scholarly journals Changes of the CO<sub>2</sub> and CH<sub>4</sub> production potential of rewetted fens in the perspective of temporal vegetation shifts

2015 ◽  
Vol 12 (8) ◽  
pp. 2455-2468 ◽  
Author(s):  
D. Zak ◽  
H. Reuter ◽  
J. Augustin ◽  
T. Shatwell ◽  
M. Barth ◽  
...  
Keyword(s):  
Plant Species ◽  
Gas Production ◽  
Shoot Biomass ◽  
Ceratophyllum Demersum ◽  
Level Control ◽  
Nitrogen And Phosphorus ◽  
Vegetation Shifts ◽  
Ch4 Emissions ◽  
Ch4 Production ◽  
The Impact

Abstract. Rewetting of long-term drained fens often results in the formation of eutrophic shallow lakes with an average water depth of less than 1 m. This is accompanied by a fast vegetation shift from cultivated grasses via submerged hydrophytes to helophytes. As a result of rapid plant dying and decomposition, these systems are highly dynamic wetlands characterised by a high mobilisation of nutrients and elevated emissions of CO2 and CH4. However, the impact of specific plant species on these phenomena is not clear. Therefore we investigated the CO2 and CH4 production due to the subaqueous decomposition of shoot biomass of five selected plant species which represent different rewetting stages (Phalaris arundinacea, Ceratophyllum demersum, Typha latifolia, Phragmites australis and Carex riparia) during a 154 day mesocosm study. Beside continuous gas flux measurements, we performed bulk chemical analysis of plant tissue, including carbon, nitrogen, phosphorus and plant polymer dynamics. Plant-specific mass losses after 154 days ranged from 25% (P. australis) to 64% (C. demersum). Substantial differences were found for the CH4 production with highest values from decomposing C. demersum (0.4 g CH4 kg−1 dry mass day) that were about 70 times higher than CH4 production from C. riparia. Thus, we found a strong divergence between mass loss of the litter and methane production during decomposition. If C. demersum as a hydrophyte is included in the statistical analysis solely nutrient contents (nitrogen and phosphorus) explain varying greenhouse gas production of the different plant species while lignin and polyphenols demonstrate no significant impact at all. Taking data of annual biomass production as important carbon source for methanogens into account, high CH4 emissions can be expected to last several decades as long as inundated and nutrient-rich conditions prevail. Different restoration measures like water level control, biomass extraction and top soil removal are discussed in the context of mitigation of CH4 emissions from rewetted fens.

scholarly journals Changes of the CO<sub>2</sub> and CH<sub>4</sub> production potential of rewetted fens in the perspective of temporal vegetation shifts

2014 ◽  
Vol 11 (10) ◽  
pp. 14453-14488 ◽  
Author(s):  
D. Zak ◽  
H. Reuter ◽  
J. Augustin ◽  
T. Shatwell ◽  
M. Barth ◽  
...  
Keyword(s):  
Plant Species ◽  
Typha Latifolia ◽  
Shoot Biomass ◽  
Ceratophyllum Demersum ◽  
Level Control ◽  
Nitrogen And Phosphorus ◽  
Vegetation Shifts ◽  
Ch4 Emissions ◽  
Ch4 Production ◽  
The Impact

