Size-dependent organo-mineral interactions and dynamics in a seasonally-flooded wetland

2020 ◽  
Author(s):  
Mohammad Afsar ◽  
Bruce Vasilas ◽  
Yan Jin
Keyword(s):  
Organic Matter ◽  
Size Fraction ◽  
Operational Definition ◽  
Organic C ◽  
Size Fractions ◽  
Size Dependent ◽  
Depressional Wetland ◽  
Mineral Associations ◽  
Delmarva Bay ◽  
Terrestrial Environments

<p>Understanding the mechanisms governing the composition and stability of organo-mineral associations is critical to predicting the dynamics of soil organic matter (SOC) and the related global carbon cycling. Redox-induced biogeochemical transformations are the key processes that control the stabilization of SOC via association with metal oxides in terrestrial environments such as wetlands. Despite its high C content (20-30% of terrestrial C), size-dependent organo-mineral associations and their dynamic changes in the redox-dynamic wetlands are poorly understood. Here we present size distribution, concentration, and composition of organo-mineral associations in pore water samples from a depressional wetland located at the Delmarva Bay in Delaware, USA, as influenced by seasonal fluctuations in water table level. The samples were collected from piezometers installed at multiple depths (50 cm, 100 cm, and 200 cm) and in three zones (upland, transitional, and wetland), respectively. Four size fractions were analyzed: dissolved (<2.3 nm), natural nanoparticle (2.3-100 nm, NNP), fine colloid (100-450 nm), and particulate (450-100 nm). Our results revealed that dissolved, NNP, fine colloid and particulate fractions comprised 47 ± 4%, 37 ± 4%, 8 ± 3% and 8 ± 3% of  the bulk organic C (<1000 nm) concentration, respectively. Relative percentages of respective Al, Mn, and Fe were 47 ± 24%, 30 ± 22%, 50 ± 18% at 2.3-450 nm and 22 ± 16%, 17 ± 12%, 25 ± 19% at 450-1000 nm size fraction. The main finding from this study are 1) dissolved and NNP fractions contain higher amount of C than colloidal and particulate fractions and 2) organo-mineral associations have significant differences in their elemental concentrations among different size fractions within colloidal size range. Additionally, the results clearly indicate that the commonly used operational definition for dissolved organic matter (DOM, <450 nm) significantly overestimates the dissolved phase C concentration by including the NNP and colloidal fractions, which contain mineral-associated C. This has important implications in the estimation of SOC decomposition rate in soils, particularly in redox sensitive wetlands, thus in assessing terrestrial C cycling and the transport of OC as well as the associated elements.</p>

scholarly journals Long term trends in fertility of soils under continuous cultivation and cereal cropping in southern Queensland. III. Distribution and kinetics of soil organic carbon in particle size fractions

Soil Research ◽  
1986 ◽  
Vol 24 (2) ◽  
pp. 293 ◽  
Author(s):  
RC Dalal ◽  
RJ Mayer
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Size Fraction ◽  
Organic C ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Clay Size Fraction ◽  
Sand Size

Distribution of soil organic carbon in sand-, silt- and clay-size fractions during cultivation for periods ranging from 20 to 70 years was studied in six major soils used for cereal cropping in southern Queensland. Particle-size fractions were obtained by dispersion in water using cation exchange resin, sieving and sedimentation. In the soils' virgin state no single particle-size fraction was found to be consistently enriched as compared to the whole soil in organic C in all six soils, although the largest proportion (48%) of organic C was in the clay-size fraction; silt and sand-size fractions contained remaining organic C in equal amounts. Upon cultivation, the amounts of organic C declined from all particle-size fractions in most soils, although the loss rates differed considerably among different fractions and from the whole soil. The proportion of the sand-size fraction declined rapidly (from 26% to 12% overall), whereas that of the clay-size fraction increased from 48% to 61% overall. The proportion of silt-size organic C was least affected by cultivation in most soils. It was inferred, therefore, that the sand-size organic matter is rapidly lost from soil, through mineralization as well as disintegration into silt-size and clay-size fractions, and that the clay fraction provides protection for the soil organic matter against microbial and enzymic degradation.

