CH and N O emissions from smallholder agricultural systems on tropical peatlands in Southeast Asia.

There are limited data for greenhouse gas (GHG) emissions from smallholder agricultural systems in tropical peatlands, with data for non-CO emissions from human-influenced tropical peatlands particularly scarce. The aim of this study was to quantify soil CH and N O fluxes from smallholder agricultural systems on tropical peatlands in Southeast Asia and assess their environmental controls. The study was carried out in four regions in Malaysia and Indonesia.

Operating at the extreme: estimating the upper yield boundary of winter wheat production in commercial practice.

Wheat farming provides 28.5% of global cereal production. After steady growth in average crop yield from 1950 to 1990, wheat yields have generally stagnated, which prompts the question of whether further improvements are possible.

Author Correction: Greenhouse gas emissions resulting from conversion of peat swamp forest to oil palm plantation.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The impact of long-term biosolids application (>100 years) on soil metal dynamics.

Biosolids application to arable land is a common, and cost-effective, practice but the impact of prolonged disposal remains uncertain. We evaluated the dynamics of potentially toxic elements (PTEs) at a long-established 'dedicated' sewage treatment farm. Soil metal concentrations exceeded regulations governing application of biosolids to non-dedicated arable land.

Greenhouse gas emissions resulting from conversion of peat swamp forest to oil palm plantation.

Conversion of tropical peat swamp forest to drainage-based agriculture alters greenhouse gas (GHG) production, but the magnitude of these changes remains highly uncertain. Current emissions factors for oil palm grown on drained peat do not account for temporal variation over the plantation cycle and only consider CO emissions. Here, we present direct measurements of GHGs emitted during the conversion from peat swamp forest to oil palm plantation, accounting for CH and NO as well as CO.

Short-Term Iodine Dynamics in Soil Solution.

Assessing the reactions of iodine (I) in soil is critical to evaluate radioiodine exposure and understand soil-to-crop transfer rates. Our mechanistic understanding has been constrained by method limitations in assessing the dynamic interactions of iodine between soil solution and soil solid phase over short periods (hours). We use microdialysis to passively extract soil solution spiked with radioiodine (I and IO) to monitor short-term (≤40 h) in situ fixation and speciation changes.

Kinetics of Tc speciation in aerobic soils.

Technetium-99 is a significant and long-lived component of spent nuclear fuel relevant to long-term assessments of radioactive waste disposal. Whilst Tc behaviour in poorly aerated environments is well known, the long-term bioavailability in aerobic soils following direct deposition or transport to the surface is less well understood. This work addresses two questions: (i) to what extent do soil properties control Tc kinetics in aerobic soils and (ii) over what experimental timescales must Tc kinetics be measured to make reliable long-term predictions of impact in the terrestrial environment? Soil microcosms spiked with TcO were incubated for 2.

Zinc uptake and phyto-toxicity: Comparing intensity- and capacity-based drivers.

Metal bioavailability and phytotoxicity may be exaggerated when derived from studies based on amending soils with soluble metal salts. It is therefore important to evaluate soil tests for their consistency in estimating plant uptake and phytotoxicity in both field-contaminated and freshly-spiked soils. This study aimed to compare the effects of zinc (Zn) on plant growth in soils (i) recently spiked with soluble Zn and (ii) historically amended with biosolids.

Assessment of potentially toxic elements in vegetables cultivated in urban and peri-urban sites in the Kurdistan region of Iraq and implications for human health.

Vegetable fields in and around urban areas in the Kurdistan region of Iraq may have higher than background concentrations of potentially toxic elements (PTEs) from contamination sources including municipal waste disposal and wastewater used for irrigation. The purpose of this study was to assess PTE concentrations in soils and the edible parts of field-grown vegetables to quantify potential health risks to the local population. In this survey, 174 soils and 26 different vegetable and fruit types were sampled from 15 areas around Sulaymaniyah and Halabja cities.

Analysis of I and I in soils of the Chernobyl Exclusion Zone, 29 years after the deposition of I.

The Chernobyl Exclusion Zone (CEZ) represents a unique natural laboratory that received significant I contamination across a range of soils and land-use types in a short time period in 1986. Data are presented on I and I in soil samples collected from highly contaminated areas in the CEZ in 2015. The geometric mean (GM) total concentration of stable iodine (I) was 6.

