The environmental impacts of foreign direct investment (FDI) and foreign trade have attracted much attention recently. This paper employs panel quantile regression to explore the effects of FDI and foreign trade on Chinese provincial CO2 emissions for the period of 1997-2014. The results indicate that the effect of FDI on CO2 emissions is negative and significant except at the 5th and 10th quantiles. Foreign trade has a significant negative effect on CO2 emissions at upper quantiles, and the degree of the effect increases gradually with the increase of CO2 emissions. The results also suggest that the inverted U-shaped environmental Kuznets curve (EKC) is valid only in the least and most polluted provinces. Nevertheless, the positive indirect effects of FDI and foreign trade on CO2 emissions are greater than the negative direct effects; thus the total effects are positive. Finally, several policy implications are proposed for China based on the empirical results obtained.

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New developments in multibeam technology now permit MBES to collect and record acoustic data not only from the strongest return (normally the seabed), but also echo returns from the complete travel paths of the acoustic pulse through the water column. This now allows they are established as standard tools for the remote detection of targets in the water column, such as gas bubbles leaking from pipeline. In this study, a multibeam sonar operating at 300kHz is used to detect the gas leakage of pipeline based on acoustic backscatter imagery. Some behavioural traits of the leakage gas bubbles have been discussed, such as shape, distribution pattern and contour centroid characteristics. Firstly, an adaptive beamforming algorithm is applied to sonar imaging for suppressing background noise and side lobe interference. And then these features are extracted by mathematic morphological processing of image sequences. Finally, a tank test with different leakage scales caused by leakage pressures, amounts and sizes has verified the validity and stability of the characteristics of gas bubbles. The proposed method is feasible to make a qualitative assessment for AUV pipeline detection surveys.

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