Tree-mediated methane emissions from tropical and temperate peatlands

Methane production and transport processes in peatlands are fairly well understood, but growing evidence for emission of methane through trees has highlighted the need to revisit methane transport processes. In wetland trees, morphological adaptations such as development of hypertrophied lenticels, aerenchyma and adventitious roots in response to soil anoxia mediates gas transport, transporting both oxygen from the atmosphere to oxygen-deprived roots and soil-produced methane from the root-zone to the atmosphere. Although, tree-mediated methane emissions from temperate tree species have been confirmed, methane emissions from tropical tree species and processes that control tree-mediated methane emissions remain unclear. This study explains the role of trees in transporting soil-produced methane to the atmosphere and uncovers the principal mechanisms of tree-mediated methane emissions. Methane emissions from eight tropical tree species and two temperate tree species were studied in situ. The mechanisms and controls on tree-mediated methane emissions were investigated using three year old common alder (Alnus glutinosa; 50 trees) grown under two artificially controlled water-table positions. Methane fluxes from whole mesocosms, the soil surface and tree stems were measured using static closed chambers. Both temperate and tropical tree species released significant quantities of methane, with tropical trees dominating ecosystem level methane fluxes. In temperate peatlands, both the methane gas transport mechanism and quantity of methane emitted from stems is tree-species dependent. In Alnus glutinosa, no correlations were observed between stomatal behaviour and tree-mediated methane emissions, however, stem methane emissions were positively correlated with both stem lenticel density and dissolved soil methane concentration. In Alnus glutinosa, no emissions were observed from leaf surfaces. The results demonstrate that exclusion of tree-mediated methane emissions from flux measurement campaigns in forested peatlands will lead to an underestimation of ecosystem-wide methane emissions

Experiences and views of patients, carers and healthcare professionals on using modems in domiciliary non-invasive ventilation (NIV): a qualitative study

BACKGROUND: Advances in technology means that domiciliary non-invasive ventilation (NIV) devices can be remotely monitored via modems in patients' homes. Possible benefits and challenges of modem technology have yet to be established. This study explored the perspectives and experiences of patients, their carers and healthcare professionals (HCPs) on the addition of modem technology in managing home NIV. METHODS: A qualitative study using a combination of focus groups for HCPs and interviews for carers/patients was undertaken. 12 HCPs and 22 patients/carers participated. These focus groups and interviews were audio-recorded, transcribed verbatim and analysed thematically. RESULTS: Five main themes were identified. 'Surveillance: a paradox of findings': HCPs were concerned about unduly scrutinising patients' lives, potentially impacting on HCP patient relationships. Conversely, patients welcomed modem monitoring and did not express concerns regarding invasion of privacy. 'Sanctions': HCPs reported the modem increased access to care and allowed appropriate assessment of ongoing treatment. 'Complacency and ethics': HCPs expressed concerns patients may become complacent in seeking help due to expectations of modem monitoring, as well as being concerned regarding the ethics of modems. There was a suggestion patients and carers' expectations of monitoring were different to that of clinical practice, resulting in complacency in some cases. 'Increased time for patient focused care': HCPs in the focus groups described a number of ways in which using modems was more efficient. 'Confidence: can be improved with technology': patients and carers were positive about the impact of the modems on their health and well-being, particularly their confidence. CONCLUSION: HCPs expressed concerns about surveillance were not corroborated by patients, suggesting acceptability of remote monitoring. Data suggests a need for increased clarity to patients/carers regarding clinical practice relating to responsiveness to modem data. The issue of complacency requires further consideration. Modem technology was acceptable and considered a useful addition by HCPs, patients and carers. TRIAL REGISTRATION NUMBER: NCT03905382

Scaling Experiments on the Dynamics and Acoustics of Travelling Bubble Cavitation

Ceccio and Brennen (1991 and 1989) recently examined the interaction between individual cavitation bubbles and the structure of the boundary layer and flow field in which the bubble is growing and collapsing. They were able to show that individual bubbles are often fissioned by the fluid shear and that this process can significantly effect the acoustic signal produced by the collapse. More recently Kumar and Brennen (1991-1992) have closely examined further statistical properties of the acoustical signals from individual cavitation bubbles on two different headforms in order to learn more about the bubble/flow interactions. All of these experiments were, however, conducted in the same facility with the same size of headform (5.08cm in diameter) and over a fairly narrow range of flow velocities (around 9m/s). Clearly this raises the issue of how the phenomena identified change with speed, scale and facility. The present paper describes experiments conducted in order to try to answer some of these important questions regarding the scaling of the cavitation phenomena. The experiments were conducted in the Large Cavitation Channel of the David Taylor Research Center in Memphis Tennessee, on similar Schiebe headforms which are 5.08, 25.4 and 50.8cm in diameter for speeds ranging up to 15m/s and for a range of cavitation numbers

