Hydraulic performance and iron removal in wetlands and lagoons treating ferruginous coal mine waters

A study of hydraulic residence time has been conducted for several UK Coal Authority mine water treatment systems to evaluate the impact of residence time on the overall hydraulic performance and iron removal within the systems. A series of tracer tests were conducted within the Coal Authority mine water treatment wetlands and lagoons to measure actual hydraulic residence time. The tracer residence time distributions (RTDs) were analysed based on a tanks-in-series (TIS) model to yield the mean residence time and corresponding hydraulic characteristics of the systems. The relationship between iron retention and residence time was tested against a first-order removal model. The mean hydraulic efficiency is 69 % for the wetlands compared to 24 % for the lagoons, mainly attributable to comparatively greater volumetric efficiency within the wetland systems. The mean number of TIS, n, is 3.9 for the wetlands and 2.1 for the lagoons, illustrating considerably different flow patterns between wetlands and lagoons. There is also a notable difference of treatment efficiency for iron; mean of 81 % and 47 % for wetlands and lagoons, respectively. Generally, it appears that system hydraulic efficiency (derived from the principle of TIS model) corresponds with iron retention in the treatment systems

Hydraulic residence time and iron removal in a wetland receiving ferruginous mine water over a 4 year period from commissioning.

Analysis of residence time distribution (RTD) has been conducted for the UK Coal Authority's mine water treatment wetland at Lambley, Northumberland, to determine the hydraulic performance of the wetland over a period of approximately 4 years since site commissioning. The wetland RTD was evaluated in accordance with moment analysis and modelled based on a tanks-in-series (TIS) model to yield the hydraulic characteristics of system performance. Greater hydraulic performance was seen during the second site monitoring after 21 months of site operation i.e. longer hydraulic residence time to reflect overall system hydraulic efficiency, compared to wetland performance during its early operation. Further monitoring of residence time during the third year of wetland operation indicated a slight reduction in hydraulic residence time, thus a lower system hydraulic efficiency. In contrast, performance during the fourth year of wetland operation exhibited an improved overall system hydraulic efficiency, suggesting the influence of reed growth over the lifetime of such systems on hydraulic performance. Interestingly, the same pattern was found for iron (which is the primary pollutant of concern in ferruginous mine waters) removal efficiency of the wetland system from the second to fourth year of wetland operation. This may therefore, reflect the maturity of reeds for maintaining efficient flow distribution across the wetland to retain a longer residence time and significant fractions of water involved to enhance the extent of treatment received for iron attenuation. Further monitoring will be conducted to establish whether such performance is maintained, or whether efficiency decreases over time due to accumulation of dead plant material within the wetland cells

Nitrous oxide fluxes from tropical peat with different disturbance history and management

Peer reviewe

French responses to the Prague Spring: connections, (mis)perception and appropriation

Looking at the vast literature on the events of 1968 in various European countries, it is striking that the histories of '1968' of the Western and Eastern halves of the continent are largely still written separately.1 Nevertheless, despite the very different political and socio-economic contexts, the protest movements on both sides of the Iron Curtain shared a number of characteristics. The 1968 events in Czechoslovakia and Western Europe were, reduced to the basics, investigations into the possibility of marrying social justice with liberty, and thus reflected a tension within European Marxism. This essay provides an analysis specifically of the responses by the French left—the Communist Party, the student movements and the gauchistes—to the Prague Spring, characterised by misunderstandings and strategic appropriation. The Prague Spring was seen by both the reformist and the radical left in France as a moderate movement. This limited interpretation of the Prague Spring as a liberal democratic project continues to inform our memory of it

Canal blocking strategies for hydrological restoration of degraded tropical peatlands in Central Kalimantan, Indonesia

In the 1990s the Government of Indonesia derided to develop one million hectares of peatlands for agriculture in Central Kalimantan on the Island of Borneo. The construction of thousands of kilometres of canals resulted in over-drainage and targets for agricultural production failed. Abandoned, the area has been subject to severe forest and peat fires. Restoration of degraded peatlands normally starts with restoring the water table to rewet the surface in order to control fire and to initiate reforestation. Canal blocking strategies are a potential means for accomplishing this. In a test plot in the Northern part of Block C of the former Mega Rice Project (MRP), a series of dams were constructed and (ground)water tables and subsidence rates were monitored to assess the effects of dam construction on peatland hydrology. The resulting higher water tables did not completely compensate for the negative effects of increased subsidence near the canals. The canals, which are "eating" themselves into the peatland, create depressions in the peatland surface leading to interception of overland- and interflow and increased risk of overtopping of dams during extreme rainfall events. The lessons learned are being used to improve blocking strategies and dam design. The changes in peatland topography caused by drainage, however, need to be better understood in order to further refine strategies for hydrological restoration of degraded peatlands in Indonesia. (C) 2013 Elsevier B.V. All rights reserved

