Ronald Benner - Profile on Academia.edu (original) (raw)

Papers by Ronald Benner

Biogeochemistry, 2016

The biodegradation of soil organic nitrogen (SON) into forms available for plant uptake is an imp... more The biodegradation of soil organic nitrogen (SON) into forms available for plant uptake is an important control on nitrogen availability, plant growth, and carbon (C) sequestration in terrestrial ecosystems. Changes in biochemical composition during SON diagenesis were investigated by analyzing hydrolysable amino acids in the organic (L, F, and H) horizons and the surface mineral (B) horizon of soil profiles from the Newfoundland and Labrador Boreal Ecosystem Latitudinal Transect (NL-BELT). The diagenetic continuum in the soil profiles provides insights about the mechanisms of SON

Deep Sea Research Part II: Topical Studies in Oceanography, 2016

We construct mass-balance based estimates of carbon (C) export fractions from the water column ac... more We construct mass-balance based estimates of carbon (C) export fractions from the water column across the Chukchi Sea shelf. Export is calculated as the difference between phytoplankton drawdown of dissolved inorganic C (DIC) and the accumulation of autochthonous particulate and dissolved organic C in the water column. Organic carbon (C org) exports of 4 50% of DIC drawdown are ubiquitous across the shelf, even during, or shortly after, phytoplankton blooms, suggesting widespread and strong pelagicbenthic coupling. Export fractions on the shelf were generally greater in the less-productive Alaska Coastal Water than in the more productive Bering Shelf-Anadyr Water. Additionally, export fractions were greater in 2011 than in 2010, highlighting the significant spatial and inter-annual variability of the fate of C org in this ecologically and biogeochemically important, and rapidly changing, ecosystem.

Frontiers in Marine Science, 2015

Linkages among fluorescent dissolved organic matter, dissolved amino acids and lignin-derived phe... more Linkages among fluorescent dissolved organic matter, dissolved amino acids and lignin-derived phenols in a river-influenced ocean margin.

Limnology and Oceanography, 2000

We determined the concentrations and compositions of coarse particulate (Ͼ63 m), fine particulate... more We determined the concentrations and compositions of coarse particulate (Ͼ63 m), fine particulate (0.1-63 m), and dissolved (0.001-0.1 m) organic matter collected along a river reach extending from a first-order stream in the Bolivian Andes, through the Beni River system, to the lower Madeira and Amazon Rivers. Dissolved organic carbon (DOC) concentrations increased down the total reach from ϳ80 to 350 M. The percentage of total DOC with a molecular weight greater than ϳ1,000 atomic mass units that could be isolated by ultrafiltration also increased downstream from 40 to 80%. Weight percentages of organic carbon in the ultrafiltered isolates also grew downstream from 5% at the uppermost station to 37% in the Amazon mainstem. Organic carbon composed only 0.4-1.2 weight percentage of the total mass of the fine particulate fraction, which accounted for 70-80% of the total organic carbon (TOC) in transport through the highly turbid (ϳ600-2000 mg L Ϫ1) Beni sequence. Observed compositional differences were related primarily to the size fractions in which the organic matter occurred. On average, coarse particulate organic material exhibited an atomic C : N of 24, whereas ultrafiltered DOM was nitrogen poor, (C : N)a ϭ 34, and fine particulate material was nitrogen rich, (C : N)a ϭ 15. The lignin and stable-carbon isotopic compositions of these fractions indicate tree leaves and other nonwoody tissues from C3 land plants as predominant sources. Three molecular parameters demonstrate that the coarse, fine, and dissolved fractions of individual water samples are increasingly degraded downstream. Elemental nitrogen, amino acids, and basic amino acids are all preferentially associated with fine minerals. Observed geographical patterns included more positive ␦ 13 C values in particulate organic matter from high altitude sites and an increase in the abundance and degradation of ultrafiltered dissolved organic matter down the drainage system. Many of these compositional patterns are imprinted within materials carried by low-order, high-altitude tributaries and appear to reflect processes occurring on the landscape.

