CUHK Study Quantifies Mangroves' Nitrogen Removal at US$8.5 Billion Annually
Thestandard · 1 SOURCESabout 2 hours ago2 MIN
Summary
A groundbreaking study by researchers at the Chinese University of Hong Kong has quantified the economic value of mangroves' nitrogen removal capabilities at more than US$8.5 billion (HK$66.6 billion) annually. The research, led by Assistant Professor Benoit Thibodeau from CUHK's Department of Earth and Environmental Sciences and School of Life Sciences, along with PhD candidate Wang Ziyan, analyzed 51 published studies and unpublished datasets covering 42 mangrove sites worldwide. Their findings, published in the journal Earth's Future, reveal that mangrove forests remove nearly 870,000 metric tons of nitrogen pollutants from coastal waters each year, with the potential to remove up to five million metric tons annually under optimal conditions—equivalent to about 3 percent of global human-generated reactive nitrogen pollution.
Key Points
- Mangrove forests remove nearly 870,000 metric tons of nitrogen pollutants from coastal waters annually, valued at over US$8.5 billion (HK$66.6 billion)
- The research team, led by Benoit Thibodeau and PhD candidate Wang Ziyan, analyzed 51 studies covering 42 mangrove sites across the globe
- Under optimal conditions, mangroves could remove up to five million metric tons of nitrogen yearly—equivalent to roughly 3 percent of global human-generated reactive nitrogen pollution
- The economic value of mangroves' nitrogen-removal function exceeds 12 times that of their carbon sequestration credits, researchers estimated
- Microbes in mangrove sediments convert reactive nitrogen compounds into nitrogen gas, providing natural water filtration for coastal ecosystems
Why It Matters
Human-caused nitrogen pollution has surged approximately 50-fold over the past century, driving harmful algal blooms, expanding marine dead zones, fisheries collapse, and threats to freshwater supplies. The study introduces the concept of "blue nitrogen" to build on the successful "blue carbon" model, enabling more comprehensive valuation of ecosystem services. By establishing nitrogen removal credits within existing conservation frameworks, coastal communities like Hong Kong can better justify protecting mangrove ecosystems that provide critical environmental services beyond carbon sequestration alone .
Human-caused nitrogen pollution has surged approximately 50-fold over the past century, driving harmful algal blooms, expanding marine dead zones, fisheries collapse, and threats to freshwater supplies. The study introduces the concept of "blue nitrogen" to build on the successful "blue carbon" model, enabling more comprehensive valuation of ecosystem services. By establishing nitrogen removal credits within existing conservation frameworks, coastal communities like Hong Kong can better justify protecting mangrove ecosystems that provide critical environmental services beyond carbon sequestration alone .