Soil organic matter (SOM) in forest soil is of major importance for cation binding and acid buffering, but its characteristics may differ among soils under different tree species. We investigated ...acidity, cation exchange properties and Al bonding to SOM in stands of Scots pine, pedunculate oak, Norway spruce, European beech and common hornbeam in southern Poland. The content of total carbon (Ct) was by far the major contributor to total cation exchange capacity (CECt) even in loamy soils and a strong relationship between Ct and CECt was found. The slope of the regression of CECt to Ct increased in the order hornbeam≈oak<beech<spruce≈pine, suggesting that the number of negatively charged sites of SOM at any value in the acid pH range was smallest for hornbeam and oak, and largest for spruce and pine soils. This was supported by the apparent dissociation constant (pKapp) values of SOM, which were largest in soils under oak. The maximum values of Al saturation were similar between the stands. However, maximum Al bonding to SOM occurred at higher pH values in soils under pine and spruce than under oak. Therefore, at any value in the acid pH range, the SOM in pine soil has less Al complexed and more adsorbed H+ than SOM from oak soils. Such differences in Al and H bonding are not only important for pH buffering and metal solubility controls, but also for stabilization of SOM via saturation of functional groups by Al and H.
•We investigated cation bonding to SOM in stands of several European tree species.•The CECt to Ct ratio increased in the order hornbeam≈oak<beech<spruce≈pine.•The apparent dissociation constant (pKapp) values were largest under oak.•Maximum Al saturation occurred at higher pH under pine and spruce than under oak.•At similar pH pine soil had less Al complexed and more adsorbed H than soils from oak.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Nitrous oxide (N2O) is a greenhouse gas that also plays the primary role in stratospheric ozone depletion. The use of nitrogen fertilizers is known as the major reason for atmospheric N2O increase. ...Empirical bottom‐up models therefore estimate agricultural N2O inventories using N loading as the sole predictor, disregarding the regional heterogeneities in soil inherent response to external N loading. Several environmental factors have been found to influence the response in soil N2O emission to N fertilization, but their interdependence and relative importance have not been addressed properly. Here, we show that soil pH is the chief factor explaining regional disparities in N2O emission, using a global meta‐analysis of 1,104 field measurements. The emission factor (EF) of N2O increases significantly (p < .001) with soil pH decrease. The default EF value of 1.0%, according to IPCC (Intergovernmental Panel on Climate Change) for agricultural soils, occurs at soil pH 6.76. Moreover, changes in EF with N fertilization (i.e. ΔEF) is also negatively correlated (p < .001) with soil pH. This indicates that N2O emission in acidic soils is more sensitive to changing N fertilization than that in alkaline soils. Incorporating our findings into bottom‐up models has significant consequences for regional and global N2O emission inventories and reconciling them with those from top‐down models. Moreover, our results allow region‐specific development of tailor‐made N2O mitigation measures in agriculture.
We identified soil pH as the chief factor modifying regional response in N2O emission to N fertilization, based on an updated global meta‐analysis of 1,104 field measurements. Both N2O emission factor (i.e. EF) and nonlinearity coefficient (i.e. ΔEF) were found to negatively correlated with soil pH. Incorporating our findings into bottom‐up models could help to construct sound global N2O inventories, to reconcile the discrepancies between top‐down and bottom‐up N2O estimates, and to develop optimized region‐specific measures for N2O mitigation from agriculture.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
•Biochar of various particle sizes was applied to light-textured tropical soils.•Biochar increased aggregate stability more strongly under soybeans than under maize.•Percent stable soil aggregates ...levelled off at high biochar content of aggregates.•Biochar altered soil pore-size distribution causing an increase in available water.•Biochar reduced soil bulk density due to soil aggregation and weight dilution.
