If increasing concentrations of CuSO₄ are added to bean sprouts, then the length of the shoot will decrease. This is because CuSO₄ can damage metabolic processes through oxidative stress within the seed, rendering it to have less plant growth and as a result a smaller shoot.

Widespread soil contamination in many parts of the world due to heavy metal contamination is a serious issue that can impact entire ecosystems and landscapes. Heavy Metals are naturally occurring elements that possess a high atomic weight and have higher densities (Envirourgence, 2021). Due to the recent leap of industrialization, heavy metals have been used in various anthropogenic processes such as mining, agriculture, waste disposal, and production operations (ScienceDirect, 2024). Soil is contaminated when heavy metals are spread through specific processes such as fertilizer runoff, factory emissions, improper incineration, and petroleum extraction. These processes release many heavy metals such as Cu, Pb, Mg, Ni, Cd, Cr, Fe, and Mn. These heavy metals can harm ecosystems and soil through the contamination of groundwater via the dissociation of metal ions due to water polarity. This groundwater will later seep into the soil, ending up being used up by plants.

Plants will first encounter heavy metals (through contaminated soil) at the root, specifically the root apical meristem and root tip and cap where physiological and anatomical damage will follow. This can lead to compromises in stem growth and root structure as well as meristematic cell growth. This will also cause a buildup of metals and particles and air pockets within the roots (NCBI, 2021). Plants will attempt to prevent the entrance of metals into photosynthetic cells as the metals start to circulate through the plant, but often the metals will enter regardless due to a lack of adequate mechanisms. This can cause a reduction in leaf thickness, mesophyll production and alterations to stomata. Soon the plant will have an influx in ROS (reactive oxygen species) due to all the oxidative being put on the plant. Overall the plant will face serious physiological and biochemical compromises and many metabolic processes such as photosynthesis, stem, root and leaf growth and pigment production will stop, ultimately leading to significantly reduced growth and potential cell death. 

For all plants, germination is the first step in growth for a plant, a process activating a variety of chemical reactions which break down existent nutrients in the seed, leading to the development of roots and a sprout. There are many different processes which help in this. Subsequently, when seeds are exposed to heavy metals, the crucial process of germination is delayed based on the amount and has the potential to stop plant growth fully. Heavy metals can cause delayed water absorption and immobilize starches by inhibiting amylase activity within seeds during the germination process (NCBI, 2020) In terms of this experiment, the heavy metal being used, CuSO2 is an inorganic compound that is highly soluble within water (NPIC, 2012). This makes it more toxic to seeds as it is not found naturally in soil making even small concentrations have an impact on the seed. Copper II Sulfate can also cause severe eye irritation and if ingested could cause damage to body tissues, the liver, blood cells and the kidneys.

Studies show that Cu is toxic to plant systems in many ways as it increases oxidative stress due to an increase in ROS and can lead to peroxidation of lipids, damage to proteins, enzymes, and nucleic acids, chloroplast modifications, and chlorosis. ROS created by Cu can chemically change protein structure, altering its functions and causing damage to metabolic pathways, DNA and various other related structures. The oxidative stress can increase Hydrogen Peroxide levels, causing accumulation of Cu within the roots, reducing growth. Normal Cu content in leaves is about 10 μg and higher concentrations are considered to be toxic.

In terms of the true threat heavy metal soil contamination can cause to us, food chains and the passing of energy from one species to another come into play. When a plant gets contaminated since they are primary producers within an ecosystem, they will indirectly impact every other trophic level. In this case, heavy metals will be passed down to the secondary consumers. In agriculture, those secondary consumers are humans whereas in natural ecosystems the organism will vary. The effects of heavy metals on the body are not good as the toxicity could severely harm oneself. Certain metals such as Ni, Cd, and Zn can cause serious skin irritation, hepatic structure failure, harm to the kidneys, and Itai-Itai disease if ingested or exposed to in a certain way (NCBI, 2023) further urging action to be taken on heavy metal contamination to protect ecological health and food security for humans and animals.

Manipulated:

-10 ml Concentrations of 0.2 mol/L CuSO₄ solution and Distilled Water (Range = 0%-100%)

 -Varying dilutions of a 0.2 mol/L solution using water

Responding:

-Germination of bean sprouts, measured by total length (cm) of shoot after a 10 day period

Controlled:

-Volume of solution given - In order for the results to be accurate and controlled, the amount of solution must be the same for all treatment groups due to the requirement of water during the germination process. To do this, 10 mL concentrations were given on day 1 as over the five days the seed would not require much solution to germinate.

-Light Source - Light is necessary for germination to occur and can be a source of error if uncontrolled. Hence, all seeds were germinated under a 60 watt light bulb, 25 cm away from the petri dishes where germination was occurring.

