Main Source Of Organic Matter Research Articles

Assessing the dietary sources of two cichlid species in River Nile sub-branches: Stomach contents, fatty acids and stable isotopes analyses

We assess the importance of four different food sources as dietary components of Oreochromis niloticus and Sarotherodon galilaeus in Nile sub-branches using stomach contents, fatty acids (FA) and stable isotopes (SI) analyses. Diatoms were the dominant food items, whereas sand and mud constitute a major part of the stomach contents of both cichlids in the northern ElBehery canal. FAs and SI were compared in cichlids and four potential food sources. Carbon isotopes excluded the fresh macrophyte Myriophyllum spicatum and its epiphytes as a potential food source, whereas FA biomarkers indicated that M. spicatum is assimilated in cichlids’ muscles as detrital materials. FA profiles of cichlids’ muscles were highly enriched by live diatom markers whereas decayed diatoms and bacterial markers were partially present. Carbon isotope signatures of cichlids were much close to that of suspended particulate organic matter (SPOM) which elucidated that SPOM was the source of diatoms and bacterial detritus incorporated in cichlids muscles. Cichlids were highly enriched with nitrogen signatures which was a result of increased anthropogenic effects and incorporation of bacterial films. SI and FA analyses precisely indicated that live diatoms and bacteria, detrital macrophytes are the main sources of organic matter incorporated in cichlids muscles.

Large variability in n-alkane δ13C values in Lake Pa Kho (Thailand) driven by wetland wetness and aquatic productivity

Understanding past climate and environmental conditions depends largely on accurate interpretations of proxy records from a range of environments, including tropical wetlands and lakes. Lipid biomarker analysis can provide important information about the sources of the accumulated organic material, and thus about the environmental information contained therein. Here we use n-alkane distributions and stable carbon isotopes of leaf waxes (δ13Cwax) to identify the sources of organic matter (OM) of a 2000-year long sediment/peat record from Lake Pa Kho (LPK) in northeastern Thailand, and to constrain the mechanisms that cause shifts in δ13Cwax and in δ13C of bulk organic matter (δ13Cbulk). Our results show three main sources of OM: terrestrial plants, aquatic macrophytes and algae. The δ13C values of the long chain n-alkanes, show two distinct groups: C27–C31 and C33–C35n-alkanes, where the δ13C values of C33–C35n-alkanes reflect that of δ13Cbulk. Lower moisture availability on the wetland, known from other sedimentary evidence, was characterized by low carbon isotope values typically seen for C3 plants, whereas greater moisture availability corresponded to higher δ13C values (around −20‰) of C33–C35n-alkanes, resembling a typical C4 plant signal. However, various lines of evidence argue against large shifts between C3 and C4 plant input. Instead, we suggest that the high δ13C values were indirectly caused by higher aquatic productivity during periods of greater moisture availability, decreasing dissolved CO2, but increasing bicarbonate availability caused by higher pH. This caused the dominant macrophytes (e.g., Potamogeton spp.) to shift their carbon source from CO2 to bicarbonate, which has much higher δ13C values. Our results show that the environmental context should be taken into account when interpreting n-alkane δ13C variability as a paleo-environmental/climatic signal as this contains several important variables that need to be disentangled and explained.

Coupling of sedimentological and limnological dynamics in subarctic thermokarst ponds in Northern Québec (Canada) on an interannual basis

Landscapes are changing at fast rates in subarctic regions due to recent climate warming and related permafrost thaw. As a consequence, thermokarst lakes and ponds are forming and their properties are changing rapidly. Here, we report on the interannual (2012-2014) variability of sedimentological and limnological conditions in a recently formed thermokarst pond in discontinuous permafrost terrain in Northern Quebec, and we discuss various aspects of pond sedimentation processes. Sediment samples from collecting traps and a short core were analyzed for particle size, organic matter content and geochemical composition, as well as 14C dating of a peat sample from the core. Results reveal the preponderance of silts containing 2 to 13% organic matter and an age of 1825–1950cal. yr. BP for the peat sample. A hypoxic hypolimnion formed in the pond during the short summers. Apparent sedimentation rates (up to 5.5mm/d) varied in relation to local meteorological conditions and snow cover. The results also reveal major parameters associated with sediment composition, most notably dissolved oxygen in the water column, sampling depth and the year of sampling. Microplankton (20–200μm) is likely the main source of organic matter, which represents up to 10 to 13% of sediment trap samples, considering its size matching a major grain size mode (44.9–59.0μm). Using sedimentation rates and an estimation of long-term sediment compaction, the pond's “life span” was calculated at 370 to 600years. This represents a baseline for the general understanding of the development of young (15–20years) subarctic thermokarst ponds overlying impermeable soils, and provides an approximate time frame for the potential response of such systems to climate change impacts on northern landscapes.

