another specific group of microorganisms convert ammonium to nitrate (NO3), and since nitrate is water soluble, excess nitrate not used by plants can leach through the soil and into the groundwater.

The widths of the red arrows show relative amounts of nitrate leaching
into groundwater.

Nitrate is also present wherever biotic biproducts are breaking down or decomposing like animal waste, and septic system absorption fields or mounds.

On Friday, October 12th, our class took a trip out to the Municipal Wetlands in Springfield, Ohio for various sampling procedures; one of which involved the concentration of nitrate in the ground water. We used varying techniques of water acquisition depending on the state of the water (standing, flowing, or ground). For standing and flowing water, we collected a predetermined volume of water in vials. Once the sample was collected, a chemical indicator was added to produce a color reaction corresponding to a concentration of nitrate in  the water of that particular locale. Using the color wheel on the measuring device, the specific color-concentration reading was obtained. For ground water samples, an additional step was needed to be performed before the chemical indicator was to be added. First, the area of interest was cored, allowing ground water to flow into the new opening. The water was collected, solid particles were allowed to settle out until the above testing procedures involving the indicator and color comparison were done.

Below is a video demonstrating the nitrate testing site as well as techniques used:
Surface, Standing Water:
Ground Water:

Why sample nitrate?
Nitrate is a common contaminant found in many wells, wetlands, rivers, and other waterways. Shallow wells, wetlands, and streams in close proximity to agricultural land, and that collect runoff from cultivated land are the most vulnerable to nitrate contamination. Major sources of nitrate contamination can be from fertilizers, animal waste, and human sewage. The Environmental Protection Agency highly recommends testing drinking water supply on a regular basis. Elevated levels of nitrate in drinking water can cause Blue Baby Syndrome in infants under six months of age and that are bottle fed. Long term health effects to older children and normal healthy adults exposed to elevated levels of nitrate in their drinking water are not yet agreed upon in the scientific community. However, the National Cancer Institute suggests a link between elevated levels of nitrate in drinking water and an increased risk of non-Hodgkin's lymphoma (a cancer of the lymphatic system).

- Evan A.

1 comment:

  1. Wetland storage isn't exactly the same as groundwater storage. Rather wetlands buffer streams from flooding by storing water in their pores, but residence time of water that remains in storage is much shorter than that of groundwater.