scholarly journals Composition Characteristics of Organic Matter and Bacterial Communities under the Alternanthera philoxeroide Invasion in Wetlands

2020 ◽  
Vol 10 (16) ◽  
pp. 5571
Author(s):  
Qingqing Cao ◽  
Haijie Zhang ◽  
Wen Ma ◽  
Renqing Wang ◽  
Jian Liu
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Constructed Wetlands ◽  
High Throughput Sequencing ◽  
Surface Sediments ◽  
Alligator Weed ◽  
Weed Invasion ◽  
Bacterial Phyla ◽  
Carbon And Nitrogen ◽  
Natural Wetlands

The influence of Alternanthera philoxeroide (alligator weed) invasion on wetland organic matter (OM) accumulation and bacterial changes is rarely studied, but is possibly an important step for revealing the invasion mechanism. Thus, the distribution characteristics of light fraction organic carbon and nitrogen (LFOC and LFON), and heavy fractions organic carbon and nitrogen (HFOC and HFON) were analyzed. Sampling was done on two sediment depths (0–15 cm and 15–25 cm) of invaded and normal habitats of two natural wetlands and two constructed wetlands, and bacterial taxa and composition in surface sediments were also analyzed by high-throughput sequencing. In the surface sediments, the LFOC and LFON contents were significantly higher in the constructed wetlands (0.791 and 0.043 g·kg−1) than in the natural wetlands (0.500 and 0.022 g·kg−1), and the contents of the C and N fractions were also prominently higher in the invaded areas than in normal wetland habitats. The OM storage was relatively stable. Proteobacteria (55.94%), Bacteroidetes (5.74%), Acidobacteria (6.66%), and Chloroflexi (4.67%) were the dominant bacterial phyla in the wetlands. The abundance of Acidobacteria, Actinobacteria, and Gemmatimonadetes were significantly higher in the invaded areas than in the normal habitats. The relative high abundance-based coverage estimator (ACE) index in the constructed wetlands and invaded areas suggested the corresponding high bacterial diversity. The significant and positive relationship between Acidobacteria and organic nitrogen concentrations suggested their potential and positive interrelationships. This study demonstrated that the alligator weed invasion could significantly change the compositions of sediment organic matterand bacteria, thus further changing the nutrition cycle and wetland microhabitat.

Soil organic carbon and nitrogen sequestration and turnover in aggregates under subtropical leucaena–grass pastures

Soil Research ◽  
2018 ◽  
Vol 56 (6) ◽  
pp. 632 ◽  
Author(s):  
Kathryn Conrad ◽  
Ram C. Dalal ◽  
Ryosuke Fujinuma ◽  
Neal W. Menzies
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Aggregates ◽  
Soil Mass ◽  
Δ13c And Δ15n ◽  
Organic C ◽  
Carbon And Nitrogen ◽  
Nitrogen Sequestration ◽  
C And N

Stabilisation and protection of soil organic carbon (SOC) in macroaggregates and microaggregates represents an important mechanism for the sequestration of SOC. Legume-based grass pastures have the potential to contribute to aggregate formation and stabilisation, thereby leading to SOC sequestration. However, there is limited research on the C and N dynamics of soil organic matter (SOM) fractions in deep-rooted legume leucaena (Leucaena leucocephala)–grass pastures. We assessed the potential of leucaena to sequester carbon (C) and nitrogen (N) in soil aggregates by estimating the origin, quantity and distribution in the soil profile. We utilised a chronosequence (0–40 years) of seasonally grazed leucaena stands (3–6 m rows), which were sampled to a depth of 0.3 m at 0.1-m intervals. The soil was wet-sieved for different aggregate sizes (large macroaggregates, >2000 µm; small macroaggregates, 250–2000 µm; microaggregates, 53–250 µm; and <53 µm), including occluded particulate organic matter (oPOM) within macroaggregates (>250 µm), and then analysed for organic C, N and δ13C and δ15N. Leucaena promoted aggregation, which increased with the age of the leucaena stands, and in particular the formation of large macroaggregates compared with grass in the upper 0.2 m. Macroaggregates contained a greater SOC stock than microaggregates, principally as a function of the soil mass distribution. The oPOM-C and -N concentrations were highest in macroaggregates at all depths. The acid nonhydrolysable C and N distribution (recalcitrant SOM) provided no clear distinction in stabilisation of SOM between pastures. Leucaena- and possibly other legume-based grass pastures have potential to sequester SOC through stabilisation and protection of oPOM within macroaggregates in soil.

