How the Chinese system of charges and subsidies affects pollution control efforts by China's top industrial polluters

There have been extensive theoretical studies of firms'responses to environmental regulations ad enforcement but few empirical analyses of firms'expenditures on pollution abatement in response to different regulations and enforcement strategies. The authors empirically analyze the pollution abatement efforts of Chinese industrial firms under a system combining pollution charges and abatement subsidies. Using data on China's top industrial polluters and on regional development in China, they find that the combination of charges and subsidies used in china has provided effective incentives for the most heavily polluting industrial firms to abate pollution. Chinese industries operate under a unique pollution control system, a market-based instrument combining emissions charges and abatement subsidies. This combination of charges and subsidies has given firms incentive to invest in wastewater treatment facilities. The pollution levy, although low, has significantly improved investments in abatement. The authors found that the more pollution a firm generates, the more likely it is to invest in pollution abatement. This study was only of top polluters, which are closely monitored by environmental agencies, so the results may not be valid for other sources of industrial pollution.Sanitation and Sewerage,Environmental Economics&Policies,Pollution Management&Control,Public Health Promotion,Water and Industry,Water and Industry,Environmental Economics&Policies,Pollution Management&Control,TF030632-DANISH CTF - FY05 (DAC PART COUNTRIES GNP PER CAPITA BELOW USD 2,500/AL,Sanitation and Sewerage

Cooperative hunting in a discrete predator-prey system

We propose and investigate a discrete-time predator-prey system with cooperative hunting in the predator population. The model is constructed from the classical Nicholson-Bailey host-parasitoid system with density dependent growth rate. A sufficient condition based on the model parameters for which both populations can coexist is derived, namely that the predator's maximal reproductive number exceeds one. We study existence of interior steady states and their stability in certain parameter regimes. It is shown that the system behaves asymptotically similar to the model with no cooperative hunting if the degree of cooperation is small. Large cooperative hunting, however, may promote persistence of the predator for which the predator would otherwise go extinct if there were no cooperation