@article {PIE3,
	title = {Measuring 15N-NH4 in marine, estuarine, and freshwaters: an adaptation of the ammonium diffusion method for samples with low ammonium concentrations.},
	journal = {Marine Chemistry},
	volume = {60},
	year = {1998},
	note = {PI Coastal},
	pages = {235-243},
	keywords = {ammonium, analytical methods, diffusion, estuarine, fresh water, inorganic nutrients, N-15, PIE LMER, sea water},
	doi = {10.1016/S0304-4203(97)00099-6},
	author = {Holmes, R.M. and McClelland, J. and Sigman, D.M. and Fry, B. and Peterson, B.J.}
}
