scholarly journals Does <i>Juncus effusus</i> enhance methane emissions from grazed pastures on peat?

2015 ◽  
Vol 12 (11) ◽  
pp. 8467-8495 ◽  
Author(s):  
A. Henneberg ◽  
L. Elsgaard ◽  
B. K. Sorrell ◽  
H. Brix ◽  
S. O. Petersen
Keyword(s):  
Soil Column ◽  
Soil Surface ◽  
Point Sources ◽  
Organic Soils ◽  
Juncus Effusus ◽  
Emission Rates ◽  
Soil Layers ◽  
Local Maxima ◽  
Ch4 Emissions ◽  
Field Campaigns

Abstract. Methane (CH4) emissions from drained organic soils are generally low, but internal gas transport in aerenchymatous plants may result in local emission hotspots. In a paired-sample field study at three different sites we measured fluxes of CH4 with static chambers from adjacent sampling quadrats with and without Juncus effusus during four field campaigns. At all three sites, CH4 was observed in the soil at all sampling depths (5–100 cm), and in most cases both above and below the groundwater table. During spring, local maxima suggested methanogenesis took place above the water table at all three sites. We found significant CH4 emissions at all three sites, but emission controls were clearly different. Across the three sites, average emission rates (±1 SE) for sampling quadrats with and without J. effusus were 1.47 ± 0.28 and 1.37 ± 0.33 mg CH4 m-2 h-1 respectively, with no overall effect of J. effusus on CH4 emissions, but a significant effect at one of the three sites. At this site, local CH4 maxima were closer to the soil surface than at the other sites, and the upper soil layers were dryer. This could have affected both root CH4 accessibility and CH4 oxidation respectively, and together with limited gas diffusivity in the soil column, cause elevated CH4 emissions from J. effusus. We conclude that aerenchymatous plants has the potential to act as point sources of CH4 from drained peatlands, but more studies on the specific conditions under which there is an effect, are needed before the results can be used in modelling of CH4 emissions.

scholarly journals Does <i>Juncus effusus</i> enhance methane emissions from grazed pastures on peat?

2015 ◽  
Vol 12 (19) ◽  
pp. 5667-5676 ◽  
Author(s):  
A. Henneberg ◽  
L. Elsgaard ◽  
B. K. Sorrell ◽  
H. Brix ◽  
S. O. Petersen
Keyword(s):  
Soil Column ◽  
Soil Surface ◽  
Point Sources ◽  
Organic Soils ◽  
Juncus Effusus ◽  
Emission Rates ◽  
Soil Layers ◽  
Local Maxima ◽  
Ch4 Emissions ◽  
Field Campaigns

Abstract. Methane (CH4) emissions from drained organic soils are generally low, but internal gas transport in aerenchymatous plants may result in local emission hotspots. In a paired-sample field study at three different sites we measured fluxes of CH4 with static chambers from adjacent sampling quadrats with and without Juncus effusus during four field campaigns. At all three sites, CH4 was observed in the soil at all sampling depths (5 to 100 cm), and in most cases both above and below the groundwater table. During spring, local maxima suggested methanogenesis also took place above the water table at all three sites. We found significant CH4 emissions at all three sites, but emission controls were clearly different. Across the three sites, average emission rates (±1 SE) for sampling quadrats with and without J. effusus were 1.47 ± 0.28 and 1.37 ± 0.33 mg CH4 m−2 h−1, respectively, with no overall effect of J. effusus on CH4 emissions. However, a significant effect of J. effusus was seen at one of the three sites. At this site, local CH4 maxima were closer to the soil surface than at the other sites, and the upper soil layers were dryer. This could have affected both root CH4 accessibility and CH4 oxidation respectively, and together with limited gas diffusivity in the soil column, cause elevated CH4 emissions from J. effusus. We conclude that J. effusus has the potential to act as point sources of CH4 from drained peatlands, but more studies on the specific conditions under which there is an effect, are needed before the results can be used in modelling of CH4 emissions.

scholarly journals Leaching of microplastics by preferential flow in earthworm (Lumbricus terrestris) burrows

