TECHNIQUES FOR STUDYING THE BIOGEOCHEMISTRY OF NUTRIENTS IN THE TAMAR CATCHMENT

Chapter One describes nitrogen and phosphorus species in the aquatic environment, their role in eutrophication, current legislation relevant to nutrient water quality and catchment management and the role of predictive modelling of nutrient export with respect to the management of river catchments. It also summarises analytical techniques for the determination of nitrogen and phosphorus species in natural waters and the use of generic ecotoxicological assays to link nutrient water quality and organism health. Data integrity is essential to biogeochemical studies that inform scientific research and environmental management. Reliable, accurate data permit valid conclusions to be drawn. The quality assurance and quality control measures undertaken to ensure good analytical data in this study, including participation in the certification of a seawater certified reference material for nutrients (MOOS-1), are discussed in Chapter Two. In Chapter Three, the nutrient biogeochemistry of the waters leaving the Tamar catchment and entering the Tamar estuary is discussed. Historical nutrient and physico-chemical data for the Tamar River at Gunnislake were used to identify long-term environmental trends (1974 to 2004) and nutrient and physico-chemical data collected in this study between May 2003 and May 2004 was used to identify short-term trends over the study period. The nutrient export coefficient modelling approach was used to model phosphorus and nitrogen export from the Tamar catchment (Chapter Four). A TP export model from the Tamar catchment was successfully constructed using historical land use data and catchment demographics, calibrated with hindcasted water quality data, and validated with TP field data (May 2003 and May 2004) collected in this study. Modelled P (43. 5 tonnes P yˉ¹) export agreed within 8 % with the measured P load (40.1 tonnes P yˉ¹). An annual TN model was also constructed and calibrated for the Tamar catchment using the May 2003 to May 2004 field data. The calibrated model agreed within I % of the measured TN export (2053 tonnes N yˉ¹). The development and deployment of a portable Fl analyser for continuous, real-time monitoring of FRP in the Tamar catchment is discussed in Chapter Five. The optimised method can be used for the determination of FRP in freshwater systems (4-150 µg Lˉ¹ P) and in coastal waters (10-150 µg Lˉ¹ P) and is capable of sampling with high temporal resolution (up to 15 samples hˉ¹) . The analyser was used in situ (bank-side and shipboard deployment) to provide real-time FRP data and in the laboratory to determine FRP in freshwater samples. All data were in good agreement with values obtained using a validated air-segmented, continuous flow laboratory reference method The acute toxicity of nitrate and nitrite on the freshwater swan mussel, Anodonta cygnea, was investigated (Chapter Six). A 96 h LC50 value of 222 mg Lˉ¹ N for the exposure of A. cygnea to nitrite was established in this study. Toxicity studies indicated that nitrate was not toxic to A. cygnea. Established indicators of physiological stress were used to determine the effect of environmentally high and extreme levels of nitrite on A. cygnea. There was no significant difference in cardiac activity, condition index or lysosomal stability between control organisms (0 mg Lˉ¹ N) and organisms exposed to sub-lethal nitrite concentrations (0.1, 1.0, 22.2 mg Lˉ¹ N). Therefore, nitrite concentrations encountered in typical freshwater catchments such as the Tamar catchment are unlikely to induce physiological stress in A.cygnea