Free soil colloids and colloidal building units of soil aggregates

2020 ◽  
Author(s):  
Ni Tang ◽  
Nina Siebers ◽  
Erwin Klumpp
Keyword(s):  
Mass Spectrometry ◽  
Organic Matter ◽  
Organic Carbon ◽  
Inductively Coupled Plasma ◽  
Soil Aggregates ◽  
Size Fraction ◽  
Ionization Mass ◽  
Soil Matrix ◽  
Size Fractions ◽  
20 Nm

<p>Nanosized mineral particles and organic matter (<100 nm) ,as well as their associations, belong to the most important ingredients for the formation of the soil aggregate structure being a hierarchically organized system. Colloids (< 220 nm) including nanoparticles can be occluded as primary building units of soil aggregates. Nevertheless, a large proportion of these colloids is mobile and presents in the solution phase (as “free”) within the soil matrix. However, the differences between “free” and occluded colloids remain unclear.</p><p>Here, both occluded and free colloids were isolated from soil samples of an arable field with different clay contents (19% and 34%) using wet sieving and centrifugation. The release of occluded colloids from soil macroaggregates (>250 µm) was carried out with ultrasonic treatment at 1000 J mL<sup>-1</sup>. The free and occluded colloidal fractions were then characterized for their size-resolved elemental composition using flow field-flow fractionation inductively coupled plasma mass spectrometry and organic carbon detector (FFF-ICP-MS/OCD). In addition, selected samples were also subjected to transmission electron microscopy as well as pyrolysis field ionization mass spectrometry (Py-FIMS).</p><p>Both, free and occluded colloids were composed of three size fractions: nanoparticles <20 nm, medium-sized nanoparticles (20 nm–60 nm), and, fine colloids (60 nm–220 nm). The fine colloid fraction was the dominant size fraction in both free and occluded colloids, which mainly consist of organic carbon, Al, Si, and Fe, probably present as phyllosilicates and associations of Fe- and Al- (hydr)oxides and organic matter. However, the organic matter contents for all three size fractions were higher for the occluded colloids than for the free ones. The role of OM concentration and composition in these colloids will be discussed in the paper.</p>

ÉTUDE COMPARATIVE DE L'AGRÉGATION ET DE LA MATIÈRE ORGANIQUE ASSOCIÉE AUX FRACTIONS GRANULOMÉTRIQUES DE SEPT SOLS SOUS CULTURE DE MAÏS OU EN PRAIRIE

1990 ◽  
Vol 70 (3) ◽  
pp. 395-402 ◽  
Author(s):  
J. ELUSTONDO ◽  
M. R. LAVERDIÈRE ◽  
D. A. ANGERS ◽  
A. N'DAYEGAMIYE
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Size Fraction ◽  
Cropping System ◽  
Clay Content ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Carbon And Nitrogen ◽  
Water Stable Aggregates ◽  
Continuous Corn

Water-stable aggregation and organic matter associated with particle-size fractions were compared for seven pairs of soils that were either under meadow or continuous corn cropping for more than 5 yr. Soils that have remained under meadow contained 25 and 29% more carbon and nitrogen than those under continuous corn. Carbon contents of the sand- and silt-size fractions were also 61 and 15% higher, respectively, under meadow than under continuous corn. The cropping system had no significant effect on the carbon and nitrogen contents of the clay-size fractions. The amount of water-stable aggregates (> 1 mm) was on average 34% higher in soils under meadow than in soils under corn cropping. Significant correlations were found between water-stable aggregates and total C (r = 0.77) and C in sand-size fraction (r = 0.79). The results also indicate that the beneficial effect of meadow over continuous corn on soil aggregation increases as soil clay content increases. Key words: Aggregation, organic matter, particle-size fractions, corn, meadow

DRIFT spectroscopy combined with sodium hypochlorite oxidation reveals different organic matter characteristics in density-size fractions of organically managed soils

2016 ◽  
Vol 96 (3) ◽  
pp. 317-327
Author(s):  
Masakazu Aoyama
Keyword(s):  
Organic Matter ◽  
Sodium Hypochlorite ◽  
Lignin Content ◽  
Soil Samples ◽  
Drift Spectroscopy ◽  
Absorption Bands ◽  
Organic C ◽  
Size Fractions ◽  
Organic Farm ◽  
Diffuse Reflectance Infrared