Sources of organic matter (PAHs and n-alkanes) in PM2.5 of Beijing in haze weather analyzed by combining the C-N isotopic and PCA-MLR analyses.

Organic molecular composition and carbon and nitrogen isotope ratios of PM2.5 samples collected in November 2013 were analyzed using gas chromatography/mass spectrometry and isotope ratio mass spectrometry. The samples represented six potential sources and seven sampling sites situated in concentric zones around Beijing under both haze and non-haze conditions. Our results showed that the average concentrations of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes were 258.2 ± 208.8 ng m(-3) and 499.5 ± 347.8 ng m(-3), while the δ(13)C and δ(15)N values for PM2.5 varied from -26.29 to -25.26‰ and from 8.68 to 14.50‰ with an average of -25.70 ± 0.3‰ and 11.97 ± 1.79‰, respectively. The highest concentrations of PAHs and n-alkanes were recorded in the sixth ring road, with the lowest ones in the third ring road. Concentrations of PAHs during haze were higher than during non-haze conditions, while concentrations of n-alkanes were not markedly different. Principal component analysis/multiple linear regression analyses indicated that the main sources of PAHs were vehicle and coal combustion emissions, while n-alkanes had high contributions from petroleum emissions. These sources were supported by isotopic analyses. Thus, the main sources of organic matter contributing to haze in Beijing were coal combustion and vehicle emissions. Such results provide guidance towards managing haze in Beijing.

Role of Soil Algae on the Initial Stages of Soil Formation in Sandy Polluted Areas

Abstract Research to evaluate the role of the soil algae in the initiation of pedogenesis in sandy areas and to establish the mineral, chemical and organic composition of soil-algal crusts was done. The investigations area is located in southern Poland in a landscape of drift sand (Bledowska Desert) formed as a result of medieval deforestation related to Ag, Pb and Fe mining activities. Fifteen species of algae (Cyanophyta, Chlorophyta and Heterokontophyta) were identified. In the soil-algal crusts, Corg contents ranged from 0.35-2.23%, Pavail from 9-34 mg · kg−1 and Nt was variable. In investigated area the ground on which soil algae developed was acidic (pH 4.4-5.7 in KCl). Among mineral components in the crust, phases rich in Fe and K dominated (776.5(±2.3) - 2803(±31) mg · kg−1 and 230.5(±3.7) - 696(±22) mg · kg−1, respectively) and elevated concentrations of Zn, Mn and Pb occurred. Soil-crust organic matter includes aliphatic and aromatic compounds, carbohydrate derivatives, phenols, furan and pyrene structures. N compounds have significant contribution in composition of soil-algal crusts - the algae are main source of organic matter in this stage of soil formation. It could accelerate the regeneration of disturbed ecological systems.

δ13Corg and n-alkane evidence for changing wetland conditions during a stable mid-late Holocene climate in the central Tibetan Plateau

Abstract This study has examined bulk and compound specific organic carbon isotopes (δ13Corg) and lipid n-alkanes of modern plants and a wetland sediment sequence from the central Tibetan Plateau and explores the usefulness of these two methods for palaeoenvironmental reconstructions. Results show that a combination of δ13Corg values and n-alkane indices can help differentiate organic matter from C3 terrestrial plant, C4 terrestrial plant and submerged macrophytes, the three main sources of organic matter in the study area. The analyses of total organic carbon, δ13Corg values and n-alkane indices for the sediment sequence imply that a wetland habitat was established about 8000 years ago, and the wetland conditions were largely stable with dominantly C3 wetland herbs covering the wetland. However, small fluctuations in the dominant organic matter supply between vascular and aquatic plants are revealed, suggesting short duration changes in the extent of open water area within the wetland or variations in the productivity of submerged macrophytes and aquatic plants within the wetland ecosystem, which reflects variations in the strength of precipitation and evaporation.

