How Important are Peatlands Globally in Providing Drinking Water Resources?

The potential role of peatlands as water stores and sources of downstream water resources for human use is often cited in publications setting the context for the importance of peatlands, but is rarely backed up with substantive evidence. We sought to determine the global role of peatlands in water resource provision. We developed the Peat Population Index (PPI) that combines the coverage of peat and the local population density to show focused (hotspot) areas where there is a combination of both large areas of peat and large populations who would potentially use water sourced from those peatlands. We also developed a method for estimating the proportion of river water that interacted with contributing peatlands before draining into rivers and reservoirs used as a drinking water resource. The Peat Reservoir Index (PRI) estimates the contribution of peatlands to domestic water use to be 1.64 km3 per year which is 0.35 % of the global total. The results suggest that although peatlands are widespread, the spatial distribution of the high PPI and PRI river basins is concentrated in European middle latitudes particularly around major conurbations in The Netherlands, northern England, Scotland (Glasgow) and Ireland (Dublin), although there were also some important systems in Florida, the Niger Delta and Malaysia. More detailed research into water resource provision in high PPI areas showed that they were not always also high PRI areas as often water resources were delivered to urban centres from non-peat areas, despite a large area of peat within the catchment. However, particularly in the UK and Ireland, there are some high PRI systems where peatlands directly supply water to nearby urban centres. Thus both indices are useful and can be used at a global level while more local refinement enables enhanced use which supports global and local peatland protection measures. We now intend to study the impacts of peatland degradation and climate change on water resource provision in hotspot PPI and PRI regions

The role of peatlands in global and regional drinking water resources

Water provision is a valuable ecosystem service that is of central importance to human well-being. Peatlands are potentially important to the sustainable provision of potable water because water draining from peatlands is often of good quality, other than being rich in dissolved organic carbon (DOC). However, there have been no attempts to date, to investigate the role of peatlands in potable water supply at a global scale. In this thesis, an improved global peatland map (PEATMAP) was developed, which is freely available as a potentially useful tool for peatland or wetland researchers. The new map provided a basis from which to estimate global hotspots of peatland-derived potable water use. The volume of annual drinking water delivered by these catchments was estimated, and the status of the water-supply peatlands were evaluated, being the first such estimates at the global scale. Application of PERSiST and INCA-C models across the nine catchments in the UK, which are among the most important peatland-derived drinking water supply catchments in the world, provided evidence of the potential changes in DOC concentration and DOC flux under 21st-century climate and sulphate deposition scenarios. The results show that total global peatland area is 4.23 million km2, approximately 2.84 % of the world land area. Water supply peatlands provide approximately 4.22 km3 yr-1 of peat-fed drinking water globally, equivalent to typical consumption of 71.4 million people, but only 28 % of water-supply peatlands are pristine or protected globally. Although DOC flux is largely insensitive to future climate change scenarios, DOC concentrations in UK water sources are likely to increase while discharges are likely to decrease under all 21st-century climate and sulphate deposition scenarios tested

X-ray fluorescent lines from the Compton-thick AGN in M51

The cold disc/torus gas surrounding active galactic nuclei (AGN) emits fluorescent lines when irradiated by hard X-ray photons. The fluorescent lines of elements other than Fe and Ni are rarely detected due to their relative faintness. We report the detection of Kα lines of neutral Si, S, Ar, Ca, Cr, and Mn, along with the prominent Fe Kα, Fe Kβ, and Ni Kα lines, from the deep Chandra observation of the low-luminosity Compton-thick AGN in M51. The Si Kα line at 1.74 keV is detected at ∼3σ, the other fluorescent lines have a significance between 2 and 2.5 σ, while the Cr line has a significance of ∼1.5σ. These faint fluorescent lines are made observable due to the heavy obscuration of the intrinsic spectrum of M51, which is revealed by NuSTAR observation above 10 keV. The hard X-ray continuum of M51 from Chandra and NuSTAR can be fitted with a power-law spectrum with an index of 1.8, reprocessed by a torus with an equatorial column density of NH ∼ 7 × 10^(24) cm^(−2) and an inclination angle of 74°. This confirms the Compton-thick nature of the nucleus of M51. The relative element abundances inferred from the fluxes of the fluorescent lines are similar to their solar values, except for Mn, which is about 10 times overabundant. It indicates that Mn is likely enhanced by the nuclear spallation of Fe

Ecological network construction based on minimum cumulative resistance for the City of Nanjing, China

With economic growth and the improvement of the urbanization level, human activities have constantly interfered with landscape patterns, resulting in serious threats to regional ecological security. Therefore, it is of great significance to study the evolution and optimization of the landscape patterns. Based on three TM images from 1990, 2000, and 2010, and selected landscape pattern indexes, the changes in the landscape pattern of Nanjing in the past twenty years were studied based on landscape ecology theory using Remote Sensing (RS) and a Geographical Information System (GIS). The ecological network was built on the basis of extracted ecological nodes and the minimum cumulative resistance. The results show that changes in the landscape pattern of the city of Nanjing were notable. Class-level indexes indicate that the farmland landscape area decreased and the degree of patch fragmentation increased. The construction land area increased, and it tended to show dispersed distribution. The proportion of forest land increased and the shape of patches became more complex. The proportion of water firstly showed a decrease, followed by an increase, and the shape of the water became more regular. Landscape-level indexes indicate that biological diversity and the degree of fragmentation increased. Spatial heterogeneity of the natural landscape increased, and the patch shape of each landscape type developed similarly. The results also call for stepping-stones to enhance the connectivity and optimization of the ecological network, which will help improve ecological services and improve the landscape pattern of the city

Future Dissolved Organic Carbon Export Dynamics in Peatland-derived Potable Water Supply Catchments in the UK

Peatlands are important global terrestrial carbon stores as well as sources of regional potable water supply. Concentrations of dissolved organic carbon (DOC) in surface waters have increased across Europe and parts of North America in the past decades, resulting in increased water treatment problems and cost. However, it is unclear how climate change may impact DOC in peatland-derived potable water. Here we use a physically based hydrological model (PERSiST) and a biogeochemical organic carbon model (INCA-C) to predict discharge and DOC concentration in nine hotspots of peatland-derived potable water use in the UK under a range of 21st-Century climate and sulphate-deposition scenarios. These catchments supply 72 % of all peat-derived water consumed in the UK, and 57 % of the global total. The annual average and seasonal variability of DOC concentrations are likely to increase while the mean discharges are likely to decrease under all future scenarios. The large increases (by as much as a factor of 1.6) in DOC concentration in the 2090s over the baseline period are projected in the autumn and winter, a time when DOC concentrations are already high in the baseline datasets. However, the total DOC flux is largely insensitive to future climate change because the projected increase in DOC concentration is mostly counterbalanced by the projected decrease in discharge. To fulfil regulations on DOC concentrations in water supplies for all nine study catchments in the 2090s, at least £.5 billion of the capital investment for new treatment plants will be required. Thus, more efficient water treatment technology and responsible stewardship of peatlands will be necessary