Spatial distribution of carbon and nitrogen stable isotope in soil of an oil palm plantation

The conversion of lowland tropical forests to oil palm plantations is known to reduce the amount of soil carbon and nitrogen. However, this has been criticised as the plantations also contribute to a net gain of the soil carbon (C) stock. In this study, carbon and nitrogen stable isotopes techniques was used to confirm the source of carbon stored in plantation soils and to prove the effects of plantation activities on soil organic carbon. The objective of this study was to investigated the total organic carbon (TOC) and nitrogen (TON) content, and δ 13C and δ 15N values of soil in an oil palm plantation at different soil depths: 0-30, 30-60 and 60-90 cm and at different distances ((1.5 m: weeded circle), 3.5 (inter-rows) and 4.5 m (frond heap)) away from the tree base. The results showed that the ratio of soil δ13C and δ15N increased with depth and unusual δ15N value was reported on topsoil 0-30cm, a non-uniform distribution of soil OM (%), TOC (%), TON (%) and C/N ratio in the surface soil among the distances were observed. Negative correlation between δ13C and δ15N and bulk density (Bd) in respect of TOC and TON content were found. Value of δ13C at 0-30, 30-60 and 60-90 cm depths was -26.50, -26.36 and -26.23% respectively. This study conclude that, a low proportion of C was lost from the plantation soil , a long phase of C3 species dominated the soil before the establishment of the oil palm plantation and that frond heaps and large concentration of roots had a significant influence on OM (%), TOC (%), TON (%) and C/N ratio in the surface soil among the distances. The δ15N value in the top soil might be a useful indicator of the source and limited level of nitrogen in the area of study, however, further research is needed to confirm our observations

A novel low-cost, high-resolution camera system for measuring peat subsidence and water table dynamics

This is the final version. Available from Frontiers Media via the DOI in this record. DATA AVAILABILITY STATEMENT: The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.Peatlands are highly dynamic systems, able to accumulate carbon over millennia under natural conditions, but susceptible to rapid subsidence and carbon loss when drained. Short-term, seasonal and long-term peat surface elevation changes are closely linked to key peatland attributes such as water table depth (WTD) and carbon balance, and may be measured remotely using satellite radar and LiDAR methods. However, field measurements of peat elevation change are spatially and temporally sparse, reliant on low-resolution manual subsidence pole measurements, or expensive sensor systems. Here we describe a novel, simple and low-cost image-based method for measuring peat surface motion and WTD using commercially available time-lapse cameras and image processing methods. Based on almost two years’ deployment of peat cameras across contrasting forested, burned, agricultural and oil palm plantation sites in Central Kalimantan, Indonesia, we show that the method can capture extremely high resolution (sub-mm) and high-frequency (sub-daily) changes in peat surface elevation over extended periods and under challenging environmental conditions. WTD measurements were of similar quality to commercially available pressure transducers. Results reveal dynamic peat elevation response to individual rain events, consistent with variations in WTD. Over the course of the relatively severe 2019 dry season, cameras in deep-drained peatlands recorded maximum peat shrinkage of over 8 cm, followed by partial rebound, leading to net annual subsidence of up to 5 cm. Sites with higher water tables, and where borehole irrigation was used to maintain soil moisture, had lower subsidence, suggesting potential to reduce subsidence through altered land-management. Given the established link between subsidence and CO2 emissions, these results have direct implications for the management of peatlands to reduce high current greenhouse gas (GHG) emissions. Camera-based sensors provide a simple, low-cost alternative to commercial elevation, WTD and GHG flux monitoring systems, suitable for deployment at scale, and in areas where existing approaches are impractical or unaffordable. If ground-based observations of peat motion can be linked to measured GHG fluxes and with satellite-based monitoring tools, this approach offers the potential for a large-scale peatland monitoring tool, suitable for identifying areas of active carbon loss, targeting climate change mitigation interventions, and evaluating intervention outcomes.United Kingdom Space Agency International Partnership ProgramBiotechnology and Biological Sciences Research CouncilNatural Environment Research CouncilNatural Environment Research Counci