Water Quality Physical, Chemical, & Nutrient Characteristics

I. Introduction

The Great Lakes hold about 20% of the entire earth's surface freshwater. Lake Erie, streams, rivers, and other lakes are the primary sources for irrigation, industry, and domestic use in most of Ohio. These water bodies also provide habitat for fish and wildlife, and so, are important to tourists, hunters and fishermen. The quality of these surface waters clearly affects their suitability for use. Water that has been polluted often is not fit for either wildlife habitat, or for human and/or animal consumption.

Hence, water quality has direct impacts upon the local economy, as well as the health and survival of people and wildlife. For example, Lake Erie alone generates approximately $2 billion for the State of Ohio in tourism.

What is water quality?

Water quality is an ambiguous concept that refers to the general "health" of the water (defined largely in human terms). However, this concept has a large number of both qualitative and quantitative characteristics. A few of the more important or commonly used parameters are discussed herein.

Physical and Chemical Parameters:

Some of the more common physical and chemical attributes of water quality that affect biota are largely defined by abiotic factors.

pH (potential Hydrogen): is the measure of the hydrogen ion activity (H+).

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It is defined as the negative logarithm of the activity, and is generally measured on a scale from 0 to 14. An acid solution has a pH < 7, and an alkaline or basic solution is > 7. Normal rain is 5-6 and most lake water is 6-9. Some very eutrophic lakes have values as high as 10-11 and acidified lakes often have pH < 5. The chemical state of many nutrients is controlled by pH, such as carbon dioxide, phosphate, and ammonia.

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In general, few aquatic organisms can withstand pH values outside 5-8, which is why acid rain can harm aquatic organisms.

Dissolved oxygen is produced by photosynthesis and diffuses into water from the atmosphere. Storm water runoff or sewage that is high in organic matter may reduce dissolved oxygen concentrations in water because oxygen is used during respiration by decomposers that decay the organic matter. When this occurs, many aquatic organisms die or are replaced by the few species that can survive at low oxygen levels. Also, the depletion of dissolved oxygen causes changes in the solubility of many metals and nutrients.

Electrical Conductivity (EC): estimates the amount of total dissolved salts (TDS), or the total amount of dissolved ions in the water. The sources of dissolved ions can arise solely from geologic process around a water body. However, more typically it used as a measure of the amount of total dissolved solids from agricultural inputs (such as soluble fertilizer, pesticide, herbicide) or road salts that have entered a water body.

Turbidity is a unit of measurement quantifying the degree to which light traveling through a water column is scattered by the suspended organic (including algae) and inorganic particles. The greater the suspended load of particles, the greater the scattering of light. High turbidity reduces light penetration, thereby suppressing photosynthetic activity of phytoplankton, algae, and macrophytes. Excess turbidity reduces primary production that serves as food sources for invertebrates and fish.

Eutrophication: is the process of enriching a water body with nutrients. Nutrients naturally enter water from the atmosphere and with sediments from runoff. Sediments originate from soil erosion, which is greatly increased by farming, overgrazing, deforestation and other activities that remove vegetation. The most common nutrients contributing to eutrophication are phosphates, ammonia, and nitrates which stimulate the rapid growth of phytoplankton. Nutrients increase the turbidity of the water, which shades the submerged benthic plants and modify the structure of the ecosystem.

Eutrophication is a natural process and two major factors control the rate: (1) the volume of the water body and (2) rates of nutrient input and outflow.

Lake Superior: Is a very large, nutrient-poor lake that would require a huge amount of nutrients to become eutrophic. However, if Lake Superior were to become eutrophic, it would take centuries for recovery, because of a very slow outflow in proportion to volume.

Lake Erie: Is the shallowest and most nutrient-rich of the Great Lakes, and therefore is the most eutrophic. However, Lake Erie can clear up within a few years, so long as we decrease the rate of input.

Cultural eutrophication results from human activities, which usually accelerate the natural process. This is the direct result of nutrient inputs to waterways. Human sewage is a major cause of cultural eutrophication, because it contains high concentrations of nutrients. Detergents that contain phosphate caused rapid eutrophication of many lakes in the 1960s, such as Lake Erie. Another source of nutrients to lakes is urban storm runoff, carrying fertilizer from lawns and golf courses, pet and wildlife feces, and sediments. Land uses that reduce vegetation (deforestation), expose bare soil (industrial farming), or reduce the infiltration of rainwater (impervious surfaces like asphalt and concrete) generally increase nutrient inputs.

