scholarly journals Can mud (silt and clay) concentration be used to predict soil organic carbon content within seagrass ecosystems?

Author(s):  
O. Serrano ◽  
P. S. Lavery ◽  
C. M. Duarte ◽  
G. A. Kendrick ◽  
A. Calafat ◽  
...  

Abstract. The emerging field of blue carbon science is seeking cost-effective ways to estimate the organic carbon content of soils that are bound by coastal vegetated ecosystems. Organic carbon (Corg) content in terrestrial soils and marine sediments has been correlated with mud content (i.e. silt and clay), however, empirical tests of this theory are lacking for coastal vegetated ecosystems. Here, we compiled data (n = 1345) on the relationship between Corg and mud (i.e. silt and clay, particle sizes <63 μm) contents in seagrass ecosystems (79 cores) and adjacent bare sediments (21 cores) to address whether mud can be used to predict soil Corg content. We also combined these data with the δ13C signatures of the soil Corg to understand the sources of Corg stores. The results showed that mud is positively correlated with soil Corg content only when the contribution of seagrass-derived Corg to the sedimentary Corg pool is relatively low, such as in small and fast growing meadows of the genera Zostera, Halodule and Halophila, and in bare sediments adjacent to seagrass ecosystems. In large and long-living seagrass meadows of the genera Posidonia and Amphibolis there was a lack of, or poor relationship between mud and soil Corg content, related to a higher contribution of seagrass-derived Corg to the sedimentary Corg pool in these meadows. The relative high soil Corg contents with relatively low mud contents (i.e. mud-Corg saturation) together with significant allochthonous inputs of terrestrial organic matter could overall disrupt the correlation expected between soil Corg and mud contents. This study shows that mud (i.e. silt and clay content) is not a universal proxy for blue carbon content in seagrass ecosystems, and therefore should not be applied generally across all seagrass habitats. Mud content can only be used as a proxy to estimate soil Corg content for scaling up purposes when opportunistic and/or low biomass seagrass species (i.e. Zostera, Halodule and Halophila) are present (explaining 34 to 91% of variability), and in bare sediments (explaining 78% of the variability).


2016 ◽  
Vol 13 (17) ◽  
pp. 4915-4926 ◽  
Author(s):  
Oscar Serrano ◽  
Paul S. Lavery ◽  
Carlos M. Duarte ◽  
Gary A. Kendrick ◽  
Antoni Calafat ◽  
...  

Abstract. The emerging field of blue carbon science is seeking cost-effective ways to estimate the organic carbon content of soils that are bound by coastal vegetated ecosystems. Organic carbon (Corg) content in terrestrial soils and marine sediments has been correlated with mud content (i.e., silt and clay, particle sizes < 63 µm), however, empirical tests of this theory are lacking for coastal vegetated ecosystems. Here, we compiled data (n =  1345) on the relationship between Corg and mud contents in seagrass ecosystems (79 cores) and adjacent bare sediments (21 cores) to address whether mud can be used to predict soil Corg content. We also combined these data with the δ13C signatures of the soil Corg to understand the sources of Corg stores. The results showed that mud is positively correlated with soil Corg content only when the contribution of seagrass-derived Corg to the sedimentary Corg pool is relatively low, such as in small and fast-growing meadows of the genera Zostera, Halodule and Halophila, and in bare sediments adjacent to seagrass ecosystems. In large and long-living seagrass meadows of the genera Posidonia and Amphibolis there was a lack of, or poor relationship between mud and soil Corg content, related to a higher contribution of seagrass-derived Corg to the sedimentary Corg pool in these meadows. The relatively high soil Corg contents with relatively low mud contents (e.g., mud-Corg saturation) in bare sediments and Zostera, Halodule and Halophila meadows was related to significant allochthonous inputs of terrestrial organic matter, while higher contribution of seagrass detritus in Amphibolis and Posidonia meadows disrupted the correlation expected between soil Corg and mud contents. This study shows that mud is not a universal proxy for blue carbon content in seagrass ecosystems, and therefore should not be applied generally across all seagrass habitats. Mud content can only be used as a proxy to estimate soil Corg content for scaling up purposes when opportunistic and/or low biomass seagrass species (i.e., Zostera, Halodule and Halophila) are present (explaining 34 to 91 % of variability), and in bare sediments (explaining 78 % of the variability). The results obtained could enable robust scaling up exercises at a low cost as part of blue carbon stock assessments.



