ABSTRACT
Excess CO2 accumulated in soils is typically transported to the atmosphere through molecular diffusion along a concentration gradient. Because of the slow and constant nature of this process, a steady state between peat CO2 production and emissions is often established. However, in peatland ecosystems, high peat porosity could foster additional non-diffusive transport processes, whose dynamics may become important to peat CO2 storage, transport and emission. Based on a continuous record of in situ peat pore CO2 concentration within the unsaturated zone of a raised bog in southern Canada, we show that changes in wind speed create large diel fluctuations in peat pore CO2 store. Peat CO2 builds up overnight and is regularly flushed out the following morning. Persistently high wind speed during the day maintains the peat CO2 with concentrations close to that of the ambient air. At night, wind speed decreases and CO2 production overtakes the transport rate leading to the accumulation of CO2 in the peat. Our results indicate that the effective diffusion coefficient fluctuates based on wind speed and generally exceeds the estimated molecular diffusion coefficient. The balance between peat CO2 accumulation and transport is most dynamic within the range of 0-2 m s-1 wind speeds, which occurs over 75% of the growing season and dominates night-time measurements. Wind therefore drives considerable temporal dynamics in peat CO2 transport and storage, particularly over sub-daily timescales, such that peat CO2 emissions can only be directly related to biological production over longer timescales. Supplementary Information: The online version contains supplementary material available at 10.1007/s10021-024-00904-1.
ABSTRACT
Malaria is a major cause of childhood morbidity and mortality in Malawi. Use of insecticide treated bed nets (ITNs) could reduce the burden of malaria. The objective of the study was to determine the general health status, and factors that influence reported access to ITNs among school children in a peri-urban area of Blantyre, Malawi. 454 school children participated in the study of which 253 (55.7%) were males and 201 (44.3%) females. Their mean age and range were 14 years (std. deviation, 1.4 years) and 10-19 years respectively. When asked about general health status questions, 263 (57.9%) reported ever having fallen ill while at school, 41.2% having ever came to school knowing they were unwell, and 40.7% of those that reported having fallen ill at school, categorized their illness as malaria. Regarding illness in the month preceding the study, 41.0% indicated that they had been ill. 40 (8.8%) participants reported that they were not allowed by their religious denominations to use medications when ill. 165 (36.3%) participants reported using bed nets themselves, 159 (35.0%) had a household member (other than parent) using nets and 254 (55.9%) had parent(s) sleeping under an ITN. Having someone in the household who uses an ITN was positively associated with ITN use while age of the participants was inversely associated with ITN access in the home. While more females (37.3%) reported using nets than males (35.6%), the difference was not statistically significant (p=0.7). It was concluded that many of the school children experience ill health in Ndirande, Malawi and malaria is perceived to be a common illness. While younger children seem to have higher access to ITNs, there seems to be no statistically significant gender differences in accessibility