Biochar (BC) has been reported to improve soil physical properties mainly in laboratory and greenhouse pot experiments. Here we study, under field conditions, the effect of BC and its particle sizes on soil aggregate stability, bulk density (BD), water retention, and pore size distribution in two experiments in Zambia. A) Farmer practice experiment in sandy loam with maize cob BC in conservation farming planting basins under maize and soybeans crops. B) Maize cob and rice husk BC particle size experiments (≤0.5, 0.5–1 and 1–5mm particle sizes) in loamy sand and sand. In the farmer practice experiment, BC increased aggregate stability by 7–9% and 17–20% per percent BC added under maize and soybeans crops respectively (p<0.05) after two growing seasons. Total porosity and available water capacity (AWC) increased by 2 and 3% respectively per percent BC added (p<0.05) under both crops, whereas BD decreased by 3–5% per percent BC added (p≤0.01). In the maize cob BC particle size experiment after one growing season, dose was a more important factor than particle size across the soils tested. Particle size of BC was more important in loamy sand than in sand, with ≤0.5 and 1–5mm sizes producing the strongest effects on the measured properties. For example, BD decreased while total porosity increased (p<0.01) for all BC particle sizes in sand whereas only 1–5mm BC significantly decreased BD and increased total porosity in loamy sand (p<0.05). However, AWC was significantly increased by only ≤0.5 and 1–5mm BCs by 7–9% per percent BC added in both loamy sand and sand. Rice husk BC effect after one year followed similar pattern as maize cob BC but less effective in affecting soil physical properties. Overall, reduced density of soil due to BC-induced soil aggregation may aid root growth and with more water available, can increase crop growth and yields.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Biochar (BC) application to soil suppresses emission of nitrous- (N2O) and nitric oxide (NO), but the mechanisms are unclear. One of the most prominent features of BC is its alkalizing effect in ...soils, which may affect denitrification and its product stoichiometry directly or indirectly. We conducted laboratory experiments with anoxic slurries of acid Acrisols from Indonesia and Zambia and two contrasting BCs produced locally from rice husk and cacao shell. Dose-dependent responses of denitrification and gaseous products (NO, N2O and N2) were assessed by high-resolution gas kinetics and related to the alkalizing effect of the BCs. To delineate the pH effect from other BC effects, we removed part of the alkalinity by leaching the BCs with water and acid prior to incubation. Uncharred cacao shell and sodium hydroxide (NaOH) were also included in the study. The untreated BCs suppressed N2O and NO and increased N2 production during denitrification, irrespective of the effect on denitrification rate. The extent of N2O and NO suppression was dose-dependent and increased with the alkalizing effect of the two BC types, which was strongest for cacao shell BC. Acid leaching of BC, which decreased its alkalizing effect, reduced or eliminated the ability of BC to suppress N2O and NO net production. Just like untreated BCs, NaOH reduced net production of N2O and NO while increasing that of N2. This confirms the importance of altered soil pH for denitrification product stoichiometry. Addition of uncharred cacao shell stimulated denitrification strongly due to availability of labile carbon but only minor effects on the product stoichiometry of denitrification were found, in accordance with its modest effect on soil pH. Our study indicates that stimulation of denitrification was mainly due to increases in labile carbon whereas change in product stoichiometry was mainly due to a change in soil pH.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Mercury (Hg) is a potentially harmful trace element in the environment and one of the World Health Organization's foremost chemicals of concern. The threat posed by Hg contaminated soils to humans is ...pervasive, with an estimated 86 Gg of anthropogenic Hg pollution accumulated in surface soils worldwide. This review critically examines both recent advances and remaining knowledge gaps with respect to cycling of mercury in the soil environment, to aid the assessment and management of risks caused by Hg contamination. Included in this review are factors affecting Hg release from soil to the atmosphere, including how rainfall events drive gaseous elemental mercury (GEM) flux from soils of low Hg content, and how ambient conditions such as atmospheric O3 concentration play a significant role. Mercury contaminated soils constitute complex systems where many interdependent factors, including the amount and composition of soil organic matter and clays, oxidized minerals (e.g. Fe oxides), reduced elements (e.g. S2−), as well as soil pH and redox conditions affect Hg forms and transformation. Speciation influences the extent and rate of Hg subsurface transportation, which has often been assumed insignificant. Nano-sized Hg particles as well as soluble Hg complexes play important roles in soil Hg mobility, availability, and methylation. Finally, implications for human health and suggested research directions are put forward, where there is significant potential to improve remedial actions by accounting for Hg speciation and transportation factors.
•Mercury contaminated soils constitute complex systems with many interdependent factors.•Speciation, complexation and particle size play important roles in subsurface transport.•Rainfall events and atmospheric ozone levels influence Hg flux to the atmosphere.•Implications for human health and suggested research directions are put forward.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The Netherlands is a low-lying country, in which 9 million people are living below sea level and 70% of the gross domestic product is being earned in areas below sea level. Therefore, protection ...against flooding is traditionally the primary focus of coastal policy in the Netherlands. Analysis shows that characteristics of Dutch coastal management very well comply with the recommendations and key concepts to support sustainable coastal management as issued by the EU in 2004 (EUROSION). Sediment management represents the core of erosion management in the Netherlands; key concepts like resilience, coastal sediment cells, favorable sediment status and strategic sediment reservoirs, are important building stones. Development and implementation of coastal erosion management in the Netherlands, has implicitly been guided by a systematic Frame-of-Reference. Characteristics of this approach are the definition of clear objectives at different levels (i.e. strategic, tactical and operational) and an operational decision recipe related to policy development and implementation. Application of the Frame-of-Reference to current problems and challenges in Dutch coastal management indicates its ability to reveal shortcomings of the existing approach, and to explore potential solutions. Where EUROSION offers important concepts to define coastal erosion management, the Frame-of-Reference offers a tool to discern different objectives and responsibilities. The combination of both strongly supports implementation of coastal erosion management.
