Controls on plot-scale growing season CO2 and CH4 fluxes in restored peatlands: Do they differ from unrestored and natural sites?

This study brings together plot-scale growing season fluxes of carbon dioxide (CO2) and methane (CH4) from six Canadian peatlands restored by the moss layer transfer technique (MLTT) and compares them with fluxes from adjacent unrestored and natural peatlands to determine1) if CO2 and CH4 fluxes return to natural-site levels and 2) whether the ecohydrological controls (e.g. water table, plant cover) on these fluxes are similar between treatments. We also examine differences between eastern (humid/maritime climate) and western (sub-humid climate) Canadian plots, and between restoration of former horticultural peat extraction sites and oil industry well-pads. Our results indicate that restored site fluxes of CO2 and CH4 are not significantly different between eastern and western Canada or between a restored well-pad and restored horticultural peat extraction sites. Restoration resulted in gross primary production rates similar to those at natural plots and significantly greater than those at unrestored plots. Ecosystem respiration was not significantly different at restored and unrestored plots, and was lower at both than at natural plots. Methane emission was significantly greater at restored plots than at unrestored plots, but remained significantly lower on average than at natural plots. Water table was a significant control on CH4 flux across restored and natural plots. Vascular plant cover was significantly related to CO2 uptake (gross photosynthesis) at restored and unrestored plots, but not at natural plots, while higher moss cover resulted in significantly greater net uptake of CO2 at natural plots but not at restored and unrestored plots. Overall, MLTT restoration greatly alters CO2 and CH4 dynamics compared to unrestored areas but fluxes remain, on average, significantly different from those in natural peatlands, in both the magnitude of mean growing season fluxes and controls on variation in these fluxes among plots. Peatland restoration by MLTT results in reduced CO2 emissions and higher CH4 emissions; however, more year-round measurements in more restored peatlands over longer periods post-restoration are needed to improve greenhouse gas emission estimates for restored Canadian peatlands

Ecohydrologically important subsurface structures in peatlands revealed by ground-penetrating radar and complex conductivity surveys.

The surface pattern of vegetation influences the composition and humification of peat laid down during the development of a bog, producing a subsurface hydrological structure that is expected to affect both the rate and pattern of water flow. Subsurface peat structures are routinely derived from the inspection of peat cores. However, logistical limits on the number of cores that can be collected means that the horizontal extent of these structures must be inferred. We consider whether subsurface patterns in peat physical properties can be mapped in detail over large areas with ground-penetrating radar (GPR) and complex conductivity by comparing geophysical measurements with peat core data along a 36 m transect through different microhabitats at Caribou Bog, Maine. The geophysical methods show promise. Peat horizons produced radar reflections because of changes in the volumetric moisture content. Although these reflections could not be directly correlated with the peat core data, they were related to the depth-averaged peat properties which varied markedly between the microhabitats. Well-decomposed peat below a hollow was characterized by a discontinuous sequence of chaotic wavy reflections, while distinct layering of the peat below an area of hummocks coincided with a pattern of parallel planar reflections. The complex conductivity survey showed spatial variation in the real and imaginary conductivities which resulted from changes in the pore water conductivity; peat structures may also have influenced the spatial pattern in the complex conductivity. The GPR and complex conductivity surveys enabled the developmental history of the different microhabitats along the studied transect to be inferred

The role of waterborne carbon in the greenhouse gas balance of drained and re-wetted peatlands

Accounting for greenhouse gas (GHG) emissions and removals in managed ecosystems has generally focused on direct land-atmosphere fluxes, but in peatlands a significant proportion of total carbon loss occurs via fluvial transport. This study considers the composition of this ‘waterborne carbon’ flux, its potential contribution to GHG emissions, and the extent to which it may change in response to land-management. The work describes, and builds on, a methodology to account for major components of these emissions developed for the 2013 Wetland Supplement of the Intergovernmental Panel on Climate Change. We identify two major components of GHG emissions from waterbodies draining organic soil: i) ‘on site’ emissions of methane (and to a lesser extent CO2) from drainage ditches located within the peatland; and ii) ‘off site’ emissions of CO2 resulting from downstream oxidation of dissolved and particulate organic carbon (DOC and POC) within the aquatic system. Methane emissions from ditches were found to be large in many cases (mean 60 g CH4 m-2 yr-1 based on all reported values), countering the view that methane emissions cease following wetland drainage. Emissions were greatest from ditches in intensive agricultural peatlands, but data were sparse and showed high variability. For DOC, the magnitude of the natural flux varied strongly with latitude, from 5 g C m-2 yr-1 in northern boreal peatlands to 60 g C m-2 yr-1 in tropical peatlands. Available data suggest that DOC fluxes increase by around 60% following drainage, and that this increase may be reversed in the longer-term through re-wetting, although variability between studies was high, especially in relation to re-wetting response. Evidence regarding the fate of DOC is complex and inconclusive, but overall suggests that the majority of DOC exported from peatlands is converted to CO2 through photo- and/or bio-degradation in rivers, standing waters and oceans. The contribution of POC export to GHG emissions is even more uncertain, but we estimate that over half of exported POC may eventually be converted to CO2. Although POC fluxes are normally small, they can become very large when bare peat surfaces are exposed to fluvial erosion. Overall, we estimate that waterborne carbon emissions may contribute about 1 to 4 t CO2-eq ha-1 yr-1 of additional GHG emissions from drained peatlands. For a number of worked examples this represented around 15 to 50% of total GHG emissions

