Mineral-rich Soil Research Articles

Ditch cleaning in boreal catchments: Impacts on water chemistry and dissolved greenhouse gases in runoff

Ditch cleaning (DC) is a forestry practice commonly conducted in boreal regions that aim to lower groundwater tables (GWT) in waterlogged soils, thereby maintaining or improving forest growth. However, there is limited information on the impact of DC on water chemistry and dissolved greenhouse gases (GHG) in draining ditch networks. Based on a repeated synoptic sampling of a paired catchment design we here evaluated water chemistry and GHG data in ditch waters from 25 cleaned sites (being cleaned 1–4 years prior to sampling) and 25 non-cleaned reference sites (REF). The sampled sites were further selected to test whether there were any differences in the DC effect if the operations were conducted in forested or clear-cut areas. Across all sites, we found that DC sites exhibited higher pH, sulfate and calcium concentrations than REF sites. Also, lower dissolved carbon dioxide and higher nitrous oxide concentrations were observed in DC sites. In forested areas, DC sites exhibited significantly higher calcium and potassium concentrations, along with reduced levels of methylmercury and carbon dioxide. In clear-cuts, sulfate concentrations were significantly elevated in the DC sites. We suggest that the observed differences in water chemistry and GHG´s between DC and REF sites were induced by the DC and largely driven by lower GWT following DC, resulting in deeper groundwater flow paths through more mineral-rich soil layers, and altered redox conditions. Also, the removal of organic rich sediments and vegetation from the ditches themselves may affect water chemistry and GHG´s e.g. by decreasing the formation of methylmercury and carbon dioxide.

Best practice for upscaling soil organic carbon stocks in salt marshes

Calculating the amount of soil organic carbon (SOC) stored in coastal environments, including salt marshes, is needed to determine their role in mitigating the Climate Crisis. Several techniques exist to calculate the SOC content of a unit of land from the upscaling of soil cores. However, no comprehensive assessment has been made on the performance of commonly used SOC upscaling techniques until now. We measured the SOC content of soil cores gathered from two Scottish salt marshes. Two SOC values were used for upscaling; SOC content for a 1 m standardised depth (as recommended by the IPCC), and SOC content of the modern marsh deposit (identified in the stratigraphy as a transition from organic-rich (marsh) to mineral-rich (intertidal flat) soil. Twenty-two upscaling techniques were used (SOC content × area, interpolative, and regression-based extrapolative calculations). Leave-one-out cross-validation procedures and prediction interval widths were used to assess the accuracy of each technique. Digital Terrain Models and Normalized Difference Vegetation Indices were used as covariate surfaces in the regression models. We found that marsh-scale SOC stocks varied by as much as fifty-two times depending on which sampling depth and upscaling technique was used. The largest differences emerged when comparing SOC stocks upscaled from 1 m deep and modern marsh deposits. Using the IPCC recommended 1 m sampling depth inflated the SOC stocks of salt marshes, as intertidal flat environments were included in the calculation. Ensemble regression models from the weighted average of seven machine learning algorithm outputs produced the highest upscaling accuracies across marshes and sampling depths. Simple SOC content × area calculations produced marsh-scale SOC stocks that were comparable to stock values produced by more advanced ensemble regression models. However, regression models produced detailed maps of SOC distribution across a marsh, and the associated uncertainty in the SOC values. Our findings are broadly applicable for other environments where large-scale SOC stock assessments and uncertainty are needed.

Environmental management: Modelling Plants Nutrients Values During the Composting Process

Composting of domestic wastes is one of the natural methods of eliminating foods wastes without damaging the environment. This process provides plants nutrients in the form of hygienic products, similar to mineral-rich soil called agricultural compost. The content of these formed components depends on several factors in the process, such as the humidity, the rejects quantities, their ratios to each other, the type of waste, the composting temperature and the elements interactions during the physico-chemical transformations. The innovation in this study, which remains the essential aim of this work, is to show how the formed essential plants nutrients, such as potassium, nitrogen, and phosphorus, depend not only on the humidity of the environment, the aeration by oxygen and the composition of the domestic wastes, but also on the interaction between them combined with the transformation time. Mathematical modelling using the design of experiments method, revealing that the presence of one element of three in the compost is a function of the two others in time, shows this. The mathematical model showing the variation of composting time as function of the minerals presence in the compost by graphs, contours and response surfaces; they simultaneously interprets the results of this process. One of the final objectives is to estimate by prediction the values of composting days without new experiments.ε

Improved wetland soil organic carbon stocks of the conterminous U.S. through data harmonization.

