Regional climate change mitigation with crops: context and assessment

The intention of this review is to place crop albedo biogeoengineering in the wider picture of climate manipulation. Crop biogeoengineering is considered within the context of the long-term modification of the land surface for agriculture over several thousand years. Biogeoengineering is also critiqued in relation to other geoengineering schemes in terms of mitigation power and adherence to social principles for geoengineering. Although its impact is small and regional, crop biogeoengineering could be a useful and inexpensive component of an ensemble of geoengineering schemes to provide temperature mitigation. The method should not detrimentally affect food security and there may even be positive impacts on crop productivity, although more laboratory and field research is required in this area to understand the underlying mechanisms.

Present state of global wetland extent and wetland methane modelling: methodology of a model inter-comparison project (WETCHIMP)

The Wetland and Wetland CH4 Intercomparison of Models Project (WETCHIMP) was created to evaluate our present ability to simulate large-scale wetland characteristics and corresponding methane (CH4) emissions. A multi-model comparison is essential to evaluate the key uncertainties in the mechanisms and parameters leading to methane emissions. Ten modelling groups joined WETCHIMP to run eight global and two regional models with a common experimental protocol using the same climate and atmospheric carbon dioxide (CO2) forcing datasets. We reported the main conclusions from the intercomparison effort in a companion paper (Melton et al., 2013). Here we provide technical details for the six experiments, which included an equilibrium, a transient, and an optimized run plus three sensitivity experiments (temperature, precipitation, and atmospheric CO2 concentration). The diversity of approaches used by the models is summarized through a series of conceptual figures, and is used to evaluate the wide range of wetland extent and CH4 fluxes predicted by the models in the equilibrium run. We discuss relationships among the various approaches and patterns in consistencies of these model predictions. Within this group of models, there are three broad classes of methods used to estimate wetland extent: prescribed based on wetland distribution maps, prognostic relationships between hydrological states based on satellite observations, and explicit hydrological mass balances. A larger variety of approaches was used to estimate the net CH4 fluxes from wetland systems. Even though modelling of wetland extent and CH4 emissions has progressed significantly over recent decades, large uncertainties still exist when estimating CH4 emissions: there is little consensus on model structure or complexity due to knowledge gaps, different aims of the models, and the range of temporal and spatial resolutions of the models.

Cost effectiveness of mitigation measures for water security and water quality in the River Thames catchment: impacts of changing climate, land use and water scarcity

The catchment of the River Thames, the principal river system in southern England, provides the main water supply for London but is highly vulnerable to changes in climate, land use and population. The river is eutrophic with significant algal blooms with phosphorus assumed to be the primary chemical indicator of ecosystem health. In the Thames Basin, phosphorus is available from point sources such as wastewater treatment plants and from diffuse sources such as agriculture. In order to predict vulnerability to future change, the integrated catchments model for phosphorus (INCA-P) has been applied to the river basin and used to assess the cost-effectiveness of a range of mitigation and adaptation strategies. It is shown that scenarios of future climate and land-use change will exacerbate the water quality problems, but a range of mitigation measures can improve the situation. A cost-effectiveness study has been undertaken to compare the economic benefits of each mitigation measure and to assess the phosphorus reductions achieved. The most effective strategy is to reduce fertilizer use by 20% together with the treatment of effluent to a high standard. Such measures will reduce the instream phosphorus concentrations to close to the EU Water Framework Directive target for the Thames.

Influence of UV radiation on chlorophyll, and antioxidant enzymes of wetland plants in different types of constructed wetland

A surface- and vertical subsurface-flow-constructed wetland were designed to study the response of chlorophyll and antioxidant enzymes to elevated UV radiation in three types of wetland plants (Canna indica, Phragmites austrail, and Typha augustifolia). Results showed that (1) chlorophyll content of C. indica, P. austrail, and T. augustifolia in the constructed wetland was significantly lower where UV radiation was increased by 10 and 20 % above ambient solar level than in treatment with ambient solar UV radiation (p < 0.05). (2) The malondialdehyde (MDA) content, guaiacol peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activities of wetland plants increased with elevated UV radiation intensity. (3) The increased rate of MDA, SOD, POD, and CAT activities of C. indica, P. australis, and T. angustifolia by elevated UV radiation of 10 % was higher in vertical subsurface-flow-constructed wetland than in surface-flow-constructed wetland. The sensitivity of MDA, SOD, POD, and CAT activities of C. indica, P. austrail, and T. augustifolia to the elevated UV radiation was lower in surface-flow-constructed wetland than in the vertical subsurface-flow-constructed wetland, which was related to a reduction in UV radiation intensity through the dissolved organic carbon and suspended matter in the water. C. indica had the highest SOD and POD activities, which implied it is more sensitive to enhanced UV radiation. Therefore, different wetland plants had different antioxidant enzymes by elevated UV radiation, which were more sensitive in vertical subsurface-flow-constructed wetland than in surface-flow-constructed wetland.

Flat, flatter, flattest: the English Heritage wetland surveys in retrospect

Since 1973, English Heritage has supported four major regional surveys of England's wetlands- in the Somerset Levels, the Fens of Eastern England, the wetlands of the northwest of England and the Humber wetlands. Each of these projects developed a range of methods and techniques particular to the landscape that was studied and the results from the surveys reflect this diversity of approach. This paper compares and contrast these approaches, and evaluates their effect on the overall results of each of these surveys.