Characteristics of biomarker in source rocks of Linxi Formation in Taohaiyingzi region, Zhalute basin

Based on gas chromatography and gas chromatography mass spectrometry techniques, the authors researched biomarker characteristics of the Linxi Formation source rocks in the area of Taohaiyingzi, and analyzed the information and petroleum geological significance that were indicated by source of organic matter, sedimentary environment, maturity and so on. Gas chromatography peak of saturated hydrocarbons from Linxi Formation source rocks showed “the former peak” of the single peak distribution and the C23-dominant main peak. This indicates that the main source of organic matter was mixed organic matter; Pr/Ph ratios ranged from 0.3 to 0.6, indicating a strongly reducing sedimentary environment. Molecular fossil assemblages in Linxi Formation source rocks were abundant in tricyclic terpane with long side chains, had high level of gammacerane, and showed dominant distribution of C27 steranes. Gammacerane ratios range from 0.15 to 0.29, with an average of 0.19, implying that Linxi Formation hydrocarbon source rocks were formed in the environment of micro-saltwater water to half-saltwater water. The hopanes/steranes ratios are mainly between 0.6 and 1.0, with an average of 0.84, implying that bacteria and algae had almost the same contribution to organic matter. C27 steranes abundance is high and the ratio of C27 steranes/C29 steranes is 1.13, showing that algae is the main source of hydrocarbon precursors.

Biogeochemical specifics of sapropel formation in Cisbaikalian undrained lakes (exemplified by Lake Ochki)

The biogeochemistry of organic lacustrine sediments (sapropels) has been poorly studied in Siberia. In this paper we show the specifics of sapropel formation caused by low pH and mineralization of water by the example of Lake Ochki in Cisbaikalia. The main sources of organic matter are zoo- and phytoplankton, which concentrate mostly basic chemical elements and also some alkaline, alkali-earth, and chalcophile elements and move them to the sediment. The calculated enrichment factors (EF) have shown that the lake plankton is strongly enriched with phosphorus and chalcophile elements. The calculations have also revealed a great contribution of the plankton to the elemental composition of sapropel (Mebio, %): P (-100), Cd (57), Br (45), Hg (40), Se and Na (30), Zn (23), K (21), and Ca (15). Elements are rather uniformly distributed throughout the 3.2m thick sapropel layer. Lithophile elements (Al, Sc, Ti, Y, Zr, Nb) and LREE are mostly from a terrigenous source. The high contents of mobile elements (Cd, Sb, Sn, Pb, Zn) in the upper part of sapropel are probably due to anthropogenic factors. The high Cu and Zn contents in some sapropel layers are probably related to the inflow of deep-level groundwaters, and the elevated contents of Hg, Cd, and Sb might have been caused by forest fires.

Aquatic Macrophytes Detritus Quality and Sulfate Availability Shape the Methane Production Pattern in a Dystrophic Coastal Lagoon

Aquatic macrophytes usually show high productivity rate, especially in shallow environments, and may constitute the main source of organic matter to these ecosystems. The coastal lagoons are shallow environments that typically present a broad colonization by aquatic macrophytes. The organic matter derived from aquatic macrophytes consists of detritus and root exudates, from live plants. Methanogens are microorganisms that use labile organic matter (e.g. acetate) in the metabolism, releasing methane (CH4) as an end product. Assessing the influence of aquatic macrophytes on methanogenesis is fundamental to understanding the carbon cycle in shallow environments, such as coastal lagoons. A peculiarity of coastal lagoons that may also influence the methanogenesis is its proximity to the sea, providing the entrance of sulfate in the environment. The methanogenesis can be inhibited by the sulfate reduction when there is sulfate availability sulfate. In this context, we aimed to analyze the methane production in an aquatic macrophyte stand and in the limnetic region of a coastal lagoon, assessing the influence of quantity and quality of organic carbon and sulfate availability on methane production in the sediment profile. We observe that the presence of aquatic macrophytes benefits the methanogenesis, not only by detritus accumulation, but particularly by the release of root exudates from the living plants. The variation in quantity and quality of organic carbon is the main factor that controls the range and shape of the methane production curves. The availability of sulfate presents probably a secondary role, being important when the organic matter is not sufficient for the occurrence of methanogenesis and sulfate reduction simultaneously.