scholarly journals Sources and accumulation of organic carbon in the Pearl River Estuary surface sediment as indicated by elemental, stable carbon isotopic, and carbohydrate compositions

2010 ◽  
Vol 7 (2) ◽  
pp. 2889-2926 ◽  
Author(s):  
B. He ◽  
M. Dai ◽  
W. Huang ◽  
Q. Liu ◽  
H. Chen ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Surface Sediments ◽  
River Estuary ◽  
Pearl River Estuary ◽  
Outer Shelf ◽  
Pearl River ◽  
Terrestrial Organic Matter ◽  
The Pearl River Estuary ◽  
The Pearl River

Abstract. Organic matter in surface sediments from the upper reach of the Pearl River Estuary and Lingdingyang Bay, as well as the adjacent northern South China Sea shelf was characterized by a variety of techniques, including elemental (C and N), stable carbon isotopic (δ 13C) composition, as well as molecular-level analyses. Total organic carbon (TOC) content was 1.61±1.20% in the upper reach down to 1.00±0.22% in Lingdingyang Bay and to 0.80±0.10% on the inner shelf and 0.58±0.06% on the outer shelf. δ13C values ranged from −25.11‰ to −21.28‰ across the studied area, with a trend of enrichment seaward. The spatial trend in C/N ratios mirrored that of δ13C, with a substantial decrease in C/N ratio from 10.9±1.3 in the Lingdingyang Bay surface sediments to 6.5±0.09 in the outer shelf surface sediments. Total carbohydrate yields ranged from 22.1 to 26.7 mg (100 mg OC)−1, and typically followed TOC concentrations in the estuarine and shelf sediments, suggesting that the relative abundance of total carbohydrate was fairly constant in TOC. Total neutral sugars as detected by the nine major monosaccharides (lyxose, rhamnose, ribose, arabinose, fucose, xylose, galactose, mannose, and glucose) yielded between 4.0 and 18.6 mg (100 mg OC)−1 in the same sediments, suggesting that a significant amount of carbohydrates were not neutral aldoses. The bulk organic matter properties, isotopic composition and C/N ratios, combined with molecular-level carbohydrate compositions were used to assess the sources and accumulation of terrestrial organic matter in the Pearl River Estuary and the adjacent northern South China Sea shelf. Results showed a mixture of terrestrial riverine organic carbon with in situ phytoplankton organic carbon in the areas studied. Using a two end-member mixing model based on δ13C values and C/N ratios, we estimated that the terrestrial organic carbon contribution to the surface sediment TOC was ca. 57±13% for Lingdingyang Bay, 19±2% for the inner shelf, which decreased further to 4.3±0.5% on the outer shelf. The molecular composition of the carbohydrate in surface sediments also suggested that the inner estuary was rich in terrestrial-derived carbohydrates but that the contribution of terrestrial-derived carbohydrates decreased offshore. Terrestrial organic carbon accumulation flux was estimated as 1.37±0.92×1011 g yr−1 in Lingdingyang Bay, which accounted for 37±25% of the terrestrial organic carbon transported to the Bay. The burial efficiency of terrestrial organic matter was markedly lower than that of suspended particulate substance (~71%) suggesting that the riverine POC undergoes significant degradation and replacement during transportation through the estuary.

scholarly journals Radiocarbon Dating of Individual Fatty Acids as a Tool for Refining Antarctic Margin Sediment Chronologies

Radiocarbon ◽  
2003 ◽  
Vol 45 (1) ◽  
pp. 17-24 ◽  
Author(s):  
Naohiko Ohkouchi ◽  
Timothy I Eglinton ◽  
John M Hayes
Keyword(s):  
Fatty Acids ◽  
Organic Matter ◽  
Organic Carbon ◽  
Radiocarbon Dating ◽  
Inorganic Carbon ◽  
Surface Sediments ◽  
Ross Sea ◽  
Dissolved Inorganic Carbon ◽  
Accumulation Rate ◽  
Sea Surface

