scholarly journals Feeding of Aulacomya atra Under Different Organic Matter Sources (Autochthonous and Allochthonous) in a Chilean Patagonia Fjord Ecosystem

2021 ◽  
Vol 8 ◽  
Author(s):  
Paulina Montero ◽  
Martina Coppari ◽  
Federico Betti ◽  
Giorgio Bavestrello ◽  
Giovanni Daneri
Keyword(s):  
Organic Matter ◽  
Stable Isotope ◽  
Particle Density ◽  
Food Pellet ◽  
Primary Role ◽  
Salmon Farming ◽  
Feeding Experiments ◽  
Chilean Patagonia ◽  
Autochthonous Organic Matter ◽  
Isotopic Signal

Aulacomya atra is an active suspension feeder, spatially dominant in the shallow-water hard-bottom benthic communities of the Chilean Patagonia fjords. In this region, the vertical flux of autochthonous organic matter (OM) reaching the benthos is augmented by allochthonous OM both from a terrestrial origin and from intensive salmon farming. This mixed pool of OM represents a potential source of food for a variety of benthic consumers, but to date little is known about the degree of utilization of these materials by filter feeders organisms. In this context, feeding experiments on A. atra in Puyuhuapi Fjord, Chilean Patagonia, were conducted during summer and winter 2018–2019. These experiments were designed to determine ingestion rates (IR) of A. atra fed with autochthonous (bacterial and microplanktonic community) and allochthonous (salmon food pellet) OM. Additionally, samples of A. atra tissues and suspended particulate organic matter (SPOM) were taken from the study area for stable isotope analysis. Data from laboratory experiments indicated that A. atra can feed on both autochthonous and allochthonous OM, but higher IR were detected in individuals fed with salmon food pellets. Because the IR is sensitive to food particle density rather than specific type of food, diet preferences of A. atra in feeding experiments could not be determined. Stable isotope analyses indicate that A. atra in natural environment preferentially exploits food with an isotopic signal corresponding to autochthonous OM, highlighting the primary role of phytoplankton carbon in their diet. Extensive utilization of terrestrially derived OM is therefore unlikely, although utilization of OM derived from salmon farming is not precluded because of the overlap in isotopic signal between food pellets and marine plankton.

scholarly journals Trophic structure of an African savanna river and organic matter inputs by large terrestrial herbivores: A stable isotope approach

2018 ◽  
Vol 63 (11) ◽  
pp. 1365-1380 ◽  
Author(s):  
Frank O. Masese ◽  
Kátya G. Abrantes ◽  
Gretchen M. Gettel ◽  
Kenneth Irvine ◽  
Steven Bouillon ◽  
...  
Keyword(s):  
Organic Matter ◽  
Stable Isotope ◽  
Trophic Structure ◽  
African Savanna

Predicting soil particle density from clay and soil organic matter contents

Geoderma ◽  
2017 ◽  
Vol 286 ◽  
pp. 83-87 ◽  
Author(s):  
P. Schjønning ◽  
R.A. McBride ◽  
T. Keller ◽  
P.B. Obour
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Particle Density ◽  
Soil Particle

A Study of the Chemical and Physical Characteristics of the Soils from the South of Piauí for Soil-Cement Brick Production

2016 ◽  
Vol 869 ◽  
pp. 112-115 ◽  
Author(s):  
Francisca Pereira de Araújo ◽  
Edson Cavalcanti Silva Filho ◽  
João Sammy Nery de Souza ◽  
Josy Anteveli Osajima ◽  
Marcelo Barbosa Furtini
Keyword(s):  
Organic Matter ◽  
Particle Density ◽  
Environmentally Friendly ◽  
Physical Characteristics ◽  
Chemical Characteristics ◽  
The South ◽  
Physical Chemical ◽  
Soil Cement ◽  
Made In

Soil-cement bricks are good examples of environmentally friendly products. This brick is the combination of soil with compacted cement with no combustion in its production. In this work the physical chemical characteristics of the soil from Piaui for producing this material were investigated. Samples of the soil were collected in three potteries from the county of Bom Jesus and pH analysis were carried out, as well as the rate of organic matter, texture, particle density, limits of liquidity and plasticity rates. The results have shown that the soils have acid tones (pH 5,49 a 6,11), which can be neutralized by adding cement, and organic matter percentages up to 1%. The samples have shown predominantly clay-rich textures with adequate plasticity limits, however, values of liquidity limits and particle density above recommended. Altogether, these soils tend to present viability concerning soil-cement brick production, provided that corrections with additives are made in order to minimize this effect.

