Isotopic fingerprints on lacustrine organic matter from Laguna Potrok Aike (southern Patagonia, Argentina) reflect environmental changes during the last 16,000 years

2008 ◽  
Vol 42 (1) ◽  
pp. 81-102 ◽  
Author(s):  
Christoph Mayr ◽  
Andreas Lücke ◽  
Nora I. Maidana ◽  
Michael Wille ◽  
Torsten Haberzettl ◽  
...  
Keyword(s):  
Organic Matter ◽  
Environmental Changes ◽  
Southern Patagonia

scholarly journals Eastern Andean environmental and climate synthesis for the last 2000 years BP from terrestrial pollen and charcoal records of Patagonia

2015 ◽  
Vol 11 (3) ◽  
pp. 2121-2157 ◽  
Author(s):  
G. D. Sottile ◽  
M. E. Echeverria ◽  
M. V. Mancini ◽  
M. M. Bianchi ◽  
M. A. Marcos ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Environmental Changes ◽  
Fire Regime ◽  
Ice Age ◽  
Circulation System ◽  
Forest Steppe ◽  
Proxy Records ◽  
The Andes ◽  
Precipitation Regimes ◽  
Southern Patagonia

Abstract. The Southern Hemisphere Westerly Winds (SWW) constitute an important zonal circulation system that dominates the dynamics of Southern Hemisphere mid-latitude climate. Little is known about climatic changes in the Southern South America in comparison to the Northern Hemisphere due to the low density of proxy records, and adequate chronology and sampling resolution to address environmental changes of the last 2000 years. Since 2009, new pollen and charcoal records from bog and lakes in northern and southern Patagonia at the east side of the Andes have been published with an adequate calibration of pollen assemblages related to modern vegetation and ecological behaviour. In this work we improve the chronological control of some eastern Andean previously published sequences and integrate pollen and charcoal dataset available east of the Andes to interpret possible environmental and SWW variability at centennial time scales. Through the analysis of modern and past hydric balance dynamics we compare these scenarios with other western Andean SWW sensitive proxy records for the last 2000 years. Due to the distinct precipitation regimes that exist between Northern (40–45° S) and Southern Patagonia (48–52° S) pollen sites locations, shifts on latitudinal and strength of the SWW results in large changes on hydric availability on forest and steppe communities. Therefore, we can interpret fossil pollen dataset as changes on paleohydric balance at every single site by the construction of paleohydric indices and comparison to charcoal records during the last 2000 cal yrs BP. Our composite pollen-based Northern and Southern Patagonia indices can be interpreted as changes in latitudinal variation and intensity of the SWW respectively. Dataset integration suggest poleward SWW between 2000 and 750 cal yrs BP and northward-weaker SWW during the Little Ice Age (750–200 cal yrs BP). These SWW variations are synchronous to Patagonian fire activity major shifts. We found an in phase fire regime (in terms of timing of biomass burning) between northern Patagonia Monte shrubland and Southern Patagonia steppe environments. Conversely, there is an antiphase fire regime between Northern and Southern Patagonia forest and forest-steppe ecotone environments. SWW variability may be associated to ENSO variability especially during the last millennia. For the last 200 cal yrs BP we can concluded that the SWW belt were more intense and poleward than the previous interval. Our composite pollen-based SWW indices show the potential of pollen dataset integration to improve the understanding of paleohydric variability especially for the last 2000 millennial in Patagonia.

Dissimilar bacterial and fungal decomposer communities across rich to poor fen peatlands exhibit functional redundancy

2015 ◽  
Vol 95 (3) ◽  
pp. 219-230 ◽  
Author(s):  
Kristine M. Haynes ◽  
Michael D. Preston ◽  
James W. McLaughlin ◽  
Kara Webster ◽  
Nathan Basiliko
Keyword(s):  
Organic Matter ◽  
Microbial Communities ◽  
Environmental Changes ◽  
Functional Redundancy ◽  
Organic Substrates ◽  
Metabolic Potential ◽  
Vegetation Communities ◽  
Chemical Complexity ◽  
Poor Fen

