IB Biology IA

The effect of nitrate concentration on the rate of growth of Hygrophila Araguaia

Research Question:

What is the effect of nitrate level in the water (0.000%, 0.001%, 0.002%, 0.003% and 0.004%) on the rate of growth of Hygrophila Araguaia, measured by average mass change per day (g/day) for a period of 5 days?

Aim

The aim of this experiment is to explore the effect of ammonium nitrate, a chemical compound, salt of the ammonia and nitrate acid (NCBI, 2005), on the growth of Hygrophila Araguaia, aquatic plants that act as water purifiers by absorbing chemical nutrients such as potassium and nitrate ions. I measured the mass change of plants in 5 different concentrations for 5 days and compared the calculated value of average mass change of plants per day (g/day).

Introduction

Nitrate ions (NO3-) provide aquatic plants with nitrogen, which is used for forming essential elements of proteins in plant cells and stimulating photosynthesis and growth (WRIG, 2019). Nowadays, nitrate level has greatly increased due to decomposition of animal and plants, excessive fertilizer use, and poor waste water treatment. However, excess nutrients such as nitrate and potassium in the water can lead to a rapid growth of algae, known as algae blooms. Algae bloom damages the diversity of aquatic plants and animals by producing toxins and its decomposition depletes oxygen needed for sustainable aquatic ecosystem in bottom water (LG Sonic, 2018). One effective method for algae bloom prevention is to increase the efficiency of aquatic plants that absorb excess nitrates. Hygrophila Araguaia is an example of aquatic plants that take up aqueous nutrients such as potassium ions and nitrate ions in water through the roots by diffusion and active transport. The species contribute to fresh water environment by reducing algae. Hence, Hygrophila Araguaia can effectively absorb nutrients and protect aquatic ecosystems when the nitrate levels in the water increases…