Abstract. Rewetting of long-term drained fens often results in the formation of eutrophic shallow lakes with an average water depth of less than 1 m. This is accompanied by a fast vegetation shift from cultivated grasses via submerged hydrophytes to helophytes. As a result of rapid plant dying and decomposition, these systems are highly-dynamic wetlands characterised by a high mobilisation of nutrients and elevated emissions of CO2 and CH4. However, the impact of specific plant species on these phenomena is not clear. Therefore we investigated the CO2 and CH4 production due to the subaqueous decomposition of shoot biomass of five selected plant species which represent different rewetting stages (Phalaris arundinacea, Ceratophyllum demersum, Typha latifolia, Phragmites australis, and Carex riparia) during a 154 day mesocosm study. Beside continuous gas flux measurements, we performed bulk chemical analysis of plant tissue, including carbon, nitrogen, phosphorus, and plant polymer dynamics. Plant specific mass losses after 154 days ranged from 25 (P. australis) to 64% (C. demersum). Substantial differences were found for the CH4 production with highest values from decomposing C. demersum (0.4 g CH4 kg−1 dry mass day) that were about 70 times higher than CH4 production from C. riparia. Thus, we found a strong divergence between mass loss of the litter and methane production during decomposition. If C. demersum as a hydrophyte is included in the statistical analysis solely nutrient contents (nitrogen and phosphorus) explain varying GHG production of the different plant species while lignin and polyphenols demonstrate no significant impact at all. Taking data of annual biomass production as important carbon source for methanogens into account, high CH4 emissions can be expected to last several decades as long as inundated and nutrient-rich conditions prevail. Different restoration measures like water level control, biomass extraction and top soil removal are discussed in the context of mitigation of CH4 emissions from rewetted fens.

scholarly journals Wildfire overrides hydrological controls on boreal peatland methane emissions

2019 ◽  
Vol 16 (13) ◽  
pp. 2651-2660 ◽  
Author(s):  
Scott J. Davidson ◽  
Christine Van Beest ◽  
Richard Petrone ◽  
Maria Strack
Keyword(s):  
Water Table ◽  
Environmental Variables ◽  
Burn Severity ◽  
Radiative Effect ◽  
Production Potential ◽  
Fort Mcmurray ◽  
Ch4 Emissions ◽  
Boreal Peatlands ◽  
Ch4 Production ◽  
The Impact

Abstract. Boreal peatlands represent a globally important store of carbon, and disturbances such as wildfire can have a negative feedback to the climate. Understanding how carbon exchange and greenhouse gas (GHG) dynamics are impacted after a wildfire is important, especially as boreal peatlands may be vulnerable to changes in wildfire regime under a rapidly changing climate. However, given this vulnerability, there is very little in the literature on the impact such fires have on methane (CH4) emissions. This study investigated the effect of wildfire on CH4 emissions at a boreal fen near Fort McMurray, Alberta, Canada, that was partially burned by the Horse River Wildfire in 2016. We measured CH4 emissions and environmental variables (2017–2018) and CH4 production potential (2018) in two different microform types (hummocks and hollows) across a peat burn severity gradient (unburned (UB), moderately burned (MB), and severely burned (SB)). Results indicated a switch in the typical understanding of boreal peatland CH4 emissions. For example, emissions were significantly lower in the MB and SB hollows in both years compared to UB hollows. Interestingly, across the burned sites, hummocks had higher fluxes in 2017 than hollows at the MB and SB sites. We found typically higher emissions at the UB site where the water table was close to the surface. However, at the burned sites, no relationship was found between CH4 emissions and water table, even under similar hydrological conditions. There was also significantly higher CH4 production potential from the UB site than the burned sites. The reduction in CH4 emissions and production in the hollows at burned sites highlights the sensitivity of hollows to fire, removing labile organic material for potential methanogenesis. The previously demonstrated resistance of hummocks to fire also results in limited impact on CH4 emissions and likely faster recovery to pre-fire rates. Given the potential initial net cooling effect resulting from a reduction in CH4 emissions, it is important that the radiative effect of all GHGs following wildfire across peatlands is taken into account.

scholarly journals Evaluation of critical nitrogen and phosphorus models for maize under full and limited irrigation conditions

2017 ◽  
pp. 80-92
Author(s):  
Koffi Djaman ◽  
Suat Irmak
Keyword(s):  
Irrigation Management ◽  
Biomass Accumulation ◽  
Shoot Biomass ◽  
Phosphorus Concentration ◽  
Nitrogen And Phosphorus ◽  
Maize Production ◽  
South Central ◽  
N Concentration ◽  
Biomass N ◽  
The Impact