Haynes, K. M., Preston, M. D., McLaughlin, J. W., Webster, K. and Basiliko, N. 2015. Dissimilar bacterial and fungal decomposer communities across rich to poor fen peatlands exhibit functional redundancy. Can. J. Soil Sci. 95: 219–230. Climatic and environmental changes can lead to shifts in the dominant vegetation communities present in northern peatland ecosystems, including from Sphagnum- to vascular-dominated systems. Such shifts in vegetation result in changes to the chemical quality of carbon substrates for soil microbial decomposers, with leaves and roots deposited in the peat surface and subsurface that potentially decompose faster. This study characterized the bacterial and fungal communities present along a nutrient gradient ranging from rich to poor fen peatlands and assessed the metabolic potential of these communities to mineralize a variety of organic matter substrates of varying chemical complexity using substrate-induced respiration (SIR) assays. Distinct microbial communities existed between rich, intermediate and poor fens, but SIR in each of the three sites exhibited the same pattern of carbon mineralization, providing support for the concept of functional redundancy, at least under standardized in vitro conditions. Preferential mineralization of simple organic substrates in the rich fen and complex compounds in the poor fen was not observed. Similarly, no preference was given to “native” organic matter extracts derived from each fen, with microbial communities opting for the most bioavailable substrate. This study suggests that soil bacteria and fungi might be able to respond relatively rapidly to shifts in vegetation communities and subsequent changes in the quality of carbon substrate additions to peatlands associated with environmental and climatic change.

scholarly journals Seabed Resuspension in the Chesapeake Bay: Implications for Biogeochemical Cycling and Hypoxia

2020 ◽  
Vol 44 (1) ◽  
pp. 103-122
Author(s):  
Julia M. Moriarty ◽  
Marjorie A. M. Friedrichs ◽  
Courtney K. Harris
Keyword(s):  
Organic Matter ◽  
Chesapeake Bay ◽  
Water Column ◽  
Primary Productivity ◽  
Environmental Changes ◽  
Light Attenuation ◽  
Sediment Resuspension ◽  
Nitrogen Dynamics ◽  
Biogeochemical Model ◽  
Order Of Magnitude

AbstractSediment processes, including resuspension and transport, affect water quality in estuaries by altering light attenuation, primary productivity, and organic matter remineralization, which then influence oxygen and nitrogen dynamics. The relative importance of these processes on oxygen and nitrogen dynamics varies in space and time due to multiple factors and is difficult to measure, however, motivating a modeling approach to quantify how sediment resuspension and transport affect estuarine biogeochemistry. Results from a coupled hydrodynamic–sediment transport–biogeochemical model of the Chesapeake Bay for the summers of 2002 and 2003 showed that resuspension increased light attenuation, especially in the northernmost portion of the Bay, shifting primary production downstream. Resuspension also increased remineralization in the central Bay, which experienced larger organic matter concentrations due to the downstream shift in primary productivity and estuarine circulation. As a result, oxygen decreased and ammonium increased throughout the Bay in the bottom portion of the water column, due to reduced photosynthesis in the northernmost portion of the Bay and increased remineralization in the central Bay. Averaged over the channel, resuspension decreased oxygen by ~ 25% and increased ammonium by ~ 50% for the bottom water column. Changes due to resuspension were of the same order of magnitude as, and generally exceeded, short-term variations within individual summers, as well as interannual variability between 2002 and 2003, which were wet and dry years, respectively. Our results quantify the degree to which sediment resuspension and transport affect biogeochemistry, and provide insight into how coastal systems may respond to management efforts and environmental changes.

scholarly journals Biomonitoring application using macrozoobenthic assemblanges at coastal area of Menjangan Besar Island, Kepulauan Karimunjawa, Indonesia

2020 ◽  
Vol 16 (3) ◽  
pp. 292-296
Author(s):  
Rafita Farantika ◽  
Sapto Purnomo Putro ◽  
Agus Indarjo
Keyword(s):  
Organic Matter ◽  
Coastal Area ◽  
Environmental Changes ◽  
Marine Ecosystem ◽  
Organic Matter Content ◽  
Water Current ◽  
Sampling Location ◽  
Physical Factors ◽  
Environmental Disturbance ◽  
Macrobenthic Assemblages

The macrozoobenthic structure inhabiting marine ecosystem may be used as a bioindicator of changes in aquatic environmental disturbance. This study is aimed to assess environmental disturbance by application of biomonitoring using macrozoobenthic assemblages at coastal area of Menjangan Besar Island, Kepulauan Karimunjawa, Indonesia. The macrozoobenthic assemblages were assessed at two sampling locations, i.e. floating net cage of monoculture and reference areas. Each sampling location consisted of three stations with three replicates for each station. The samples were taken in two sampling times, i.e. August and November 2018. Data of abiotic parameters included the composition of organic matter content, sediment substrates, DO, pH, salinity, temperature, and water current. Sediments were sampled using Ekman grab from 15 m deep. The relationship between biotics (macrozoobenthos) and abiotics (physical-chemical factors) was assessed using a non-parametric multivariate procedure (BIO-ENV; Primer 6.1.5). Macrobenthic assemblages consisted of 89 species with the total abundance of 50,071 individuals/m2, consisting of 52 families and 4 classes of macrozoobenthos. The values of indices were ranging from 2,54-3,40 for diversity index (H'), 0,99 for Pielou’s evenness index (e’), and 0,09-0,17 for dominance index (C). The most common classes were a member of Gastropods and bivalves. Diversity and evennes indices exhibited differed by location (monoculture vs reference) and time sampling. Fluctuation of macrobenthic structure was considered as a results of environmental changes spatially and temporally, especially sediment composition and food availability as the form of organic matter. Nitrogen and silt were the most chemical and physical factors influencing the structure of macrozoobenthos (r = 0,632; BIO-ENV).