Nutrient Parameters:

Primary nutrients affecting biological activities in aquatic environments are phosphorus and nitrogen.

Phosphorus: is an extremely important component of cellular energy molecules (ATP), nucleic acids (DNA) and cell membranes. It is a common cause of eutrophication and may even be lethal at high concentrations. Sources of phosphate include rocks, animal wastes and sewage, laundry detergents and decaying organic matter. Phosphorus is often the least abundant nutrient in aquatic systems relative to the nutritional requirements of plants and algae. Therefore, eutrophication may occur rapidly with even small inputs. Only orthophosphate (PO4) can be used directly by algae, so it is an important measure of water quality. However, PO4 often is present in such low concentrations that it cannot be measured precisely.

Nitrogen: in aquatic ecosystems is present mostly as a gas (N2) and in organic forms. Other compounds such as nitrate (NO3-) and ammonium (NH4+) are less abundant but are much more important as usable sources of nitrogen. These compounds are more soluble than phosphate and their availability influence the variety, abundance, and nutritional value of aquatic plants.

Ammonium can exist in water in two forms, un-ionized ammonia (NH3) and the ammonium ion (NH4+). Ammonia is toxic to fish, while the ammonium ion is nontoxic, except at extremely high levels. Both forms are readily soluble and normally result from the decay of organic matter. Both pH and temperature regulate the proportion of ammonia and ammonium in water.

Nitrate (NO3-) is usually the most common form of inorganic nitrogen in lakes and streams. The concentration and rate of supply are tied to surrounding land use practices within the watershed. For example, nitrogen derived from fertilizer runoff or soil erosion and waste-discharges from cities and farms often flow into streams and lakes. Excessive amounts of nitrate in water can cause death, illness and spontaneous abortion in vertebrates.

This lab will acquaint you with some standard water quality tests that are commonly used to assess water supplies. This lab will be conducted on campus, using water samples from the Ottawa River watershed.

II. Lab Exercise: Water Quality

This lab will acquaint you with some standard water quality tests that are commonly used to assess water supplies. This lab will be conducted on campus, using water samples from the Ottawa River watershed.

Supplies

1. Water from two sources in the Ottawa River Watershed

2. 6 Solo Cups (3 for each treatment)

3. Masking Tape & Sharpie

4. EC meter

5. pH meter

6. Rinse Bottle with DI Water

7. Ammonia, Nitrate, & Phosphorus Test Strips

8. Waste Water Container

General Instructions:

Make all recordings with meters 30 seconds after placing probe in the water sample. Rinse all meters with DI water between samples into a waste water container.

Coordinate with your team members to obtain at least three estimates of each analysis for each water sample. Perform at least one of each type of analysis, yourself.

Coordinate with your members to calculate mean, variance, and standard deviation and perform t-tests on DIFFERENT parameters.

Procedure

Label three solo cups with the Treatment name and Replicate # (ex. Ottawa-01) using masking tape and Sharpie. Label three more with the second Treatment name and Replicate #.

Acquire (three) ~100 mL samples of water from the two sources of water that you have selected for a total of six samples.

Use the pH and EC meters to test pH and EC (electric conductivity). For combo-meters, use the on/off button to switch between the two. Record pH and EC after 30 seconds of sampling. Rinse the meter with DI water when switching between replicates and treatments.

Using the HACH test strips, test the concentration of Ammonia, Nitrate, and Orthophosphate in each water sample. Only use one strip per nutrient per sample. Be sure to follow the specific instructions of each dip strip bottle. Record concentrations of all nutrient parameters in your data table. Dispose of test strips in the trash.

Dispose of water down the drain. Remove masking tape from the solo cup and rinse the solo cup using RO water (the handle with the white knob). Stack the cups in a pyramid that they may drain for the next class.

IMPORTANT: Collect data for the same locations from one other group!

Updated: Oct 10, 2024
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Water Quality Physical, Chemical, & Nutrient Characteristics. (2019, Dec 09). Retrieved from https://studymoose.com/water-quality-physical-chemical-nutrient-characteristics-essay

Water Quality Physical, Chemical, & Nutrient Characteristics essay
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