scholarly journals Total mercury distribution among soil aggregate size fractions in a temperate forest podzol

2018 ◽  
Vol 8 ◽  
Author(s):  
Antía Gómez Armesto ◽  
Lucía Bibián-Núñez ◽  
Claudia Campillo-Cora ◽  
Xabier Pontevedra-Pombal ◽  
Manuel Arias-Estévez ◽  
...  
Keyword(s):  
Temperate Forest ◽  
Aggregate Size ◽  
Fine Sand ◽  
Soil Aggregate ◽  
Coarse Sand ◽  
Coarse Silt ◽  
Fine Silt ◽  
Size Fractions ◽  
Total Hg ◽  
Sand Size

This study determined the distribution of total Hg (Hg<sub>T</sub>) among aggregate size fractions in the A, E, Bh and Bs horizons of a representative temperate forest podzol. The aggregate distribution was dominated by the coarse sand size fraction (average of 55%) followed by fine sand (29%), fine silt (10%), coarse silt (4%) and clay (2%). In general, Hg<sub>T</sub> mean values increased as the aggregate size become smaller: clay (170 ng g<sup>-1</sup>) &gt; fine silt (130 ng g<sup>-1</sup>) &gt; coarse silt (80 ng g<sup>-1</sup>) &gt; fine sand (32 ng g<sup>-1</sup>) &gt; coarse sand (14 ng g<sup>-1</sup>). Total Hg enrichment in clay-sized aggregates ranged from 2 to 11 times higher than the values shown by the bulk soil (&lt; 2 mm). The accumulation of Hg<sub>T</sub> in the finer size aggregates was closely related to total organic C, Na-pyrophosphate extracted C, metal (Al, Fe)-humus complexes and Al and Fe oxyhydroxides. Indeed, these parameters varied significantly (<em>p </em>&lt; 0.05) with the aggregate size and their highest values were found in the finer fractions. This suggested the role of these soil compounds in the increase of the specific surface area per mass unit and negative charges in the smallest aggregates, favouring Hg retention. Mercury accumulation factor (Hg<sub>AF</sub>) values reached up to 10.8 in the clay size aggregates, being close to 1 in sand size fractions. Regarding Hg enrichment factors (Hg<sub>EF</sub>), they were &lt; 4 (“moderate pollution” category) in most of the horizons and aggregate sizes. Grain size mass loading (GSF<sub>Hg</sub>) revealed that finer fractions had a higher Hg loading than their mass fractions, with a notable contribution of fine silt which made up &gt; 50% of Hg<sub>T</sub> in Bh and Bs horizons. The potential ecological risk index (PERI<sub>Hg</sub>) increased as the aggregate size decreased, with the highest values in the illuvial horizons (45-903) and lowest in the E horizon (3-363). Heterogeneous distribution of Hg in the soil aggregate size fractions must be considered for Hg determination for purposes such as critical loads, background values or environmental risk indices. In addition, Hg accumulation in finer aggregates could be of concern due to its potential mobility in forest soils, either transferred by leaching to groundwater and freshwaters or mobilized by runoff in surface horizons.

scholarly journals Dust Particle Size and Statistical Parameters

2021 ◽  
pp. 57-93
Author(s):  
Noor Al-Dousari ◽  
Modi Ahmed ◽  
Ali Al-Dousari ◽  
Musaad Al-Daihani ◽  
Murahib Al-Elaj
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Size Distribution ◽  
Fine Sand ◽  
Coarse Sand ◽  
Optical Methods ◽  
Size Analysis ◽  
Coarse Silt ◽  
Statistical Parameters ◽  
Fine Silt

AbstractGrain ‘size’ can be specified and measured in several different ways. All methods of grain size determination have blemishes, and the choice of the most appropriate method is governed by the nature of the sample and the use to which the data are placed. Four main methods are currently used for size analysis of sands: (a) sieving; (b) settling tube analysis; (c) electro-optical methods, including Coulter Counter analysis and laser granulometry; and (d) computerized image analysis. The classification of the particle size distribution of Kuwait dust was mapped according to the parameters proposed by Folk And Ward (1957) which were widely used for quantitative comparisons between natural grain size distribution and the lognormal distribution that shows better sorted sediments have lower values of σ1. Maps of the distribution of dust in Kuwait were obtained that included: fine sand (F.S.), Coarse sand (C.S), Medium Sand (M.S), Very Fine Sane (V.F.S), Very Coarse Silt (V.C.Silt), Coarse Silt (C.Silt), Medium Silt (M.Silt), Fine Silt (F.Silt), Very Fine Silt (V.F.Silt), in addition to that, the deposition percentage of Clay, Sand, mud (silt plus clay) and silt were provided.