2019 ◽  
Vol 16 (1) ◽  
pp. 31 ◽  
Author(s):  
Miao Yu ◽  
Martine van der Ploeg ◽  
Esperanza Huerta Lwanga ◽  
Xiaomei Yang ◽  
Shaoliang Zhang ◽  
...  
Keyword(s):  
Preferential Flow ◽  
Soil Depth ◽  
Soil Column ◽  
Soil Surface ◽  
Lumbricus Terrestris ◽  
Soil Samples ◽  
Average Weight ◽  
Soil Layers ◽  
Groundwater Systems ◽  
Set Up

Environmental contextMicroplastics found in soil pose several potential environmental risks. This study shows that microplastics on the soil surface can be ingested by earthworms and transported to the lower soil layers. In this way, microplastics may enter the food chain and find their way into groundwater systems, especially in cases where the water table is shallow. AbstractIn the current study, we examine how the activities of earthworms (Lumbricus terrestris) affect microplastic (MP) distribution and concentration in soil, with a focus on low density polyethylene (LDPE). We also want to determine if MPs can be flushed out with water. We used a laboratory sandy soil column (polyvinyl chloride tube) experimental set-up and tested five different treatments: (1) treatment with just soil (control) to check if the saturated conductivity (Ksat) could be impacted by MP, (2) treatment with MP, (3) treatment with MP and litter, (4) treatment with earthworms and litter as a second control for treatment 5 and (5) treatment with MPs, earthworms and litter. Each treatment consisted of eight replicates. For the treatments with MP, the concentration of MP added at the start of the experiment was 7% by weight (3.97g, polyethylene, 50% 1mm–250µm, 30% 250µm–150µm and 20% &lt;150µm) based on 52.78g of dry litter from Populus nigra. In the treatments using earthworms, two adult earthworms, with an initial average weight of (7.14±0.26) g, were placed in each column. Results showed that LDPE particles could be introduced into the soil by the earthworms. MP particles were detected in each soil sample and within different soil layers for the earthworm treatments. Earthworms showed a tendency to transport the smaller MP particles and that the amount of MPs in size class &lt;250μm increased in soil samples with increasing soil depth in comparison to the other size classes. After leaching, MPs were only detected in the leachate from the treatments with the earthworms, and the MP had similar size distributions as the soil samples in the 40–50cm layer of the treatment with MP, earthworms and litter. The results of this study clearly show that biogenic activities can mobilise MP transport from the surface into the soil and even be leached into drainage. It is highly likely that biogenic activities constitute a potential pathway for MPs to be transported into soil and groundwater.

scholarly journals Factors influencing CO<sub>2</sub> and CH<sub>4</sub> emissions from coastal wetlands in the Liaohe Delta, Northeast China

2015 ◽  
Vol 12 (4) ◽  
pp. 3469-3503 ◽  
Author(s):  
L. Olsson ◽  
S. Ye ◽  
X. Yu ◽  
M. Wei ◽  
K. W. Krauss ◽  
...  
Keyword(s):  
Water Table ◽  
Coastal Wetlands ◽  
Northeast China ◽  
Ecosystem Respiration ◽  
Soil Surface ◽  
Emission Rates ◽  
Ch4 Emission ◽  
Ch4 Emissions ◽  
Water Tables ◽  
Liaohe Delta

Abstract. Many factors are known to influence greenhouse gas emissions from coastal wetlands, but it is still unclear which factors are most important under field conditions when they are all acting simultaneously. The objective of this study was to assess the effects of water table, salinity, soil temperature and vegetation on CH4 emissions and ecosystem respiration (Reco) from five coastal wetlands in the Liaohe Delta, northeast China: two Phragmites australis (common reed) wetlands, two Suaeda salsa (sea blite) marshes and a rice (Oryza sativa) paddy. Throughout the growing season, the Suaeda wetlands were net CH4 sinks whereas the Phragmites wetlands and the rice paddy were net CH4 sources emitting 1.2–6.1 g CH4 m−2 y−1. The Phragmites wetlands emitted the most CH4 per unit area and the most CH4 relative to CO2. The main controlling factors for the CH4 emissions were water table, temperature and salinity. The CH4 emission was accelerated at high and constant (or managed) water tables and decreased at water tables below the soil surface. High temperatures enhanced CH4 emissions, and emission rates were consistently low (< 1 mg CH4 m−2 h) at soil temperatures <18 °C. At salinity levels > 18 ppt, the CH4 emission rates were always low (< 1 mg CH4 m−2 h−1) probably because methanogens were outcompeted by sulphate reducing bacteria. Saline Phragmites wetlands can, however, emit significant amounts of CH4 as CH4 produced in deep soil layers are transported through the air-space tissue of the plants to the atmosphere. The CH4 emission from coastal wetlands can be reduced by creating fluctuating water tables, including water tables below the soil surface, as well as by occasional flooding by high-salinity water. The effects of water management schemes on the biological communities in the wetlands must, however, be carefully studied prior to the management in order to avoid undesirable effects on the wetland communities.

