Sediment is made up of small pieces of soil and rock that are washed away by rain and floods. The material travels through rivers and drains until it reaches the ocean. A very fine sediment is known as mud (it feels smooth and slippery), and the large particles are sand. Sediment can be suspended, floating in the water, and deposited once it settles at the bottom of the river, streams, or the ocean. Too much sediment in water is considered pollution because it can harm the environment.
Where Does Sediment Come From?
Sediment is a natural part of the environment, but human activities can increase it. Some of the common causes are cutting down trees (forestry), construction and digging (earthworks), and farming. These activities can loosen the soil, making it easier for rain to wash it away. Some sediment in the ocean today can come even from the activities that happened many years ago.
There are various rocks, like sandstone, that break down easily and create more sediment. It can also come from the ocean itself. Waves and wind can stir up the materials that have settled on the seafloor and put them back into the water.
How Is Sedimentation Harmful to Ocean Life
When there is too much sediment in the ocean, it can be very harmful, especially fine particles like mud. Both floating sediment and sediment that settles on the bottom can damage marine plants and animals. It can block sunlight. Plants like seagrass and kelp need sunlight to grow beneath the water.
Sediment makes the water cloudy by reducing light and sometimes killing these plants. Most animals rely on clear water to find food. When the water is murky, animals like seals and penguins find it difficult to hunt. Sediment can settle on the plants and animals that cover them and even bury them. It can also clog the gills of animals like cockles and mussels that filter water for food.
In most cases, sediment can bring harmful substances like bacteria, chemicals, and metals to the rivers and oceans. Too much of it can disturb the balance of marine ecosystems and can harm different forms of ocean life.
How Does Marine Sediment Harm People?
Sediment is harmful to an entire ecosystem. It has a direct impact on how people collect food from nature, such as catching fish, collecting shellfish, and protecting endangered species.
When the water becomes murky, it becomes harder for people to enjoy activities like diving or spending time near the coast. In some areas, sediment can even cause bigger problems because of what places are known for. For example, once a good place for gathering or enjoying the scenery can be affected by too much sediment.
The build-up originally came from healthy topsoil on land, but it can damage the ocean environment. The topsoil is very important for growing food and forests, so keeping it on land is beneficial for both the environment and people.
To learn how dredging helps manage sediment buildup, read Is Marine Dredging Worth It? Here’s Real Return on Investment
Why Sediments Differ From Place To Place
The type of sediment in the marine water is not the same everywhere. It partly depends on where the sediment comes from, but mostly on the marine conditions like currents, waves, and water movements. These conditions can determine where different sediments settle. Because each type of sediment needs specific conditions, it gets sorted naturally in different areas.
The Main Sources of Ocean Sediment
Sediment from Rivers
Rivers can carry materials like clay, silt, and sand from land to the ocean. These usually settle near the edges of the continents. Sometimes, they even slide down into the deeper areas and get collected along the underwater slopes instead of spreading evenly.
Dust and Volcanic Ash
Wind can carry dust from dry regions and ash from the volcanoes into the ocean. These particles settle slowly on the seafloor, but they make up only a small part of the ocean sediment.
Remains of Marine Organisms
Most tiny sea organisms have shells made of calcium. When they die, their remains sink and form sediments. However, in very deep water, these remains can dissolve due to high pressure and chemical conditions.
Remains of Silica-based Organisms
Some marine organisms are made of silica. Their remains also settle on the ocean floor and are more common in certain regions like the Pacific and Southern oceans.
Here is What to Expect Before, During, and After a Marine Dredging Project
Clay On The Ocean Floor
The ocean floor also contains different types of clay. Most of the clay comes from land and is carried by rivers and wind. Some clay also forms from volcanic ash or near underwater volcanic areas. There are different types of clay found in different oceans depending on their sources.
Sediments On Beaches and Shore Areas
Sediments near the shore usually come from nearby rivers or older deposits offshore. The area is very active due to strong waves, which prevent fine particles from settling. Coarser materials such as sand and gravel are most common. Larger particles are found where waves break, and finer particles are found further offshore or in dunes.
The size of the sediment affects the slope of the beach. And, the beaches with larger grains are usually steeper, and the finer sediments create gentler slopes. However, factors such as tides, waves, and local conditions also influence it. In areas with a lot of fine sediment, thick muddy layers can form. These layers absorb wave energy and change how the shoreline behaves.
Manage Sediment With Dredging
Sediment naturally builds up in rivers, lakes, and oceans over time, but too much of it can create serious problems. It can even make waterways shallow, harm marine life, reduce water quality, and even lead to coastal erosion. It can also affect important human activities like fishing and recreation.
An effective way to manage the problem is dredging. The process removes extra sediment from the bottom of the water bodies using equipment. It helps restore water depth, improve navigation, and reduce environmental risks. Dredging can help protect aquatic ecosystems and keep waterways safe and usable.