Wetland soil stocks are important global repositories of carbon (C) but are difficult to quantify and model due to varying sampling protocols, and geomorphic/spatio-temporal discontinuity. Merging scales of soil-survey spatial extents with wetland-specific point-based data offers an explicit, empirical and updatable improvement for regional and continental scale soil C stock assessments. Agency-collected and community-contributed soil datasets were compared for representativeness and bias, with the goal of producing a harmonized national map of wetland soil C stocks with error quantification for wetland areas of the conterminous United States (CONUS) identified by the USGS National Landcover Change Dataset. This allowed an empirical predictive model of SOC density to be applied across the entire CONUS using relational %OC distribution alone. A broken-stick quantile-regression model identified %OC with its relatively high analytical confidence as a key predictor of SOC density in soil segments; soils less than 6% OC (hereafter, mineral wetland soils, 85% of the dataset) had a strong linear relationship of %OC to SOC density (RMSE = 0.0059, ~4% mean RMSE) and soils greater than 6% OC (organic wetland soils, 15% of the dataset) had virtually no predictive relationship of %OC to SOC density (RMSE = 0.0348 g C cm-3, ~56% mean RMSE). Disaggregation by vegetation type, or region did not alter the breakpoint significantly (6% OC) nor improve model accuracies for inland and tidal wetlands. Similarly, SOC stocks in tidal wetlands were related to %OC, but without a mappable product for disaggregation to improve accuracy by soil class, region or depth. Our layered, harmonized CONUS wetland soil maps revised wetland SOC stock estimates downward by 24% (9.5 vs. 12.5Pg C) with the overestimation being entirely an issue of inland, organic wetland soils, (35% lower than SSURGO-derived SOC stocks). Further, SSURGO underestimated soil carbon stocks at depth, as modeled wetland SOC stocks for organic-rich soils showed significant preservation downcore in the NWCA dataset (<3% loss between 0-30 cm and 30-100 cm depths) in contrast to mineral-rich soils (37% downcore stock loss). Future CONUS wetland soil C assessments will benefit from focused attention on improved organic wetland soil measurements, land history, and spatial representativeness.

Organic Matter Causes Chemical Pollutant Dissipation Along With Adsorption and Microbial Degradation

Views on the entry of organic pollutants into the organic matter (OM) decaying process are divergent, and in part poorly understood. To clarify these interactions, pesticide dissipation was monitored in organic and mineral soils not adapted to contaminants for 241 days; in groundwater sediment slurries adapted to pesticides for 399 days; and in their sterilized counterparts with and without peat (5%) or compost-peat-sand (CPS, 15%) mixture addition. The results showed that simazine, atrazine and terbuthylazine (not sediment slurries) were chemically dissipated in the organic soil, and peat or CPS-amended soils and sediment slurries, but not in the mineral soil or sediment slurries. Hexazinone was chemically dissipated best in the peat amended mineral soil and sediment slurries. In contrast, dichlobenil chemically dissipated in the mineral soil and sediment slurries. The dissipation product 2,6-dichlorobenzamide (BAM) concentrations were lowest in the mineral soil, while dissipation was generally poor regardless of plant-derived OM, only algal agar enhanced its chemical dissipation. Based on sterilized counterparts, only terbutryn appeared to be microbially degraded in the organic soil, i.e., chemical dissipation of pesticides would appear to be utmost important, and could be the first response in the natural cleansing capacity of the environment, during which microbial degradation evolves. Consistent with compound-specific dissipation in the mineral or organic environments, long-term concentrations of pentachloroaniline and hexachlorobenzene were lowest in the mineral-rich soils, while concentrations of dichlorodiphenyltrichloroethane (DTT) and metabolites were lowest in the organic soils of old market gardens. OM amendments changed pesticide dissipation in the mineral soil towards that observed in the organic soil; that is OM accelerated, slowed down or stopped dissipation.