Trophic interactions of Platichthys flesus and Solea solea juveniles in the Lima estuary nursery (NW Portugal)

Event Abstract Back to Event Trophic interactions of Platichthys flesus and Solea solea juveniles in the Lima estuary nursery (NW Portugal) Cláudia Mendes1, 2*, Sandra Ramos2, Michael Elliott3 and A.A. Bordalo1, 2 1 Institute of Biomedical Sciences, University of Porto (ICBAS-UP), Portugal 2 Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), Portugal 3 Institute of Estuarine and Coastal Studies, University of Hull, United Kingdom Trophic interactions play a key role in nursery habitats, and by affecting growth and condition of the juveniles, may control the quality of a given estuarine nursery. This study investigated the trophic ecology of flounder (Platichthys flesus) and common sole (Solea solea) juveniles in the Lima estuary nursery. Feeding location, main organic matter sources, and prey of the target species were assessed by carbon (δ13C) and nitrogen (δ15N) stable isotopes, as well as by stomach content analysis. The juveniles, macroinvertebrates, and sediment and water column samples were collected in August 2014 in the lower, middle and upper sections of the Lima estuary. The diet of 0+ flounder relied upon prey from the upper estuary (salinity >5), namely Chironomid larvae and Corophium spp. which showed the role of the upper estuary prey to the 0+ flounder diet and suggest the relative site fidelity of the young juveniles. In contrast, 1+ flounder juveniles had a diverse diet based on bivalves, polychaetes and crustaceans, and a variable stable isotope signature indicating they fed in different areas along the estuary. The 1+ sole juveniles also fed on polychaetes, crustaceans, and bivalves, but the stable isotope values suggested a dependence on the lower estuary (salinity >30) and marine food web sources. Such differential use of food may be understood as a strategic approach to reduce intra- and interspecific competition and thus ensuring the use of Lima estuary as nursery area for these two flatfish species. Acknowledgements This study was supported by FCT through SFRH/BD/86325/2012 and SFRH/BPD/26782/2006 and project Pest-C/MAR/LA0015/2013. Keywords: Platichthys flesus, Solea solea, trophic ecology, stable isotope analysis, Nursery area Conference: XV European Congress of Ichthyology, Porto, Portugal, 7 Sep - 11 Sep, 2015. Presentation Type: Oral Presentation Topic: Life Cycles, Migration and Connectivity Citation: Mendes C, Ramos S, Elliott M and Bordalo A (2015). Trophic interactions of Platichthys flesus and Solea solea juveniles in the Lima estuary nursery (NW Portugal). Front. Mar. Sci. Conference Abstract: XV European Congress of Ichthyology. doi: 10.3389/conf.FMARS.2015.03.00252 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 30 Dec 2015; Published Online: 30 Dec 2015. * Correspondence: Ms. Cláudia Mendes, Institute of Biomedical Sciences, University of Porto (ICBAS-UP), Porto, 4050-313, Portugal, claudiavrmendes@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Cláudia Mendes Sandra Ramos Michael Elliott A.A. Bordalo Google Cláudia Mendes Sandra Ramos Michael Elliott A.A. Bordalo Google Scholar Cláudia Mendes Sandra Ramos Michael Elliott A.A. Bordalo PubMed Cláudia Mendes Sandra Ramos Michael Elliott A.A. Bordalo Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Identifying the sources of organic matter in marine and riverine sediments of Bohai Bay and its catchment using carbon and nitrogen stable isotopes

Carbon and nitrogen stable isotopes are useful tracers for distinguishing marine and terrestrial plant sources of sedimentary organic matter (OM), and for identifying OM from different types of plants. By analyzing the carbon and nitrogen stable isotopes of marine and riverine sediments from Bohai Bay and its catchment, we were able to identify the source of OM in these sediments. The stable carbon isotope values of Bohai Bay sediments were between −22.94‰ and −23.90‰, while those of riverine sediments were from −24.45‰ to −32.50‰. Marine algae were the main source of OM in Bohai Bay sediments. However, lacustrine algae were the main source of riverine sediments, not terrestrial OM. The nitrogen isotopes in Bohai Bay sediments decreased in eastward direction, with increasing distance from the coastline, which suggested a higher degree of impact from human activities along the coast.

