Limnology

Situated at an altitude of 139 metres above sea level, Mahil Pond is a two-century-old water body located in the city of Orai, U.P., known as the city of King Mahil who was the ruler of this region during the 18th century AD. The pond is located at 25°98′ N latitude and 79°47′ E longitude. The maximum depth of the pond at full water level is about 4.0m and the average depth is about 2.0m. The surface area is about 10,000 sq.m. Having an elliptical outline, the pond has granite steps and concrete walls on all sides.

Physio-chemical properties

Various physiochemical properties of the pond are mentioned below:-

Rainfall

Monthly rainfall variation showed that the average monthly rainfall ranged from 12.93mm to 251.81mm. Heavy rainfall occurred only in the monsoon period, while light rain showers during winter resulted in higher levels of nutrients in the water bodies. It was observed that the seasonal variation in rainfall increased the number of nutrients and organic matter which is vital for maintaining a healthy aquatic ecosystem. Rainfall affects many things like vegetation, soil and water bodies, and thus influences different aspects of hydrology in Mahil Pond.

Cloud Cover

The data shows that the cloud cover in Mahil Pond was maximum during August (53.42%) and minimum (22.46%) in November. The high cloud cover in August and low Cloud Cover in November clearly shows that there is a positive relationship between Cloud Cover and Temperature in Mahil Pond.

Humidity

The average humidity at Mahil Pond over a year is 55%. Generally in the tropical regions, it is observed that during the hot and humid rainy season maximum humidity is observed while minimum humidity is observed during other seasons. In the case of Mahil Pond, maximum humidity was recorded in August (i.e., 81%) while minimum in April (i.e., 29%.)

Atmospheric and Water Temperature

Atmospheric and Water temperature are important physical factors that can have a large impact on water that affects its ability to hold and transfer heat, the rate at which energy is converted into the movement of water through evaporation, plant growth, and reactivity. In most cases, warmer water is preferred because it has a higher carrying capacity and can carry more dissolved nutrients than cooler water. Warm-water species tend to outcompete cool-water species because they have a higher requirement for oxygen. The recorded temperature in the pond was 29.03°C in the rainy season, 19.11°C in winter and 31.25°C in the summer season.

Secchi Transparency

The Secchi transparency was low during summer and higher during the winter season. It was lower in the summer season due to the high planktonic population, while it was low in the rainy season because of an increase in the suspended matter brought in through surface runoff. The results of Secchi transparency ranged between 25 cm to 60 cm. This property can provide a good insight into the planktonic population too.

pH

Major environmental factors influencing the limnological value of pH include substrate availability (organicity) and calcium carbonate saturation. It is a limiting factor and works as an index of general environmental conditions. The Mahil pond has an alkaline trait and the maximum pH value has been recorded in April (i.e., 9.4) and the minimum in (October i.e., 8.88.)

Electrical Conductivity

The electrical conductivity of water depends on the nature and concentration of salts present. The salt content in water affects its electrical properties. Water that has high conductivity is often called “soft water,” while low-conductivity water is more accurately called “hard” or “mineral” water. The electrical conductivity recorded in the lake was in the range of 2.13 mScm-1 and 3.23 mScm-1, which depicts maximum electrical conductivity in the rainy season and minimum in the winter season.

Total Dissolved Solids

Total dissolved solids (TDS) is the total of all salts dissolved in water. This includes both ionic and molecular solutes, which are responsible for the physical, chemical and biological properties of water.  The maximum value of total dissolved solids has been recorded in July (1449.50 mgl-1) and the minimum in January (816.50 mgl-1). The reason behind high TDS in July can be attributed to the rains which lead to the addition of domestic wastewater, garbage and sewage, etc.

Dissolved Oxygen

It is important in the cycle of aquatic ecosystems because it affects the solubility of nutrients and thus affects the periodicity of the aquatic ecosystem (Wetzel, 1983). The oxygen content in tropic waters is generally low owing to their high temperature. In Mahil pond, the value of dissolved oxygen increased from July to January, in which 10.50 mgl-1 was recorded highest, while from February to June it starts decreasing with the minimum being recorded as 5.15 mgl-1.

Biochemical Oxygen Demand

BOD is a measure of the amount of oxygen consumed by aerobic bacteria in a given volume of water. The rate of oxygen consumption depends on the concentration of dissolved oxygen and the temperature of the water. BOD presents an excellent index to study the quality of water and its change over time. In Mahil pond, the observation showed the highest value of Biochemical Oxygen Demand (BOD) was 3.26 mgl-1 in June and the lowest was 1.55 mgl-1 in January. The BOD of unpolluted water is less than 1.00 mgl-1 moderately polluted water 2.00-9.00 mgl-1 while heavily polluted water has BOD of more than 10.00 mgl-1.

Total Alkalinity

The alkalinity in natural water typically consists primarily of bicarbonate and carbonate salts. These salts get hydrolyzed in solution, resulting in the production of hydroxyl ions. A rise in alkalinity is also considered to be arise in calcium carbonate, CaCO3. In Mahil pond, the total alkalinity ranged between 418.25 to 583.01 mgl-1, which started decreasing from July to September and then increased in October and again decreased in November and December.

Bicarbonate Alkalinity

Since carbonate is a major component in aquatic bodies, it plays an important role in these bodies’ buffering capacity and ability to create life. The maximum bicarbonate alkalinity in the pond was recorded in October (i.e., 486.85 mgl-1 ) and minimum in May (i.e., 290.78 mgl-1, with an increasing trend from July to October.

Recommendations

The following recommendations can help to maintain and protect the pond:

• Proactive measures are essential to maintaining healthy water bodies. Regular cleaning of this lake will help the water remain clean and healthy; dustbins should be installed at all corners and the visitors ought to be encouraged to not through wrappers here and there.

• Using lake dyes to treat the water in your body of water prevents algae growth by adding more pigment to the water that acts like a shade and blocks sunlight from penetrating underneath the surface. This means there’s not enough sunlight available for their photosynthesis, preventing excessive algal growth (and no murky waters or “green” skin).

• Bacterial treatment for the lake needs to be done as it is one of the most environmentally friendly ways to maintain the quality of the water bodies. These micro-organisms do not harm fish nor plants as they are beneficial and natural bacteria that provide a long term solution for keeping water clean.

Conclusion

Data gathered from field surveys and various studies suggest that the water condition of Mahil Pond is just a little below the levels of eutrophication. It is also been observed that the present drainage system is not efficient to reduce the number of pollutants entering into the pond.’  Efforts need to be made to prevent the runoff from land that carries debris and products of the reproduction – the recommendations will come to aid.

References

Yadav, Priyanka, et al. “Physico-chemical characteristics of a freshwater pond of Orai, UP, Central India.” Octa Journal of Biosciences 1.2 (2013).

Kumar, Jitendra, and Amit Pal. “Water Quality of Two Century-old Freshwater Pond of Orai, Jalaun district Bundelkhand Region, UP, India.” Recent Research in Science and Technology 2.2 (2010).

Sharma, Sonam, and V. K. Yadav. “A LIMNOLOGICAL STUDY OF PRIMARY PRODUCTIVITY IN SEASONAL VARIATIONS OF A TYPICAL TROPICAL POND OF BUNDELKHAND REGION, INDIA.”