Innovation of Coffee Bali : from Aromatherapy to Immune Booster

Balinese Coffee might sound unfamiliar since it is a new player in the premium gourmet world. Bringing a rich aroma and distinctive smoky taste, it has attracted coffee connoisseurs to feel at home on vacation in Bali. Thanks to the mineral-rich volcanic soil, practices involving natural fertilizers and plantings method according to the Tri Hita Karana concept. Coffee has a distinctive flavors to hook its audience, creating many coffee-drinking cultures in most countries, including Indonesia. Coffee can be consumed as a beverage or processed into other products without reducing its high selling value. Many innovations to turn coffee beans into perfume, aromatherapy, and coffee bean accessories have been highly-demanded. Taking advantage of the uprising prestige of coffee, the Governor of Bali Wayan Koster also proposed an idea that herbal drink experts doubted, namely mixing Coffee with Balinese arak. However, expert doubted the Governor’s proposal and advised the public to look for other herbal drinks references.

Process Controls of the Live Root Zone and Carbon Sequestration Capacity of the Sundarbans Mangrove Forest, Bangladesh

The conservation of coastal wetland ecosystems, like mangrove forests and salt marshes, represents a critical strategy for mitigating atmospheric emissions and climate change in the 21st century. Yet the existence of these environments is threatened by human-induced disturbances, namely deforestation and accelerated sea-level rise. Coastal systems maintain surface elevation in response to sea-level rise through a combination of physical and biological processes both above and below the ground surface. The quantification and relative contribution of belowground process controls (e.g., seasonal water content, organic matter decomposition) on surface elevation change is largely unexplored but crucial for informing coastal ecosystem sustainability. To address this knowledge deficit, we integrated measurements of surface elevation change of the live root zone (0.5 to 1 m depth) with geotechnical data from co-located sediment cores in the Sundarbans mangrove forest (SMF) of southwest Bangladesh. Core data reveal that the primary belowground controls on surface elevation change include seasonal fluctuations in pore-water content and the relative abundance of fine-grained sediments capable of volumetric expansion and contraction, supporting an elevation gain of ~2.42 ± 0.26 cm year−1. In contrast to many mangrove environments, the soils of the SMF contain little organic matter and are dominantly composed (&gt;90%) of inorganic clastic sediments. The mineral-rich soil texture likely leads to less compaction-induced subsidence as compared to organic-rich substrates and facilitates surface equilibrium in response to sea level rise. Despite a relatively high soil bulk density, soil carbon (C) density of the SMF is very low owing to the dearth of preserved organic content. However, rates of C accumulation are balanced out by locally high accretion rates, rendering the SMF a greater sink of terrestrial C than the worldwide mangrove average. The findings of this study demonstrate that C accumulation in the SMF, and possibly other alluvial mangrove forests, is highly dependent on the continued delivery of sediment to the mangrove platform and associated settings.

TimeFun-InSAR algorithm to investigate physical changes at Bromo volcano by using ALOS/PALSAR data sets

Mt. Bromo is geographically located in eastern of Java Island at 112°57'30'' longitude and 7°56' latitude, with a large area of caldera ~10 Km2. The land over the volcano is a perfect area for farming, one of the important factor affects the level of soil fertility is the most mineral rich soils. Volcanic activities at Mt. Bromo has been recorded in 1775 which characterized by small eruptions with cycles ranging from one to five years. Regarding this evidence, we tried to investigate the surface changes over the Mt. Bromo by using Time-Series InSAR with TimeFun algorithm. TimeFun is an extension of SBAS to allow incorporating various functions such as seasonal oscillations, polynomials, and step functions as generally it estimates DEM errors as well and allows missing observation. The maximum allowed baseline value is defined and used to constrain the interferogram pair by selecting manual after differential InSAR processing in single face working. The proposed analysis is based on 27 SAR data sets acquired by the ALOS/PALSAR sensors during the 2007–2017 time interval. The result shows us deformation occurred up to ~10 cm at summit of Mt. Bromo during the eruption period. Time-series monitoring of surface deformation to infer volume changes, geometries and locations of sources of deformation involved in the future eruption