2012 ◽  
Vol 63 (11) ◽  
pp. 967 ◽  
Author(s):  
James W. Fourqurean ◽  
Gary A. Kendrick ◽  
Laurel S. Collins ◽  
Randolph M. Chambers ◽  
Mathew A. Vanderklift

Seagrass meadows in Florida Bay and Shark Bay contain substantial stores of both organic carbon and nutrients. Soils from both systems are predominantly calcium carbonate, with an average of 82.1% CaCO3 in Florida Bay compared with 71.3% in Shark Bay. Soils from Shark Bay had, on average, 21% higher organic carbon content and 35% higher phosphorus content than Florida Bay. Further, soils from Shark Bay had lower mean dry bulk density (0.78 ± 0.01 g mL–1) than those from Florida Bay (0.84 ± 0.02 mg mL–1). The most hypersaline regions of both bays had higher organic carbon content in surficial soils. Profiles of organic carbon and phosphorus from Florida Bay indicate that this system has experienced an increase in P delivery and primary productivity over the last century; in contrast, decreasing organic carbon and phosphorus with depth in the soil profiles in Shark Bay point to a decrease in phosphorus delivery and primary productivity over the last 1000 y. The total ecosystem stocks of stored organic C in Florida Bay averages 163.5 MgCorg ha–1, lower than the average of 243.0 MgCorg ha–1 for Shark Bay; but these values place Shark and Florida Bays among the global hotspots for organic C storage in coastal ecosystems.



Soil Research ◽  
1998 ◽  
Vol 36 (6) ◽  
pp. 883 ◽  
Author(s):  
P. N. Nelson ◽  
J. A. Baldock ◽  
J. M. Oades

Measurement of dispersible clay is important for the diagnosis of structural stability problems in soil. However, clay dispersibility is known to change with water content and time. The purpose of the present study was to determine how incubation of sodic soil under different water content regimes influences clay dispersibility. Two topsoils (depth 0-0·1 m), one sodic [exchangeable sodium percentage (ESP) 9 · 7] and the other non-sodic (ESP 3·8), were collected from an experimental pasture at Kyabram, Victoria, and 2 soils, a sodic topsoil (depth 0-0·1 m, ESP 6·9) and the corresponding subsoil (depth 0·2-0 m, ESP 25·7), were collected from a cropped field at Two Wells, South Australia. The soils were incubated for 264 days in a split-plot design. The main treatments were soil type and incubation water content: continuously air-dry, continuously wet (-50 kPa), or with wet/dry cycles. The subtreatment was water content at analysis: air dry or wet (-50 kPa). Clay dispersion was greater when measured on wet soils than dry soils, irrespective of water contents during the prior incubation. Electrical conductivity increased, and sodium adsorption ratio (SAR), pH, and organic carbon content decreased as a function of the time for which the soils were wet. In the Kyabram soils that were wet when analysed, easily dispersible clay content increased with SAR. Decreases in moderately dispersible clay under the wetting/drying regime were not related to electrolyte composition, and were attributed to particle rearrangement and cementation. The decreases in clay dispersibility with time occurred despite net losses of carbohydrate and aliphatic materials. An implication of the work is that the decomposition of soil organic matter, even in the absence of fresh additions, may reduce clay dispersion in sodic soils by altering electrolyte concentration and composition.



1987 ◽  
Vol 59 (2) ◽  
pp. 63-65
Author(s):  
Raina Niskanen ◽  
Väinö Mäntylahti

Drying of three mineral soil samples (clay content 4—58 %, organic carbon content 1—5 %) equilibrated at 75.5 % relative humidity was studied. The soils were dried in an oven at +50°C, +70°C and + 105°C for 4 and 8 hours and in a desiccator over pure concentrated H2SO4 and P2O5. Drying over desiccants for 8 hours removed less water than drying at + 50°C. Drying over desiccants for 3—7 days was as efficient as drying at +70°C, for 14—24 days as efficient as 4 hours of drying at + 105°C. Eight hours of drying at + 105°C seemed to be too drastic, because it caused a greater weight loss in the clay sample of 5 % organic carbon content than did prolonged desiccant-drying. Drying at + 70°Cremoved as much water from fine sand which contained 4 % clay as prolonged desiccant-drying.



1959 ◽  
Vol 39 (2) ◽  
pp. 92-97 ◽  
Author(s):  
J. J. Doyle ◽  
A. A. MacLean

Ammonium-base waste sulphite liquor (solids) (W.S.L.S.) was added to three soils and incubated for 7 weeks. Weekly measurements of organic carbon content and aggregation showed an increase in aggregation to a maximum at 3 weeks, followed by a decline and then by a second increase at 6 weeks. This increase and decline in aggregation paralleled very closely the corresponding biological activity as indicated by loss of organic carbon. Results suggest that decomposition of sugars is responsible for the⁁ development of aggregation in the early stages of incubation and that the ligninsulphonates may have an effect after further incubation.The aggregating effect of W.S.L.S. was compared with that of two synthetic conditioners HPAN and VAMA. The effect of all materials varied considerably with the clay content of the soil. Results indicate that W.S.L.S. is about 1/16 as effective as HPAN and about 1/36 as effective as VAMA.





2020 ◽  
Vol 23 (3) ◽  
pp. 291-298
Author(s):  
Aditya Hikmat Nugraha ◽  
Ilham Antariksa Tasabaramo ◽  
Udhi E Hernawan ◽  
Susi Rahmawati ◽  
Risandi Dwirama Putra ◽  
...  