The objective of this study was to characterize the organic matter (OM) in density-size fractions of soil samples from a commercial organic farm using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The soil samples were separated by density fractionation with a sodium iodide (Nal) solution (1.6 g cm–3) into free particulate OM (fPOM), occluded particulate OM (oPOM), heavy particulate OM (hPOM), and mineral-associated OM (MAOM) fractions. The OM characterization by DRIFT spectroscopy was the difference in spectra obtained before and after sodium hypochlorite (NaClO) oxidation. However, the infrared absorption bands derived from the soil mineral matrix interfered with the detection of the absorption bands of polysaccharides. An increase in the amount of organic C under organic management was observed for all the density-size fractions, but the functional group composition of the NaClO-oxidizable OM differed among the fractions. The NaClO-oxidizable OM in the fPOM fraction was characterized by a high lignin content, whereas the oPOM fraction had high amounts of aliphatic compounds and lignin. The hPOM fraction contained less lignin and more proteinous materials, and the MAOM fraction was rich in proteinous materials. This study demonstrates that DRIFT spectroscopy combined with NaClO oxidation is a powerful tool for characterizing the relatively unstable OM in soils.

Turnover of soil organic matter and storage of corn residue carbon estimated from natural 13C abundance

1995 ◽  
Vol 75 (2) ◽  
pp. 161-167 ◽  
Author(s):  
E. G. Gregorich ◽  
C. M. Monreal ◽  
B. H. Ellert
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Forest Soil ◽  
Half Life ◽  
Light Fraction ◽  
Organic C ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Corn Residue

Total organic C and natural C abundance were measured in a forest soil and a soil under corn (Zea mays L.) to assess management-induced changes in the quantity and initial source of organic matter. The total mass of organic C in the cultivated soil was 19% lower than in the forest soil. It was estimated that after 25 yr of continuous corn, 100 Mg C ha−1 was returned to the soil as residues, of which only 23 Mg ha−1 remained in the soil; 88% of the remaining corn-derived C (C4-derived C) was in the plow layer. About 30% of the soil organic C in the plow layer (0–27 cm) was derived from corn. Assuming first order kinetics, the half-life of C3-derived C in the 0- to 15-cm layer was 13 yr. The half-life of C3-derived C in the 0- to 30-cm layer, which included organic C below the plow layer, was 24 yr. Mineralization of the light fraction (LF) was faster than that of organic matter associated with particle-size fractions. More than 70% of the LF had turned over since the start of corn cropping, and 45% of organic matter in the sand fraction comprised corn residue. The half-life of C3-derived C in the LF was 8 yr. The mineralization of C from native organic matter associated with the coarse silt fraction was the slowest of all particle-size fractions. Key words: Soil organic matter, carbon storage, natural 13C abundance, light fraction, particle-size fractions, mineralization

Can We Estimate the True Weight of Zooplankton Samples after Chemical Preservation?

1989 ◽  
Vol 46 (3) ◽  
pp. 522-527 ◽  
Author(s):  
Louis A. Giguère ◽  
J.-F. St-Pierre ◽  
B. Bernier ◽  
A. Vézina ◽  
j.-G. Rondeau
Keyword(s):  
Weight Loss ◽  
Body Length ◽  
Freeze Drying ◽  
Size Fraction ◽  
Dry Weight ◽  
Ash Content ◽  
Caloric Content ◽  
Size Fractions ◽  
Size Dependent ◽  
Weight Losses

Zooplankton are collected and sorted into two size fractions from which samples are randomly alloted to a battery of commonly used preservation techniques. We determine dry weight, ash content, and caloric content. We compute organic and inorganic losses of the samples to examine potential causes of variation in dry weight estimates. Treatments are: no preservation, preservation with one of three chemicals (75% ethanol, 5% or 10% buffered formaldehyde), preservation for 1 or 66 wk, and oven- or freeze-drying. Overall dry weight losses are independent of preservation methods. Chemical preservation reduces dry weight by 37 to 43%. Organic and inorganic losses range from 25 to 33% and 73 to 82%, respectively. Because inorganic losses are large, chemical preservation increases the caloric content of samples by 13 – 27%. Dry weight losses are somewhat size-dependent (37 versus 43% for the large and small size fraction respectively, after 66 wk of preservation). A regression of percent dry weight losses on body length (in millimetres) is obtained for our data, and published reports where formaldehyde is used as a preservative. It is: In[dry weight loss] = 4.149 − 0.576 length0.333. This relationship can be used to adjust the weight of zooplankton samples which have been preserved chemically. A survey of studies published in 1983 indicates that most authors did not adjust for dry weight losses due to preservation.

