Sedimentary Organic Nitrogen Research Articles

Ammonium regeneration in intertidal sediments of the Yangtze estuary during air-exposure

The influences of exposure to the atmosphere on ammonium cycle in the intertidal surface sediments were in situ studied with a geochemical approach at a typical station in the Yangtze Estuary during three tidal cycles in September 2003. During an about 8-h emersion period of each diurnal tide, six high-resolution vertical profiles of adsorbed and dissolved ammonium were measured. It was observed that both adsorbed and dissolved ammonium generally had an increasing trend in sediment cores during the exposure. The rate of ammonium regeneration in sediments was estimated using the accumulation amount of ammonium including adsorbed and soluble fractions during the daytime emersion. The calculation result showed that there was relatively high ammonification rate (˜500 nmol N cm−3 day−1), which reflected that organic nitrogen in sediments was quickly decomposed with a residence time of ˜52.7 days. Due to the dramatic temperature difference observed in sediment profiles, free convection was considered an important mechanism of regulating the efflux of produced ammonium into overlying waters. The total estimated amount of regenerated ammonium was ˜1.35×105 t N year−1 in the intertidal flat of the Yangtze Estuary, which occupied 7.6% of the total inorganic nitrogen annually transported to the estuarine ecosystem.

A comparison of non-hydrolytic methods for extracting amino acids and proteins from coastal marine sediments

Advances in analytical techniques now allow for the potential analysis of intact peptides and proteins isolated from marine sediments. However, there is no established technique for the extraction of macromolecular materials from marine sediments. Six different methods for extracting the amino acid component from coastal marine sediments were compared to the standard hot acid hydrolysis technique for their percent recovery and amino acid composition. The standard hot acid hydrolysis on dried, whole sediments released the greatest concentration of total amino acids ( PS-THAA; 3.52 mg gdwt − 1 ± 10% (SMD)), yet this only accounted for 22% of the total nitrogen in Puget Sound sediments (Washington, USA). Repeated hydrolysis of the same samples did not improve the recovery of nitrogen by more than an additional 10%. Base extraction (0.5 N NaOH) was the second best method for recovering amino acid nitrogen, releasing 60% of the Puget Sound total hydrolyzable amino acids ( PS-THAA) (corresponding to 13% of the total sedimentary nitrogen), and has the advantage that it does not rely on peptide hydrolysis to free the nitrogenous component from the sediment matrix. The amino acid distribution of the 0.5 N NaOH extract was not significantly different than the initial THAA. Other non-hydrolyzing methods released lower yields of amino acids (Triton X-100 ≥ hot water > 50 mM NH 4HCO 3 > HF), but might prove to be of use to investigators interested in specific fractions of sedimentary organic nitrogen because these four methods had distinctly different amino acid compositions (enrichments in basic amino acids and depletions in acidic amino acids). Treatments with HF both before and after traditional hydrolysis and/or extractions with base did not release any more of the sedimentary nitrogen. Our results are consistent with the hypothesis that a large fraction of the sedimentary nitrogen (TN) is protected within an organic matrix.

Microbial nitrogen removal in a developing suburban estuary along the South Carolina coast

The conversion of undisturbed coastal regions to commercial and suburban developments may pose a threat to surface and groundwater quality by introducing nitrate-nitrogen (NO3 −-N) from runoff of land-applied wastewater and fertilizers. Microbial denitrification is an important NO3 −-N removal mechanism in coastal sediments. The objective of this study was to compare denitrification and nitrate conversion rates in coastal sediments from a golf course, suburban site, undeveloped marsh, and nonmarsh area near rapidly developing Hilton Head Island, South Carolina. Nitrous oxide was measured using gas chromatography and nitrate and ammonium concentrations were measured using a flow injection autoanalyzer in microcosms spiked, with 50 μg NO3 −-N gdw−1. The two marsh sites had the greatest ammonium production, which was correlated with fine sediment particle size and higher background sediment nitrate and surface water sulfate concentrations. The golf course swale had greatest denitrification rates, which were correlated with higher total carbon and organic nitrogen in sediments. Nitrate was consumed in golf course sediments to a greater extent than in the undeveloped marsh and upland freshwater sites, suggesting that the undeveloped sites and receiving estuaries may be more susceptible to nitrate contamination than the golf course swale and marsh under nonstorm conditions. Construction of swales and vegetated buffers using sediments with high organic carbon content as best management practices may aid in removing nitrate and other contaminants from runoff prior to its transport to the receiving marsh and estuary.