Growth and water-use characteristics of Romaine lettuce cultivated in Histosol as affected by irrigation management, compaction, and seeding type

2020 ◽  
Vol 100 (3) ◽  
pp. 278-288
Author(s):  
Jacynthe Dessureault-Rompré ◽  
Jean Caron ◽  
Laurie Plamondon ◽  
Linda Gaudreau ◽  
Sylvain Jutras ◽  
...  
Keyword(s):  
Water Use ◽  
Water Uptake ◽  
Soil Column ◽  
Water Productivity ◽  
Direct Seeding ◽  
Column Height ◽  
Rooting Depth ◽  
Organic Soils ◽  
Romaine Lettuce ◽  
Soil Layers

In Canada, most lettuce (Lactuca sativa L.) is produced on cultivated organic soils, which can be very productive but are also very sensitive to degradation and compaction. The objective of this work was to evaluate the effect of soil compaction, irrigation thresholds, and transplant type on the growth and water-use characteristics of Romaine lettuce that is grown in organic soil. The experiments were conducted in greenhouses at Laval University. Tensiometers and time-domain reflectometer probes were used to characterize the water-use characteristics of the Romaine lettuce. Most of the growth characteristics of the Romaine lettuce, with the exception of the dry weight, were significantly influenced by the available rooting depth (soil column height) and by the irrigation threshold used. Lettuce water uptake decreased significantly as the depth increased. In addition, in drier conditions, the deeper soil layers contributed more to the total water uptake than the surface soil layers. The water productivity was lower in the presence of a compacted layer combined with a direct seeding treatment, compared with all of the other treatments. First, it is concluded that the irrigation method should allow a certain degree of dryness by use of a lower irrigation threshold (ideally between −20 and −30 kPa) to stimulate deep rooting. Second, the use of small lettuce plant preseeded in small block of peat substrate instead of direct seeding in the field can compensate for a possible compaction effect.

scholarly journals Factors influencing CO<sub>2</sub> and CH<sub>4</sub> emissions from coastal wetlands in the Liaohe Delta, Northeast China

2015 ◽  
Vol 12 (16) ◽  
pp. 4965-4977 ◽  
Author(s):  
L. Olsson ◽  
S. Ye ◽  
X. Yu ◽  
M. Wei ◽  
K. W. Krauss ◽  
...  
Keyword(s):  
Water Table ◽  
Coastal Wetlands ◽  
Northeast China ◽  
Ecosystem Respiration ◽  
Soil Surface ◽  
Emission Rates ◽  
Ch4 Emission ◽  
Ch4 Emissions ◽  
Water Tables ◽  
Liaohe Delta

Abstract. Many factors are known to influence greenhouse gas emissions from coastal wetlands, but it is still unclear which factors are most important under field conditions when they are all acting simultaneously. The objective of this study was to assess the effects of water table, salinity, soil temperature and vegetation on CH4 emissions and ecosystem respiration (Reco) from five coastal wetlands in the Liaohe Delta, Northeast China: two Phragmites australis (common reed) wetlands, two Suaeda salsa (sea blite) marshes and a rice (Oryza sativa) paddy. Throughout the growing season, the Suaeda wetlands were net CH4 sinks whereas the Phragmites wetlands and the rice paddy were net CH4 sources emitting 1.2–6.1 g CH4 m−2 yr−1. The Phragmites wetlands emitted the most CH4 per unit area and the most CH4 relative to CO2. The main controlling factors for the CH4 emissions were water table, temperature, soil organic carbon and salinity. The CH4 emission was accelerated at high and constant (or managed) water tables and decreased at water tables below the soil surface. High temperatures enhanced CH4 emissions, and emission rates were consistently low (< 1 mg CH4 m−2 h−1) at soil temperatures < 18 °C. At salinity levels > 18 ppt, the CH4 emission rates were always low (< 1 mg CH4 m−2 h−1) probably because methanogens were out-competed by sulphate-reducing bacteria. Saline Phragmites wetlands can, however, emit significant amounts of CH4 as CH4 produced in deep soil layers are transported through the air-space tissue of the plants to the atmosphere. The CH4 emission from coastal wetlands can be reduced by creating fluctuating water tables, including water tables below the soil surface, as well as by occasional flooding by high-salinity water. The effects of water management schemes on the biological communities in the wetlands must, however, be carefully studied prior to the management in order to avoid undesirable effects on the wetland communities.

