INTRODUCTION
Research rationale
Eutrophication is a significant environmental challenge that deteriorates water quality and hinders the goals set by the Water Framework Directive (2000/60/EC) in Europe According to the International Lake Environment Committee, eutrophication affects 54% of Asian lakes, 53% in Europe, 48% in North America, 41% in South America, and 28% in Africa This process, driven by an increase in nutrient contributions—primarily nitrogen and phosphorus—overwhelms the self-purification capacity of water bodies, leading to structural changes While natural eutrophication occurs over thousands of years, human activities have accelerated this process through significant nutrient discharges The consequences include threats to fish and aquatic life, reduced water quality, limited access to safe drinking water, potential health risks, and negative impacts on fishing and recreational opportunities.
Eutrophication leads to algal blooms that block sunlight from penetrating the water, negatively impacting the aquatic flora and fauna that rely on it As algae overgrowth escalates, it can deplete oxygen levels in the water, resulting in hypoxic conditions and creating dead zones where organisms cannot survive.
Solar energy offers a sustainable and eco-friendly solution for electricity generation, free from toxic emissions and global warming effects Solar power plants do not contribute to air or water pollution, nor do they emit greenhouse gases By reducing reliance on more harmful energy sources, solar energy can positively impact the environment However, critics point out that the production of solar panels requires energy and may involve harmful chemicals Consequently, extensive research and projects are underway to evaluate the environmental effects of solar panel installations.
Taiwan prioritizes environmental stability and sustainability, making the impacts of eutrophication and solar panel installations on water quality significant concerns for the nation.
Allowing for all aspects and problems that I mentioned above, I suggest research: “Monitoring eutrophication of freshwater”.
Research’s objectives
- The objective of my research was to assess the eutrophication and manage the water quality in local areas (two regions in North and South) of Taiwan
- In addition, evaluating the possible effects of solar panels on the research water environment where they are installed
This study used parameters of Water Quality Index and calculated by River Pollution Index equations.
Research question
- How does eutrophication take place at two research sites?
- Is the solar panel having any impact on water quality in two research regions?
Limitations
Due to the limited time of my internship in Taiwan, there are not many observations the fluctuation about the effects of eutrophication and solar panels factors on research regions
LITERATURE REVIEW
Eutrophication
Eutrophication is the process of nutrient enrichment in water bodies, leading to increased primary productivity due to factors such as light, temperature, oxygen, and retention time This phenomenon is often indicated by a greenish slim layer that reduces light penetration and limits oxygen mixing, negatively impacting other aquatic species Eutrophication is classified into four trophic states: Oligotrophic, characterized by low nutrient levels and minimal marine life; Mesotrophic, with moderate nutrient levels and emerging water quality concerns; Eutrophic, indicating high nutrient richness and significant productivity; and Hypertrophic, marked by very high nutrient concentrations, severe water quality issues, and rampant plant growth.
The above mentioned trophic states category is described in Table 2.1 as adopted from Chapman (1996)
Table 2.1: Nutrient level, biomass and productivity of lakes at each trophic category
Annual mean Sec chi disc transparency (m)
Eutrophication Index
The Eutrophication Index (E.I) is a key Water Quality Indicator (WQI) used to evaluate aquatic systems, as highlighted by Giordani et al (2009) Various methods exist for assessing eutrophication quality, including the trophic index TRIX (Vollenweider et al., 1998; Primpas and Karydis, 2011), chl-a biomass classification schemes (Simboura et al., 2005; Pagou et al., 2002), and the Eutrophication Index (E.I.) itself (Primpas et al., 2010).