Australia: Mansfield — kaolin

Nitrogen isotopic compositions and concentrations in micas from kimberlite-hosted MARID (mica-amphibole-rutile-ilmenite-diopside) suite of xenoliths from the Kimberley area of the Kaapvaal Craton, South Africa, were measured using continuous-flow isotope-ratio mass spectrometry and Fourier transform infrared spectroscopy. Fourier transform infrared spectroscopy data suggest that the nitrogen in MARID phlogopite is from ammonium in the mica structure. The replacement of potassium by ammonium is the major mechanism for the storage of nitrogen within these phlogopites. The δ15N values of micas from MARID xenoliths range from − 11 to + 9‰, and nitrogen contents range between 113 and 272 ppm. The 15N enrichment of most samples relative to the average upper mantle δ15N value of − 5‰ suggests that the nitrogen reflects a recycled reservoir from subducted material within their source region. The presence of nitrogen from a recycled reservoir indicates that sedimentary organic nitrogen in the sub-continental lithosphere is not effectively cycled to the surface resulting in a geochemically heterogeneous upper mantle.

Annual nitrogen budget of a temperate coastal barrier salt-marsh system along a productivity gradient at low and high marsh elevation

Abstract An annual nitrogen budget was established for a temperate back barrier salt-marsh system along a productivity gradient at low and high marsh elevation. We measured plant biomass and nitrogen content in three plant compartments to deduce plant N-allocation patterns. Measurements were done along a successional sequence in a salt-marsh system. In addition, N-mineralization, wet and dry atmospheric N-deposition and sediment N-deposition were measured. Plant-species dominance changed along the successional sequence. In early stages, Elymus farctus and Spergularia media formed a large part of total plant biomass. Festuca rubra and Puccinellia maritima were dominant at intermediate stages, whereas Elymus pycnanthus and Limonium vulgare were dominant at late stages of succession. Shoot biomass was highest in June, whereas litter biomass was highest in September and December. Root biomass formed by far the largest fraction of total plant biomass, especially at a low-marsh elevation. Wet deposition of nitrate and ammonium was 1.7 g N m −2 yr −1 , whereas throughfall deposition (dry and wet deposition) amounted to 2.1–3.6 g N m −2 yr −1 , and was positively related to the height of an artificial plant canopy. Sediment organic nitrogen deposition rate was 0.3–5.4 g N m −2 yr −1 , and negatively related to marsh elevation. Nitrogen mineralization rate increased from 2.5–2.8 g N m −2 yr −1 in young marshes towards 8.0–12.7 g N m −2 yr −1 at older marshes, depending on marsh elevation. At a low-marsh elevation, plant N-availability depended equally on tidal N, atmospheric N and mineralized N, especially in young marshes, whereas the decomposition pathway became more important in older marshes. Tidal N contributed most to ecoystem N-accumulation rate at early successional stages, whereas atmospheric N was more important at later stages. Tidal influence was low at high-marsh elevation sites. Here, atmospheric deposition was the dominant exogenous nitrogen source both in young and old marshes.

Isotope study on organic nitrogen of Westphalian anthracites from the Western Middle field of Pennsylvania (U.S.A.) and from the Bramsche Massif (Germany)

The objective of this study was to examine an aspect of the thermal cycling of organic nitrogen in sediments and metasediments. The cycling of organic nitrogen is important because sedimentary organic matter is a shuttle of nitrogen from the atmosphere to the lower crust and thermal decomposition of organic matter is a critical step in the recycling of nitrogen between the different nitrogen pools. Abundance and isotopic composition of organic nitrogen were determined in the particular case of two low sulfur Westphalian anthracites series from Pennsylvania and Bramsche Massif. They represent good examples of Euramerica coals spanning the whole range of anthractization in single fields. Gold cell experimental simulation of the denitrogenation process was conducted at moderate pressure to show that both suites make ideal metamorphic profiles without any shift due to change of facies or to hydrothermal disturbance. During anthracitization, organic nitrogen content decreases rapidly while organic nitrogen isotopic composition does not change with rank increase. The preservation of the isotopic signature implies that organic nitrogen isotopes could be used as indicators for the paleoecological and paleodepositional history reconstruction of the basins. The striking contrast between the rapid and sharp decrease of nitrogen organic content and the invariance of its isotopic composition during the whole anthracitization suggests that ammonia is an important product of the denitrogenation process.