Trophic resource use by macrozoobenthic primary consumers within a semi-enclosed coastal ecosystem: Stable isotope and fatty acid assessment

The diet of different macrozoobenthic trophic groups was investigated in the Arcachon Bay—a semi-enclosed macrotidal ecosystem that shelters the largest Zostera noltei seagrass meadow in Europe—in early spring and late summer 2009, using stable isotopes and fatty acids. Fatty acid profiles and literature information about the biology and physiology of benthic consumers were combined to identify the main organic matter sources for the benthic primary consumers. An isotope mixing model was then run to evaluate the contribution of each organic matter source to each identified trophic group (suspension feeders, sub-surface deposit feeders, micro-and macrograzers, suspension-oriented interface feeders and deposit-oriented interface feeders). Variations in organism' diets with respect to both habitats (intertidal seagrass meadows, intertidal bare sediments and subtidal bare sediments) and study periods were also investigated. At the scale of this study, it appeared that the diet of macrozoobenthos primary consumers was based exclusively on autochthonous material (no use of terrestrial organic matter): mainly microphytobenthos, seagrasses and their epiphytes, and phytoplankton. In addition, the different trophic groups relied on different organic matter pools: for instance, suspension feeders mainly fed on microphytobenthos and phytoplankton, whereas subsurface deposit feeders fed on microphytobenthos, decayed seagrasses and bacteria, and grazers mainly fed on microphytobenthos, and seagrasses and their epiphytes. The same pattern was observed in both early spring and late summer, indicating a stability of the benthic system at a six-month time scale. Finally our results showed that, in Arcachon Bay, the seagrass meadow directly or indirectly (through detritus) plays a significant role in the diet of most benthic consumers.

The organic geochemistry of the Eocene–Oligocene black shales from the Lunpola Basin, central Tibet

This paper reports on the depositional paleoenvironment and the potential hydrocarbons of the Eocene–Oligocene black shales from the Dingqinghu and Niubao Formations in the Lunpola Basin, central Tibet. Nineteen samples from two outcrop profiles were analysed. The contents of the total organic carbon (TOC) and sulphur were measured; other analyses included Rock–Eval pyrolysis, solvent extraction and gas chromatography–mass spectrometer (GC–MS). The results indicated that the shales from the Dingqinghu and Niubao Formations are thermally immature. The pyrolysis data show that the shales contain Type I organic matter and that lacustrine algal are the main organic matter sources. The low pristane to phytane ratios and the high gammacerane indices indicate that the shales were deposited in a reducing, stratified, and hypersaline palaeo-lake, which is consistent with the climate information provided by the development history of palaeo-lakes from the Eocene to the Oligocene epochs.

Characteristics of biomarkers in source rocks of the Ganquan Formation in the Dahulishan region, Ejina Banner

Based on gas chromatography and gas chromatography mass spectrometry techniques, the authors examined biomarker characteristics of the Ganquan Formation source rocks in the area of Dahulishan, Ejina, and analyzed the information and petroleum geological significance that were indicated by the source of organic matter, sedimentary environment and maturity and so on. Gas chromatography peak of saturated hydrocarbons from the Ganquan Formation source rocks showed “the former peak” of the single peak distribution, the main peak of carbon being C18, indicating the main sources of organic matter with marine organic matter. Pr/Ph ranges from 0.3 to 0.6, indicating a strongly reducing sedimentary environment. Biomarker assemblages of the Ganquan Formation source rocks are abundant in tricyclic terpane with long side chains, with a high level of gammacerane, showing dominant distribution of C27 sterane. High contents of gammacerane in organic matter show organic facies of source rocks in the saltwater sedimentary environment. That average hopane/sterane ratio is 0.59, showing that algae have made more contributions to organic matter than bacteria. And the high level of C27 steranes shows that algae are the main source of hydrocarbon precursors. The Ganquan Formation’s methylphenanthrene index, which is an effective molecular parameter index to measure thermal evolution of organic matter, ranges from 0.35 to 0.50, and the conversion of vitrinite reflectance Rc from it is within the range of 2.00–2.09, indicating that the Ganquan Formation source rocks are in the over-mature stage of thermal evolution.

