Suspended Matter Pollution: Where Does It Lurk?

Suspended matter pollution is caused by the adsorption of pollutants to suspended particles. This can occur in rivers, reefs, and the ocean. Suspended solids include organic matter, plastic rubber waste, and other substances that find their way into aquatic and terrestrial ecosystems. In rivers, suspended matter can make water more turbid, which has a negative impact on river and stream biology. In the Rhine, for example, persistent organic pollutants have been detected in suspended matter, sediments, and fish.

Suspended matter pollution in the Rhine

Suspended matter pollution occurs when pollutants are adsorbed to suspended particles. These particles can get into the Rhine via the atmosphere, runoff, leaching and erosion. The Rhine is a river that runs through six countries in central and western Europe, including Germany, France, Switzerland, Liechtenstein, Austria and the Netherlands.

The natural turbidity of rivers caused by suspended matter is often mistaken for pollution. However, true suspended matter pollution can have a negative impact on river and stream biology. In the Rhine, this mainly applies to the Upper Rhine.

In 2009, the ICPR drafted a Sediment Management Plan aimed at reducing the pollutant load of suspended matter and sediments. This was due to the fact that a large share of the total amount of organic and inorganic substances transported with suspended matter consists of pollutants.

One persistent organic pollutant that has been detected in the Rhine is HCB (hexachlorobenzene). HCB contents mainly originate from a chemical plant near Rheinfelden, which has since been shut down. HCB contents fall from the Upper Rhine (Weil am Rhein) to the German-Dutch border at Bimmen-Lobith.

Another pollutant that has been detected in the Rhine is lead (Pb), which reaches the river via exhaust fumes from cars and the atmosphere. Lead used to be an antiknock additive in petrol, but due to its toxicity, it was replaced in the beginning of the 1990s. The lead contents of suspended matter in the Rhine have continuously fallen ever since.

Suspended matter pollution in reef ecosystems

Plastic pollution is a significant contributor to suspended matter pollution in reef ecosystems. The widespread use of plastics in packaging, construction, automobiles, and furniture, coupled with their slow rate of decomposition in nature, has made them one of the major pollutants of aquatic ecosystems, including coral reefs. According to a study, approximately 11.1 billion plastic items were entangled on coral reefs across the Asia-Pacific region, and this number is projected to increase by 40% by 2025.

Another source of suspended matter pollution in reef ecosystems is runoff and erosion, which can carry pollutants from the land into the ocean. This is particularly true for rivers, where natural turbidity caused by suspended matter can be mistaken for pollution. However, true pollution of suspended matter occurs when pollutants adsorb to suspended particles, entering the water through atmospheric deposition, runoff, leaching, and erosion.

Additionally, dredging activities can remobilise older, polluted sediments, transporting them further downstream and increasing the pollutant load of suspended matter in reef ecosystems. To address this issue, the ICPR drafted a Sediment Management Plan in 2009 to reduce the pollutant load of suspended matter and sediments.

In some cases, suspended matter pollution in reef ecosystems can be traced back to specific sources, such as the chemical plant near Rheinfelden, which was found to be the origin of HCB (hexachlorobenzene) contents in the Rhine River. Despite efforts to reduce pollution, persistent organic pollutants like HCB and lead (Pb) from car exhaust fumes and tetraethyllead in petrol continue to be detected in suspended matter, sediments, and fish, posing a threat to the health of reef ecosystems.

Suspended matter pollution in the atmosphere

Another way suspended matter pollution can occur is through the remobilisation of older, polluted sediments. This can happen during dredging activities, where the sediments are transported further downstream. A large proportion of the organic and inorganic substances transported with suspended matter are, in fact, pollutants.

Suspended solids, such as organic matter and plastic rubber waste, can also contribute to pollution. These solids can find their way into reef ecosystems, posing health threats to the organisms, particularly those that are photosynthetic. Plastic pollution is of particular concern, as its widespread use and slow rate of decomposition have made it one of the major pollutants of aquatic and terrestrial ecosystems.

Additionally, chemical plants can be a source of suspended matter pollution. For instance, the HCB (hexachlorobenzene) contents in the Rhine mainly originated from a chemical plant near Rheinfelden, which has since been shut down.

Suspended matter pollution in sediments

A study found that approximately 11.1 billion plastic items were entangled on coral reefs across the Asia-Pacific region, and this number is projected to increase by 40% by 2025. The wide use of plastics for packaging, buildings, automobiles, and furniture, coupled with their slow rate of decomposition, has made them one of the major pollutants of aquatic and terrestrial ecosystems, including reef ecosystems.

In rivers, suspended matter can be mistaken for natural turbidity. However, true suspended matter pollution occurs when pollutants are adsorbed to suspended particles. These pollutants can enter rivers via the atmosphere, runoff, leaching, and erosion. For example, lead (Pb) reaches the Rhine River via exhaust fumes from cars and the atmosphere, as it is a component of tetraethyllead, which was previously used as an antiknock additive in petrol.

To address this issue, the ICPR drafted a Sediment Management Plan in 2009 to reduce the pollutant load of suspended matter and, consequently, sediments. Additionally, a concept for quantitative sediment management is set to be developed in 2027, addressing HCB (hexachlorobenzene) contents that originate from a chemical plant near Rheinfelden.

Suspended matter pollution in fish

Suspended matter pollution is a persistent organic pollutant that can be found in fish, sediments and the water column. It is often mistaken for natural turbidity, but true suspended matter pollution occurs when pollutants are adsorbed to suspended particles. These particles can include organic matter, plastic rubber waste, and other solids that find their way into aquatic ecosystems, such as reefs and rivers. Suspended matter can originate from a variety of sources, including sewage, floods, storms, and runoff. In the case of the Rhine River, suspended matter pollution has been detected despite being forbidden in the bordering states. This pollution is believed to come from a chemical plant near Rheinfelden, as well as from car exhaust fumes and atmospheric lead. The ICPR has drafted a Sediment Management Plan to reduce the pollutant load of suspended matter, and efforts are being made to address the issue. The presence of suspended matter pollution in fish and other aquatic organisms poses a significant threat to their health and well-being, highlighting the importance of effective management and mitigation strategies.

Frequently asked questions