Dissolved organic carbon and amino sugar concentrations measured in surface water during POLARSTERN cruise ANT-XXV/1

National Science Review, 2018

Carbon is a keystone element in global biogeochemical cycles. It plays a fundamental role in biot... more Carbon is a keystone element in global biogeochemical cycles. It plays a fundamental role in biotic and abiotic processes in the ocean, which intertwine to mediate the chemistry and redox status of carbon in the ocean and the atmosphere. The interactions between abiotic and biogenic carbon (e.g. CO2, CaCO3, organic matter) in the ocean are complex, and there is a half-century-old enigma about the existence of a huge reservoir of recalcitrant dissolved organic carbon (RDOC) that equates to the magnitude of the pool of atmospheric CO2. The concepts of the biological carbon pump (BCP) and the microbial loop (ML) shaped our understanding of the marine carbon cycle. The more recent concept of the microbial carbon pump (MCP), which is closely connected to those of the BCP and the ML, explicitly considers the significance of the ocean's RDOC reservoir and provides a mechanistic framework for the exploration of its formation and persistence. Understanding of the MCP has benefited from a...

Journal of Geophysical Research: Oceans, 2017

Dissolved lignin phenols, chromophoric dissolved organic matter (CDOM) absorption, and fluorescen... more Dissolved lignin phenols, chromophoric dissolved organic matter (CDOM) absorption, and fluorescence were analyzed along cross-slope mooring locations in the Barents, Laptev, and East Siberian Seas to gain a better understanding of terrigenous dissolved organic carbon (tDOC) dynamics in Arctic shelf seas and the Arctic Ocean. A gradient of river water and tDOC was observed along the continental shelf eastward into the East Siberian Sea. Correlations of carbon-normalized yields of lignin-derived phenols supplied by Siberian rivers with river water fractions and known water residence times yielded in situ decay constants of 0.18-0.58 per year. Calculations showed about 50% of annual tDOC discharged by Siberian rivers was mineralized in estuaries and on the Eurasian shelves per year indicating extensive removal of tDOC. Bioassay experiments and in situ decay constants indicated a reactivity continuum for tDOC. CDOM parameters and acid/aldehyde ratios of vanillyl (V) and syringyl (S) lignin phenols showed biomineralization was the dominant mechanism for the removal of tDOC. Characteristic ratios of p-hydroxy (P), S, and V phenols (P/V, S/V) also identified shelf regions in the Kara Sea and regions along the Western Laptev Sea shelf where formation of Low Salinity Halocline Waters (LSHW) and Lower Halocline Water (LHW) occurred. The efficient removal of tDOC demonstrates the importance of Eurasian margins as sinks of tDOC derived from the large Siberian Rivers and confirms tDOC mineralization has a major impact on nutrients budgets, air-sea CO 2 exchange, and acidification in the Siberian Shelf Seas.

DOC, CDOM, optical properties, and lignin phenols (terrigenous biomarker) during POLARSTERN cruise ARK-XXII/2 (2007), in the Arctic Ocean

This data set was collected during Polarstern cruise ARKXXII/2 in 2007. It contains data on disso... more This data set was collected during Polarstern cruise ARKXXII/2 in 2007. It contains data on dissolved organic carbon concentrations, lignin phenol concentration and optical properties measured as absorbance and fluorescence from insitu sensors (Haardt fluorometer) and laboratory measurements on discrete water samples (absorbance scans and fluorescence scans-EEMs).

The Results section needs to include BP, BCD, and PP (the latter is perhaps from another study... more 1) The Results section needs to include BP, BCD, and PP (the latter is perhaps from another study, but it could still be summarized). My first thought on looking at Figure 4, in context of the authors’ discussion of accumulating DOCsl, was that it seemed like BCD and PP might be reversed. While I quickly realized that’s not the case, as the manuscript stands, there is no way to double-check the figure against numerical values.

Earth System Science Data Discussions, 2019

The Green Edge initiative was developed to investigate the processes controlling the primary prod... more The Green Edge initiative was developed to investigate the processes controlling the primary productivity and the fate of organic matter produced during the Arctic phytoplankton spring bloom (PSB) and to determine its role in the ecosystem. Two field campaigns were conducted in 2015 and 2016 at an ice camp located on landfast sea ice southeast of Qikiqtarjuaq Island in Baffin Bay (67.4797N, 63.7895W). During both expeditions, a large suite of physical, chemical and biological variables was measured beneath a consolidated sea ice cover from the surface