Fit-for-purpose modelling of radiocaesium soil-to-plant transfer for nuclear emergencies: a review.

Numerous radioecological models have been developed to predict radionuclides transfer from contaminated soils to the food chain, which is an essential step in preparing and responding to nuclear emergencies. However, the lessons learned from applying these models to predict radiocaesium (RCs) soil-to-plant transfer following the Fukushima accident in 2011 renewed interest in RCs transfer modelling. To help guide and prioritise further research in relation to modelling RCs transfer in terrestrial environments, we reviewed existing models focussing on transfer to food crops and animal fodders.

Quantification of root water uptake in soil using X-ray computed tomography and image-based modelling.

Spatially averaged models of root-soil interactions are often used to calculate plant water uptake. Using a combination of X-ray computed tomography (CT) and image-based modelling, we tested the accuracy of this spatial averaging by directly calculating plant water uptake for young wheat plants in two soil types. The root system was imaged using X-ray CT at 2, 4, 6, 8 and 12 d after transplanting.

Forage grasses with lower uptake of caesium and strontium could provide 'safer' crops for radiologically contaminated areas.

Substitution of a species or cultivar with higher uptake of an element by one with lower uptake has been proposed as a remediation strategy following accidental releases of radioactivity. However, despite the importance of pasture systems for radiological dose, species/cultivar substitution has not been thoroughly investigated for forage grasses. 397 cultivars from four forage grass species; hybrid ryegrass (Lolium perenne L.

The response of soil microbial diversity and abundance to long-term application of biosolids.

The disposal of biosolids poses a major environmental and economic problem. Agricultural use is generally regarded as the best means of disposal. However, its impact on soil ecosystems remains uncertain.

Derivation of irrigation requirements for radiological impact assessments.

When assessing the radiological impacts of radioactive waste disposal, irrigation using groundwater contaminated with releases from the disposal system is a principal means of crop and soil contamination. In spite of their importance for radiological impact assessments, irrigation data are scarce and often associated with considerable uncertainty for several reasons including limited obligation to measure groundwater abstraction and differences in measuring methodologies. Further uncertainty arises from environmental (e.

Assessing the influence of the rhizosphere on soil hydraulic properties using X-ray computed tomography and numerical modelling.

Understanding the dynamics of water distribution in soil is crucial for enhancing our knowledge of managing soil and water resources. The application of X-ray computed tomography (CT) to the plant and soil sciences is now well established. However, few studies have utilized the technique for visualizing water in soil pore spaces.

Kinetics of zinc and cadmium release in freshly contaminated soils.

The kinetics of metal release from the solid phase to solution was measured on two sets of 14 freshly contaminated soils with diverse properties. From measurements of metal concentrations in extracted soil pore water, the amount accumulated from the soil by diffusive gradients in thin-film (DGT) devices, and the distribution coefficient for labile metal, Kdl, estimated by isotopic exchange, we calculated the response time, Tc, of the soil-solution system to the removal of metal by DGT and the rate constant for release from the solid phase, k(-1). Resupply was so fast for Zn that Tc (and k(-1)) could be measured only in three of the soils, with either a silty or a sandy loam texture and low to intermediate pH (4.

Kinetics of metal fixation in soils: measurement and modeling by isotopic dilution.

The bioavailability of metal contaminants in soils varies widely, depending on soil characteristics and the source of the contaminant. As a consequence, site-specific risk assessment requires accurate prediction of the bioavailable (or labile) fraction of soil metal. Moreover, metals in soil are subject to time-dependent processes, which affect their bioavailability and thereby complicate the prediction of future risk.

Effects of gamma irradiation on Holcus lanatus (Yorkshire fog grass) and associated soil microorganisms.

An investigation was conducted to determine the impact of acute doses of gamma radiation on the microbial community structure of a Holcus lanatus dominated grassland soil. Mesocosms containing soil and established grass were irradiated using a sealed (137)Cs source (7.0 Gy min(-1)).

Assessing potential risk of heavy metal exposure from consumption of home-produced vegetables by urban populations.

We performed a risk assessment of metal exposure to population subgroups living on, and growing food on, urban sites. We modeled uptake of cadmium, copper, nickel, lead, and zinc for a selection of commonly grown allotment and garden vegetables. Generalized linear cross-validation showed that final predictions of Cd, Cu, Ni, and Zn content of food crops were satisfactory, whereas the Pb uptake models were less robust.