Process Controls of the Live Root Zone and Carbon Sequestration Capacity of the Sundarbans Mangrove Forest, Bangladesh

The conservation of coastal wetland ecosystems, like mangrove forests and salt marshes, represents a critical strategy for mitigating atmospheric emissions and climate change in the 21st century. Yet the existence of these environments is threatened by human-induced disturbances, namely deforestation and accelerated sea-level rise. Coastal systems maintain surface elevation in response to sea-level rise through a combination of physical and biological processes both above and below the ground surface. The quantification and relative contribution of belowground process controls (e.g., seasonal water content, organic matter decomposition) on surface elevation change is largely unexplored but crucial for informing coastal ecosystem sustainability. To address this knowledge deficit, we integrated measurements of surface elevation change of the live root zone (0.5 to 1 m depth) with geotechnical data from co-located sediment cores in the Sundarbans mangrove forest (SMF) of southwest Bangladesh. Core data reveal that the primary belowground controls on surface elevation change include seasonal fluctuations in pore-water content and the relative abundance of fine-grained sediments capable of volumetric expansion and contraction, supporting an elevation gain of ~2.42 ± 0.26 cm yr−1. In contrast to many mangrove environments, the soils of the SMF contain little organic matter and are dominantly composed (&gt;90%) of inorganic clastic sediments. The mineral-rich soil texture likely leads to less compaction-induced subsidence as compared to organic-rich substrates and facilitates surface equilibrium in response to sea level rise. Despite a relatively high soil bulk density, soil carbon (C) density of the SMF is very low owing to the dearth of preserved organic content. However, rates of C accumulation are balanced out by locally high accretion rates, rendering the SMF a greater sink of terrestrial C than the worldwide mangrove average. The findings of this study demonstrate that C accumulation in the SMF, and possibly other alluvial mangrove forests, is highly dependent on the continued delivery of sediment to the mangrove platform and associated settings.

Process Controls of the Live Root Zone and Carbon Sequestration Capacity of the Sundarbans Mangrove Forest, Bangladesh

The conservation of coastal wetland ecosystems, like mangrove forests and salt marshes, represents a critical strategy for mitigating atmospheric emissions and climate change in the 21st century. Yet the existence of these environments is threatened by human-induced disturbances, namely deforestation and accelerated sea-level rise. Coastal systems maintain surface elevation in response to sea-level rise through a combination of physical and biological processes both above and below the ground surface. The quantification and relative contribution of belowground process controls (e.g., seasonal water content, organic matter decomposition) on surface elevation change is largely unexplored but crucial for informing coastal ecosystem sustainability. To address this knowledge deficit, we integrated measurements of surface elevation change of the live root zone (0.5 to 1 m depth) with geotechnical data from co-located sediment cores in the Sundarbans mangrove forest (SMF) of southwest Bangladesh. Core data reveal that the primary belowground controls on surface elevation change include seasonal fluctuations in pore-water content and the relative abundance of fine-grained sediments capable of volumetric expansion and contraction. In contrast to many mangrove environments, the soils of the SMF contain little organic matter and are dominantly composed (&gt;90%) of inorganic clastic sediments. The mineral-rich soil texture likely leads to less compaction-induced subsidence as compared to organic-rich substrates and facilitates surface equilibrium in response to sea level rise. Despite a relatively high soil bulk density, soil carbon (C) density of the SMF is very low owing to the dearth of preserved organic content. However, rates of C accumulation are balanced out by locally high accretion rates, rendering the SMF a greater sink of terrestrial C than the worldwide mangrove average. The findings of this study demonstrate that C accumulation in the SMF, and possibly other alluvial mangrove forests, is highly dependent on the continued delivery of sediment to the mangrove platform and associated settings.

