Soil pollution, challenging ambitions

One fifth of the human population lives in China, while its soil only accounts for 7% of the world’s arable land. In the last few decades, 2.5% of this soil has become too polluted for agriculture, according to official reports. Water safety poses a related problem: according to official numbers, 10% of water resources are highly polluted. Studies around 2007 have shown that only 50% of all freshwater is safe to process into safely drinkable water [1]. Health problems occur when heavy metals, such as lead and cadmium, accumulate in the human body by drinking water, or consumption of crops that have been irrigated with contaminated water.

Last month, the Science magazine published two documents mentioning the devastating levels of soil pollution in China [2] … and the incentive to reverse it [3]. One report described the town of Shangba, residing on the banks of the Hengshi river, which 4 decades ago became a sewer for copper and sulphur mines. The resulting pollution has alarmed non-governmental organizations because of the elevated cancer incidence among residents. The second report summarizes an interview taken by Science Editor-in-chief Marcia McNutt with Chinese Premier Li Keqiang, stressing the importance of access to clean drinking water (still not available for over 100M people in rural China) and the huge investments made to provide clean energy, with a soon-to-be-expected market value of 100 Trillion USD.

The two reports combine a realistic rural situation with a political and bureaucratic perspective. Li Keqiang proposes ambitiously to provide all people in China with clean drinking water within 2 years. Before 2020, the pollution issue should be solved. There is however a need for innovative technological advances for soil treatment. Otherwise, most of the soil pollutants will be drained via the freshwater system, causing paradoxically a short-term rise in surface water pollution [1]. The Shangba residents may need a direct and pragmatic measure to relieve their exposure to heavy metals. As the cadmium accumulation in rice increases in acid soil, treatment of soil with biochar, thereby raising its pH, results in 50% lower cadmium levels in the most popular staple in south China [2]. Such a reduction may be significant, but better ideas are more than welcome.

adapted from http://www.sciencemag.org/content/343/6178/1415.full
Hengshi river, adapted from [2]

 

 

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