Carbon and nitrogen stable isotope compositions of organic matter in marine sediment cores from the Abrolhos region: indicators of sources and preservation

Organic matter is an important source of information on the transport and consolidation processes of sediments. In this study, were utilized the isotopes of carbon and nitrogen (δ13C and δ15N), total organic carbon (TOC), total nitrogen, carbon/nitrogen (C/N) ratio and 13C-NMR to understand the origin and behavior of organic material in the Abrolhos region. Were analyzed nine sediment cores taken from a mangrove, a channel between the mainland and the coral reefs. The average value of the carbon/nitrogen ratio in the mangrove was 18, which characterizes purely terrigenous areas. For the reefs, the average value of the C/N ratio was 8,which is characteristic of marine and coastal regions. For the sediment cores taken from the channel, the average value of the C/N ratio was 10, a typical value of areas under the influence of mangroves. The mean values of δ13C were -26.9‰ for the mangrove, -20.7‰ for the channel region and -18.2‰ for the reefs. This variation is associated with the main source of organic matter, which in the mangrove is derived from vascular plants (mainly C3 metabolism), and for the reefs is derived from phytoplankton. The 13C-NMR results corroborate the results of isotopic and elemental analyses. The analyses of these cores indicates that the anthropogenic influence on the coast did not significantly alter the composition of the material that has been deposited in about the last 80 years in the region of study.

Identifying carbon sources and trophic position of coral reef fishes using diet and stable isotope (δ15N and δ13C) analyses in two contrasted bays in Moorea, French Polynesia

Stable isotope ratios (δ15N and δ13C) and diet of three fish species, Stegastes nigricans, Chaetodon citrinellus and Epinephelus merra, were analyzed on the fringing coral reefs of two bays that are differentially exposed to river runoff on Moorea Island, French Polynesia. S. nigricans and C. citrinellus relied mostly on turf algae and presented similar trophic levels and δ15N values, whereas E. merra fed on large invertebrates (crabs and shrimps) and had higher trophic levels and δ15N values. Discrepancies existed between stomach content and stable isotope analyses for the relative importance of food items. Bayesian mixing models indicated that sedimented organic matter was also an important additional food for S. nigricans and C. citrinellus, and fishes for E. merra. The main sources of organic matter involved in the food webs ending with these species were algal turfs and surface sediments, while water particulate organic matter was barely used. Significant spatial differences in C and N isotopic ratios for sources and fishes were found within and between bays. Lower 13C and higher 15N values were observed for various compartments of the studied trophic network at the end of each bay than at the entrance. Differences were observed between bays, with organic sources and consumers being, on average, slightly more 13C-depleted and 15N-enriched in Cook’s Bay than in Opunohu Bay, linked with a higher mean annual flow of the river at Cook’s Bay. Our results suggest that rivers bring continental material into these two bays, which is partly incorporated into the food webs of fringing coral reefs at least close to river mouths. Thus, continental inputs can influence the transfer of organic matter within coral reef food webs depending on the diet of organisms.

PRODUCCIÓN DE HOJARASCA EN UN RODAL DE Pinus cembroides Zucc. EN ARTEAGA, COAHUILA, MÉXICO Y SU RELACIÓN CON LAS VARIABLES CLIMÁTICAS

La caída de hojarasca constituye la fuente principal de materia orgánica en los ecosistemas terrestres. La evaluación de la caída de hojarasca es importante para entender la productividad forestal, pero también proporciona información relevante como indicador fenológico de los efectos del cambio climático. Este estudio se llevó a cabo en un rodal joven de Pinus cembroides Zucc. en la sierra de Arteaga, Coahuila, México. La hojarasca fue colectada mensualmente usando 40 colectores (1 m2) ubicados sistemáticamente dentro de una parcela de 1 ha. La prueba no paramétrica de Kruskal-Wallis se utilizó para detectar diferencias significativas entre fechas de colecta. Las relaciones de producción de hojarasca con las variables climáticas se evaluaron mediante análisis de componentes principales y modelos de regresión. La deposición total de hojarasca fue poco más de 1,000 kg·ha-1·año-1, la cual fue dependiente de la temperatura y el viento. Las acículas y ramas constituyeron cerca del 33 y 22 % de la deposición total, respectivamente.

