Healthy Oceans, Healthy Planet: Cleaning up Marine Debris from Natural Disasters

IN THE USUAL HAVOC CREATED BY SCATTERED DEBRIS AFTER FLOODS, ONE MIGHT EVEN BE PLEASED IF ALL OF IT GETS WASHED OFF TO THE OCEAN, A COURSE OF ACTION OFTEN TAKEN FOR GRANTED TO REMOVE GARBAGE AND WASTE FROM COASTAL AREAS

The World Oceans Day is marked today, under the theme ‘Healthy oceans, healthy planet’; at a time Sri Lanka is striving to recover from a major natural disaster. While natural disasters cause sudden surges of ocean debris, taking tonnes of garbage from land into the ocean, it is much worse during floods, especially when populated areas adjoining the coastal belt are affected – as it did during the recent floods in Sri Lanka’s Western Province.

As the country is still struggling to overcome from the trauma in the wake of the disaster, the serious impact this has on oceans is likely to be neglected, as more immediate problems on land naturally take priority. In the usual havoc created by scattered debris after floods, one might even be pleased if all of it gets washed off to the ocean, a course of action often taken for granted to remove garbage and waste from coastal areas. However, such thinking may be counterproductive, causing long-term damages to the marine environment, leading to a situation of ‘sick oceans, sick planet’, the opposite of today’s theme.

Marine pollution due to disasters that occur in the ocean such as ship accidents, oil spills, chemical spills, etc., have been well recognized and many countries are prepared to face these at least to a certain level. Similarly, there is also awareness on marine debris from ships and various land sources. However, comparatively, the knowledge of marine pollution caused due to natural disasters on land areas is somewhat limited. Studies show that natural disasters that occur on land can lead to a heavy collection of ocean debris.

Disasters such as hurricanes, tropical storms, and tsunamis are usually associated with high winds, heavy rains, storm surges and flooding that can pull large amounts of land debris into surrounding seas. Such debris include small to large structures, household items and garbage washed off from flooded areas. Observations on such marine debris have been made after many reported cases such as Hurricanes Katrina and Rita and cyclone Sandy. National Oceanic and Atmospheric Administration (NOAA) of the USA has carried out such studies on marine pollution associated with disasters.

The 2011 tsunami in Japan and Fukushima disaster captured world attention due to the possible involvement of radiation contaminated marine debris. According to the estimates of the Government of Japan, the disaster brought over five million tons of debris into the sea. Sudden influx of debris flows caused by disasters could lead to various unfavourable outcomes such as public safety and health issues, problems for navigation due to obstruction of navigation channels and threats to marine biodiversity and ecosystems.

Studies have shown that significant amount of debris breakup into parts and get sunk in the sea, mostly in near shore areas. However, there is floating debris that could take different paths. Part of it is washed ashore sooner or later. Observations indicate some floating debris may get carried over by waves, scattering over the ocean, sometimes ending up in distant places. Depending on the nature of float, the speed and distance travelled may vary. For instance, some debris generated in Japan’s tsunami disaster has been reported in West coast of the USA. Sometimes debris could get caught up in a circular ride of currents (e.g., North Pacific Subtropical Gyre), ending up in ‘garbage patches’ where debris has accumulated. Some materials in the disaster debris could stay in the environment without being degraded for long periods of time (e.g., some types of plastics).