scholarly journals Stability of soil aggregates and their ability of carbon sequestration

2014 ◽  
Vol 9 (No. 3) ◽  
pp. 111-118 ◽  
Author(s):  
V. Šimanský ◽  
D. Bajčan
Keyword(s):  
Organic Matter ◽  
Carbon Sequestration ◽  
Soil Organic Matter ◽  
Soil Aggregates ◽  
Size Fraction ◽  
Size Fractions ◽  
Water Stable Aggregates ◽  
Binding Agents ◽  
Carbon Reservoir ◽  
The Stability

One of the most important binding agents for forming stable aggregates is a soil organic matter (SOM), which can be retained in various size fractions of aggregates. If aggregates are water-resistant, they retain more carbon. Therefore, the aim of this study was to evaluate the stability of aggregates and their ability of carbon sequestration in different soil types and soil management systems in Slovakian vineyards. The highest content of water-stable macro-aggregates (WSA<sub>ma</sub>) was determined in Cambisols, and the lowest in Fluvisols. The highest content of WSA<sub>ma</sub> (size fraction 0.5&ndash;3 mm) was determined in Chernozems, decreasing within the following sequence: Fluvisols &gt; Leptosols &gt; Cambisols &gt; Luvisols. The soil type had a statistically significant influence on the re-distribution of soil organic matter in size fractions of water-stable aggregates. The highest content of SOM in water-stable aggregates of the vineyards was determined in grassy strips in-between the vineyard rows in comparison to intensively cultivated rows of vineyard. The highest values of carbon sequestration capacity (CSC) in WSA<sub>ma</sub> were found in Cambisols &gt; Leptosols and the lowest values of CSC were in Fluvisols. The micro-aggregates represented a significant carbon reservoir for the intensively cultivated soils (rows of vineyard). On the other hand, increasing of macro-aggregates (size fraction 0.5&ndash;3 mm) was characteristic for grassland soils (between the rows of vineyard).

Characterizing organic matter retention for surface soils in eastern Canada using density and particle size fractions

2003 ◽  
Vol 83 (1) ◽  
pp. 11-23 ◽  
Author(s):  
M. R. Carter ◽  
D. A. Angers ◽  
E. G. Gregorich ◽  
M. A. Bolinder
Keyword(s):  
Organic Matter ◽  
Soil Depth ◽  
Light Fraction ◽  
Degree Of Saturation ◽  
Soil Organic C ◽  
Eastern Canada ◽  
Organic C ◽  
Size Fractions ◽  
Capacity Level ◽  
C And N

Interest in the storage of organic matter in terrestrial ecosystems has identified a need to better understand the accumulation and retention of organic C and N in soil. The proportions of C and N associated with clay and silt particles (i.e., “capacity level”), water-stable macro-aggregates (WSA) (>250 µm), particulate (POM) (>53 µm), and light fraction (LF) organic matter, for the 0- to 10-cm soil depth, were assessed at 14 agricultural experimental sites established on Gleysolic, Podzolic, Luvisolic , and Brunisolic soils in the cool, humid region of eastern Canada. Organic C and N in the clay plus silt particles was at or near the capacity level for soils with clay plus silt content < 40%. For soils with >60% clay plus silt, the degree of saturation was 65–70% indicating a potential for further organic C and N retention. The mean proportion of C and N found in the POM was 22 and 27%, whil e the LF organic matter contained 7 and 5% C and N, respectively. Mean soil WSA content, determined by wet-sieving analysis, was 42% for air-dry soil and 54% for wetted soil, and was significantly (P < 0.05) related to both soil clay plus silt (r = 0.65) and organic C (r = 0.54). Water-stable macro-aggregate C content was proportional to soil organic C (r = 0.96, P < 0.01). At four of the sites, where soil C and N were influenced by management, an increasing level of soil organic C and N was associated with both the clay plus silt particles and the POM fraction until the former was saturated. Once the capacity level was saturated, further organic C and N accumulation was associated with the POM fraction. Although stabilized organic C and N in soil exists as a continuum, both soil particle and particulate fractions provided a practical approach to monitor, quantify and differentiate the storage and retention of C and N in soils of eastern Canada. Key words: Soil organic matter, clay plus silt associated organic C and N, size fractions, particulate organic matter, light fraction organic matter, water-stable macro-aggregates, organic amendments, Canada