MEASUREMENT OF CO2 EVOLVED FROM ORGANIC SOIL AT DIFFERENT DEPTHS IN SITU

1981 ◽  
Vol 61 (1) ◽  
pp. 137-144 ◽  
Author(s):  
J. A. CAMPBELL ◽  
L. FRASCARELLI
Keyword(s):  
Soil Column ◽  
Soil Surface ◽  
Organic Soil ◽  
Organic Soils ◽  
Concentration Profiles ◽  
Undisturbed Soil ◽  
Surface Evolution ◽  
Different Depths ◽  
A New Technique

A new technique for measuring CO2 evolved from organic soil at different depths in situ was used to monitor CO2 evolution in four experimental sites in southwestern Quebec and in an undisturbed soil column in the laboratory. The technique can be used in conjunction with in situ measurements of surface evolution of CO2, which are used as indicators of total subsidence by oxidation. Subsurface measurements of CO2 evolution provide more detailed estimates of where oxidation is occurring within the profile in organic soils. It also provides a simpler, more direct way of measuring CO2 fluxes below the soil surface than modelling from concentration profiles.

A physically-based soil surface model and its combination with numerical models for predicting bare-soil evaporation rates

2021 ◽  
Author(s):  
Xiaocheng Liu ◽  
Chenming Zhang ◽  
Yue Liu ◽  
David Lockington ◽  
Ling Li
Keyword(s):  
Numerical Model ◽  
Surface Resistance ◽  
Numerical Models ◽  
Soil Column ◽  
Soil Surface ◽  
Bare Soil ◽  
Water Vapor Transport ◽  
Surface Model ◽  
Vapor Flow ◽  
Physically Based

&lt;p&gt;Estimation of evaporation rates from soils is significant for environmental, hydrological, and agricultural purposes. Modeling of the soil surface resistance is essential to estimate the evaporation rates from bare soil. Empirical surface resistance models may cause large deviations when applied to different soils. A physically-based soil surface model is developed to calculate the surface resistance, which can consider evaporation on the soil surface when soil is fully saturated and the vapor flow below the soil surface after dry layer forming on the top. Furthermore, this physically-based expression of the surface resistance is added into a numerical model that considers the liquid water transport, water vapor transport, and heat transport during evaporation. The simulation results are in good agreement with the results from six soil column drying experiments.&amp;#160; This numerical model can be applied to predict or estimate the evaporation rate of different soil and saturation at different depths during evaporation.&lt;/p&gt;

scholarly journals Isoprene emissions from a tundra ecosystem

2013 ◽  
Vol 10 (2) ◽  
pp. 871-889 ◽  
Author(s):  
M. J. Potosnak ◽  
B. M. Baker ◽  
L. LeStourgeon ◽  
S. M. Disher ◽  
K. L. Griffin ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Global Climate ◽  
Common Species ◽  
Emission Rates ◽  
Arctic Ecosystems ◽  
Field Station ◽  
Isoprene Emission ◽  
Tundra Ecosystem ◽  
Leaf Level ◽  
Field Campaigns

Abstract. Whole-system fluxes of isoprene from a moist acidic tundra ecosystem and leaf-level emission rates of isoprene from a common species (Salix pulchra) in that same ecosystem were measured during three separate field campaigns. The field campaigns were conducted during the summers of 2005, 2010 and 2011 and took place at the Toolik Field Station (68.6° N, 149.6° W) on the north slope of the Brooks Range in Alaska, USA. The maximum rate of whole-system isoprene flux measured was over 1.2 mg C m−2 h−1 with an air temperature of 22 °C and a PAR level over 1500 μmol m−2 s−1. Leaf-level isoprene emission rates for S. pulchra averaged 12.4 nmol m−2 s−1 (27.4 μg C gdw−1 h−1) extrapolated to standard conditions (PAR = 1000 μmol m−2 s−1 and leaf temperature = 30 °C). Leaf-level isoprene emission rates were well characterized by the Guenther algorithm for temperature with published coefficients, but less so for light. Chamber measurements from a nearby moist acidic tundra ecosystem with little S. pulchra emitted significant amounts of isoprene, but at lower rates (0.45 mg C m−2 h−1) suggesting other significant isoprene emitters. Comparison of our results to predictions from a global model found broad agreement, but a detailed analysis revealed some significant discrepancies. An atmospheric chemistry box model predicts that the observed isoprene emissions have a significant impact on Arctic atmospheric chemistry, including a reduction of hydroxyl radical (OH) concentrations. Our results support the prediction that isoprene emissions from Arctic ecosystems will increase with global climate change.