scholarly journals Particle size partitioning of metals in humus horizons of two small erosional landforms in the middle Protva basin – a comparative study

2020 ◽  
Vol 13 (1) ◽  
pp. 260-271 ◽  
Author(s):  
Olga A. Samonova ◽  
Elena N. Aseyeva
Keyword(s):  
Particle Size ◽  
Mixed Forest ◽  
Coarse Sand ◽  
Particle Sizes ◽  
Coarse Silt ◽  
Fine Silt ◽  
Forest Zone ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Humus Horizons

Partitioning of metals in soil particles of various size classes has been receiving greater significance due to the necessity to predict the behaviour and pathways of the potentially toxic elements in the environment. In this study the analysis of metals’ distribution in various particle size fractions was performed to characterize and compare geochemical features of the topsoil horizons of two small erosional landforms located in uncontaminated area of the central part of European Russia (the Middle Protva basin, mixed forest zone). The landforms represent two typical lithological types of gullies in the study area. Soil samples were fractionated and the concentrations of Fe, Mn, Ti, Zr, Ni, Co, Cr, Zn, Cu, Pb were determined in five particle size fractions: 1–0.25, 0.25-0.05, 0.05−0.01, 0.01–0.001 and <0.001 mm. The metals’ concentrations and their distribution in various particle sizes were found to be related to gully litho-type. The contribution of the clay to the total amount of metals was the greatest for Mn, Zn, Ni and Co in both systems. The highest mass loading for Ti, Zr and Cr came from the coarse silt, while for Cu and Pb it was made by different particle size fractions: the medium and fine silt or the coarse silt. The highest contribution of Fe also came from different fractions, either from the coarse sand or the clay depending on the system.

Aging shapes the distribution of copper in soil aggregate size fractions

2018 ◽  
Vol 233 ◽  
pp. 569-576 ◽  
Author(s):  
Qi Li ◽  
Huihui Du ◽  
Wenli Chen ◽  
Jialong Hao ◽  
Qiaoyun Huang ◽  
...  
Keyword(s):  
Aggregate Size ◽  
Soil Aggregate ◽  
Size Fractions

scholarly journals Particle Size Imbalance Index from Compositional Analysis to Evaluate Cereal Sustainability for Arid Soils in Eastern Algeria

Agriculture ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 296
Author(s):  
Siham Zaaboubi ◽  
Lotfi Khiari ◽  
Salah Abdesselam ◽  
Jacques Gallichand ◽  
Fassil Kebede ◽  
...  
Keyword(s):  
Particle Size ◽  
Management Practices ◽  
Compositional Analysis ◽  
Fine Sand ◽  
Particle Size Analysis ◽  
Coarse Sand ◽  
Richards Equation ◽  
Size Analysis ◽  
Fine Silt ◽  
Eastern Algeria

For homogeneous fertilization and crop management practices, this work hypothesized that texture could influence cereal yield, particularly in dry regions. Particle size analysis could help improve knowledge of the soil-plant relationship to obtain favorable conditions for better yield. The objective of this work is to develop a single granulometric index for durum wheat (Triticum durum) that is well correlated with yield. For this purpose, 350 independent samples of cereal soils from eastern Algeria were taken and the recorded yields were linked to these samples. The cutoff yield, which separates sub-populations with acceptable yield from those with less acceptable yield, was determined from the inflection point of the cumulative variance ratio functions related to yield by the Richards’ equation. The result obtained is 2.0 Mg.ha−1, with a theoretical critical chi-square value of 4.2, close to 4.6, which is the critical value of r2granulo as obtained by the Cate-Nelson procedure. The five-granulometric indices were found to be symmetrical around zero as follows: ±0.83 for clay (IC), ±1.73 for fine silt (IFL), ±0.31 for coarse silt (ICL), ±0.44 for fine sand (IFS), and ±1.30 for coarse sand (ICS). The two fractions that most influence the textural imbalance are fine silt (IFL) and coarse sand (ICS), with a contribution of 41% and 37%, respectively. The critical single imbalance index r g r a n u l o 2 can be used for determining cereal suitability for soils in the arid region of eastern Algeria. The lower the   r g r a n u l o 2 is, the better the soil for cereal crops.

