van der Veeren, R.J.H.M. and Tol, R. (2001). Benefits of a reallocation of nitrate emission reductions in the Rhine river basin Environmental and Resource Economics, 18(1):19--41.

In an attempt to improve ecological conditions of the Rhine, emission reduction targets have been set for different substances. For most substances targets have been met. However, nutrient emission reductions are behind schedule. It may be clear from intuition, and has also often been described in economic literature, that a flat reduction rate applied to all emitting sectors, though appealing because of equity reasons, may not be cost-effective. This paper explores the least cost allocation of nitrate emission reductions for the Rhine river basin, analysing different agricultural sectors and wastewater treatment plants. Results show that costs of meeting emission reduction targets can be brought down by almost 20% through a clever allocation of these targets.