MMTask2

=__Dissolved Oxygen Test__=

Have you ever wondered how fish breathe in water? They do not use the oxygen that is found in the molecule (H2O). Instead, fish and other aquatic animals use oxygen gas, that has been dissolved in water, to breathe. This oxygen gas is referred to as dissolved oxygen and it is very important in maintaining the balance of the ecosystem.

Dissolved oxygen enters the water in a couple ways. One way is through the process of photosynthesis in aquatic plant life. The other is through diffusion of oxygen in the air at the surface. Ideally a good level of dissolved oxygen is 7 - 11 mg/L. This level is good enough for most stream fish to thrive. A level of 4-7 mg/L is good for most pond animals; 2 -4mg/L is good for few species of aquatic animals. Anything less than 2mg/L is not enough for most animals to survive.

Factors that effect the levels of dissolved oxygen (DO for short) are human factors and naturally occurring factors. Human factors that effect the levels of dissolved oxygen are the addition of sewage wastes and fertilizers. The addition of waste such as sewage contains organisms that use up the oxygen. The addition of nutrients (eutrophication) causes the plants and algae to rapidly grow and die off, due to over crowding This brings in high levels of bacteria which use up the oxygen. Natural factors which effect the level of dissolved oxygen are increasing the temperature of the water, water at high altitudes, slow moving water, and water with high levels of plant life.

__**Prelab**__ 1.) Where do aquatic organisms get the oxygen they need to breathe? Aquatic organisms get the oxygen to breathe from oxygen gas which has been dissolved in water.

2.) How does oxygen enter the water supply? Oxygen enters the water a few different ways. One being through photosynthesis. another way is through diffusion of oxygen in the air at the surface.

3.) What human factors effect the levels of dissolved oxygen? Human factors that effect the levels of dissolved oxygen are sewage wastes and fertilizers.

4.) What natural factors effect the levels of dissolved oxygen? Natural factors that effect the levels of dissolved oxygen are increasing temperature if the water, water at high altitudes, slow moving water, and water with high levels of plant life.

5.) Predict: If Mashamoquet were a healthy ecosystem, what level of dissolved oxygen might you expect to find there? From what i hear about Mashamoquet, i would not think of it as a healthy ecosystem at all. The ideal level of dissolved oxygen is 7-11 mg/L, so my guess is that the level of dissolved oxygen at Mashamoquet is higher!

__**Procedure and Materials**__ Please see La Motte: Dissolved Oxygen Test kit Instructions. Chose a collection point. Hold sample bottle at the base. Hold sample bottle

Please be aware of the safety warnings for Manganous Sulfate Solution, Alkaline Potassium Iodide Azide, Sodium Thiosulfate, and Sulfamic acid.

<span style="font-family: Helvetica; font-size-adjust: none; font-size: 12px; font-stretch: normal; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal; margin: 0px;">- Identify any safety precautions you should take or any warnings that the chemicals you are using may have. Be aware of how these chemicals may cause you harm

<span style="font-family: Helvetica; font-size-adjust: none; font-size: 12px; font-stretch: normal; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal; margin: 0px;">Wear goggles, and if needed gloves. Put hair back if required and be careful with a=the chemicals.

<span style="font-family: Helvetica; font-size-adjust: none; font-size: 12px; font-stretch: normal; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal; margin: 0px;">__**Data**__

<span style="font-family: Helvetica; font-size-adjust: none; font-size: 12px; font-stretch: normal; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal; margin: 0px;">Identify where you obtained your experimental sample from: A pond like area of water near the school.

<span style="font-family: Helvetica; font-size-adjust: none; font-size: 12px; font-stretch: normal; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal; margin: 0px;">List the level of dissolved oxygen. Dissolved oxygen level our sample had was 5.8.

<span style="font-family: Helvetica; font-size-adjust: none; font-size: 12px; font-stretch: normal; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal; margin: 0px;">**Analysis** <span style="font-family: Helvetica; font-size-adjust: none; font-size: 12px; font-stretch: normal; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal; margin: 0px;">Is the level of dissolved oxygen for your sample a safe and a healthy level for fish and other aquatic organisms? The level of dissolved oxygen for the sample is a safe and a healthy level for fish and other aquatic organisms to be in.

<span style="font-family: Helvetica; font-size-adjust: none; font-size: 12px; font-stretch: normal; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal; margin: 0px;">**Conclusion** <span style="font-family: Helvetica; font-size-adjust: none; font-size: 12px; font-stretch: normal; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal; margin: 0px;">1.) Do you think you have may encountered any errors in the lab? If so, describe them. I think we were careful enough during this lab that our results are good.

<span style="font-family: Helvetica; font-size-adjust: none; font-size: 12px; font-stretch: normal; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal; margin: 0px;">2.) How might you overcome those errors next time you are collecting this data? <span style="font-family: Helvetica; font-size-adjust: none; font-size: 12px; font-stretch: normal; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal; margin: 0px;">An error that could have happened was adding too much of the substance. that can be fixed by starting over again and being more careful with what is happening.

Graded, missing some questions, see procedure questions.