Soil aggregate size affects C sequestration and microorganisms inside aggregate under straw addition

2020 ◽  
Author(s):  
Jinjing Lu ◽  
Sheng ping Li ◽  
Xueping Wu ◽  
Aurore Degre
Keyword(s):  
Large Scale ◽  
Soil Aggregates ◽  
Aggregate Size ◽  
C Sequestration ◽  
Soil Aggregate ◽  
Basic Unit ◽  
Size Fractions ◽  
Soil Microbial ◽  
Relationship Of ◽  
The Relationship

&lt;p&gt;As the basic unit of soil, aggregates are considered as a stable soil organic ( SOC ) pool. Changes in organic subtract due to straw addition induce variations in soil microbial community or activity, which may effect the C sequestration in aggregates. Most of the previous studies on soil microorganisms assessment was done at large scale i.e. larger quantities of soil, however, few studies on SOC is known in aggregate size fractions. This study investigated the effects of soil aggregate size on the distribution of microorganism and SOC, and the relationship of microorganism and C sequestration inside aggregate size fractions with &lt;sup&gt;13&lt;/sup&gt;C-labelled straw addition. Soil samples were collected from 0-15 cm and classified into 5 aggregates sizes classes ( &amp;#65310;5 mm, 2-5 mm, 1-2 mm, 0.25-1 mm and &amp;#65308;0.25 mm ), and the graded aggregates were incubated for 180 days at 20&amp;#160;&amp;#176;C, with or without&amp;#160;&lt;sup&gt;13&lt;/sup&gt;C-labelled straw residue. The incorporation of &lt;sup&gt;13&lt;/sup&gt;C into the five aggregate size fractions was analyzed.&lt;/p&gt;&lt;p&gt;After incubation, the SOC, DOC and ROC contents were increased more rapidly and significantly in aggregate ( &amp;#65310;5 mm ) than that in aggregate ( &amp;#65308;5 mm ) under straw addition, with the same trend of new carbon derived from straw. The total PLFAs was increased most significantly in aggregate ( &amp;#65310;5 mm ), especially fungi and negative bacteria ( G- ), while the positive bacteria ( G+ ) increased slightly in aggregate ( &amp;#65308;0.25 mm ), with no significant change in total PLFAs. The proportion of bacteria in total microorganism increased gradually, as the aggregate size increased in straw treatment. The results imply that aggregate ( &amp;#65310;5 mm ) have more space for C sequestration and greater contribution to new carbon turnovering in soil than other small aggregates, and it gradually tended to be bacterial with the enrichment of carbon. In addition, the SOC contents were strongly related to the amount of fungi and G- in aggregate ( &amp;#65308;5 mm ), while related to G+ in aggregate ( &amp;#65308;0.25 mm ) under straw addition.&lt;/p&gt;

scholarly journals Microbial activity promoted with organic carbon accumulation in macroaggregates of paddy soils under long-term rice cultivation

2016 ◽  
Vol 13 (24) ◽  
pp. 6565-6586 ◽  
Author(s):  
Yalong Liu ◽  
Ping Wang ◽  
Yuanjun Ding ◽  
Haifei Lu ◽  
Lianqing Li ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Organic Carbon ◽  
Soil Respiration ◽  
Soil Aggregates ◽  
Fine Sand ◽  
Coarse Sand ◽  
Rice Cultivation ◽  
Rice Soils ◽  
Size Fractions ◽  
Gene Abundance

