This study analyzed the regional economic feasibility of greenhouse gases (GHGs) reduction technology in paddy rice. Firstly, the impact of GHGs reduction technol-ogy on productivity, emission reduction, and costs is different from region to region. Secondly, the water irrigation system contributes to productivity, GHGs reduction, and water reduction, but the profit of paddy rice will decrease because of increase in fixed costs and variable costs. Thirdly, the economic feasibility shows that water-savings plot has a 1.41 in a benefit-cost ratio.

The polycyclic aromatic hydrocarbons(PAHs) content in sewage sludge was determined by gas chromatography linked to ion trap mass spectrometry(GC/ITMS) with five deuterated PAHs as internal standards. The minimum detection limit was from 1.66 to 7.14 pg for individual PAH by GC/ITMS. For determining total PAHs(∑PAH) in sewage sludge 84 samples from 74 waste water treatment plants in whole country were analyzed. The average content of ∑PAH for whole samples was 3,289±3,098 μg/kg, and ranged from 142 to maximum 20,102 μg/kg. According to the number of population of the city, the areas were classified as five regions, ie. big, large, middle, small, and rural area in which the waste water treated plants were grown. The contents of PAHs were 4,689±5,503, 5,839±6,401, 3,725±2,053, 2,237±2,069, and 2,475±1,489 μg/kg, in big, large, middle, small, and rural area, respectively.