-Temperature - The temperature of a space can change the rate of germination by affecting the metabolic processes occurring within the seed. High temperatures can denature essential proteins and enzymes which is why the temperature was controlled to be room temperature (21 degrees celsius).

Procedure:

1. Cut 12 sheets of paper towel to be the size of the petri dishes being used and line each petri dish with two. This will serve as a germination base.
2. Label the six petri dishes in relation to the varying molarities (0%, 20%, 40%, 60%, 80%, 100%)
3. Prepare 30 Vigna radiata . Put five bean sprout seeds in each petri dish.
4. Prepare a 500 mL stock solution with a concentration of 0.2mol/l solution of CuSO₄ using the following calculations:
   1. C = 0.2 mol/L, V=(0.5L)
   2. C = nv, n = 0.2 mol/2 = 0.1 mol
   3. 0.1 mol1159.607g1 mol

0.2 mol x 159.607 g/mol = 15.9607 g CuSO₄ 

• In this case 100 mL of H₂O is used which requires 15.96g or 16g of CuSO₄ 

• Create the varying concentrations of stock solution and distilled water in six 10 ml labeled graduated cylinders:

-0%: 15 mL of distilled water

-20%: 3 mL of 0.5mol/L CuSO₄ solution + 12 mL of distilled water

-40%: 6 mL of 0.5mol/L CuSO₄ solution + 9 mL of distilled water

-60%: 9 mL of 0.5mol/L CuSO₄ solution + 6 mL of distilled water

-80%: 12 mL of 0.5mol/L CuSO₄ solution + 3 mL of distilled water

-100%: 15mL of 0.5mol/L CuSO₄ solution

5. Pour 10ml of the varying solutions into the corresponding petri dish. For example, pour 10 ml of the 60% solution into the 60% petri dish.
6. Make seeds are arranged properly with even space between the five seeds. 
7. Close the petri dishes and seal sides using 30cm strips of Parafilm.
8. Set up a light fixture with a distance about 25 cm away from petri dishes to ensure even light distribution. Place all petri dishes under the light fixture. Make sure to keep the light on for 12 hours everyday.
9. Over a 21 day period, make qualitative observations on petri dishes. Make sure to remove the top layer of paper towel to fully see seeds and replace it after each viewing.
10.  At the end of the fifteen day period, use tweezers to take out seeds from the petri dish and measure sprouts from the seed coat to the primary root using a ruler. Record

Day 1-2:

-The 0% petri dish had one trial sprouted with the seed cover broken to let the root out. This root was thick with a lime-white coloration. The other treatment groups (20%,40%,60%,80%,100%) appeared to not have seeds sprouted. Some of the 100% seeds looked slightly saggy with the seed cover looking worn down.

-All petri dishes had solidified CuSO₄ concentrate at the rims of the petri dishes. This concentrate was crystal like and appeared to be dry.

Day 2-5:

-The seeds of the 0% treatment group had all spouted thick roots, with a coloration of a green-white hue. The seed cover was still only broken where the root had come out and was not saggy or discolored.

-The other treatment groups still had not fully germinated. All of the 100% treatment group’ trials had their seed covers saggy even more so now and looked slightly soft. Slight darkening in discoloration occured with all other treatment groups, the most severe seeming to be 100% concentration with an olive green appearance.

Day 6-9:

-Growth within the treatment group 20% - all five seeds had successfully germinated. The sprouted seeds looked yellow-white and appeared to have thin roots but also had a bluish tint due to the color of the CUSO4.and water solution.

Day 10:

-The treatment groups 40%-80% had very little growth but 1-2 seeds did seem have the seed cover broken. The spout held a yellow coloration and the seed cover looked very fragile on these trials. The roots had not spread out at all, staying bunched in the seed, leading to no change in length of roots.

-All of the 20% treatment groups had germinated. However, none of the 100% treatment group’s trials had germinated, taking on a soft and squishy appearance.

- The 40% seeds had no apparent change in root growth and was the same size as the day before

-Discoloration in 40%, 60%, 80%, and 100% treatment groups was apparent and got more severe as the CUSO4 content increased. The 100% treatment groups took on the appearance of a dark military green for its seeds whereas the 40% had more of a Sea green color.

-The odor had gotten stronger however germinated seeds were growing.