Isolation and characterization of mineral-dissolving bacteria from different levels of altered mica schist surfaces and the adjacent soil

Microorganisms play important role in mineral weathering. However, little is known about rock-associated mineral-dissolving bacteria. In this study, 129 bacterial isolates were obtained from the less and more weathered mica schist surfaces and the adjacent soil and characterized for mineral dissolving activity, population, and the linkage of rock weathering level and distribution of the bacteria. Among the 129 isolates, 112 isolates could dissolve biotite. The relative abundance of the highly effective Fe solubilizers was significantly higher on the more altered rock surface (89.6%) than in the soil (51.2%) and on the less altered rock surface (22.5%), while the relative abundance of the highly effective Si solubilizers was significantly higher in the soil (65.9%) than on the more (41.7%) and less (12.5%) altered rock surfaces. Furthermore, 17.5-42.5%, 87.5%, and 60.9-90.2% of the highly effective acid- and siderophore-producing isolates were obtained in the less and more weathered rocks and the soil, respectively. The mineral-dissolving bacteria belonged to 18 genera and Burkholderia, Bacillus, and Paenibacillus were the dominant and highly effective mineral-dissolving bacteria. Phylogenetic analysis found 2, 9, and 5 bacterial species in the highly effective mineral-dissolving bacteria on the less and more altered rock surfaces and in the soil, respectively. The results showed the abundant and diverse mineral-dissolving bacterial populations on the more weathered rock surfaces. The results also suggested distinct mineral-dissolving activities and mechanisms of the bacteria and highlighted the possibility for the development of bacterial inocula for plant nutrition improvement in silicate mineral-rich soils.

Use of Fine-textured, Mineral-rich Soils by a Northern Flicker (Colaptes auratus) in North-central British Columbia

Abstract Consumption of fine-textured soils by birds is common in South and Central America and some parts of Southeast Asia. Many bird species eat fine-textured soils to aid in digestion, detoxification, and mineral supplementation, but there are few documented cases of such behavior in North America. Here, I describe the consumption of clay soils from an expansive clay bank in north-central British Columbia, Canada by a Northern Flicker (Colaptes auratus L.) in the autumn of 2015. Texture analysis of soils used by the Flicker and collected from the clay bank indicated the soil texture was 61.84% silt, 38.16% clay, and 0.00% sand, which is similar to soils eaten by tropical birds where geophagy has been recorded. Trace element analysis indicated total concentrations of main elements tested ranged from 9 ppm for boron to nearly 40,000 ppm for iron, while minor elements ranged from below detectable limits for mercury, molybdenum, antimony, selenium, and tin to over 1700 ppm for titanium. Total concentratio...

Propensity for erosion and deposition in a deltaic wetland complex: Implications for river management and coastal restoration

The Mississippi River Delta is one of the most rapidly changing area on Earth, with large areas experiencing land loss and smaller areas experiencing loss. While some of the drivers of these changes are well known (high rates of relative sea level rise, reduced sediment inputs, canal dredging), debate exists about other drivers. One area that has received substantial attention is the role of, “river diversions,” areas where sediments and water are diverted from the Mississippi River into degrading wetlands with the hope of reinitiating deltaic land building processes. Some authors have argued that diversions lead to reduced shear strengths of wetland soils that make them more vulnerable to storm driven erosion, while other authors have argued that sediments from river diversions will develop stable land. This study examined this controversy in the Cubits Gap Subdelta, an analogue for a large (>1420m3s−1) river diversion by testing the hypothesis that areas of land gain, and/or resilience to erosion occurred in areas that actively received river sediments and as a result had mineral rich soils with high shear strength. To accomplish this, a Normalized Difference Water Index (NDWI) was developed for Landsat-7 Enhanced Thematic Mapper (ETM+) and Landsat-8 Operational Land Imager (OLI) images. The NDWI was calculated from (Blue−SWIR)/(Blue+SWIR), where SWIR is the shorter wavelength, and yielded land/water boundary maps with 30m resolution. Results indicate that land gain occurred predominantly in the riverside section of this subdelta where sediments were imported from Mississippi River crevasses and/or dredging. Land loss typically occurred in the distal regions of the subdelta, which had lower levels of sediment supply and greater wave exposure. Sediment geotechnical analyses revealed land loss pixels generally correlated sediments with to high organic contents (9.0±1.9%), water contents (54.8±3.7%) and salinity (6.5±2.0PSU), with low shear strengths (5.7±0.8kNm−2) and low bulk density (0.6±0.8g cm−3), whereas land gain pixels generally correlate with low organic content (3.9±0.6%), water content (38.1±4.2%) high shear strength (10.9±4.1kNm−2) and bulk density (1.00±0.1gcm−3). This study suggests plans to restore the region by partially diverting the flow of the Mississippi River will be most successful if they carry high loads of sediment, and that concerns about the integrity of fresh marsh may be unwarranted if those marshes are sediment rich.