Proper nitrogen (N) fertiliser application rates and timing of application, coupled with optimum irrigation management can improve the sustainability of maize production and reduce the risk of environmental contamination by nutrients. The impact of full and limited irrigation and rainfed conditions on in-season maize (Zea mays L.) shoot biomass nutrient concentration and critical N and phosphorus (P) indices were evaluated using a combination of measured nutrients and critical N and P models in south central Nebraska in 2009 and 2010. Four irrigation treatments [fully-irrigated treatment (FIT), 75% FIT, 60% FIT and 50% FIT) and rainfed] were imposed. Irrigation regimes impacted the shoot biomass N concentration. The shoot biomass N concentration was above the critical N (Ncrit) concentration throughout the growing season under FIT and 75% FIT and was below the Ncrit value for the most limited irrigation (60% FIT and 50% FIT) and rainfed treatments. Nitrogen nutrient index (NNI) varied from 0.68 to 2.0. Biomass N concentration was below Ncrit [i.e., NNI<1] from 105 days after planting (DAP) to harvest under rainfed and 50% FIT and from 114 DAP to harvest under 60% FIT. Overall, the FIT and the 75% FIT had NNI values greater than 1.0 throughout both growing seasons. Phosphorus concentration, which decreased with biomass accumulation and irrigation amounts, varied from 1.0 to 4.8 g kg–1, with FIT having the highest biomass P concentration. The critical N model combined with NNI can be used to evaluate N and P in maize for in-season nutrient diagnosis under the conditions presented in this research.

Natural revegetation of hydrocarbon-contaminated soil in semi-arid grasslands

2004 ◽  
Vol 82 (1) ◽  
pp. 22-30 ◽  
Author(s):  
Diana Bizecki Robson ◽  
J Diane Knight ◽  
Richard E Farrell ◽  
James J Germida
Keyword(s):  
Functional Groups ◽  
Plant Species ◽  
Contaminated Soils ◽  
Oil Spills ◽  
Abundant Species ◽  
Perennial Grasses ◽  
Soil Conditions ◽  
Nitrogen And Phosphorus ◽  
Litter Cover ◽  
The Impact

One way to identify hydrocarbon-tolerant plant species for reclamation is to sample vegetation at contaminated sites allowed to recover naturally. We compared vegetation and soils of 14 hydrocarbon-contaminated plots in southern Saskatchewan to those of nearby uncontaminated plots to determine the impact on plant communities and soil properties. Contaminated plots had less vegetation and litter cover than uncontaminated plots, and significantly higher soil carbon to nitrogen ratios, pH, and hydrocarbon concentration, and lower nitrogen and phosphorus. Although species richness was not significantly different, Shannon's diversity was lower on contaminated plots. Mean compositional similarity of the plots, measured using Jaccard's index, was only 31%, and cover similarity, measured using Spatz's index, was only 22%. Vegetation composition differences occurred because mycorrhizal, woody and vegetatively reproducing species, and species using birds or unassisted means for seed dispersal were significantly less common on contaminated than uncontaminated plots. Self-pollinated species were significantly more common on contaminated plots. The most abundant species on contaminated soils were the annual forb Kochia scoparia and the native perennial grasses Hordeum jubatum, Distichlis stricta, Agropyron smithii, Agropyron trachycaulum, and Poa canbyi. This research shows that some plant species and functional groups are tolerant of the altered soil conditions at hydrocarbon-contaminated sites.Key words: functional groups, oil spills, phytoremediation, reclamation, succession, vegetation recovery.

scholarly journals The Use of Constructed Wetland for Mitigating Nitrogen and Phosphorus from Agricultural Runoff: A Review

