| Through the use of a refined Dumas combustion, this study sought information on the natural abundance levels of the (delta)('15)N of organic nitrogen in the marine environment. Individual studies included the mixing of organic matter, the effect of diagenesis on (delta)('15)N, the tracing of oil pollution, the resolution of animal-diet relationships, and the analysis of isotope effects in natural tetrapyrroles.;Diagenetic processes may result in an increase in (delta)('15)N of the residual material on the order of 3 to 5('o)/oo. This enrichment was observed in both blue-green algal mats and seagrass beds of South Texas.;A broad range of (delta)('15)N values and the conservative nature of (delta)('15)N during weathering of oil enabled this study to distinguish sources of tarballs on the beaches of Port Aransas, Texas. Principal sources of tarballs were two major oil spills in the Gulf of Mexico: the Ixtoc I well blow-out of June, 1979, and the breakup of the tanker BURMAH AGATE in November, 1979 ((delta)('15)N= + 0.6 and + 5.5, respectively). When in conjunction with (delta)('13)C, the (delta)('15)N values of oil aid in determining the source of the petroleum.;Animal-diet relationships have been mapped by (delta)('15)N analyses. Amphipods (Ampithoe valida) grown on different diets have shown the same fractionation (-0.3 per mil) while Parhyale hawaiiensis, raised on the same diets has shown a different fractionation (+2.3 per mil). Natural populations of the same animals had similar fractionations.;The knowledge of (delta)('15)N and (delta)('13)C of sedimentary materials has enabled the resolution of sources of organic matter during mixing at six different locations. These studies included: mixing of planktonic matter with either algal mat, brown algal, or seagrass material, terrestrial nitrogen mixing with marine nitrogen, and recently fixed nitrogen mixing with detrital mangrove nitrogen. If (delta)('15)N had not been used, different types of organic matter may have been confused. In Maine estuaries, organic material from fucoids was discerned even though the (delta)('13)C values of those plants resembled other local organic inputs. Support for the model of the Baffin Bay algal mat mud layers originating from catastrophic events resulted from (delta)('15)N analyses of them.;Naturally occurring tetrapyrrole (delta)('15)N values (chlorophylls) have been observed to be variable with respect to whole plant (delta)('15)N values. Marine plants associated with sediments tended to have (delta)('15)N enriched tetrapyrroles while water column and terrestrial tetrapyrroles were similar to whole plant (delta)('15)N values. |