► We show that Dutch coastal policy is characterized by objectives at 3 scale levels. ► Sediment management is the core of erosion management, defined by 4 key concepts. ► Resilience, sediment cells, favorable sediment status and strategic reservoirs. ► Development and implementation is guided by a systematic Frame-of-Reference. ► A tool to discern different objectives and responsibilities.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
We review and synthesize the current state of knowledge regarding acid deposition and its environmental effects across Asia. The extent and magnitude of acid deposition in Asia became apparent only ...about one decade after this issue was well described in Europe and North America. In addition to the temperate zone, much of eastern and southern Asia is situated in the tropics and subtropics, climate zones hitherto little studied with respect to the effects of high loads of acid deposition. Surface waters across Asia are generally not sensitive to the effects of acid deposition, whereas soils in some regions are sensitive to acidification due to low mineral weathering. However, soil acidification was largely neutralized by such processes as base cation deposition, nitrate (NO3−) denitrification, and sulfate (SO42−) adsorption. Accompanying the decrease in S deposition in recent years, N deposition is of increasing concern in Asia. The acidifying effect of N deposition may be more important than S deposition in well drained tropical/subtropical soils due to high SO42− adsorption. The risk of regional soil acidification is a major threat in Eastern Asia, indicated by critical load exceedance in large areas.
•Here review more recent studies on acid deposition in Asia, especially in Eastern Asia.•Surface waters are generally not sensitive to acid deposition in comparison with soils.•Soil acidification is not very serious because of base cation deposition, N denitrification, and SO42− sorption.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Analysis of the pattern of proteins or messenger RNAs (mRNAs) in histological tissue sections is a cornerstone in biomedical research and diagnostics. This typically involves the visualization of a ...few proteins or expressed genes at a time. We have devised a strategy, which we call "spatial transcriptomics," that allows visualization and quantitative analysis of the transcriptome with spatial resolution in individual tissue sections. By positioning histological sections on arrayed reverse transcription primers with unique positional barcodes, we demonstrate high-quality RNA-sequencing data with maintained two-dimensional positional information from the mouse brain and human breast cancer. Spatial transcriptomics provides quantitative gene expression data and visualization of the distribution of mRNAs within tissue sections and enables novel types of bioinformatics analyses, valuable in research and diagnostics.
We studied the role of biochar in improving soil fertility for maize production. The effects of biochar on the alleviation of three potential physical-chemical soil limitations for maize growth were ...investigated, i.e. water stress, nutrient stress and acid stress. Experiments involved soils with two dosages of biochar (0.5% and 2% w:w), as well as ones without biochar, in combination with four different dosages of NPK fertilizer, water and lime. Biochar was produced from the invasive shrubby weed Eupatorium adenophorum using flame curtain kilns. This is the first study to alleviate one by one the water stress, nutrient stress and acid stress in order to investigate the mechanisms of biochar effects on soil fertility.
Biochar addition increased soil moisture, potassium (K) and plant available phosphorous (P-AL), which all showed significant positive relationship (p<0.001) with above ground biomass of maize. However, biochar was much more effective at abundant soil watering (+311% biomass) than at water-starved conditions (+67% biomass), indicating that biochar did increase soil moisture, but that this was not the main reason for the positive biomass growth effects. Biochar addition did have a stronger effect under nutrient-stressed conditions (+363%) than under abundant nutrient application (+132%). Biochar amendment increased soil pH, but liming and pH had no effect on maize dry biomass, so acidity stress alleviation was not the mechanism of biochar effects on soil fertility.
In conclusion, the alleviation of nutrient stress was the probably the main factor contributing to the increased maize biomass production upon biochar addition to this moderately acidic Inceptisol.
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•Soil limitations (moisture, nutrients, acidity) were manipulated one by one to find out why biochar improved crop growth.•Biochar addition increased soil pH, plant available P, K and soil moisture retention in this weathered Nepalese soil.•The biochar effect on plant growth was mainly due to alleviation of nutrient stress.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Blood is the predominant source for molecular analyses in humans, both in clinical and research settings. It is the target for many therapeutic strategies, emphasizing the need for comprehensive ...molecular maps of the cells constituting human blood. In this study, we performed a genome-wide transcriptomic analysis of protein-coding genes in sorted blood immune cell populations to characterize the expression levels of each individual gene across the blood cell types. All data are presented in an interactive, open-access Blood Atlas as part of the Human Protein Atlas and are integrated with expression profiles across all major tissues to provide spatial classification of all protein-coding genes. This allows for a genome-wide exploration of the expression profiles across human immune cell populations and all major human tissues and organs.
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