Influence of Organo-Metal Interactions on Regeneration of Exhausted Clay Mineral Sorbents in Soil Columns Loaded with Heavy Metals

Natural clay minerals can play an important role in crude remediation of wastewater polluted with the heavy metals (HMs) Cu, Zn and Ni. The presence and timing of addition of natural dissolved organic matter (DOM) have a significant effect on the HM removal by clay mineral sorbents. However, the influence of the presence of DOM on the remediation of the used clay mineral sorbents once saturated with HMs is largely unknown. To resolve this, clay mineral-rich soil column of varying composition, loaded (i) with Cu, Zn and Ni only, (ii) first with DOM followed by Cu, Zn and Ni, or (iii) with DOM, Cu, Zn and Ni simultaneously, was used in a set of desorption experiments. The soil columns were leached with 0.001 mol L−1 CaCl2 dissolved in water as control eluent and 0.001 mol L−1 CaCl2 dissolved in DOM as treatment eluent. During the preceding loading phase of the sorbent, the timing of DOM addition (sequential or concurrent with HMs) was found to have a significant influence on the subsequent removal of the HMs. In particular when the column was loaded with DOM and HMs simultaneously, largely irreversible co-precipitation took place. Our results indicate that the regeneration potential of clay mineral sorbents in wastewater treatment will be significantly reduced when the treated water is rich in DOM. In contrast, in manured agricultural fields (where HMs enter together with DOM), HM mobility will be lower than expected from interaction dynamics of HMs and clay minerals.

The vegetation and wildlife habitats of the Savuti-Mababe-Linyanti ecosystem, northern Botswana

This study classified the vegetation of the Savuti-Mababe-Linyanti ecosystem (SMLE), northern Botswana and developed a detailed map that provides a reliable habitat template of the SMLE for future wildlife habitat use studies. The major vegetation units of the SMLE were determined from satellite imagery and field visits and then mapped using Landsat 8 and RapidEye imagery and maximum likelihood classifier. These units were sampled using 40 m x 20 m (800 m²) plots in which the coverage of all plant species was estimated. Non-metric multidimensional scaling (NMS) demonstrated that plant communities were determined by gradients in soil texture or fertility and wetness. NMS 1 represented a gradient of soil texture with seven woodland communities on sandy soils (sandveld communities and Baikiaea forest) dominated by Baikiaea plurijuga in Baikiaea forest and Terminalia sericea and Philenoptera nelsii in sandveld, with various indicator species differentiating the various sandveld community types. Mopane woodland further from and riparian woodland adjacent to permanent water was common on less sandy alluvial soils. Mineral-rich, heavy clay soils in the sump of a large paleolake system support open grassland and mixed Senegalia/Vachellia (Acacia) savanna, with the mineral-rich soils supporting grasses high in minerals such as phosphorus, calcium, sodium and potassium, and thus this region is a critical wet season range for migratory zebra. Taller, high-quality grasses in the mosaic of sandveld and mopane woodland communities provide critical grazing for taller grass grazers such as buffalo, roan and sable antelope, whereas wetland communities provide reliable green forage during the dry season for a variety of herbivores, including elephant. This study has demonstrated how large-scale environmental gradients determine functional habitat heterogeneity for wildlife.Conservation implications: Our study demonstrated that the functionality of protected areas is determined by large-scale environmental gradients. Thus conservation science must aim to ensure that protected areas cover the full range of key environmental gradients in a region (soil texture and wetness in our study). Our habitat map provides a data base for wildlife habitat use studies in the region.

