Water lanterns, often released onto rivers, lakes, or oceans during celebrations and memorials, are floating decorative devices designed to drift on the water’s surface. These lanterns carry a light source, traditionally a small candle or fuel cell, within a structure that provides buoyancy. While they offer a visually appealing spectacle, their aesthetic appeal must be weighed against the potential environmental consequences when their journey ends. This analysis will focus on the various materials used in their construction and the resulting ecological impact on marine and freshwater environments.
Material Composition and Immediate Litter
Water lanterns are composed of several materials. The main body and upper structure are usually made from paper, such as rice or washi paper, which is generally considered biodegradable. A buoyant base is necessary to keep the lantern afloat and has historically been constructed from wood or bamboo. However, some bases use less environmentally friendly materials like plastic foam or polystyrene.
The immediate environmental concern arises when the light source extinguishes and the lantern sinks or washes ashore, depositing its components into the ecosystem. Non-biodegradable elements, such as plasticized coatings, metal wire frames used for structural support, or plastic foam bases, instantly become marine debris. Some modern variations may also include LED lights and small batteries, which introduce heavy metals and synthetic materials into the aquatic environment.
When released in large quantities, such as during a festival or mass memorial, the cumulative volume of this debris can overwhelm local cleanup efforts. Even when manufacturers claim their products are “100% biodegradable,” the inclusion of small amounts of non-natural materials, like glues or thin wire, means the entire structure will not harmlessly break down.
Hazards to Aquatic Wildlife
Water lantern debris poses direct physical and chemical threats to aquatic wildlife. One acute hazard is entanglement, primarily caused by metal wire frames, strings, or ropes used for structural integrity. Fish, turtles, and aquatic birds can become ensnared, severely restricting their movement. This impaired mobility reduces an animal’s ability to forage, escape predators, and surface for air, often leading to exhaustion and death.
Ingestion is another significant danger, as animals may mistake pieces of the lantern for food, or prey that has already consumed the debris. Fragments of plastic, foam, or paper can cause internal blockages in the digestive tract, leading to a false sense of satiation. This prevents the animal from consuming necessary nutrition, resulting in starvation despite a full stomach. Furthermore, if the lantern debris includes metal components, such as wire or battery parts, the sharp edges can cause internal lacerations and bleeding.
The inclusion of electrical components, like small batteries or LED lights, introduces a chemical hazard. As these batteries corrode, they can leach toxic substances, including lead, mercury, and cadmium, into the environment. These heavy metals accumulate in the tissues of aquatic organisms through the food chain, leading to long-term health issues, reproductive failure, or death.
Long-Term Pollution and Material Breakdown
While natural materials like paper and bamboo fibers will eventually decompose, synthetic elements persist in the environment for extended periods. Plastic foam and certain plastic bases, used for buoyancy, can take hundreds of years to fully degrade.
During this extended period, larger pieces of plastic debris break down into smaller fragments known as microplastics, which are particles less than five millimeters in size. This process is accelerated by exposure to sunlight and wave action, but the material never truly disappears. These tiny plastic particles are easily ingested by organisms at the bottom of the food web, from zooplankton to filter-feeding oysters.
As microplastics accumulate, they attract and concentrate other pollutants present in the water, such as pesticides and industrial chemicals. When marine life consumes these contaminated particles, the concentrated toxins transfer into their bodies. These toxins move up the food chain to larger predators and potentially impact human health.