A study of soil organic carbon distribution and storage in the Northeast Plain of China

Employing the Unit Soil Carbon Amount （USCA） approach, soil carbon storage was calcu- lated across the Northeast Plain of China based on the Multi-purpose Regional Geochemical Survey conducted in 2004-2006 （MRGS）. The results indicated that the soil organic carbon （SOC） storage in topsoil （0-0.2 m）, subsoil （0-1 m） and deep soil （0-1.8 m） was 768.1 Mt, 2978.4 Mt and 3729.2 Mt with densities of 3327.8 t/km^2, 12,904.7 t/km^2 and 16,157.5 t/km^2, respectively. These values were consistent with national averages, whereas the soil carbon densities showed a clear increasing trend from the southern area of the Northeast Plain （Liaoning）, to the middle （Jilin） and the northern Plain （Heilongjiang） -- particularly in terms of topsoil carbon density, which increased from 2284.2, to 3436.7 and 3861.5 t/kin2, respectively. In comparison to carbon data obtained from the Second National Soil Survey in 1984--1986 （SNSS）, the topsoil SOC storage values from the MRGS were found to have decreased by 320.59 Mt （29.4%）, with an average annual decline of 16.0 Mt （1.73%） over the 20 years. In the southern, middle and northern areas of the plain, soil carbon densities decreased by 1060.6 t/km^2, 1646.4 t/kin2 and 1300.2 t/km^2, respectively, with an average value of 1389.0 t/km^2 for the whole plain. These findings indicate that the decrease in soil carbon density varied according to the different ecosystems and land-use types. Therefore, ratios of soil carbon density were calculated in order to study the carbon dynamic balance between ecosystems, and to further explore distribution characteristics, as well as the sequestration potential of SOC.

A review of whole-process control of industrial volatile organic compounds in China

Volatile organic compounds(VOCs)play an important role in the formation of ground-level ozone and secondary organic aerosol(SOA),and they have been key issues in current air pollution prevention and control in China.Considerable attention has been paid to industrial activities due to their large and relatively complex VOCs emissions.The present research aims to provide a comprehensive review on whole-process control of industrial VOCs,which mainly includes source reduction,collection enhancement and end-pipe treatments.Lower VOCs materials including water-borne ones are the keys to source substitution in industries related to coating and solvent usage,leak detection and repair(LDAR)should be regarded as an efficient means of source reduction in refining,petrochemical and other chemical industries.Several types of VOCs collection methods such as gas-collecting hoods,airtight partitions and others are discussed,and airtight collection at negative pressure yields the best collection efficiency.Current end-pipe treatments like UV oxidation,low-temperature plasma,activated carbon adsorption,combustion,biodegradation,and adsorption-combustion are discussed in detail.Finally,several recommendations are made for future advanced treatment and policy development in industrial VOCs emission control.