TRIX was measured according to the equation based on Vollenweider et al
(1998), whereas eutrophication ranges have been modified and applied following to Primpas and Karydis (2011):
TRIX = log10 [(CPO4*CDIN*CChl-a*D%O2) +1.5]/1.2
The E.I was calculated by the following mathematical equation (Primpas et al., 2010): E.I = 0.279*CPO4 + 0.261*CNO3 + 0.296*CNO2 + 0.275*CNH4 + 0.261*CChl-a
Where: CDIN is the concentration of dissolved inorganic nitrogen (= CNO3+
The nutrient concentrations relevant for TRIX include CNO2 (nitrite concentration), CNH4 (ammonium concentration), CPO4 (phosphate concentration), and CNO3 (nitrate concentration), measured in mg*m^-3 for TRIX and mmol*m^-3 for E.I calculations Additionally, CChl-a represents the concentration of phytoplankton chlorophyll-a, also measured in mg*m^-3 The D%O2 indicates the percentage deviation of oxygen concentration from saturation conditions.
Table 2.2 outlines various methods for estimating eutrophication, detailing the indices associated with each method, the classifications of eutrophication status, and the corresponding eutrophication ranges Nutrient levels, dissolved oxygen (DO), and chlorophyll-a (chl-a) concentrations were assessed using standardized techniques and quality assurance protocols in accordance with ISO 17025 certification procedures, referencing established studies by Mullin and Riley (1955), Murphy and Riley (1962), Holm-Hansen et al (1965), Carpenter (1965), Koroleff (1970), and Strickland and Parsons (1977), along with Welschmeyer's research.
Table 2.2: The methodological tools, indicators, and ranges are used for Greek coastal areas in the eutrophication assessment
High Good Moderate Poor Bad
High Good Moderate Poor Bad
NO3 -, NO2 -, NH4 + , PO4 3-, Chl-a
High Good Moderate Poor Bad
>1.51 a Vollenweider et al (1998) b Primpas and Karydis (2011) c Simpoura et al (2005)
8 d Pagou et al (2002) e Primpas et al (2010).
Eutrophication assessment in Taiwan
The E.P.A evaluates river quality using the "River Pollution Index," a comprehensive measure that assesses pollution levels based on the concentration of four key water quality parameters.
- Dissolved Oxygen (DO): The amount of gaseous oxygen dissolved in water
- Biochemical Oxygen Demand (BOD5): The amount of dissolved oxygen that is consumed by aerobic microorganisms when they decompose organic matter in water
- Suspended Solids (SS): Small solids particles which remain in suspension in water
- Ammonia Nitrogen (NH3-N): Concentration of all of the nitrogen in the form of ammonia and ammonium combined
For assessment of eutrophication levels of the water reservoirs, the E.P.A uses
“Carlson’s Trophic State Index” (CTSI) which is calculated based on the concentration of three independent water quality variables:
- Transparency (SD): The depth of light penetration into the water
- Chlorophyll-a (Chl-a): Liable for the absorption of light that supplies energy for photosynthesis
- Total Phosphorus (TP): The sum of all phosphorous compounds that occur in various forms
MATERIALS AND METHODS
Water sampling and analysis
Water samples were taken from different locations of the two regions in the North and South of Taiwan
Table 3.1: Location of water sample Site A (North of Taiwan) Site B (South of Taiwan)
Name of location - Flood detention pond: an excavated area installed on, or adjacent to, tributaries of rivers, streams…
- Irrigation water: moves from surface water (come from rivers, lakes or reservoirs)
Function - Manage water quantity while having a limited effectiveness in protecting water quality
- Helps to cultivate agricultural products, maintain scenery, and revegetate disturbed soils in dry spaces
- Water samples were taken twice a month, from
- Water samples were taken every two months from 2018/03/29 to 2018/05/16
Figure 3.1: Flood detention pond in North of Taiwan
Water quality assessment
Principle: Chlorophyll is extracted in 90% alcohol and the absorbances are read at 665 and 750 nm in a spectrophotometer Using the absorption coefficients, the amount of chlorophyll is calculated (Arnon, 1949)
Figure 3.2: Steps to estimate chlorophyll- α index
Figure 3.3: Alcohol 90% and a DR 6000 spectrophotometer using in Chl- α estimation
Calculation: Calculate the amount of chlorophyll present in the extract in àg using the following equations:
-Ve: the concentration of C2H5OH (mL)
-Vs: the concentration of water (L)
Suspended solids are quantified by filtering a homogenized sample through a 0.45 µm glass fiber filter, with the retained residue dried to a constant weight at temperatures between 103-105 °C, as outlined by Joe Ferry in 2004.