Limnology and Oceanography, 2009

Amino sugars and amino acids, including the bacterial biomarkers muramic acid and D-amino acids, ... more Amino sugars and amino acids, including the bacterial biomarkers muramic acid and D-amino acids, were measured to investigate the diagenetic alterations of and microbial contributions to detrital organic matter in the Amazon River system. Three size fractions of detrital material were analyzed: coarse and fine particulate organic matter (CPOM and FPOM), and ultrafiltered dissolved organic matter (UDOM). CPOM was depleted in amino sugars and had high percentages of total N as amino acids (32-37%), consistent with relatively fresh plant debris being a major source of CPOM. FPOM had the highest percentages of total C as amino acids (5-8%), and its composition appeared to be influenced by the preferential sorption of N-containing molecules. UDOM had the highest percentages of total N as amino sugars (up to 2.3%) indicating the relatively important contributions from microorganisms. A consistent trend of increasing proportions of D-amino acids among detrital size fractions, CPOM , FPOM , UDOM, suggests this parameter is a useful diagenetic indicator. About 4-17% of the C and 17-37% of the N in FPOM and CPOM were of bacterial origin based on D-alanine and D-glutamic acid yields. Similar bacterial contributions to UDOM were evident from the biomarker data, but they were not quantified due to insufficient information about representative yields of source biomarkers. Relationships between biomarker N and total N suggest that microbial activity influences the N content of detrital material. Bacterial contributions to detrital material were primarily as cellular remnants rather than living cells.

Organic Geochemistry, 1999

Long-term changes in the carbohydrate composition of 5 dierent vascular plant tissues, including ... more Long-term changes in the carbohydrate composition of 5 dierent vascular plant tissues, including black mangrove leaves and wood (Avicennia germinans), cypress needles and wood (Taxodium distichum) and smooth cordgrass (Spartina alterni¯ora), were measured as these tissues decomposed over a 4 yr period under sub-aqueous conditions. Carbohydrate composition was measured using a molecular-level analysis for neutral sugars and a modi®ed version of the MBTH (3-methyl-2-benzothiazolinone hydrazone hydrochloride) method for colorimetric determination of total carbohydrate yields. Minimal cross contamination from non-carbohydrate vascular plant constituents indicated the MBTH method was highly speci®c for carbohydrates. The dierence between total carbohydrate yields using the MBTH method and total neutral sugar yields revealed a substantial carbohydrate fraction (7±23% of the total plant carbon) in fresh and senescent tissues that was not identi®ed at the molecular level. The molecularly uncharacterized fraction of carbohydrates probably consisted of ketoses, uronic acids and amino sugars. The decomposition series demonstrated certain features about carbohydrate diagenesis not apparent from previous short-term degradation studies. During the latter phase of decomposition (2±4 yr), selective carbohydrate loss relative to bulk tissue was not evident in 2 of 3 herbaceous tissues. This indicates that carbohydrates may be of similar reactivity as bulk tissue in highly decomposed particulate organic matter. The extent and timing of all compositional changes were tissue dependent, yet certain trends emerged which were consistent with geochemical observations. In herbaceous tissues, both glucose and xylose were selectively degraded while deoxy sugars increased in relative abundance. These changes resulted in an increased abundance of initially minor neutral sugars and a general trend towards a more uniform neutral sugar composition. A clear reduction in carbohydrate yields (mg carbohydrate carbon/100 mg organic carbon) among all tissues provided the most consistent indicator of diagenetic status. Total carbohydrate yields, mole percentages of glucose and percent deoxy sugars in highly degraded herbaceous tissues were similar to those measured in particulate organic matter fractions of major world rivers, and provide diagenetic parameters which link relatively fresh plant tissues to their degraded counterparts in aquatic environments.