The purpose of this experiment was to see how a heavy metal could affect seed germination. Within this experiment, seeds were put in petri dishes with varying concentrations of CuSO₄ and distilled water (0%-100%). There were five trials within each treatment group (petri dish) and these were then set under a light fixture to germinate for fifteen days. It was expected that the treatment groups with higher contents of CuSO₄ would not germinate as well due to how inorganic heavy metals can disrupt and modify several metabolic processes when absorbed and generate toxic oxidative stress leading to plant and germination inhibition. What was observed was that the treatment group 100% had the lowest growth with a primary root length average of 0 cm and treatment group 20% had the most growth with heavy metal content, having a primary root length of 0.6 cm. The negative control group, 0%, had the highest growth out of all treatment groups with an average primary root length of 1.6 cm. This data clearly demonstrates the hypothesis and the effect heavy metals have on germination because research shows that heavy metals directly disrupt seed germination via delaying water absorption and reducing nutrient reserves. As the seed is exposed more to heavy metal content, these effects will occur at bigger magnitudes hence why the 100% treatment group had no root growth and the 20% had slightly less root growth compared to the negative control. A source of error in this experiment was the use of paper towels to cover the petri dishes. These covers were not initially added to each treatment group however after the visible reduction in moisture, these covers were added with an extra 5 ml of water sprayed to replenish it. The absorption of CuSO4 had already taken place and this reduced the risk of the incorrect data being collected. This could be improved by adding the cover at the beginning of the experiment. This experiment is important because it shows the effect of soil contamination and how they hurt plants but most of all the impact industrialization and humans have had on soil that harm our environment by poisoning entire ecosystems.

The effects of heavy metals on plants have a strong connection regarding ecological health and agricultural stability. Heavy metals such as lead, cadmium, and copper (which was used in this project) can accumulate in plants, leading to decreased growth, and immobilize some metabolic processes such as photosynthesis and mesophyll production.When researching remediation approaches for alleviating this issue in the world, it is crucial to know the adverse effects and properties that Heavy Metals can have while absorbed by a  plant. Furthermore, such research provides farmers, policymakers, and industry leaders with knowledge on how to take out safe measures to avoid further environmental issues such as potential biomagnification and food instability, therefore keeping ecosystems in balance. Such information then enables impactful solutions for this issue to be made as well as sustainable practices to be cultivated all around the world.

• Random Instrumental Uncertainty  - Certain lab equipment such as beakers and graduated cylinders had a concentration value of 5± (+ or -5, value is not exact but rather a range) which may have led to slightly inaccurate measurements in dilutions. To improve upon this, lab equipment that has a rating under 5± should be used to provide better accuracy for solutions.
• Humidity Changes - Throughout the project, potential leaks in sealing may have caused humidity shifts within the petri dishes. The leaks would make the solution evaporate, leaving the seeds with reduced moisture for germination. 
• Absorption rates - The seeds of Vigna Radiata were collected from an old source, which may have inhibited germination in the first place for some seeds. To improve upon this, more recent seeds should be used to provide more accurate data. Furthermore, as seeds naturally move around in the petri dish due to external movement and force, competition may have occurred between the seeds. To improve upon this, promising seeds from a resilient lineage should be used along with trying to control the community.

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Author links open overlay panelAtoosa Haghighizadeh a, a, b, c, d, e, f, g, & lead, A. contamination by. (2024, April 5). Comprehensive analysis of heavy metal soil contamination in mining environments: Impacts, monitoring techniques, and remediation strategies. Arabian Journal of Chemistry. https://www.sciencedirect.com/science/article/pii/S1878535224001795#:~:text=Abstract,management%20practices%2C%20and%20atmospheric%20sediments 

Author links open overlay panelIqra Noor a, a, b, c, Highlights•HM stress is a global issue that deteriorates the production and quality of horticultural crops.•Free radicals induced by HM cause oxidative stress and alter cellular activities in plants.•Plants respond to stress by activating signaling pathwa, AbstractHeavy metal/metalloids (HMs) are among the primary soil pollutants that limit crop production worldwide. Plants grown in HM contaminated soils exhibit reduced growth and development, Alaboudi, K. A., Alaraidh, I. A., Balal, R. M., Berni, R., Chaoui, A., Chatterjee, J., Chen, S., Duan, L., Edelstein, M., Fan, W., Gangwar, S., Ghosh, R., Hu, Y. F., … Fargašová, A. (2022, June 1). Heavy metal and metalloid toxicity in horticultural plants: Tolerance mechanism and remediation strategies. Chemosphere. https://www.sciencedirect.com/science/article/abs/pii/S0045653522016897 

 Boone, C.; Gervais, J.; Luukinen, B.; Buhl, K.; Stone, D. 2012. Copper Sulfate Technical Fact Sheet; National Pesticide Information Center, Oregon State University Extension Services. https://npic.orst.edu/factsheets/archive/cuso4tech.html.

I would like to acknowlege the provisions my school provided me with throughout the execution of the project. I was able to successfully set up the project thanks to the Science Lead teacher, Nairn Mclean. Under his guidance, I recieved feedback on my work as well as help with any concepts I was not aware of. In a controlled manner, I also gained valuable experience on handling toxic substances, including how to handle spills safely. My curiosity was sparked from my sister, Ria Christian, who valued biology. Naturally, I was also interested in learning about plant processes and eventually I found the concept of Heavy Metals quite favourable for science fair, leading me to this project.