One of the ecological functions of the seagrass ecosystem is the ability to absorb carbon coming from the atmosphere. The ability of seagrass to absorb carbon is carried out through photosynthesis. The absorbed carbon will then be stored in the form of seagrass biomass in the seagrass body. This study aims to estimate the carbon stock content stored in seagrass ecosystems in the Northern waters of Papua including on Liki Island, Befondi Island, and Meossu Island. The calculation of carbon stock is done by converting seagrass biomass using constants derived from representative values of seagrass carbon content in Indonesian waters. In general, based on the results obtained indicate that the biomass at the bellow ground of the seagrass is greater than the biomass at above ground the seagrass. The value of organic carbon content in seagrasses is influenced by seagrass biomass. The carbon stock content in the seagrass ecosystem in the study area is in the range of 18,04 – 419,46 g C / m2. Stations on Liki Island have generally higher carbon stocks compared to stations on other islands.Salah satu fungsi ekologi dari ekosistem lamun yaitu memiliki kemampuan dalam menyerap karbon yang berasal dari atmosfer. Kemampuan lamun dalam menyerap karbon dilakukan melalui proses fotosintesis. Karbon yang terserap selanjutnya akan disimpan dalam bentuk biomassa lamun  pada tubuh lamun. Penelitian ini bertujuan untuk mengestimasi kandungan stok karbon yang tersimpan pada ekosistem lamun di Perairan Utara Papua tepatnya di Pulau Liki, Pulau Befondi dan Pulau Meossu. Perhitungan stok karbon dilakukan dengan melakukan konversi biomassa lamun menggunakan konstanta yang berasal dari nilai representatif konsentrasi kandungan karbon pada lamun yang berada di Perairan Indonesia. Secara umum berdasarkan hasil yang diperoleh menunjukkan bahwa biomassa pada bagian bawah lamun lebih besar dibandingkan dengan biomassa pada bagian atas lamun. Nilai kandungan karbon organik pada lamun dipengaruhi oleh biomassa lamun. Kandungan stok karbon pada ekosistem lamun di wilayah penelitian  berada pada kisaran 18,04 – 419,46 gC/m2. Stasiun yang berada di Pulau Liki memiliki stok karbon yang umumnya lebih tinggi dibandingkan dengan stasiun yang berada di pulau lainnya. 



Soil Research ◽  
1996 ◽  
Vol 34 (6) ◽  
pp. 1041 ◽  
Author(s):  
NS Bolan ◽  
S Baskaran

The adsorption-desorption behaviour and the degradation of an ionic herbicide (2,4-D) were examined using 10 soils from New Zealand that differed in their organic matter and clay content. Adsorption isotherms for 2,4-D were adequately described by the Freundlich isotherm and the values of the exponent N of the Freundlich isotherm were close to 1 (0.92-0.98), indicating that the adsorption isotherm tended to become linear. The extent of adsorption, as measured by the distribution coefficient (Kd), increased with an increase in soil organic carbon. The rate of desorption of 2,4-D followed first-order reaction kinetics with respect to surface concentration, and decreased with an increase in the organic carbon content of the soils. The rate of degradation of 2,4-D, as measured by the half-life (t1/2), decreased with an initial increase in soil organic carbon, which is attributed to the increase in adsorption. With increasing adsorption, the rate of desorption decreased, resulting in a low concentration of 2,4-D in the soil solution that is available for microbial degradation. When the organic carbon content was more than 12%, however, both the adsorption and rate of degradation increased. The enhanced degradation of 2,4-D at these levels of organic carbon may be related to the increased biological activity of the soil, as measured by substrate-induced respiration, and the decreased 2,4-D-induced inhibitory effect on microbial activity.



Soil Research ◽  
1980 ◽  
Vol 18 (4) ◽  
pp. 447 ◽  
Author(s):  
RF Brennan ◽  
JW Gartrell ◽  
AD Robson

The effect of moist incubation on the availability of applied copper to wheat was examined in a range of Western Australian soils. Incubating soil with copper reduced its availability relative to freshly applied copper by up to 70%. The availability of copper to wheat plants decreased with increasing time of incubation up to 120 days. The extent of the decline in availability differed among soils. The difference did not appear to be specifically related to any one of the following soil properties-pH, organic carbon content, clay content, free sesquioxide content and levels of total and extractable copper.



Weed Science ◽  
1989 ◽  
Vol 37 (3) ◽  
pp. 440-444 ◽  
Author(s):  
Mark M. Loux ◽  
Rex A. Liebl ◽  
Fred W. Slife

Regression analysis of clomazone adsorption on 19 soils and sediments yielded a positive correlation and linear relationship between distribution adsorption constants (Kd) and soil organic carbon content. The agreement of the experimental mean Kocwith Kocvalues predicted from the octanol-water partition coefficient and water solubility of clomazone indicated hydrophobic bonding was one mechanism responsible for adsorption. Kaolinite and montmorillonite had a strong affinity for clomazone, and adsorption increased with the charge of the cation on the clay exchange sites. Adsorption was not correlated with the clay content of soils and sediments, indicating that organic coatings on clay in soils may block adsorption sites on clay surfaces. The adsorption of clomazone on some soils and sediments with high clay contents was greater than predicted based on organic carbon content alone, however, indicating clay contributed to adsorption on these samples.



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