scholarly journals Long term trends in fertility of soils under continuous cultivation and cereal cropping in southern Queensland .VI. Loss of total nitrogen from different particle size and density fractions

Soil Research ◽  
1987 ◽  
Vol 25 (1) ◽  
pp. 83 ◽  
Author(s):  
RC Dalal ◽  
RJ Mayer
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Light Fraction ◽  
Labile Organic Matter ◽  
Total N ◽  
Organic C ◽  
Size Fractions ◽  
Density Fractions ◽  
Organic Matter Fractions ◽  
Sand Size

The dynamics of total N in particle-size and density fractions of six major soils which have been used for cereal cropping for 20-70 years were studied in order to identify the labile organic matter fractions in soil. For virgin soils, no single particle-size was consistently enriched in N as compared with the whole soil. The clay fraction contained the largest proportion (53% overall) of total N. Silt-size and sand-size N fractions accounted for 26% and 21% of total N, respectively. Upon cultivation, the sand-size fraction lost most of its N (as much as 89% in Langlands-Logie soil). However, N losses also occurred from silt-size and clay-size fractions in most soils. Changes in C : N ratios of different particle-size fractions upon cultivation were not consistent in all soils, possibly because of the transfer of organic C and N among these fractions. Therefore, the separation of labile organic matter fractions from the whole soil based upon particle-size may not be successful in all soils. On the other hand, the density fractionation of soil into a light fraction (<2 Mg m-3) containing relatively labile organic matter (76-96% lost upon cultivation) and a heavy fraction (>2 Mg m-3) containing less labile organic matter appears to be more successful in most soils. It is suggested that the cultural practices that enhance the amount of light fraction would increase the rate of nutrient cycling through microbial biomass and may increase the overall availability of nutrients in soil.

Possible role of aluminum in stabilizing organic matter in particle size fractions of Chernozemic and solonetizic soils

2002 ◽  
Vol 82 (2) ◽  
pp. 265-268 ◽  
Author(s):  
D. Curtin
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Specific Surface ◽  
Clay Fraction ◽  
Organic Matter Content ◽  
Ultrasonic Dispersion ◽  
Organic C ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Organic Matter Stabilization

Although phyllosilicate clays, with their large surface areas, are often considered to play the leading role in stabilizing soil organic matter against microbial attack, several studies have suggested recently that oxides of Al and Fe may stabilize organic matter in some soils. The distribution of organic C and oxides in clay (< 0.2 and 0.2–2 mm) and silt fractions (2–5, 5–20, and 20–50 mm) of four Saskatchewan soils (organic C ranged from 21 to 46 g kg-1) was examined to differentiate the contributions of oxides and specific surface to organic matter retention. Carbon concentrations in the particle size fractions (separated following ultrasonic dispersion of the soils) tended to be highest in the fine silt and coarse clay fractions, not in the fine clay as would be expected if specific surface was the sole factor governing organic matter content. When data for the four soils were pooled there was a strong relationship between organic C (y) in the size fractions and Al (x) extracted by dithionite-citrate-bicarbonate [y = 33.9 x0,5 - 7.3; R2 = 0.90***], suggesting a role for A1 in determining the C storage capacity of the size fractions. The C: A1 ratio increased from an average of 12:1 in clay-sized material to 28:1 in coarse silt. Because it had less A1 per unit mass of C, organic matter in the silt separates may be more weakly bonded to mineral material than is clay-associated organic matter. This may imply that organic matter bound to silt is less stable, and thus susceptible to mineralization, than is organic matter residing in the clay fraction. Key words: Organic matter stabilization, particle size separates, extractable A1 and Fe

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