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Heavy metals are naturally occurring elements found in rocks and soil. Some metals, such as copper (Cu) and zinc (Zn), are essential for living organisms in small amounts to support normal biological processes. However, when these metals accumulate at high concentrations, it can be toxic. Other metals such as lead (Pb), mercury (Hg) and cadmium (Cd) can be harmful even in low concentrations. Human activities like industrial discharge, mining, agriculture, urban development and improper waste disposal have dramatically increased the amount of heavy metals entering rivers, lakes and coastal waters.

Every Aquatic Organism Is Affected

Heavy metals such as lead, mercury and cadmium can seriously harm aquatic organisms even in low concentrations. These heavy metals can damage fish gills, making it harder for them to breathe, lower reproduction rates, and reduce growth. As for aquatic plants, heavy metals will interfere with photosynthesis, reducing growth and limiting the food supply for other organisms. Small invertebrates such as shrimp and snails may suffer from slower development, lower survival rates and low reproduction. Heavy Metals can reduce microorganisms activities, which will slow nutrient cycling and lead to less decomposition activity. Thus, it can reduce the overall health of aquatic organisms. 

A Closer Look at the Yeh River in Che Minah Sayang Recreational Park

For a better understanding of how heavy metals affect freshwater ecosystems, a study was conducted at Yeh River in Che Minah Sayang Recreational Park, Jengka, Pahang (Figure 1). The river is surrounded by secondary forest, oil palm plantations and nearby residential areas. It is also a popular place for swimming, fishing and picnics, making it an important river for both wildlife and the local community.

Although the river looks crystal clear and clean, pollutants can still enter the water through surface runoff, domestic waste and agricultural activities. These pollutants may carry heavy metals that can affect water quality and aquatic life. Nineteen samples of water were collected from two different points of the river (Figure 2). To assess the condition of the river, water quality parameters such as pH, dissolved oxygen, turbidity, total dissolved solids, biochemical oxygen demand, electrical conductivity and heavy metal concentrations were measured. Frequent monitoring of the Yeh River also helps to detect pollution early. This also provides important information to support conservation efforts for a valuable freshwater ecosystem for future generations.

What did we find?

In the Yeh River, several heavy metals were detected, including aluminium (Al), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), lead (Pb) and zinc (Zn). The results were compared with the Malaysian National Water Quality Standards (NWQS).

Most heavy metals, including cadmium, chromium, copper, and zinc, were below detection limit. Meanwhile, Al and Fe were also at below the recommended limits. Only one sampling point showed a slightly higher concentration of Pb than the NWQS limit, while all other samples remained within the acceptable range. Overall, the results of Yeh River are currently in good condition with respect to heavy metal pollution. Continuous monitoring will help protect aquatic life and ensure the river remains safe for recreational activities and future generations (Figure 3).

Why should we care?

Healthy rivers provide clean water to support biodiversity and create recreational opportunities for local communities. Heavy metal pollution can reduce biodiversity by damaging aquatic habitats and threaten the health of the ecosystem. Contaminated fish and other aquatic animals may also pose risks to human health if consumed regularly. As development continues around freshwater ecosystems, protecting rivers like Sungai Che Minah Sayang becomes increasingly important. Preventing pollution today helps ensure the ecosystems remain healthy for future generations.

Protecting Our Freshwater Ecosystems

Everyone has a role in protecting rivers from pollution. Industries should treat wastewater before releasing it into the environment. Farmers should adopt sustainable agricultural practices and use less fertiliser to avoid excessive nutrient runoff into the river. Local communities should develop awareness about protecting our river by properly disposing of waste. Government agencies should continue monitoring water quality and enforcing environmental regulations to minimise pollution. By working together, we can reduce heavy metal pollution and preserve freshwater ecosystems for wildlife and future generations.

Looking Beyond the Water

Heavy metals may be invisible, but their effects can last for many years. They accumulate in aquatic organisms, move through the food chain and may eventually affect human health. Although rivers like Sungai Che Minah Sayang may appear clean, protecting their water quality requires continuous monitoring and responsible environmental management.

Beneath the surface is a complex ecosystem of fish, plants and microscopic organisms that depend on clean water to survive. Protecting these rivers today ensures they continue to support biodiversity, recreation and local communities for many years to come.

Rujukan

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3. Department of Environment Malaysia. (2021). National water quality standards for Malaysia. Ministry of Natural Resources and Environmental Sustainability. https://www.doe.gov.my/wp-content/uploads/2021/10/ii-Standard-Kualiti-Air-Kebangsaan.pdf

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