Concentrations of nitrogen in sandy sediments of a eutrophic estuarine lagoon

Concentrations of sediment organic nitrogen, dissolved inorganic nitrogen (ammonium, nitrite and nitrate), and dissolved organic nitrogen (DON) in sediments were measured at two sites in a eutrophic estuarine lagoon. One is a shallow aerobic site where macrobenthos are abundant and the other is a deep anaerobic site devoid of macrobenthos. Four species of macrobenthos (Bivalvia: Corbicula japonica, Annelida: Notomastus sp., Neanthes japonica and Oligochaeta sp.) were found in 8 sandy sediment cores collected at a shallow site in three succcessive summers. DON (170–1500 μg atom N l-1) was the major constituent of dissolved nitrogen with 10 times greater concentration than ammonium (55–180 μg atom N l-1) and 1000 times greater than nitrate (0.14–5.9 μg atom N l-1) and nitrite (0.21–1.4 μg atom N l-1). The ammonium content in anaerobic muddy sediments at the deep site (210–350 μg atom N l-1) was higher than in aerobic sandy sediments, whereas DON was higher in aerobic sediments than anaerobic sediments (90–240 μg atom N l-1). In aerobic sediments, depth profiles of DIN were nearly constant whereas DON was mostly highest at the surface. On the other hand, the increase of DON and ammonium was observed where macrobenthos was found. The occurrence of macrobenthos and high content of DON and ammonium content in the layers of sediment may suggest the influence of macrobenthos in the partitioning of nitrogen species through their motion and excretion.

95/00159 The origin and diagenesis of sedimentary organic nitrogen

95/00159 The origin and diagenesis of sedimentary organic nitrogen

Adsorption of amino acids and glucose by sediments of Resurrection Bay, Alaska, USA: Functional group effects

The adsorption of amino acids and glucose was investigated in sediments from Resurrection Bay, Alaska. Adsorption of the basic amino acid lysine was greater than adsorption of glutamic acid, alanine, leucine, or glucose. Formaldehyde and heat treatments were used to separate adsorption from biological uptake, but can alter adsorption significantly; formaldehyde treatment, followed by a seawater rinse, was the most satisfactory. Much of the rapid amino acid adsorption by these sediments was due to the formation of ionic bonds, since adsorbed amino acids could be extracted using concentrated solutions of amino acid, cesium chloride, sodium citrate, ammonium chloride, or sodium acetate. However, most amino acid adsorption was not reversible by ion exchange solutions, indicating that additional processes or chemical reactions occur which result in irreversible binding to sediment. Consistent with literature reports of the negative surface charge of marine particulate matter, lysine (with a net positive charge) was adsorbed to the greatest extent and had the largest cation-exchangeable adsorption. However, negatively charged amino acid functional groups also influenced adsorption. Chemical modification of sediments with reagents reactive with aldehydes decreased lysine adsorption. This suggests that reactive functional groups of sediment organic matter contribute to adsorption, consistent with a melanoidintype reaction. An estimate of the rate of amino acid adsorption indicates that adsorption could produce a significant amount of the total refractory sediment organic nitrogen.

Provenance, concentrations and nature of sedimentary organic nitrogen in the gulf of Maine

Factors controlling the provenance, concentrations, and nature of sedimentary organic matter (SOM), particularly the nitrogenous fraction, were examined for sites throughout the Gulf of Maine and two of its estuaries. Stable nitrogen isotope data corroborate previously reported Br: C ratios in indicating that macroalgae are important contributors to organic nitrogen pools in estuarine sediments. Significant contributions of terrigenous organic carbon in both the estuaries and the deep basins of the open Gulf are not accompanied by significant contributions of terrigenous organic nitrogen. Variations in concentrations of organic carbon, nitrogen, chlorophyll, and enzymatically hydrolyzable protein throughout the Gulf and its estuaries can be explained largely by variations in the delivery rate of organic matter to the benthos and the specific surface area of minerals in the sediments. Chlorophyll and protein concentrations represent relatively fresh organic matter and exhibit greater sensitivity to organic delivery variations than do total organic carbon or nitrogen. A strong, linear relationship between organic carbon and surface area is consistent with monolayer adsorption of SOM on mineral surfaces, which appears to inhibit degradation of the SOM. Amino acid compositions are remarkably constant throughout the Gulf, with large differences seen only with elevated tyrosine in estuaries and elevated basic amino acids and methionine in the open Gulf. Leucine and glutamic acid correlate with chlorophyll concentrations in open Gulf sites. Enzymatically hydrolyzable protein comprises small to major fractions of total hydrolyzable amino acids. Amino acid-nitrogen: total nitrogen correlates inversely with total nitrogen.