Temporality, cultural biography and seasonality: rethinking time in wetland archaeology

Wetland archaeology is uniquely well placed to investigate questions of chronology, temporality, life-cycles and seasonality. Beyond the usual archaeological approaches to time (eg seriation, typology and stratigraphy), most wetland archaeological investigations have access to a ready supply of samples (ie wood, peat and organic deposits) for absolute scientific dating, particularly radiocarbon and dendrochronology. Indeed, the success of dendrochronology in revealing dynamic sequences of site and regional occupation, use and abandonment are well known. Investigating wetland archaeological sites, environmental archaeologists have used the evidence of insects' plant remains, seeds and even testate amoeba to establish the season, or months, of a site's occupation. Soil micromorphologists have carried out innovative studies of settlement deposits to reconstruct the chronological sequences of processes and events leading to their formation. In brief, wetland archaeology has become adept at calibrating past times.

Places, perceptions, boundaries and tasks: rethinking landscapes in wetland archaeology

This paper is an elaboration of one of the chapters in our Rethinking Wetland Archaeology (Van de Noort & O'Sullivan 2006), and concerns the archaeological study of wetland landscapes. In this book, we argue that many approaches to the archaeology of wetlands have failed to influence our peers and colleagues in the broader field of landscape archaeology and, indeed, archaeology itself, and thus the great promise of wetland archaeology remains unfulfilled (Coles 2001).

The lake-dwellings in Holderness, East Yorkshire, revisited: a journey into antiquarian and contemporary wetland archaeology

The story presented in this paper began in the 1880s with the discovery of five unusual wet sites in the low-lying region of Holderness, East Yorkshire, during drainage works: West Furze, Round Hill, Barmston Drain, Gransmoor and Kelk (fig 1). The changing interpretation of the significance of these wet sites, from contemporary local accounts to their 'expert' publication early in the twentieth century (Smith 791I), contributed to the tale of the Holderness lake-dwellings, echoing the then already famous lake-dwellings of the Alpine region and elsewhere in Europe (Keller 1878). The tale of the Holderness lake-dwellings survived more recent work intact, as excavators approached the sites without challenging the preconception of these being genuine lake settlements (eg Varley 1968).

Thorne Moors: a contested wetland in north-eastern England

This paper explores the past, present and future of Thorne Moors. First, the paper addresses the landscape context of the Moors within the Humberhead Levels, and the archaeological and palaeoenvironmental resource. It also explores the management and protection of the archaeological and palaeoenvironmental resource of the Moors. Finally, it looks at the future with reference to the opportunity provided by its possible designation as a Ramsar site.

Science-based conservation and management in wetland archaeology: the example of Sutton Common, UK

This paper addresses the perception of different wetlands in and around the Humber estuary in the Bronze Age. Combining past and current research, it will be argued that the perception of intertidal wetlands was nearly diametrically opposed to the perception of riverine floodplains. This contrasting perception is reflected in the material culture of the Bronze Age, and may be explained through the particular manner in which landscapes changed following marine transgressions. This work was largely undertaken within the framework of the Humber Wetlands Survey, an integrated archaeological and palaeoenvironmental research programme funded by English Heritage since 1992

Where are Yorkshire’s terps? Wetland exploitation in the early medieval period

Where are the terps in Yorkshire, or for that matter where is any other evidence of exploitation of the wetlands in the early medieval period? Archaeological evidence remains largely elusive for the period between the early fifth and the late ninth century. Among the very few sites in wetland landscapes dated to this period are the settlement of York and the middle Anglo-Saxon bridge at Skerne in the Hull valley. Sites from the free-draining soils adjacent to wetlands are more frequent, and include a monastery (Beverley), settlements (e.g. Nafferton and North Frodingham), cemeteries (e.g. Hornsea, Burton Pidsea, Hessle, North Frodingham, Swine and Stamford Bridge) and various isolated finds (recently summarised in Van de Noort and Davies 1993).

Wetland habitats, their resource potential and exploitation: a case study from the Humber wetlands

The notion that wetlands are among the most productive environments in the world is widely quoted, but its relationship with the exploitation of wetland ecosystems during the prehistoric and early historic period has been the subject of few investigations. The current paper discusses the primary production of different wetland habitats and its relationship to the resource potential of these habitats and their actual exploitation, using recent results from the Humber Wetlands Survey. It is argued that during the early Holocene, wetland landscapes were central to the subsistence economy and that a clear association exists between the primary productivity of wetlands and the intensity of exploitation. With the introduction of agriculture, however, wetland habitats become increasingly peripheral to the economy.

The forms of bioavailability of phosphorus in integrated vertical flow constructed wetland with earthworms and different substrates

A sequential extraction method was utilized to analyze seven forms of P in an integrated vertical-flow constructed wetland (IVFCW) containing earthworms and different substrates. The aluminum-bound P (Al-P) content was found to be lower, and the occluded P (Oc-P) content was higher in the IVFCW. The addition of earthworms into the influent chamber of IVFCW increased the exchange P (Ex-P), iron-bound P (Fe-P), calcium bound P (Ca-P), Oc-P, detritus-bound (De-P) and organic P (Org-P) content in the influent chamber, and also enhanced P content uptake by wetland plants. A significantly positive correlation between P content of above-ground wetland plants and the Ex-P, Fe-P, Oc-P and Org-P content in the rhizosphere was found (P < 0.05), which indicated that the Ex-P, Fe-P, Oc-P and Org-P could be bio-available P. The Ex-P, Fe-P, De-P, Oc-P and Ca-P content of the influent chamber was higher where the substrate contained a mixture of Qing sand and river sand rather than only river sand. Also the IVFCW with earthworms and both Qing sand and river sand had a higher removal efficiency of P, which was related to higher P content uptake by wetland plants and P retained in IVFCW. These findings suggest that addition of earthworms in IVFCW increases the bioavailable P content, resulting in enhanced P content uptake by wetland plants.