We have measured the radiocarbon contents of individual, solvent-extractable, short-chain (C14, C16, and C18) fatty acids isolated from Ross Sea surface sediments. The corresponding 14C ages are equivalent to that of the post-bomb dissolved inorganic carbon (DIC) reservoir. Moreover, molecular 14C variations in surficial (upper 15 cm) sediments indicate that these compounds may prove useful for reconstructing chronologies of Antarctic margin sediments containing uncertain (and potentially variable) quantities of relict organic carbon. A preliminary molecular 14C chronology suggests that the accumulation rate of relict organic matter has not changed during the last 500 14C yr. The focus of this study is to determine the validity of compound-specific 14C analysis as a technique for reconstructing chronologies of Antarctic margin sediments.

Carbon Isotope Ratios of Particulate Organic Matter in the Gulf of St. Lawrence

1979 ◽  
Vol 36 (6) ◽  
pp. 678-682 ◽  
Author(s):  
F. C. Tan ◽  
P. M. Strain
Keyword(s):  
Organic Matter ◽  
Surface Water ◽  
Organic Carbon ◽  
Carbon Isotope ◽  
Particulate Organic Matter ◽  
Surface Sediments ◽  
Isotope Ratios ◽  
Lawrence Estuary ◽  
Carbon Isotope Ratios ◽  
Surface Samples

Sixteen offshore surface samples within the Gulf of St. Lawrence show low δ13C values and are similar to eight offshore surface samples collected seaward of the Gulf of St. Lawrence. The δ13C surface values are consistent with δ13C values in plankton produced at the temperature found in the euphotic zone in the study area. Higher values are observed in four surface samples from the mouth of the St. Lawrence Estuary and probably result from high carbon demand during periods of high biological productivity. Lower values found in seven deep POC samples indicate changes in the nature of the POC caused by biological degradation of the organic matter. Significant differences (2–6‰) between the uniformly high δ13C values of the organic carbon in surface sediments and the low values of near-bottom water POC have been observed. The similarity between the δ13C values of surface water POC and the surface sediments suggest that surface water POC is an important source of organic carbon in surface sediments. Several observations of large vertical δ13C gradients in deep water POC suggest the presence of resuspended sediments 30–60 m above the sediment–water interface. Key words: particulate organic matter, carbon isotope ratios, isotope fractionation, sediment resuspension, sediment sources, Gulf of St. Lawrence

Studies on the Carbon and Nitrogen Cycles in the soil. II. The Extraction of the Organic Matter of the Soil With Alkali

1930 ◽  
Vol 20 (3) ◽  
pp. 460-477 ◽  
Author(s):  
C. W. B. Arnold ◽  
H. J. Page
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Caustic Soda ◽  
Organic Manure ◽  
Humic Matter ◽  
Colour Intensity ◽  
Alkali Extraction ◽  
Carbon And Nitrogen ◽  
Manurial Treatment

The alkali extraction of the organic matter from the soils of certain plots of the classical permanent experiments on Barnfield and Broadbalk at Rothamsted, receiving respectively organic manure, artificial fertilisers and no manurial treatment, has been studied, together with a colorimetric examination of the extracts for the comparison of the content of humic matter.It is shown that, in spite of the different cultural and manurial treatments which the different plots have received, there is a marked similarity in the properties of the organic matter of these soils, with regard to its behaviour on extraction with cold and hot dilute caustic soda, and the colour intensity of the organic matter in the extracts.The methods used for the determination of organic carbon in the soils and their extracts are noted in an Appendix.The results discussed in this paper are further considered, along with those in the two next following Parts (III and IV), in Part V of this series, in their bearings on the origin of the humic matter of the soil.