Woody stem methane emission in mature wetland alder trees

Methane (CH4) is an important greenhouse gas that is predominantly emitted to the atmosphere from anoxic wetland ecosystems. Understanding the sources and emissions of CH4 is crucially important for climate change predictions; however, there are significant discrepancies between CH4 source estimates derived via so-called bottom-up and top-down methods. Here we report CH4 emission from the stems of mature wetland alder (Alnus glutinosa) trees in the UK, a common tree of northern hemisphere floodplains and wetlands. The alder stems most likely behave as conduits for soil-produced CH4 either in the gaseous or aqueous phase, and may, therefore, help to reconcile methodological differences in the way the wetland CH4 source is estimated. Alder tree stems emitted average peak CH4 fluxes of 101 μg CH4 m−2 h−1 (on a stem area basis) in early October, a rate that is similar to that obtained from mature Japanese ash (Fraxinus mandshurica var. japonica) in Japan and amounting to approximately 20% of the measured CH4 flux from the soil surface. The finding suggests that trees, which occupy 60% of Earth's wetlands and are normally excluded from the measurement programmes that form the basis for bottom-up estimates of the global wetland source, could be important contributors to overall terrestrial ecosystem CH4 flux

The Mersey Estuary : sediment geochemistry

This report describes a study of the geochemistry of the Mersey estuary carried out between April 2000 and December 2002. The study was the first in a new programme of surveys of the geochemistry of major British estuaries aimed at enhancing our knowledge and understanding of the distribution of contaminants in estuarine sediments. The report first summarises the physical setting, historical development, geology, hydrography and bathymetry of the Mersey estuary and its catchment. Details of the sampling and analytical programmes are then given followed by a discussion of the sedimentology and geochemistry. The chemistry of the water column and suspended particulate matter have not been studied, the chief concern being with the geochemistry of the surface and near-surface sediments of the Mersey estuary and an examination of their likely sources and present state of contamination

The impact of adoption of conservation agriculture on smallholder farmers’ food security in semi-arid zones of southern Africa

BACKGROUND In southern Africa, conservation agriculture (CA) has received a lot of research and promotional support from various organizations in the past decades. Conservation agriculture is largely promoted as one of the few win–win technologies affordable to farmers, in the sense that potentially it improves farmers’ yields (in the long term) at the same time conserving the environment. This is because conservation agriculture reduces nitrogen loss in the soil, promotes water and soil conservation and improves agronomic use efficiency of applied nutrients. However, some concerns have been raised over the feasibility of conservation agriculture on smallholder farms given constraints imposed by the biophysical and institutional realities under which smallholder farmers operate. The main aim of this study is to answer the question whether conservation agriculture is resulting in tangible livelihood outcomes to smallholder farmers. The counterfactual outcome approach was used to estimate ex post impact of conservation agriculture adoption on one of the key livelihood outcomes—food security. RESULTS The study that utilized a data set covering 1623 households in Zimbabwe, Malawi and Mozambique found no significant impact of conservation agriculture adoption on Food Consumption Score of farmers in Zimbabwe and Malawi. Possible reasons for the insignificant of CA impact on food security in Zimbabwe and Malawi could include the small land areas currently devoted to CA, and the failure to implement the full complement of practices necessary to set off the biophysical process that are expected to drive yield increases. In Mozambique, conservation agriculture significantly improved the Food Consumption Score for farmers exposed to the technology. A possible reason for effectiveness of CA in Mozambique could be due to the fact that often CA is being promoted together with other better cropping management practices such as timely weeding and improved seed varieties, which are poorly practiced by the generality of farmers in a country just emerging from a war period. CONCLUSION This paper provides one of the few ex post assessments of the impact of conservation agriculture adoption on household livelihood outcomes—food security. Given the mixed findings, the study suggests that conservation agriculture farmers in the three countries need to be supported to adopt a value chain approach to conservation agriculture. This entails the introduction of commercial or high-value crops in the conservation agriculture programmes, value addition on farmers produce, access to the necessary support services such as markets for seed, fertilizer, herbicides and equipment as well as reliable extension. We believe that under such circumstances conservation agriculture can effectively reduce food insecurity and poverty in the medium to long term

The State-Moro Armed Conflict in the Philippines: Unresolved national question or question of governance?

The continuing struggle of the Moro secessionist movement in the Philippines is one of Southeast Asia’s longest armed conflicts. The tenacity of the conflict lies in two competing concerns: the assertion of self-determination rights of the Moro separatist movement; and the affirmation of the Philippines’ sovereign right to territorial integrity. However, beneath these rights are crucial issues that remain unanswered both by the contending forces—problems where internecine violence and conflict emanate from. This article argues that self-determination rights can be adequately exercised by people who have clearly defined their national identity and concept of a nation. Unfortunately, the Moro multi-ethnic national identity has yet to be crystallised while the idea of a Bangsamoro (Bangsa Nation) remains weak. On the other hand, the state has yet to address the Moros’ legitimate demands of political autonomy, socio-economic development, and social justice and discrimination. Without underestimating the ethnic component of secessionism, the article concludes that poor governance has prolonged, complicated, and further justified the Moros’ quest to secede from the Republic