Abstract. While soil organic carbon (SOC) accumulation and stabilization has been increasingly the focus of ecosystem properties, how it could be linked to soil biological activity enhancement has been poorly assessed. In this study, topsoil samples were collected from a series of rice soils shifted from salt marshes for 0, 50, 100, 300 and 700 years from a coastal area of eastern China. Soil aggregates were fractioned into different sizes of coarse sand (200–2000 µm), fine sand (20–200 µm), silt (2–20 µm) and clay (< 2 µm), using separation with a low-energy dispersion protocol. Soil properties were determined to investigate niche specialization of different soil particle fractions in response to long-term rice cultivation, including recalcitrant and labile organic carbon, microbial diversity of bacterial, archaeal and fungal communities, soil respiration and enzyme activity. The results showed that the mass proportion both of coarse-sand (2000–200 µm) and clay (< 2 µm) fractions increased with prolonged rice cultivation, but the aggregate size fractions were dominated by fine-sand (200–20 µm) and silt (20–2 µm) fractions across the chronosequence. SOC was highly enriched in coarse-sand fractions (40–60 g kg−1) and moderately in clay fractions (20–25 g kg−1), but was depleted in silt fractions (∼ 10 g kg−1). The recalcitrant carbon pool was higher (33–40 % of SOC) in both coarse-sand and clay fractions than in fine-sand and silt fractions (20–29 % of SOC). However, the ratio of labile organic carbon (LOC) to SOC showed a weakly decreasing trend with decreasing size of aggregate fractions. Total soil DNA (deoxyribonucleic acid) content in the size fractions followed a similar trend to that of SOC. Despite the largely similar diversity between the fractions, 16S ribosomal gene abundance of bacteria and of archaeal were concentrated in both coarse-sand and clay fractions. Being the highest generally in coarse-sand fractions, 18S rRNA gene abundance of fungi decreased sharply but the diversity gently, with decreasing size of the aggregate fractions. The soil respiration quotient (ratio of respired CO2–C to SOC) was the highest in the silt fraction, followed by the fine-sand fraction, but the lowest in coarse-sand and clay fractions in the rice soils cultivated over 100 years, whereas the microbial metabolic quotient was lower in coarse-sand-sized fractions than in other fractions. Soil respiration was higher in the silt fraction than in other fractions for the rice soils. For the size fractions other than the clay fraction, enzyme activity was increased with prolonged rice cultivation, whereas soil respiration appeared to have a decreasing trend. Only in the coarse-sand fraction was both microbial gene abundance and enzyme activity well correlated to SOC and LOC content, although the chemical stability and respiratory of SOC were similar between coarse-sand and clay fractions. Thus, biological activity was generally promoted with LOC accumulation in the coarse-sand-sized macroaggregates of the rice soils, positively responding to prolonged rice cultivation management. The finding here provides a mechanistic understanding of soil organic carbon turnover and microbial community succession at fine scale of soil aggregates that have evolved along with anthropogenic activity of rice cultivation in the field.

scholarly journals Major Characteristics of Surface Sediments Within the Shallow Water of the Cat Ba Island, North Vietnam

2020 ◽  
Vol 36 (4) ◽  
Author(s):  
Nguyen Huy Hoang ◽  
Bui Van Vuong ◽  
Evgenii Egidarev ◽  
Vasiliy Zharikov ◽  
Le Anh Xuan ◽  
...  
Keyword(s):  
Mineral Composition ◽  
Surface Sediments ◽  
Ph Value ◽  
Fine Sand ◽  
Coarse Sand ◽  
Coarse Silt ◽  
Terrigenous Sediment ◽  
Fine Grained ◽  
Reducing Environment ◽  
North Vietnam

The Cat Ba is one of the largest Islands offshore North Vietnam, which is characterized by an abundance of coral reefs in the East and Southeast of the island. The surface sediments are considered the basic elements for the coral ecosystem development. In this study, the authors present some new results studying pH, Eh, mineral composition, and grain size as the basic information for environmental assessment of this area. The results show that the pH value of the surface sediment varies from 6.90 to 8.09, with an average of 7.24 while the Eh value of the sediment ranges from -121.10 to -48.20mV,  an average of -68.39mV, demonstrating a reducing environment. The surface sediments have been classified into 8 size classes: the coarse silt > very coarse silt > medium sand, very fine sand > very coarse sand, fine sand > coarse sand, very fine gravel. Most of the sediments are poorly sorted - very poorly sorted, only a few sedimentary samples are well sorted, moderately sorted, and moderately well sorted. The average mineral composition of the surface sediments consists of: 25% quartz, 17% illite, 16% aragonite, 13% kaolinite, 10% calcite, 5% chlorite, 4% gothite, 3% halite, 2% feldspar and less montmorillonite, and dolomite. These results allowed the researcher to interpret that the sediments have been deposited in a relatively calm environment and the terrigenous sediment sources are dominant over the marine sources. Source marine sediment groups are characterized by coarse grains, high pH, and are rich in carbonate minerals, which have been produced by biological materials. In contrast, the terrigenous sediment group is dominated by fine-grained sediments, rich clay minerals, quartz, and gothite. These fine-grained sediments are commonly distributed in the area and are favorable places for pollutant accumulation.  

Sign in / Sign up

Export Citation Format

Share Document