Proteins: Amino Acids and Amines

2011 ◽  
Author(s):  
Thomas S. Bianchi ◽  
Elizabeth A. Canuel
Keyword(s):  
Amino Acids ◽  
Organic Matter ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Particulate Organic Carbon ◽  
Nitrogen Cycle ◽  
Organic Nitrogen ◽  
Building Blocks ◽  
Marine Organisms ◽  
Carbon And Nitrogen

This chapter discusses proteins, which make up approximately 50% of organic matter and contain about 85% of the organic nitrogen in marine organisms. Peptides and proteins comprise an important fraction of the particulate organic carbon (13–37%) and particulate organic nitrogen (30–81%), as well as dissolved organic nitrogen (5–20%) and dissolved organic carbon (3–4%) in oceanic and coastal waters. In sediments, proteins account for approximately 7 to 25% of organic carbon and an estimated 30 to 90% of total nitrogen. Amino acids are the basic building blocks of proteins. This class of compounds is essential to all organisms and represents one of the most important components in the organic nitrogen cycle. Amino acids represent one of the most labile pools of organic carbon and nitrogen.

Organic Carbon and Nitrogen stocks in two soil types of Northwestern Tunisia: Temporal and spatial variation

2020 ◽  
Author(s):  
Ahlem Tlili ◽  
Imene Dridi ◽  
Moncef Gueddari
Keyword(s):  
Organic Matter ◽  
Global Warming ◽  
Soil Organic Matter ◽  
Organic Carbon ◽  
Experimental Period ◽  
North West ◽  
Carbon And Nitrogen ◽  
Forest Region ◽  
Nitrogen Sequestration ◽  
Deep Horizon

&lt;p&gt;Soil organic matter has generated international interest in carbon and nitrogen sequestration. In reality, small fluctuations of soil organic stock could have large impacts on global warming. Therefore, quantification of Soil Organic Carbon (SOCs) and Total Nitrogen (TNs) stocks in surface and deep horizons are important to control the release of greenhouse gases. The present research was undertaken in order to determine SOCs and TNs evolution over 50 years. For this aim, we selected two soils (P1 and P2) developed under contrasted pedogenetic conditions in North-West of Tunisia (Beja governorate). P1 is a Luvisol located in a forest region. However, P2 is a Cambisol situated in an agriculture zone. Soil samples were gathered from surface (0-30 cm) and deep (50-100 cm) horizons in 1971, 2005, 2012 and 2019. SOCs declined in surface and deep horizons during the experimental period in both studied soils. In the case of Luvisol, the values declined from 91.01 t/ha to 75.54 t/ha and from 53.00 t/ha to 24.51 t/ha, respectively in surface horizons and deep horizons. Likewise, the SOCs values decreased from 84.24 t/ha to 25.52 t/ha in surface horizons and from 24.45 t/ha to 14.20 t/ha in deep horizons of the Cambisol. The TNs recorded lower values than SOCs. Nevertheless, they showed the same behavior. Our results showed that the highest values of SOCs and TNs were recorded in the Luvisol. This soil exhibited the greatest amount of organic matter since it was developed under forest vegetation. In addition, the results showed an enrichment in SOCs and TNs of super&amp;#239;&amp;#172;&amp;#129;cial horizons to the detriment of the deep horizons. Nevertheless, this decrease in organic stocks with depth occurred following different patterns according to soil type. In fact, the Cambisol reported an important depletion of soil organic stocks as compared to the Luvisol. The loss of SOCs and TNs were estimated to be 69.71% and 54.17% in surface horizon, and 41.94 % and 28.28 % in deep horizon, respectively. Indeed, the land-use change increases the decomposition of soil organic matter principal source of SOCs and TNs. Such a reduction has wider implications on global warming and soil fertility.&amp;#160;&amp;#160;&lt;/p&gt;

Studies on soil organic matter: Part III. The extraction of organic carbon and nitrogen from soil

1949 ◽  
Vol 39 (3) ◽  
pp. 280-282 ◽  
Author(s):  
J. M. Bremner
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Carbon ◽  
Organic Nitrogen ◽  
Carbon And Nitrogen

A study has been made of the extraction of organic carbon and nitrogen from soil by various inorganic reagents. The results show that the organic carbon and nitrogen of soil are so intimately associated that, under the influence of any one of the reagents tested, the organic carbon is dissolved only along with, and in proportion to, the organic nitrogen. The relative proportions of carbon and nitrogen extracted vary, however, with both the soil and the extractant.

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