Early indicators of soil formation in the Icelandic sub-arctic highlands

Publisher's version (útgefin grein)Andisols are carbon-rich soils that persist in volcanic regions with cool climates. They are the main soil type in Iceland, where there are also large areas of premature or degraded mineral soils with the possible potential to become andisols. This study examines soils from vegetated and unvegetated sites to look at the earliest indicators of andisol formation and soil organic carbon accumulation. Soils from 12 sites in the southern Icelandic highlands, which are characterised by harsh climate, shallow soils and limited vegetation cover, were sampled at four depths (0–5 cm, 5–10 cm, 10–20 cm and 20–30 cm). Three sites were sparsely vegetated gravels (M1–M3) and nine were fully vegetated, including 8 grassland sites (G1–G8) with mosses and dwarf shrubs, and a sandy fluvial wetland (S) with grasses, mosses and dwarf shrubs. Soils with vegetative cover were characterised as weak or structureless ranging from loamy sand to silty clay loam, while soils at the sparsely vegetated sites were structureless and sandy. The soil depth is greater in the vegetated sites, indicating greater soil development. On average, the bulk density of soils (0.75–1.16 g cm−3) was lower at vegetated sites than sparsely vegetated sites (0.90–1.17 g cm−3). The average carbon (%C), nitrogen (%N) and the overall soil organic matter (%SOM) of vegetated sites were higher (1.60%C, 0.10%N, 4.9%SOM) than for sparsely vegetated sites (0.27%C, 0.02%N, 1.81%SOM) with lower pH at the vegetated sites (pH 7.2), indicating the difference in soil development. Silandic allophanic material is present throughout the study area: all soils had >10% amounts of amorphous clay minerals (allophane, ferrihydrite or aluminium-humus complexes) and high aluminium and iron percentages. Strong associations between pyrophosphate-extractable Fe and Al and the soil C, indicative of Al and Fe complexed with humus or allophane and ferrihydrite clays of vegetated sites were observed. The %C, %SOM, Fe/Al associations, soil structure and soil depth all suggest that there is gradient of increasing soil genesis from sparsely vegetated to vegetated sites. Although the soils at the vegetated sites may be considered to be andisols, they are still immature, while the less developed soils at the sparsely vegetated sites are vitrisols (<1% C) and have not yet developed into andisols. Both of these groups are still undergoing pedological transformation and have not yet reached the C content of more mature andisols but indicate the potential for increased C accumulation. This study suggests there is potential for these soils to develop into the more fertile andisols over time through vegetation and vegetative succession.The research was financed by Landsvirkjun and we specially wish to thank Hákon Aðalsteinsson, of Lansvirkjun, for his interest and support of this project. We would also like to thank María Svavarsdóttir, Höskuldur Þorbjarnarson, Olga Kolbrún Vilmundardóttir, Eydís S. Eiríksdóttir, and Friðþór Sófus Sigurmundsson of the University of Iceland, Brita Berglund of the Agricultural University of Iceland and Joe Jephson.Peer Reviewe

Designing Aquaponic Production Systems towards Integration into Greenhouse Farming

Publisher's version (útgefin grein).Aquaponics is a sustainable method of food production, whereby aquaculture and hydroponics are combined in one circular system. A few aquaponics startup companies are emerging in Europe with a limited production area of a few hundred or a few thousand square meters, whereas hydroponics is a common practice in a commercially viable manner most often with production units of several hectares. In Iceland, greenhouse farmers operate on relatively small production units, often between 2000 and 5000 m2. The aim of the present study was, therefore, to develop and design aquaponic production systems towards integration into small greenhouse farming strengthening economic viability and sustainability. Since the local market in Iceland is small and import is relatively expensive due to the distance from other markets, the suitability of commercially available fish feed and the selection of plant species were assessed in relation to production efficiency and available market and resources. The effects of water flow on plant growth and on nutrient utilization in culture water were measured and evaluated. Four aquaponics test systems were designed, built and operated, and results were used to develop a pilot commercial aquaponics system implemented for greenhouse farming in Iceland. One of the test systems was a media filled flood and drain system and the other three were deep water culture systems. Tilapia (Oreochromis niloticus), one of the most popular fish in aquaculture, was reared in all systems, while different leafy greens and fruiting vegetables were grown in the hydroponics. The fish was fed with commercial aquaculture feed made for cod and charr. The feed conversion ratio (FCR) was used to assess the effectiveness of feed on fish growth. The FCR observed in this research was between 0.9 and 1.2, within the typical values for tilapia growth in aquaculture. The production of the leafy green plants (e.g., pak-choi) was approximately four times, by weight, that of the production of fish, a similar yield as shown in other researches in the field. The continuous rise of nitrate and phosphate concentrations in the aquaponic system indicated the potential to support even higher crop yield. Long daylength in the summer in Iceland is clearly beneficial for crop production in aquaponics. Based on the results, it is concluded that aquaponics can be a feasible opportunity for greenhouse farming at least to diversify the current business model. Not only can the fish provide an extra income but also the effluent from the aquaculture is easily used as fertilizer for the plants, thus the circular production system offers new innovative ideas for diversifying and value-adding the business further, for example into crayfish production and/or into educational and experience tourism.Coworkers at the University of Iceland, the Agricultural University of Iceland, Svinna-verkfraedi Ltd and growers providing assistance and infrastructure are acknowledged. This research was funded by The Icelandic Centre for Research grant number 142372 and the European Commission grant number ECO/12/332783. The APC was funded by the University of Iceland.Peer Reviewe