Carbon dioxide flux and net primary production of a boreal treed bog: Responses to warming and water-table-lowering simulations of climate change

Midlatitude treed bogs represent significant carbon (C) stocks and are highly sensitive to global climate change. In a dry continental treed bog, we compared three sites: control, recent (1–3 years; experimental) and older drained (10–13 years), with water levels at 38, 74 and 120 cm below the surface, respectively. At each site we measured carbon dioxide (CO2) fluxes and estimated tree root respiration (Rr; across hummock–hollow microtopography of the forest floor) and net primary production (NPP) of trees during the growing seasons (May to October) of 2011–2013. The CO2–C balance was calculated by adding the net CO2 exchange of the forest floor (NEff-Rr) to the NPP of the trees. From cooler and wetter 2011 to the driest and the warmest 2013, the control site was a CO2–C sink of 92, 70 and 76 g m−2, the experimental site was a CO2–C source of 14, 57 and 135 g m−2, and the drained site was a progressively smaller source of 26, 23 and 13 g CO2–C m−2. The short-term drainage at the experimental site resulted in small changes in vegetation coverage and large net CO2 emissions at the microforms. In contrast, the longer-term drainage and deeper water level at the drained site resulted in the replacement of mosses with vascular plants (shrubs) on the hummocks and lichen in the hollows leading to the highest CO2 uptake at the drained hummocks and significant losses in the hollows. The tree NPP (including above- and below-ground growth and litter fall) in 2011 and 2012 was significantly higher at the drained site (92 and 83 g C m−2) than at the experimental (58 and 55 g C m−2) and control (52 and 46 g C m−2) sites. We also quantified the impact of climatic warming at all water table treatments by equipping additional plots with open-top chambers (OTCs) that caused a passive warming on average of ~ 1 °C and differential air warming of ~ 6 °C at midday full sun over the study years. Warming significantly enhanced shrub growth and the CO2 sink function of the drained hummocks (exceeding the cumulative respiration losses in hollows induced by the lowered water level × warming). There was an interaction of water level with warming across hummocks that resulted in the largest net CO2 uptake at the warmed drained hummocks. Thus in 2013, the warming treatment enhanced the sink function of the control site by 13 g m−2, reduced the source function of the experimental by 10 g m−2 and significantly enhanced the sink function of the drained site by 73 g m−2. Therefore, drying and warming in continental bogs is expected to initially accelerate CO2–C losses via ecosystem respiration, but persistent drought and warming is expected to restore the peatland's original CO2–C sink function as a result of the shifts in vegetation composition and productivity between the microforms and increased NPP of trees over time

Responses of carbon dioxide flux and plant biomass to water table drawdown in a treed peatland in northern Alberta: a climate change perspective

Northern peatland ecosystems represent large carbon (C) stocks that are susceptible to changes such as accelerated mineralization due to water table lowering expected under a climate change scenario. During the growing seasons (1 May to 31 October) of 2011 and 2012 we monitored CO2 fluxes and plant biomass along a microtopographic gradient (hummocks-hollows) in an undisturbed dry continental boreal treed bog (control) and a nearby site that was drained (drained) in 2001. Ten years of drainage in the bog significantly increased coverage of shrubs at hummocks and lichens at hollows. Considering measured hummock coverage and including tree incremental growth, we estimate that the control site was a sink of −92 in 2011 and −70 g C m−2 in 2012, while the drained site was a source of 27 and 23 g C m−2 over the same years. We infer that, drainage-induced changes in vegetation growth led to increased biomass to counteract a portion of soil carbon losses. These results suggest that spatial variability (microtopography) and changes in vegetation community in boreal peatlands will affect how these ecosystems respond to lowered water table potentially induced by climate chang