Geophagia: A Scientific Approach to a Historical Practice to Sustainably Treat Endemic Iron Deficiency in a Rural Community in Nepal

Geophagia is the practice of eating earth or clay and is nearly universal around the world in traditional rural societies. Many animals across genera are known to eat mineral rich soil. Some animals travel long distances to seek specific soils that are rich in minerals that they are deficient. According to the WHO dietary iron deficiency is a documented threat to public health in Nepal and iron deficiency anaemia affects 60-85% in the general population. Iron deficiency holds developing communities back with reduced growth, reduced academic achievement and reduced physical productivity. While it would be possible to simply provide iron medications, the long term delivery to remote areas would make this logistically difficult to be sustainable and in our view would provide the wrong sort of aid.We analysed local Nepalise hill clays in Kavre District to assess feasibility of use as an iron supplement. Providing a manual pill press would allow communities to make their own clay iron tablets facilitating more precise dosing in a truly sustainable way at ongoing zero cost. 23 mineral elements were measured by Inductively Coupled Mass Spectrometry in the two common clays, white and red, following a protocol based on the UK Environmental Protection Agency method "Acid digestion of sediments, sludges and soils (Method 3050B)".Iron was present in useful amounts in both white and red clays; 33,485 μg/g and 35,091 μg/g respectively. All other mineral elements were present at low levels and unlikely to pose a health threat, with the exception of aluminium. Aluminium was present at 20,577 μg/g in white clay and 53,125 μg/g in red clay, which is above UK recommended dietary intake levels. However, in the absence of dialysis dependant renal failure, excess aluminium is excreted in urine and there are no documented cases of environmental aluminium toxicity. Aluminium levels in antacid tablets can be 20% with no toxicity documented even with chronic use.This is a project with local Nepali community leaders working together with UK laboratories and haematologists. Further work will assess the homogeneity of the clay composition over a wider area. We are currently developing methods to facilitate the production of clay pills with a hand press alongside developing a school based education and iron supplementation programme. Iron deficiency is a worldwide problem in developing countries. We believe this approach could be used to empower communities to improve iron nutrition across the globe. DisclosuresNo relevant conflicts of interest to declare.

Evaluation of the particle sizes of four clay minerals

The particle size distributions (PSD) of four clay minerals from the US Clay Minerals Society, kaolinite, illite, Ca2+-montmorillonite, and Na+-montmorillonite, were analyzed using different dispersion techniques to evaluate their PSD variability and intrinsic particle sizes. Both dry dispersion in pressurized air and wet dispersion in water and ethyl alcohol with and without an interlayer expanding agent, glycerol, were employed, along with mechanical ultrasound disaggregation and chemical dispersion. Results show that all four clay minerals exhibit multimodal PSD consisting of superimposed subordinate lognormal distributions from submicron and 1–2μm primary particles, 10–20μm flocculi (and trace impurities). Microflocs of 50–500μm occur only in the dry dispersion mode. Owing to the presence of relatively strong flocculi that are not prone to breakdown to smaller primary particles, the intrinsic PSD of these clay minerals cannot be readily obtained by the adopted dispersion methods. The two swelling clay minerals, Na+-montmorillonite and Ca2+-montmorillonite, are more sensitive than the non-swelling ones, kaolinite and illite, to different dispersion solvents. The variability of these clay minerals' PSD is further discussed in terms of the complex interactions among clay mineral particles, polar or less polar solvent, and dispersant, such as swelling, cation exchange, exfoliation, and electrical double layer repulsion. A significant practical implication is that most existing dispersion methods for PSD analysis tend to overestimate the silt-sized fraction but underestimate the clay-sized fraction, which may yield misleading classification for clay mineral-rich soils. For expansive clay minerals, appropriate dispersants should be selected to avoid cation exchange between the sample and dispersants, which can change their intrinsic PSD.