Particle densities of wetland soils in northern Alberta, Canada

2006 ◽  
Vol 86 (1) ◽  
pp. 57-60 ◽  
Author(s):  
T. E. Redding ◽  
K. J. Devito
Keyword(s):  
Organic Matter ◽  
Particle Density ◽  
Physical Property ◽  
Organic Soils ◽  
Wetland Soil ◽  
Loss On Ignition ◽  
Simple Method ◽  
Mean Values ◽  
Northern Alberta ◽  
Wetland Types

Particle density is a fundamental soil physical property, yet values of soil and organic matter particle density (ρs and ρo) vary widely in the literature. We measured particle density of organic soils from five wetland types, and from exposed sediments of drying ponds, in northern Alberta, Canada. Our measured values of organic soil and pond sediment ρs varied widely (1.43–2.39 Mg m-3); however, calculated values of ρo (1.34–1.52 Mg m-3) were relatively constant. The measured and calculated ρs and ρo values were similar to those obtained in published studies using similar methods, but were higher than the values provided in many reference texts. Given the relatively small variability in ρo, the use of mean values of ρo, combined with measurements of organic matter loss-on-ignition, shows promise as a simple method for obtaining reliable estimates of ρs across a range of wetland types. Key words: Particle density, peat, organic matter, wetland soil, loss-on-ignition

Stable-isotope Raman microspectroscopy for the analysis of soil organic matter

2017 ◽  
Vol 410 (3) ◽  
pp. 923-931 ◽  
Author(s):  
Alexandra C. Wiesheu ◽  
Ramona Brejcha ◽  
Carsten W. Mueller ◽  
Ingrid Kögel-Knabner ◽  
Martin Elsner ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Stable Isotope ◽  
Raman Microspectroscopy

scholarly journals Barium stable isotopes as a fingerprint of biological cycling in the Amazon River basin

2020 ◽  
Vol 17 (23) ◽  
pp. 5989-6015
Author(s):  
Quentin Charbonnier ◽  
Julien Bouchez ◽  
Jérôme Gaillardet ◽  
Éric Gayer
Keyword(s):  
Organic Matter ◽  
Stable Isotope ◽  
Trace Element ◽  
Isotope Composition ◽  
Silicate Weathering ◽  
Biological Cycling ◽  
Biological Uptake ◽  
Dissolved Load ◽  
Silicate Rocks

Abstract. The biological cycle of rock-derived nutrients on the continents is a major component of element transfer between the Earth's surface compartments, but its magnitude currently remains elusive. The use of the stable isotope composition of rock-derived nutrients, which can be fractionated during biological uptake, provides a promising path forward with respect to quantifying biological cycling and its overall contribution to global element cycling. In this paper, we rely on the nutrient-like behaviour of the trace element barium (Ba) and use its elemental and stable isotope compositions in dissolved and sediment load river samples to investigate biological cycling in the Amazon Basin. From these measurements, we show that dissolved Ba mainly derives from silicate rocks, and a correlation between dissolved Ba and K abundances suggests that biological cycling plays a role in the Ba river budget. Furthermore, the isotope composition of Ba (δ138Ba) in the dissolved load was found to be significantly different from that of the parent silicate rocks, implying that dissolved Ba isotopic signatures are affected by (i) the precipitation of soil-forming secondary phases as well as (ii) biological uptake and release from dead organic matter. Results from an isotope mass balance method applied to the river dissolved load data indicate that, after its release to solution by rock weathering, Ba is partitioned between the river dissolved load, secondary weathering products (such as those found in soils and river sediments), and the biota. In most sub-catchments of the Amazon, river Ba abundances and isotope compositions are significantly affected by biological cycling. Relationships between estimates of Ba cycled through biota and independent metrics of ecosystem dynamics (such as gross primary production and terrestrial ecosystem respiration) allow us to discuss the role of environmental parameters such as climate or erosion rates on the biological cycling of Ba and, by extension, the role of major rock-derived nutrients. In addition, catchment-scale mass and isotope budgets of Ba show that the measured riverine export of Ba is lower than the estimated delivery of Ba to the Earth surface through rock alteration. This indicates the existence of a missing Ba component, which we attribute to the formation of Ba-bearing particulate organics (possibly accumulating as soil organic matter or currently growing biomass within the catchments) and to organic-bound Ba exported as “unsampled” river particulate organic matter. Given our findings on the trace element Ba, we explore whether the river fluxes of most major rock-derived nutrients (K, Mg, Ca) might also be significantly affected by biological uptake or release. A first-order correction of river-derived silicate weathering fluxes from biological cycling shows that the carbon dioxide (CO2) consumption by silicate weathering at the mouth of the Amazon could be several times higher than the previously reported value of 13 × 109 mol CO2 yr−1 (Gaillardet et al., 1997). Overall, our study clearly shows that the chemical and isotope compositions of rivers in the Amazon – and most likely in other large river basins – bear a biological imprint, thereby challenging common assumptions made in weathering studies.

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