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 476
Author(s):  
Jiayu Li ◽  
Bohong Zheng ◽  
Xiao Chen ◽  
Zhe Li ◽  
Qi Xia ◽  
...  
Keyword(s):  
Plant Species ◽  
Constructed Wetlands ◽  
Constructed Wetland ◽  
Lemna Minor ◽  
Hydrilla Verticillata ◽  
Agricultural Runoff ◽  
Structure Design ◽  
Ceratophyllum Demersum ◽  
Nitrogen And Phosphorus ◽  
Emergent Plants

The loss of nitrogen and phosphate fertilizers in agricultural runoff is a global environmental problem, attracting worldwide attention. In the last decades, the constructed wetland has been increasingly used for mitigating the loss of nitrogen and phosphate from agricultural runoff, while the substrate, plants, and wetland structure design remain far from clearly understood. In this paper, the optimum substrates and plant species were identified by reviewing their treatment capacity from the related studies. Specifically, the top three suitable substrates are gravel, zeolite, and slag. In terms of the plant species, emergent plants are the most widely used in the constructed wetlands. Eleocharis dulcis, Typha orientalis, and Scirpus validus are the top three optimum emergent plant species. Submerged plants (Hydrilla verticillata, Ceratophyllum demersum, and Vallisneria natans), free-floating plants (Eichhornia crassipes and Lemna minor), and floating-leaved plants (Nymphaea tetragona and Trapa bispinosa) are also promoted. Moreover, the site selection methods for constructed wetland were put forward. Because the existing research results have not reached an agreement on the controversial issue, more studies are still needed to draw a clear conclusion of effective structure design of constructed wetlands. This review has provided some recommendations for substrate, plant species, and site selections for the constructed wetlands to reduce nutrients from agricultural runoff.

In vitro evaluation of the methane mitigation potential of a range of grape marc products

2017 ◽  
Vol 57 (7) ◽  
pp. 1437 ◽  
Author(s):  
V. M. Russo ◽  
J. L. Jacobs ◽  
M. C. Hannah ◽  
P. J. Moate ◽  
F. R. Dunshea ◽  
...  
Keyword(s):  
Production Systems ◽  
Gas Production ◽  
Feed Additive ◽  
Chemical Compositions ◽  
Ch4 Emissions ◽  
Grape Marc ◽  
Ch4 Production ◽  
Eastern Australia ◽  
Red Grape

Grape marc consists of the skins, seeds and stems remaining after grapes have been pressed to make wine. Interest in grape marc for use as a dietary feed additive for ruminants has grown after recent research showed that inclusion of grape marc in the diet of dairy cows reduced their enteric methane (CH4) emissions. In the present research, in vitro fermentations were conducted on 20 diverse grape marcs to evaluate their potential as ruminant feed supplements and, in particular, mitigants of enteric CH4 emissions. The grape marcs, which were sourced from vineyards in south-eastern Australia, contained a range of red and white grape varieties with different proportions of skins, seeds and stalks, and had diverse chemical compositions. For each grape marc, four replicate samples, each of 1 g DM, were incubated in vitro with ruminal fluid. The volumes of total gas and CH4 produced after 48 h of incubation were determined. Total gas production ranged from 21.8 to 146.9 mL and CH4 production from 6.8 to 30.3 mL. White grape marcs produced more (P < 0.05) total gas (81.8 mL) than did red grape marcs (61.0 mL), but had a lower (P < 0.05) percentage of CH4 (25.3% and 30.3% of total gas). Grape marcs with a higher proportion of seeds produced less (P < 0.05) total gas than did the types composed of either skin or stalks; however, the seed types produced the greatest (P < 0.05) percentage of CH4 (49.8% of total gas). It is concluded that grape marcs differ greatly in their potential as mitigants of enteric CH4 emissions for ruminal production systems.

scholarly journals Wildfire switches the typical understanding of boreal peatland methane emissions

