Researchers install environmental monitoring equipment at ancient Buddhist site
Friday, Jul 19th 2013

In order to help preserve one of the oldest and grandest Buddhist sites in China, researchers recently installed environmental monitoring equipment at the Bingling Temple Grottoes, the Xinhua news agency reported. The Bingling Temple Grottoes are a series of caves located in central China that hold a number of historically significant Buddhist statues and murals.

According to Xinhua, the grottoes were first established around 420 B.C. on the Silk Road, the noteworthy trade route that used to be the key overland connection between China, the Middle East and Europe. Chinese authorities are working to have the Bingling Temple Grottoes as well as other notable points along theold Silk Road be classified on the World Heritage List.

How environmental monitoring facilitates historic preservation
Although the grottoes remain even more than 1,000 years after they were first created, their future is not guaranteed due to a number of external variables that can degrade the statues and murals over time. In particular, excess humidity, whether from additional water vapor generated by tourists visiting the region or from the air, can erode the rock. To better track and monitor the effects variables such as heat, humidity and carbon dioxide have on the grottoes, Xinhua reported that researchers recently installed environmental monitoring equipment on 20 of the 183 caves within the temple complex.

"The data will help us analyze the impact of visitors and weather on the caves' environment," said Shi Jingsong, head of an institute in charge of protecting the grottoes, according to Xinhua.

One of the reasons why the statues and murals have been able to survive for so long is because the air in the region is naturally devoid of moisture and because the top part of the cliff protects the grottoes from rain and sunlight, according to the Lanzhou Institute of Chemical Physics and the Chinese Academy of Sciences. This is especially notable in this instance because the temple is made from sandstone, which is more porous and brittle than many other natural building materials.

The issues presented by sandstone have also plagued researchers working in other parts of the world, Geotimes reported. For example, humidity threatens to degrade the ancient structures in Petra, the city located in modern-day Jordan that served as a backdrop for scenes from the original Indiana Jones trilogy. Sandstone is more absorbent than other rocks, so it more easily absorbs the moisture that will eventually degrade its surface. 

"What I found was that the greatest weathering was on western faces, where you get wetting from storms, rain and sun." Tom Paradise, a geomorphologist from the University of Arkansas at Fayetteville, told Geotimes about Petra. "It's these little tiny super-frequent events, like wetting and drying from dew every morning, that causes the sand to disaggregate."

This problem is also present in Afghanistan's Bamiyan Valley, which has housed Buddhist statues and fresco art for approximately the last 17 centuries, Geotimes reported. Although political issues have caused more damage than any other factor, the soft sandstone that facilitates the easy carving of artwork also exposes the area to external damage over time.

Although its effects are especially pronounced with sandstone, excess moisture can erode any rock surface over time. As such, humidity monitoring equipment is one of the best tools researchers can use to protect historic sites like the Bingling Temple Grottoes.