Figure 3.4: Procedure of Suspended Solids measurement
Figure 3.5: Glass fiber filter, furnace and electronic balance using in SS measurement
- :The original weight of the filter paper (mg)
- : The weight of the filter paper after filtration through the water sample (mg)
3.2.3 Analyze the Chemical Oxygen Demand (COD) index
The Chemical Oxygen Demand (COD) is measured in mg/L, representing the milligrams of O2 consumed per liter of sample during a specific procedure This process involves heating the sample with sulfuric acid and potassium dichromate, a strong oxidizing agent, for two hours During this reaction, oxidizable organic compounds reduce the dichromate ion (Cr2O72-) to green chromic ion (Cr3+) Depending on the method used, either the remaining Cr6+ is calculated for the 0-740 mg/L or 3150 mg/L range, or the produced Cr3+ is measured for the 201-1500 mg/L or 200-15,000 mg/L range The COD reagent also includes silver ions as a catalyst and mercury ions to mitigate chloride interference, with results tested at a wavelength of 420 nm.
Figure 3.6: Hach COD test kit and a DR 6000 spectrophotometer using in COD analysis
3.2.4 Measurement of the Dissolved Oxygen (DO) and Biochemical Oxygen Demand (BOD 5 ) index:
Figure 3.7: The measurement device using in measuring DO index
To prepare a water sample for analysis, take 10 mL of the sample and transfer it into a container Fill the container with deionized water and ensure the lid is tightly sealed Store the closed container at a temperature of 20°C After a period of 5 days, measure the sample for results.
Figure 3.8: Low temperature incubator using in keeping water sample
3.2.5 Measure pH and ORP values
Figure 3.9: The device using in measuring pH and ORP values
The Secchi disk, a 20 cm diameter white and black disk, is used to measure water transparency by being lowered into the water until it is no longer visible The depth at which it disappears indicates the water's transparency level, known as the Secchi depth.
Figure 3.10: Secchi disk using in measuring the transparency
The Mineral Stabilizer effectively complexes hardness in samples, while the Polyvinyl Alcohol Dispersing Agent enhances the color formation during the reaction between Nessler Reagent and ammonia, as well as specific amines The intensity of the yellow color produced is directly proportional to the concentration of ammonia present, measured at a specific wavelength.
Figure 3.11: Ammonia Nitrogen test procedure
Figure 3.12: Hach NH 3 -N reagent set
2.3.8 Analyze the Total Phosphorous (TP) index:
To analyze phosphates, both organic and condensed inorganic forms (such as meta-, pyro-, or polyphosphates) must first be converted into reactive orthophosphate This transformation is achieved by pretreating the sample with acid and heat, which facilitates the hydrolysis of condensed inorganic phosphates Organic phosphates are converted to orthophosphates through heating with acid and persulfate In an acidic medium, orthophosphate reacts with molybdate to form a mixed phosphate/molybdate complex The addition of ascorbic acid reduces this complex, producing a distinct molybdenum blue color, which is measured at a wavelength of 880 nm.
Figure 3.13: Hach Total Phosphorous Test Kit using in TP analysis
Calculation RPI and CTSI
After obtaining the results for DO, BOD5, SS, and NH3-N parameters, the RPI is calculated using Table 3.3.1 The total score is divided by the number of items to assess water quality, and the resulting value is then compared to the Pollution Index Integral Value.
Table 3.2: The calculation and comparison baselines for RPI (Environmental
Protection Administration Executive Yuan, R.O.C, Taiwan)
DO (mg/L) DO≥6.5 6.5>DO≥4.6 4.5≥DO≥2 DO