2019 ◽  
Author(s):  
Scott J. Davidson ◽  
Christine Van Beest ◽  
Richard Petrone ◽  
Maria Strack
Keyword(s):  
Water Table ◽  
Environmental Variables ◽  
Burn Severity ◽  
Radiative Effect ◽  
Production Potential ◽  
Fort Mcmurray ◽  
Ch4 Emissions ◽  
Boreal Peatlands ◽  
Ch4 Production ◽  
The Impact

Abstract. Boreal peatlands represent a globally important store of carbon, and disturbances such as wildfire can have a negative feedback to the climate. Understanding how carbon exchange and greenhouse gas (GHG) dynamics are impacted after a wildfire is important, especially as boreal peatlands may be vulnerable to changes in wildfire regime under a rapidly changing climate. Yet, given this vulnerability, there is very little in the literature on the impact such fires have on methane (CH4) emissions. This study investigated the effect of wildfire on CH4 emissions at a boreal fen near Fort McMurray, AB, Canada, that was partially burned by the Horse River Wildfire in 2016. We measured CH4 emissions and environmental variables (2017–2018) and CH4 production potential (2018) in two different microform types (hummocks and hollows) across a burn severity gradient (unburned (UB), moderately burned (MB) and severely burned (SB)). Results indicated a switch in the typical understanding of boreal peatland CH4 emissions. For example, emissions were much lower in the MB and SB hollows in both years compared to UB hollows. Interestingly, across the burned sites, hummocks had higher fluxes in 2017 than hollows at the MB and SB sites. We found typically higher emissions at the UB site where the water table was close to the surface. However, at the burned sites, no relationship was found between CH4 emissions and water table, even under similar hydrological conditions. This further strengthens the argument on the overriding influence of fire. There was also significantly higher CH4 production potential from the UB site than the burned sites. The reduction in CH4 emissions and production in the hollows at burned sites highlights the sensitivity of hollows to fire, removing labile organic material for potential methanogenesis. The previously demonstrated resistance of hummocks to fire also results in limited impact to CH4 emissions and likely faster recovery to pre-fire rates. Given the potential initial net cooling effect resulting from a reduction in CH4 emissions, it is important that the radiative effect of all GHG following wildfire across peatlands is taken into account.

Repeated Selective Cutting Controls Neotropical Bracken (Pteridium arachnoideum) and Restores Abandoned Pastures

2014 ◽  
Vol 7 (4) ◽  
pp. 580-589 ◽  
Author(s):  
Karla Aguilar-Dorantes ◽  
Klaus Mehltreter ◽  
Heike Vibrans ◽  
Martin Mata-Rosas ◽  
Valentín A. Esqueda-Esquivel
Keyword(s):  
Plant Species ◽  
Control Method ◽  
Fold Increase ◽  
Shoot Biomass ◽  
Leaf Biomass ◽  
First Year ◽  
Selective Cutting ◽  
Rhizome Biomass ◽  
The Impact

AbstractNeotropical bracken fern invades disturbed forests and burned and abandoned pastures in Latin America, inhibiting the growth of associated vegetation and altering community structure. Cutting of all aboveground vegetation every 6 to 12 mo has proven to be inefficient as a control method. We studied the impact of selective cutting of bracken every 2 mo, shading, and a combination of cutting + shading during 14 mo in a bracken-dominated, abandoned pasture in Veracruz, Mexico. At the end of the experiment, cutting with or without shading drastically reduced bracken cover from >90% to less than 1%, decreased leaf number from 18 to fewer than two leaves per m2, and depleted bracken leaf biomass. The significant reduction of bracken was correlated with a significant 3.9- to 5.7-fold increase in richness of other plant species. Cutting without shading was the only treatment that significantly reduced rhizome biomass to less than 62% of control plots, whereas cutting + shading was the only treatment to promote a significant increase in both cover and shoot biomass of successional plant species. Selective cutting of P. arachnoideum repeated every 2 mo was more successful than nonselective cuttings repeated at longer intervals, because it removed newly emerging leaves before their complete expansion and supported the recovery and reestablishment of other plant species, which may help to control bracken. Although costs for the first year of selective cutting were twice as much as for nonselective cutting, it may prove less expensive and more efficient than nonselective cutting in the long term.