Eco-environmental implications of elemental and carbon isotope distributions in ornithogenic sediments from the Ross Sea region, Antarctica

Seabirds have substantial influence on geochemical circulation of elements, serving as a link for substance exchange between their foraging area and colonies. In this study, we investigated the elemental and carbon isotopic composition of five penguin-affected sediment profiles excavated from Ross Island and Beaufort Island in the Ross Sea region, Antarctica. Among the three main constituents of the sediments (including weathered bedrock, guano and algae), guano was the main source of organic matter and nutrients, causing selective enrichment of several elements in each of the sediment profiles. In the 22 measured elements, As, Cd, Cu, P, S, Se and Zn were identified as penguin bio-elements in the Ross Sea region through statistical analysis and comparison with local end-member environmental media such as weathered bedrock, fresh guano and fresh algae. Carbon isotopic composition in the ornithogenic sediments showed a mixing feature of guano and algae. Using a two-member isotope mixing equation, we were able to reconstruct the historical change of guano input and algal bio-mass. Compared with research in other parts of Antarctic, Arctic, and South China Sea, we found apparent overlap of avian bio-elements including As, Cd, Cu, P, Se, and Zn. Information on the composition and behavior of bio-elements in seabird guano on a global scale, and the role that bio-vectors play in the geochemical circulation between land and sea, will facilitate future research on avian ecology and paleoclimatic reconstruction.

Monitoring of slaughterhouse wastewater biodegradation in a SBR using fluorescence and UV–Visible absorbance

The aim of this study was to demonstrate that the effectiveness of slaughterhouse wastewater treatment by activated sludge could be enhanced through the use of optical techniques, such as UV–Visible absorbance and fluorescence spectroscopy, to estimate the hydraulic retention time necessary to remove the biodegradable chemical oxygen demand (COD). Two experiments were conducted. First, a batch aerobic degradation was performed on four wastewater samples collected from four different cattle processing sites in order to study the changes in the spectroscopic properties of wastewater during biodegradation. Second, a sequencing batch reactor was used in order to confirm that the wastewater fluorescence could be successfully used to monitor wastewater biodegradation in a pilot-scale experiment. Residual blood was the main source of organic matter in the wastewater samples. The absorbance at 416nm, related to porphyrins, was correlated to the COD during wastewater biodegradation. The tryptophan-like/fulvic-like fluorescence intensity ratio was related to the extent of biodegradation. The COD removal efficiency ranged from 74% to 94% with an hydraulic retention time (HRT) of 23h. A ratio of tryptophan-like/fulvic-like fluorescence intensities higher than 1.2 indicated incomplete biodegradation of the wastewater and the need to increase the HRT.

Petrological and geochemical composition of lignite from the D field, Kolubara basin (Serbia)

The Upper Miocene lignite from the Main coal seam in the D field, Kolubara basin, is a typical humic coal with huminite, liptinite and inertinite concentrations of up to 83.7vol.%, 17.2vol.% and 15.5vol.%, respectively. In the huminite group, textinite and ulminite are the most abundant macerals with variable amounts of densinite and attrinite. Liptodetrinite and sporinite are the most common macerals of the liptinite group, while inertodetrinite is the most abundant maceral of the inertinite group. The mineral matter consists mostly of clay minerals. The main sources of organic matter were gymnosperms (conifers) and microbial biomass, followed by angiosperms. Based on composition of saturated and aromatic diterpenoids it has been established that coal forming plants belonged to the gymnosperm families Taxodiaceae, Podocarpaceae, Cupressaceae, Araucariaceae, Phyllocladaceae and Pinaceae. Peatification occurred in neutral to slightly acidic, fresh water environment. Composition and distribution of biomarkers show that diagenetic changes of the organic matter were mainly governed by bacterial activity in a suboxic to oxic environment. Based on distribution of aromatic diterpenoids a novel diagenetic pathway for transformation of abietane-type precursors under suboxic to oxic conditions is proposed. Variations in compositions of macerals and biomarkers are in concordance with pronounced seasonality during Pontian, which caused changes in the water level, redox conditions during peatification, and to some extent vegetation differences in the paleo-plant communities.