Seasonal changes of concentrations of inorganic and organic nitrogen in coastal marine sediments

The seasonal fluctuations of the concentration of nitrogenous compounds in sediments was investigated for three regions of the Seto Inland Sea in Japan; the variation of nitrogenous compounds in sediments was also studied in a laboratory experiment. The amounts of ammonium, dissolved organic nitrogen, nitrite and nitrate, as percentages of the dissolved total nitrogen of the interstitial water, were in the ranges of 47–99%, 10–50%, 0·1–0·6% and 0·3–4·1%, respectively. Ammonium was the major component and organic nitrogen was the next most important. The concentrations of these nitrogenous compounds changed seasonally: dissolved total nitrogen was higher in the warm month of September than in May; ammonium increased in warm months and decreased in cold months, but nitrite and nitrate increased in cold months. It was possible to explain the seasonal fluctuation of nitrogenous compounds in terms of the rates of the metabolic pathways of nitrogen in the sediments. Ammonium was not necessarily correlated with dissolved organic nitrogen. From this, it was considered that ammonium did not occur from solubilization of particulate organic nitrogen followed by mineralization, but from direct mineralization of particulate organic nitrogen in sediments. For the sediments of Suho Nada, Hiuchi Nada and station B-47 in Beppu Bay, the ratio of dissolved ammonium to adsorbed ammonium in the sediments was in the range 10–25%, but the ratio was 60–70% of adsorbed ammonium in the considerably anaerobic sediments at station B-45 in Beppu Bay. The ratio of dissolved ammonium to adsorbed ammonium increased with the increase of the concentration of sulfide in sediments. It was recognized that the anaerobic conditions of the sediments led to the dissolution of adsorbed ammonium.

15N and 13C abundances in the Antartic Ocean with emphasis on the biogeochemical structure of the food web

Distributions of δ 15N and δ 13C for biogenic substances in the Antarctic Ocean were investigated to construct a biogeochemical framework for assessing the Antarctic ecosystem. Phytoplankton exhibited particularly low δ 15N (0.5%) and 13C (-26.9%) values in pelagic plankton samples. High nitrate concentrations, and high P CO 2 in the surface waters on the southern side of the polar front and the resulting slow growth rate of phytoplankton under low light intensity are suggested as possible factors in causing the low isotopic compositions. Mean fractionation factors of 1.029 and 1.006 were estimated for photosynthetic carbon fixation and for the assimilation of inorganic nitrogeneous compounds (ammonium plus nitrate) during algal growth, respectively. Enrichment of 15N with increasing trophic level was confirmed for Antarctic ecosystems: δ 15N animal% = 3.3 (trophic level −1) + δ 5N algae, whereas 13C content did not increase in the same manner. Differences in lipid content among animals may be the main factor in causing this δ 13C anomaly. 15N and 13C abundance of sedimentary organic nitrogen differed from phytoplankton and settling particles. An exact mechanism for explaining the high δ 15N (around 5%) is not known. The very high δ 13C value of −20.5% at Sta. 3B may originate in ice algae that had grown under CO 2-limited conditions. Particles collected by sediment traps gave characteristically low δ 15N values (−3.0 to 0.9%), strongly suggesting a phytoplankton origin. The δ 15N and δ 13C values of settling material showed similar vertical profiles with depth which might arise from temporal variation of algal growth.

The effect of sewage effluent on the population density and size of the clam Parvilucina tenuisculpta

Changes in the population density and size of the clam Parvilucina tenuisculpta were related to municipal waste effluent (in particular, organic nitrogen concentration) off the coast of Palos Verdes, California. Average clam size increased as sediment organic nitrogen concentration increased, but population density increased until organic nitrogen concentration reached a critical level when population density decreased dramatically. These effects were explained in terms of increased available nutrition (in the form of sediment organic nitrogen pollutants) enhancing both population and individual size growth. However, when a critical concentration of organic decomposition products was reached, population density decreased due to the toxicity of the released compounds. It is suggested that Parvilucina tenuisculpta would make a good bioindicator of organic enrichment pollution.

