introduction: detection of cryptosporidium and giardia parasites in water samples is usually performed by us environmental protection agency 1623 method. nevertheless, the usepa1623 method still need improvement, to prevent and control the water borne parasitic disease. therefore, we undertook the present study. materials and methods: totally 48 surface water samples were collected. four sample...

Most environmental policy is targeted at specific goals: a reduction in greenhouse gas emissions, achievement of some interim deposition or concentration level of air pollutants, improvements in water quality etc. These are policy targets or policy levels. Achieving given targets can involve different policy choices: standard setting, environmental taxes, public information campaigns, negotiate...

Because of the uncertainties and irreversibilities that are often inherent in environmental degradation, its prevention, and its economic consequences, environmental policy design can involve important problems of timing. I use a simple two-period model to illustrate these optimal timing problems and their implications for environmental policy. I then lay out and solve a continuous-time model o...

Because of the uncertainties and irreversibilities that are often inherent in environmental degradation, its prevention, and its economic consequences, environmental policy design can involve important problems of timing. I use a simple two-period model to illustrate these optimal timing problems and their implications for environmental policy. I then lay out and solve a continuous-time model o...