Representativeness of European biochar research: part II–pot and laboratory studies

Biochar research is extensive and there are many pot and laboratory studies carried out in Europe to investigate the mechanistic understanding that govern its impact on soil processes. A survey was conducted in order to find out how representative these studies under controlled experimental conditions are of actual environmental conditions in Europe and biomass availability and conversion technologies. The survey consisted of various key questions related to types of soil and biochar used, experimental conditions and effects of biochar additions on soil chemical, biological and physical properties. This representativeness study showed that soil texture and soil organic carbon contents used by researchers are well reflected in the current biochar research in Europe (through comparison with published literature), but less so for soil pH and soil type. This study provides scope for future work to complement existing research findings, avoiding unnecessary repetitions and highlighting existing research gaps. © 2017 The Author(s) Published by VGTU Press and Informa UK Limited, [trading as Taylor & Francis Group]

Representativeness of European biochar research : part II – pot and laboratory studies

Biochar research is extensive and there are many pot and laboratory studies carried out in Europe to investigate the mechanistic understanding that govern its impact on soil processes. A survey was conducted in order to find out how representative these studies under controlled experimental conditions are of actual environmental conditions in Europe and biomass availability and conversion technologies. The survey consisted of various key questions related to types of soil and biochar used, experimental conditions and effects of biochar additions on soil chemical, biological and physical properties. This representativeness study showed that soil texture and soil organic carbon contents used by researchers are well reflected in the current biochar research in Europe (through comparison with published literature), but less so for soil pH and soil type. This study provides scope for future work to complement existing research findings, avoiding unnecessary repetitions and highlighting existing research gaps.Peer reviewe

Representativeness of European biochar research : Part I - field experiments

A representativeness survey of existing European Biochar field experiments within the Biochar COST Action TD1107 was conducted to gather key information for setting up future experiments and collaborations, and to minimise duplication of efforts amongst European researchers. Woody feedstock biochar, applied without organic or inorganic fertiliser appears over-represented compared to other categories, especially considering the availability of crop residues, manures, and other organic waste streams and the efforts towards achieving a zero waste economy. Fertile arable soils were also over-represented while shallow unfertile soils were under-represented. Many of the latter are likely in agroforestry or forest plantation land use. The most studied theme was crop production. However, other themes that can provide evidence of mechanisms, as well as potential undesired side-effects, were relatively well represented. Biochar use for soil contamination remediation was the least represented theme; further work is needed to identify which specific contaminants, or mixtures of contaminants, have the potential for remediation by different biochars.Peer reviewe

Representativeness of European biochar research: part I–field experiments

A representativeness survey of existing European Biochar field experiments within the Biochar COST Action TD1107 was conducted to gather key information for setting up future experiments and collaborations, and to minimise duplication of efforts amongst European researchers. Woody feedstock biochar, applied without organic or inorganic fertiliser appears over-represented compared to other categories, especially considering the availability of crop residues, manures, and other organic waste streams and the efforts towards achieving a zero waste economy. Fertile arable soils were also over-represented while shallow unfertile soils were under-represented. Many of the latter are likely in agroforestry or forest plantation land use. The most studied theme was crop production. However, other themes that can provide evidence of mechanisms, as well as potential undesired side-effects, were relatively well represented. Biochar use for soil contamination remediation was the least represented theme; further work is needed to identify which specific contaminants, or mixtures of contaminants, have the potential for remediation by different biochars. © 2017 The Author(s) Published by VGTU Press and Informa UK Limited, [trading as Taylor & Francis Group]