Variables associated with the secure attachment relationship with the teacher in adolescent students:: systematic review protocol

This document is a systematic review protocol that aims to investigate the variables associated with adolescent students' secure attachment relationship with teachers. The existing systematic review on this topic found that children with a secure attachment relationship with teachers have better academic and socio-emotional indices. However, there are currently no similar reviews for adolescents. Inclusion criteria for articles include: published in peer-reviewed journals in Portuguese, English, or Spanish; from 1969 to present; a sample of adolescents (10 to 19 years old); and results related to attachment with teachers. Furthermore, studies must be empirical, have Attachment Theory as a theoretical basis, and gathered from the following databases: ERIC (EBSCO), MEDLINE (EBSCO), PsycINFO (Ovid), Web of Science, Scopus, Scielo, Redalyc. The JBI Critical Appraisal checklists will be used to verify the risk of bias as well as the quality of the studies. It intends to present the outcomes through narrative descriptions and, if possible, meta-analytical statistics

O impacto das medidas de melhoria do abastecimento de água e esgoto sobre a diarréia e parasitose intestinal: experiência brasileira com crianças de comunidades de baixa renda

During the second half of 1986 the impact of the improvement of water supply and excreta disposal facilities on diarrheal diseases and intestinal parasitosis was studied in 254 children up to six years of age from two favelas (shanty towns) of Belo Horizonte, Brazil. The estimated incidence of diarrhea was 6.2 episodes/child year and the estimated period prevalence reached 31.0 episode days/ child/ year. The point prevalence of parasitosis was 70.7% (Ascaris lumbricoides: 55.4%, Trichuris trichiura: 19.6%, Giardia lamblia: 17.9%). The estimated prevalence of diarrhea decreased with improvement of water supply and sanitation facilities to 45% and 44% respectively, but no statistically significant impact was observed in the case of parasitosis. School education and weaning practice were found to be other important determinants of diarrhea.Em 1986 pesquisou-se, junto a 254 crianças de até 6 anos de idade, residentes em duas favelas de Belo Horizonte (Brasil), o impacto das medidas de melhoramento do abastecimento de água e esgoto na incidência de diarréia e parasitose intestinal. Até então, a incidência de diarréia era estimada em 6,2 casos por criança e ano, com uma duração predominante de 31,0 dias por caso/criança/ano. A taxa de difusão de parasitose alcançava 70,7% (Ascaris lumbricoides: 55,4%, Trichuris trichiura: 19,6%; Giardia lamblia: 17,9%). Após os melhoramentos no abastecimento de água e esgoto, a incidência de diarréia caiu para 45% e 44%, respectivamente. Quanto à parasitose, entretanto, não se constatou nenhum impacto estatisticamente significante. Também verificou-se que o grau de educação escolar e práticas de desmame são determinantes de grande importância na incidência de diarréia

Effect of thermal and ultrasonic treatments on technological and physicochemical characteristics of fibrous residues from ahipa and cassava starch extraction

Fiber-enriched residues from cassava and ahipa roots starch extraction were analyzed by their structural, physicochemical, and techno-functional properties, before and after being subjected to overpressure thermal and ultrasound treatments. Thermal treatment efficiently reduced the residual starch content of both residues (up to 3.4 and 9.6% for ahipa and cassava, respectively), and its combination with ultrasound modified the structural and functional properties of cassava residue, while ahipa bagasse resulted almost unaffected. Ahipa residues swelling power (5.1-5.4 mL/g), WHC (6.9-7.3 g H2O/g), WBC (4.4-5.4 g H2O/g), and OBC (3.1-3.3 g oil/g) were in the range reported for several fiber-enriched ingredients, and resulted higher than those of cassava bagasse. Gel-forming capacity was observed for cassava residues coming from starch extraction, mainly due to their residual starch content. This property was lost after thermal treatment, but ultrasound restored the thermally driven gelling capacity. This recovery was associated with fiber structural changes revealed by microscopy, particle size distribution, and FTIR spectra. Based on their gelling properties, thermal and ultrasound-treated cassava bagasse could contribute to modify textural properties in low-calories fruit spreads. Although none of ahipa residues exhibited gelling capacity, their hydration properties and OBC can be applied in the formulation of fiber-enriched bakery products.Fil: Strack, Karen Nataly. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Dini, Cecilia. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Garcia, Maria Alejandra. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Viña, Sonia Zulma. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales; Argentin