Dear Linda: It's just to say that last week I receipt your publications that you send me. Thank you a lot. I began to read your article and the chapter of the book. I think it will be very interesting for my knowledge and my work because it gives a little different point of view of what I read before, and also it is a very detailed work. The major part of the bibliography I read until now is from hydrogeologyst's works, where they have worked with 15N-(NO3-(NO2)-NH4) and 18O-(NO3-(NO2)). As you said to Carol, I think that there are lots of publications that will also be interesting for your work as a complement of your point of view. If you want I can tell/send you some of them, which I'm sure that Carol know them as well. You can also ask her if you want. Thanks again cheers Laura Dear Carol: For a less pessimistic perspective of the uses of N and O isotopes you told me two reviews that I could look. But unfortunately I couldn't find them in my University library. Even so, I have already read two differents reviews from ARAVENA, R. (1993 and 1998), and some other scientifics writing abaout N and O isotopes in groundwater. But if you think that those two that you have told me, they are, very, very interesting I would like to have them and I will be very pleased if you can also send them to me in the adress below. It will be very gratefull. Thank you a lot. Best wishes Laura Vitoria i Codina Grup Consolidat de Mineralogia Aplicada i Medi Ambient Dpt. Cristal.lografia, Mineralogia i Dipòsits Minerals Facultat de Geologia Universitat de Barcelona C/ Martí i Franqués s/n 08028 Barcelona, Spain Tel.34-93-4021345; Fax. 34-93-4021340 e-mail: [log in to unmask]