Downcore variation in sediment organic nitrogen

An historical record of natural (pre-cultural) and anthropogenic (influenced by man's activities) chemical inputs to the environment is contained in accumulating sediment deposits and is commonly expressed as a depositional flux1. This flux is traditionally calculated as the product of the sediment accumulation rate and the concentration of a substance in the sediment1. Previous work has quantified depositional fluxes of metals and nutrients by assuming that the vertical distribution of these substances in sediments is unaffected by post-depositional migration, chemical reaction or porosity variations2–10. We present here a procedure for calculating the historical depositional flux (loading record) of a substance which undergoes post-depositional chemical reaction in a compacting sediment column. The method is demonstrated by calculating the loading record of organic nitrogen at one locality in Lake Erie.

Feeding of Holothuria atra and Stichopus chloronotus on bacteria, organic carbon and organic nitrogen in sediments of the Great Barrier Reef

Organic carbon and nitrogen and bacterial biomass were measured in the sediments and gut contents of H. atra and S. chloronotuson the Great Barrier Reef. Organic carbon averaged from 3.4 to 4.7 mg g-1, organic nitrogen from 0.20 to 0.31 mg g-1 and muramic acid from 1.4 to 3.3�g g-1 dry weight of surface sandy sediments. Bacterial biomass, determined by muramic acid measurements, averaged 3-8% of organic carbon in the sediments; blue-green algae accounted for 3-7% of muramic acid. Significantly higher values of organic carbon and nitrogen and muramic acid were found in foregut contents of the holothurians, indicating selective feeding on organically rich components of the sediment. Carbon values were 16-34% higher in the foregut than in the sediment. nitrogen values 35-111% higher and muramic acid values 33-300% higher. These values indicate that bacteria and nitrogenous components of the organic matter were selectively eaten. Values for organic carbon and nitrogen and muramic acid were generally lower in the hindgut than in the foregut, due to digestion and assimilation. Assimilation efficiencies averaged 30% for organic carbon, 40% for organic nitrogen and 30-40% for muramic acid (bacteria). Detritus (non-living matter) probably constituted 60-80% of the organic matter in the sediment and thus the food of the holothurians.

The distribution and nature of amino acids and other nitrogen-containing compounds in Lake Ontario surface sediments

Five surface sediment samples (0–3 cm), two suspended sediment samples and a zooplankton sample from Lake Ontario were analysed for nitrogen-containing compounds. Amino acids, amino sugars, ethanolamine and urea were separated and characterized by ion-exchange chromatography. Free amino acids and soluble combined amino acids and amino sugars accounted for less than 0–25 per cent of the total nitrogen in the sediments. Insoluble combined amino acids and amino sugars were the most abundant nitrogen fraction in the sediments, making up from 49 to 55 per cent of the total nitrogen. Evidence is presented that asparagine, glutamine and citrulline are present in the interstitial waters and may make up part of the sediment organic nitrogen that was not characterized. The free amino acids released by the proteolytic enzyme, pronase, from the interstitial waters and sediment humic and fulvic acid extracts were determined. Pronase released 65 per cent of the soluble combined amino acids and 34 per cent of the fulvic acid amino acids as free amino acids. Enzyme activity was inhibited in the presence of the humic acid extract. The results indicate that the combined amino acids in the interstitial waters and fulvic acid extracts are intermediates between the primary aquatic detritus and the sediment humic acids. The enzyme experiments and infra-red data indicate that part of the sediment amino acids are combined through peptide linkages.

Source Rocks and Criteria for Their Recognition

The fact has been established that, as the quantity of organic matter in a rock increases, the chloroform-bitumen content of the organic matter decreases. The writer's researches showed that, as the oil fraction in the chloroform bitumen increases, the chloroform-bitumen content in the organic matter regularly decreases. Therefore, a greater quantity of oil fraction in the chloroform bitumen, together with a comparatively smaller quantity of chloroform bitumen in the organic matter, serves as positive criterion for considering the sediments as better source rocks. Additional conclusions from the writer's study are: (1) the presence of numerous hydrocarbon accumulations, particularly of oil, in wholly lithologic (stratigraphic) traps is a positive criterion in the recognition of source rocks; (2) high content of organic nitrogen in sediments is a positive criterion for source rocks; whereas (3) high content of humic acid is a negative criterion; (4) relatively higher specific gravity and increased content of higher molecular-weight paraffins and heavier higher-boiling-point fractions in oils suggest that the oil deposit is nearer its source rock; and (5) plant matter is of great importance as a source of hydrocarbons.