A comment on scaling methane emissions from vegetation and grazing ruminants in New Zealand

2006 ◽  
Vol 33 (7) ◽  
pp. 613 ◽  
Author(s):  
Francis M. Kelliher ◽  
Harry Clark ◽  
Zheng Li ◽  
Paul C. D. Newton ◽  
Anthony J. Parsons ◽  
...  
Keyword(s):  
New Zealand ◽  
Standard Deviation ◽  
Forest Canopy ◽  
Emission Rate ◽  
Oxidative Capacity ◽  
Emission Rates ◽  
Ch4 Emission ◽  
Ch4 Emissions ◽  
Grazed Pasture ◽  
Indigenous Forest

Keppler et al. (2006, Nature 439, 187–191) showed that plants produce methane (CH4) in aerobic environments, leading Lowe (2006, Nature 439, 148–149) to postulate that in countries such as New Zealand, where grazed pastures have replaced forests, the forests could have produced as much CH4 as the ruminants currently grazing these areas. Estimating CH4 emissions from up to 85 million ruminants in New Zealand is challenging and, for completeness, the capacity of forest and pastoral soils to oxidise CH4 should be included. On average, the CH4 emission rate of grazing ruminants is estimated to be 9.6 ± 2.6 g m–2 year–1 (±standard deviation), six times the corresponding estimate for an indigenous forest canopy (1.6 ± 1.1 g m–2 year–1). The forest’s soil is estimated to oxidise 0.9 ± 0.2 g m–2 year–1 more CH4 than representative soils beneath grazed pasture. Taking into account plant and animal sources and the soil’s oxidative capacity, the net CH4 emission rates of forest and grazed ecosystems are 0.6 ± 1.1 and 9.8 ± 2.6 g m–2 year–1, respectively.

scholarly journals The environmental forming and productional functions of the haloxylon aphyllum in the Karnabchul desert

2019 ◽  
pp. 34-38
Author(s):  
E. Z. Shamsutdinova
Keyword(s):  
Soil Moisture ◽  
Outer Part ◽  
Soil Surface ◽  
Hydrothermal Conditions ◽  
Noticeable Effect ◽  
Soil Layers ◽  
Haloxylon Aphyllum ◽  
Aged State ◽  
Ephemeral Vegetation ◽  
Black Saxaul

We have conducted investigation of the environmental function of the desert tree of black saxaul (Haloxylon aphyllum) in the Karnabchul desert. As a result, it was found that different age plants of black saxaul had different effects on the degree of illumination. The greatest influence on the intensity of solar radiation was exerted by the saxaul plant of the black middle-aged state, the least the old generative individuals. Saxaul black had a significant impact on the temperature of the air: in the daytime, especially in the period 13-16 h, reducing the temperature under the crown and on the edge of the crown, and at night increasing it in the same areas. It also had a noticeable effect on the temperature of the soil. The temperature of the soil surface under the crown at night is higher, and during the day the warming was slower than in the outer part of the saxaul crown. Under the influence of black saxaul and soil moisture changed. Under the saxaul crown soil moisture is significantly higher compared to the control (open natural pastures). The highest soil moisture was observed in the upper soil layers at the base of the saxaul trunk. As a result, under the environmental action of black saxaul more favorable hydrothermal conditions for the growth and development of natural wormwood-ephemeral vegetation under the protection of strips and adjacent areas of pastures are formed. The result of production activities chemotaxonomic postbestowal bands consists of two following components: production of fodder mass of the Haloxylon and fodder productivity of wormwood-ephemeral vegetation of natural pastures. By increasing the yield of natural pastures under the protection of pasture protection strips and the harvest of the black saxaul fodder productivity of desert pastures increases more than twice.

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