River delta areas can provide clue to environmental changes in 21st century

May 12th, 2009 - 1:54 pm ICT by ANI  

Washington, May 12 (ANI): Researchers at Texas A and M University, US, have determined that the historical information that can be gathered from sediment cores collected in and around river delta areas regions is critical for a better understanding of environmental changes in the 21st century.

The research was carried out by Thomas Bianchi, a professor in the Department of Oceanography, Texas A and M University, and colleague Mead Allison.

The researchers have examined sediments from delta areas around the world, most notably the Mississippi in the United States and the (Huanghe) Yellow and Yangtze in China.

“These sediments contain information that can provide data on past changes in nitrogen application in the drainage basin from agricultural fertilizers, records of past flooding and hurricane events, to name a few,” Bianchi said.

“These deltaic sediments can serve as a history book of sorts on land-use change in these large drainage basins which is useful for upland and coastal management decisions as related to climate change issues,” he explained.

“Although the information stored in these sediments can be altered during its transport from the upper drainage basin to the coast, we still find very stable tracers, both organic and inorganic, that can be used to document changes induced by natural and human forces,” he added.

According to the researchers, such sediments are ever-present, noting that 87 percent of the Earth’s land surface is connected to the ocean by river systems.

Much of the sediment from rivers forms into what are called large river delta-front estuaries (LDEs), and human activity in some of these can be traced back more than 5,000 years ago to some of the first cities in Mesopotamia, along the Nile and in regions of China.

The knowledge learned from these delta areas tell about the history of the region from how the land was used - or not used - through time, according to the researchers.

In the US, hypoxic areas - where there is little or no oxygen - can in some cases be linked with deltaic regions that are releasing large amounts of water and nutrients, Bianchi explained.

“Low oxygen in aquatic systems is clearly not good for the organisms in those systems, but not all aquatic systems respond in the same way,” he noted.

“It affects marine life in some areas severely, while other areas seem unchanged. We need to find out why,” he added. (ANI)

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