The ocean reservoir of dissolved organic matter (DOM) is among the largest global reservoirs (∼70... more The ocean reservoir of dissolved organic matter (DOM) is among the largest global reservoirs (∼700 Pg C) of reactive organic carbon. Marine primary production (∼50 Pg C/yr) by photosynthetic microalgae and cyanobacteria is the major source of organic matter to the ocean and the principal substrate supporting marine food webs. The direct release of DOM from phytoplankton and other organisms as well as a variety of other processes, such as predation and viral lysis, contribute to the ocean DOM reservoir. Continental runoff and atmospheric deposition are relatively minor sources of DOM to the ocean, but some components of this material appear to be resistant to decomposition and to have a long residence time in the ocean. Concentrations of DOM are highest in surface waters and decrease with depth, a pattern that reflects the sources and diagenesis of DOM in the upper ocean. Most (70-80%) marine DOM exists as small molecules of low molecular weight (<1 kDalton). Surprisingly, highmolecular-weight (>1 kDalton) DOM is relatively enriched in major biochemicals, such as combined neutral sugars and amino acids, and is more bioavailable than low-molecular-weight DOM. The observed relationships among the size, composition, and reactivity of DOM have led to the size-reactivity continuum model, which postulates that diagenetic processes lead to the production of smaller molecules that are structurally altered and resistant to microbial degradation. The radiocarbon content of these small dissolved molecules also indicates these are the most highly aged components of DOM. Chemical signatures of bacteria are abundant in DOM and increase during diagenesis, indicating bacteria are an important source of slowly cycling biochemicals. Recent analyses of DOM isolates by ultrahigh-resolution mass spectrometry have revealed an incredibly diverse mixture of molecules. Carboxyl-rich alicyclic molecules are abundant in DOM, and they appear to be derived from diagenetically-altered terpenoids, such as sterols and hopanoids. Thermally-altered molecules, including black carbon, also appear to be important components of DOM, but their origins are unclear. We are rapidly acquiring novel information about the composition and molecular identity of DOM, and novel insights about the origins, transformations and fates this vast reservoir of DOM are emerging. This presentation will review and synthesize this information for comparison with non-living organic matter in other systems.

Frontiers in Marine Science

Dissolved lignin is a well-established biomarker of terrigenous dissolved organic matter (DOM) in... more Dissolved lignin is a well-established biomarker of terrigenous dissolved organic matter (DOM) in the ocean, and a chromophoric component of DOM. Although evidence suggests there is a strong linkage between lignin concentrations and chromophoric dissolved organic matter (CDOM) absorption coefficients in coastal waters, the characteristics of this linkage and the existence of a relationship that is applicable across coastal oceans remain unclear. Here, 421 paired measurements of dissolved lignin concentrations (sum of nine lignin phenols) and CDOM absorption coefficients [a g (λ)] were used to examine their relationship along the river-ocean continuum (0-37 salinity) and across contrasting coastal oceans (sub-tropical, temperate, high-latitude). Overall, lignin concentrations spanned four orders of magnitude and revealed a strong, non-linear relationship with a g (λ). The characteristics of the relationship (shape, wavelength dependency, lignin-composition dependency) and evidence from degradation indicators were all consistent with lignin being an important driver of CDOM variability in coastal oceans, and suggested physical mixing and long-term photodegradation were important in shaping the relationship. These observations were used to develop two simple empirical models for estimating lignin concentrations from a g (λ) with a ±20% error relative to measured values. The models are expected to be applicable in most coastal oceans influenced by terrigenous inputs.

Limnology and Oceanography

Biological hot spots and the accumulation of marine dissolved organic matter in a hig...

Frontiers in Marine Science, 2016

Does oxygen exposure time control the extent of organic matter decomposition in peatlands?

Journal of Geophysical Research: Biogeosciences, 2014

ABSTRACT The extent of peat decomposition was investigated in four cores collected along a latitu... more ABSTRACT The extent of peat decomposition was investigated in four cores collected along a latitudinal gradient from 56˚N to 66˚N in the West Siberian Lowland. The acid:aldehyde ratios of lignin phenols were significantly higher in the two northern cores compared with the two southern cores, indicating peats at the northern sites were more highly decomposed. Yields of hydroxyproline, an amino acid found in plant structural glycoproteins, were also significantly higher in northern cores compared with southern cores. Hydroxyproline-rich glycoproteins are not synthesized by microbes and are generally less reactive than bulk plant carbon, so elevated yields indicated northern cores were more extensively decomposed than the southern cores. The southern cores experienced warmer temperatures, but were less decomposed, indicating temperature was not the primary control of peat decomposition. The plant community oscillated between Sphagnum and vascular plant dominance in the southern cores, but vegetation type did not appear to affect the extent of decomposition. Oxygen exposure time appeared to be the strongest control of the extent of peat decomposition. The northern cores had lower accumulation rates and drier conditions, so these peats were exposed to oxic conditions for a longer time before burial in the catotelm, where anoxic conditions prevail and rates of decomposition are generally lower by an order of magnitude.