NUTRIENT LOADING IN THE TAMAR CATCHMENT, UK: REFINEMENT OF THE COEFFICIENT MODELLING APPROACH

An export coefficient model for the prediction of TP export from the Tamar catchment was successfully refined and calibrated in this study. Modelled TP export (43,549 kg P) from the Tamar catchment in 1998 was within 12 % agreement measured TP export (49,507 kg) over the same period. Further refinement of the model to predict seasonal (monthly) TP export from the catchment indicated that the modelled monthly TP loads are in good agreement with the measured loads (r² = 0.85). TP export from the catchment is dominated by land use practices and lands dedicated to grazing (meadows and grazed turf) dominate the land use of the area. A sensitivity analysis (± 10 %) indicated that the nutrient export from meadows (3.65 %), STWs (1.90 %) and mown/grazed turf (1.42%) are the major factors affecting the model outcome. The Tamar River as it leaves the Tamar catchment and enters the Tamar estuary appears to be P limited based on an estimated TN:TP ratio of 58:1. The calibrated model was used to assess the impact of 50% loss of sheep and cattle and conversion of the associated grazing lands to tilled lands. The predicted an increase in TP export (12%). This study also attempted to refine a model to predict TN export from the catchment. Although TN export was modeled but model calibration was constrained by the unavailability of measured TN data. A comparison was attempted with TN data estimated from DIN field data for the catchment. Modelled TN export from the catchment was 2508 metric tonnes TN and was within 8% agreement of TN estimated from observed DIN data. A sensitivity analysis (± 10 %) showed that the outcome of TN model would be most strongly influenced by exports from rainfall (8.1 %) which was also the largest contribution to modelled N exports from the Tamar catchment (81%)

Soil Research Concepts that will Underpin European Soil Sustainability. Soil sustainability in Europe as deduced from investigation of the Critical Zone

SoilCritZone, an FP6 Specific Support Action, organised a series of four workshops to discuss the future of soil research in Europe. These workshops included participants from the European, African, Chinese and US soil communities. In these workshops the community formulated research questions based on four Working Groups: 1) Soil Degradation, 2) Weathering, 3) Biodiversity and Cross-cutting Issues, and 4) Modelling the Life Cycle of Soils. The outcomes of the Working Groups from Workshop 1 (Bristol, UK – October 2007) and Workshop 2 (Sofia, Bulgaria – April 2008) were presented to and discussed with Early Stage Researchers in Workshop 3 (Chania, Crete, Greece – September 2008) and with stakeholders in Workshop 4 (Vienna, Austria – April 2009). In the SoilCritZone project, we have set the soil system within the Critical Zone and by doing so have enlarged the research agenda so that the whole life-cycle of soil can be investigated and modelled. The SoilCritZone Project extended its research goals beyond the protection and remediation of soils, by including the question about the rate of soil formation through weathering and further biological processes (including soil biodiversity), as a natural counterbalance to anthropogenic soil degradation. We also framed soil system parameters for modelling the life cycle of soils, thus defining gains and losses of soils on a quantifiable basis. The Working Groups formulated a number of research questions that are necessary in order to be able to model the life cycle of soils. The key outcomes of the SoilCritZone project are that the European research community should develop soil research questions within the framework of the Earth´s Critical Zone and, that soil observatories should be set up where measured parameters allow the modelling of the life cycle of soils. This report suggests criteria, based on geology, geography, climate, hydrology, European soil types and land use, for the selection of European soil observatories. We took into account sites suggested by the workshop participants and the research that has already taken place within the European and the US (www.czen.org) soil community. Our contribution thus sets the scene for a new approach in soil research so that the soils of Europe and the world can be protected for future generations. This final report from the SoilCritZone Specific Support Action can be used to underpin the forthcoming EU Soil Framework Directive, which is based on the Thematic Strategy for Soil Protection that was adopted by the European Commission in September, 2006

Challenges of Sustainable and Commercial Aquaponics

The world is facing a number of serious problems of which population rise, climate change, soil degradation, water scarcity and food security are among the most important. Aquaponics, as a closed loop system consisting of hydroponics and aquaculture elements, could contribute to addressing these problems. However, there is a lack of quantitative research to support the development of economically feasible aquaponics systems. Although many studies have addressed some scientific aspects, there has been limited focus on commercial implementation. In this review paper, opportunities that have the potential to fill the gap between research and implementation of commercial aquaponic systems have been identified. The analysis shows that aquaponics is capable of being an important driver for the development of integrated food production systems. Arid regions suffering from water stress will particularly benefit from this technology being operated in a commercial environment