Identification conformity of wetlands biotopes of the Northwest of the Black Sea region

This publication presents the analysis of the mostly used international and Ukrainian classification systems for wetland areas performed for identification of different-type marsh biotopes of steppe rivers in the Northwest Black Sea Region. Among the classification systems, the most well-known are the Ramsar Classification System for Wetland Type (1971) and Classification of Wetlands and Deepwater Habitats of the United States (Cowardin et al., 1979). In these systems, valley marsh biotopes are identified as riverine and palustrine, non-tidal, unstable (perennial impounded and seasonal/intermittent) freshwater marshes on mineral rich soils predominantly covered by grasslike plants (rush, reedmace, sedge). The delta marshes of the Danube, Dniester and Dnieper are referred to as tidal brackish and freshwater marshes. According to Ukrainian classification systems for hygromorphic geosystem, marsh biotopes are regarded as mouth wetlands, which is peculiar to delta marsh areas of the Danube and Dnieper interfluve. Thus, riverbed marshes of small and medium-sized rivers are located in other areas and are usually met both in the lower (continuous marsh areas), middle (fragmented marsh mosaic), and upper (coastland) river flow areas, which is caused by an unstable watercourse rate and transforming of their riverbed parts into marsh sections covered by eurytopic wetland species.

Evaluating soil salinity and water management in Chaco Canyon, New Mexico

Previous studies in Chaco Canyon, New Mexico suggested that water management systems constructed during periods of increased aridity resulted in elevated salinity levels to the point that soils were no longer viable for growing cultigens. Salinity, pH, powder X-ray diffraction, and inductively coupled plasma atomic emission spectroscopy analyses of sediments and water collected from Chaco Canyon between the years 2013 and 2015 demonstrate conclusively that soils were suitable for the cultivation of maize by Ancestral Puebloans. Our findings clearly indicate that the salts are non-deleterious sulfate minerals. All of the cations and anions needed to form these minerals occur in the water of Chaco Canyon. Thus, increased soil salinity was not a critical factor in the abandonment of Chaco Canyon by Ancestral Puebloans. Sulfate and volcanogenic minerals increased soil fertility that allowed for the development and maintenance of an agricultural urban center in this dryland environment. Water management of sulfate and volcanic mineral rich soils created an environ ideal for maize agriculture. The occurrence of non-local Ancestral Puebloan maize in Chaco Canyon can be explained in terms of kinship mobility, the distance that goods and services move between extended families.

Warming increases methylmercury production in an Arctic soil

Rapid temperature rise in Arctic permafrost impacts not only the degradation of stored soil organic carbon (SOC) and climate feedback, but also the production and bioaccumulation of methylmercury (MeHg) toxin that can endanger humans, as well as wildlife in terrestrial and aquatic ecosystems. Currently little is known concerning the effects of rapid permafrost thaw on microbial methylation and how SOC degradation is coupled to MeHg biosynthesis. Here we describe the effects of warming on MeHg production in an Arctic soil during an 8-month anoxic incubation experiment. Net MeHg production increased >10 fold in both organic- and mineral-rich soil layers at warmer (8 °C) than colder (−2 °C) temperatures. The type and availability of labile SOC, such as reducing sugars and ethanol, were particularly important in fueling the rapid initial biosynthesis of MeHg. Freshly amended mercury was more readily methylated than preexisting mercury in the soil. Additionally, positive correlations between mercury methylation and methane and ferrous ion production indicate linkages between SOC degradation and MeHg production. These results show that climate warming and permafrost thaw could potentially enhance MeHg production by an order of magnitude, impacting Arctic terrestrial and aquatic ecosystems by increased exposure to mercury through bioaccumulation and biomagnification in the food web.