Organic Matter in the Early Toarcian Shales, Paris Basin, France: a Response to Environmental Changes

1991 ◽  
Vol 46 (5) ◽  
pp. 543-562 ◽  
Author(s):  
D. J. Hollander ◽  
G. Bessereau ◽  
S. Belin ◽  
A. Y. Huc ◽  
J. P. Houzay
Keyword(s):  
Organic Matter ◽  
Environmental Changes ◽  
Paris Basin

scholarly journals CHARACTERIZATION OF HEADWATERS PEATS OF THE RIO ARAÇUAÍ, MINAS GERAIS STATE, BRAZIL

2015 ◽  
Vol 39 (2) ◽  
pp. 475-489 ◽  
Author(s):  
Diêgo Faustolo Alves Bispo ◽  
Alexandre Christofaro Silva ◽  
Cristiano Christofaro ◽  
Max Leandro Naves Silva ◽  
Maurício Soares Barbosa ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Environmental Changes ◽  
Chemical Properties ◽  
Carbon Accumulation ◽  
Advanced Stage ◽  
Conservation Area ◽  
14C Age ◽  
And Function ◽  
Physical And Chemical

Peatlands are soil environments that accumulate water and organic carbon and function as records of paleo-environmental changes. The variability in the composition of organic matter is reflected in their morphological, physical, and chemical properties. The aim of this study was to characterize these properties in peatlands from the headwaters of the Rio Araçuaí (Araçuaí River) in different stages of preservation. Two cores from peatlands with different vegetation types (moist grassland and semideciduous seasonal forest) from the Rio Preto [Preto River] headwaters (conservation area) and the Córrego Cachoeira dos Borges [Cachoeira dos Borges stream] (disturbed area) were sampled. Both are tributaries of the Rio Araçuaí. Samples were taken from layers of 15 cm, and morphological, physical, and chemical analyses were performed. The 14C age and δ13C values were determined in three samples from each core and the vertical growth and organic carbon accumulation rates were estimated. Dendrograms were constructed for each peatland by hierarchical clustering of similar layers with data from 34 parameters. The headwater peatlands of the Rio Araçuaí have a predominance of organic material in an advanced stage of decomposition and their soils are classified as Typic Haplosaprists. The organic matter in the Histosols of the peatlands of the headwaters of the Rio Araçuaí shows marked differences with respect to its morphological, physical, and chemical composition, as it is influenced by the type of vegetation that colonizes it. The peat from the headwaters of the Córrego Cachoeira dos Borges is in a more advanced stage of degradation than the peat from the Rio Preto, which highlights the urgent need for protection of these ecosystems/soil environments.

scholarly journals The Regulation by Phenolic Compounds of Soil Organic Matter Dynamics under a Changing Environment

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Kyungjin Min ◽  
Chris Freeman ◽  
Hojeong Kang ◽  
Sung-Uk Choi
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Environmental Changes ◽  
N Deposition ◽  
Interactive Effects ◽  
Plant Metabolites ◽  
Regulatory Effects ◽  
Dynamics Models ◽  
The Relationship

Phenolics are the most abundant plant metabolites and are believed to decompose slowly in soils compared to other soil organic matter (SOM). Thus, they have often been considered as a slow carbon (C) pool in soil dynamics models. Here, however, we review changes in our concept about the turnover rate of phenolics and quantification of different types of phenolics in soils. Also, we synthesize current research on the degradation of phenolics and their regulatory effects on decomposition. Environmental changes, such as elevated CO2, warming, nitrogen (N) deposition, and drought, could influence the production and form of phenolics, leading to a change in SOM dynamics, and thus we also review the fate of phenolics under environmental disturbances. Finally, we propose the use of phenolics as a tool to control rates of SOM decomposition to stabilize organic carbon in ecosystems. Further studies to clarify the role of phenolics in SOM dynamics should include improving quantification methods, elucidating the relationship between phenolics and soil microorganisms, and determining the interactive effects of combinations of environmental changes on the phenolics production and degradation and subsequent impact on SOM processing.

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