Heterotrophic Kinetic Parameter Estimation for Enhanced Biological Phosphorus Removal Processes Operated in Conventional and Membrane-Assisted Modes

2006 ◽  
Vol 41 (1) ◽  
pp. 72-83 ◽  
Author(s):  
Zhe Zhang ◽  
Eric R. Hall
Keyword(s):  
Parameter Estimation ◽  
Phosphorus Removal ◽  
Growth Yield ◽  
Pilot Scale ◽  
Enhanced Biological Phosphorus Removal ◽  
Biological Phosphorus Removal ◽  
Nitrogen And Phosphorus ◽  
Parameter Values ◽  
The Impact ◽  
Biological Phosphorus

Abstract Parameter estimation and wastewater characterization are crucial for modelling of the membrane enhanced biological phosphorus removal (MEBPR) process. Prior to determining the values of a subset of kinetic and stoichiometric parameters used in ASM No. 2 (ASM2), the carbon, nitrogen and phosphorus fractions of influent wastewater at the University of British Columbia (UBC) pilot plant were characterized. It was found that the UBC wastewater contained fractions of volatile acids (SA), readily fermentable biodegradable COD (SF) and slowly biodegradable COD (XS) that fell within the ASM2 default value ranges. The contents of soluble inert COD (SI) and particulate inert COD (XI) were somewhat higher than ASM2 default values. Mixed liquor samples from pilot-scale MEBPR and conventional enhanced biological phosphorus removal (CEBPR) processes operated under parallel conditions, were then analyzed experimentally to assess the impact of operation in a membrane-assisted mode on the growth yield (YH), decay coefficient (bH) and maximum specific growth rate of heterotrophic biomass (µH). The resulting values for YH, bH and µH were slightly lower for the MEBPR train than for the CEBPR train, but the differences were not statistically significant. It is suggested that MEBPR simulation using ASM2 could be accomplished satisfactorily using parameter values determined for a conventional biological phosphorus removal process, if MEBPR parameter values are not available.

Fish farming in Denmark: environmental impact of regulative legislation

1995 ◽  
Vol 31 (10) ◽  
pp. 73-84 ◽  
Author(s):  
T. M. Iversen
Keyword(s):  
Organic Matter ◽  
Environmental Impact ◽  
Freshwater Fish ◽  
Aquatic Environment ◽  
Action Plan ◽  
Fish Farming ◽  
Fish Farms ◽  
Nitrogen And Phosphorus ◽  
Local Impact ◽  
The Impact

The main environmental problems associated with fish farming in Denmark are attributable to the dam, the “dead reach” and nutrient and organic matter discharge. The environmental regulation of fish farming in Denmark started with the Environmental Protection Act of 1974, the Statutory Order of 1985 forbidding wet feed, and the Action Plan on the Aquatic Environment of 1987. In the case of freshwater fish farms, the latter was implemented through the measures stipulated in the 1989 Statutory Order on Fish Farms. The impact of Danish legislative measures to reduce and regulate the environmental effects of freshwater fish farms can be summarized as follows: - the number of fish farms has been reduced from about 800 in 1974 to about 500 at present; - production has tripled since 1974 and has been stable since 1989; - a change from wet to dry feed has reduced the environmental impact of the farms; - the national goals of the Action Plan on the Aquatic Environment of 1987 for reducing fish farm discharges of organic matter, nitrogen and phosphorus have been fulfilled. The main remaining problems are that: - the local impact of fish farms on downstream stream quality is still much too high in about 15% of cases; - the problem of the passage of migrating invertebrates and fish is still unsolved at some farms; - the problems posed by “dead reaches” are still unsolved. It is concluded that sustainable fish farming is possible in Denmark, but with the present technology production will have to be significantly reduced.

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