The development of highly concentrated phosphorus (P) fertilizers, such as triple superphosphate, by the Tennessee Valley Authority helped mark the beginning of a revolution in the way we manage food ...crop nutrition. Since then, scientists, with the help of farmers, have made great advancements in the understanding of P fate and transport across many environments but largely have failed to produce a new generation of products and/or application techniques that are widely accepted and that vastly improve plant acquisition efficiency. Under certain conditions, important advancements have been made. For example, applying liquid formulations of phosphates in lieu of dry granules in some highly calcareous soils has dramatically reduced precipitation as sparingly soluble calcium phosphate minerals, but other attempts, such as the co‐application of humic substances, sorption to layered double hydroxides, or use of nanoparticles, have not generated the kind of results necessary to continue economically increasing crop yields without further environmental cost. New sources of fertility will need to be affordable to produce, transport, and furnish P to soil solution in a manner well synchronized with crop demand. This paper provides a review of recent literature on cutting‐edge phosphorus fertilizer technology. The goal is that this synthesis will be used as a starting point from which a larger discussion on responsible nutrient management and increased P use efficiency research can be built.
Core Ideas
Reaction with some soil constituents limits P availability and crop yield.
A variety of approaches to improve fertilizer use efficiency are being explored.
Ideally, P availability should be well synchronized to crop demand.
More innovation along with mechanistic and field‐scale trials is required.
Current child blood lead (Pb) screening guidelines assume that blood lead levels (BLLs) are relatively stable over time, and that only youngest children are vulnerable to the damaging effects of ...lower-range BLLs. This study aimed to test the stability of lower-range (≤ 10 μg/dL) child BLLs over time, and whether lower-range BLLs diminished with age among children aged 6 months to 16 years living in a lower-income neighborhood with a density of pre-1986 housing and legacy contamination. Age, sex, family income, age of residence, and/or residence proximity to point sources of Pb, were tested as potential additional factors. Capillary blood samples from 193 children were analyzed by inductively coupled plasma mass spectrometry (ICPMS). Multiple imputation was used to simulate missing data for 3 blood tests for each child. Integrated Growth Curve models with Test Wave as a random effect were used to test BLL variability over time. Among N = 193 children tested, at Time 1 testing, 8.7% had the BLLs ≥ 5 μg/dL (CDC "elevated" BLL reference value at the time of data collection) and 16.8% had BLLs ≥ 3.5 μg/dL (2021 CDC "elevated" BLL reference value). Modeling with time as a random effect showed that the variability of BLLs were attributable to changes within children. Moreover, time was not a significant predictor of child BLLs over 18 months. A sex by age interaction suggested that BLLs diminished with age only among males. Of the additional environmental factors tested, only proximity to a major source of industrial or vehicle exhaust pollution predicted child BLL variability, and was associated with a small, but significant BLL increase (0.22 μg/dL). These findings suggest that one or two BLL tests for only infants or toddlers are insufficient for identifying children with Pb poisoning.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Zinc oxide (ZnO) nanoparticles may provide a more soluble and plant available source of Zn in Zn fertilizers due to their greater reactivity compared to equivalent micron- or millimetre-sized (bulk) ...particles. However, the effect of soil on solubility, spatial distribution and speciation of ZnO nanoparticles has not yet been investigated. In this study, we examined the diffusion and solid phase speciation of Zn in an alkaline calcareous soil following application of nanoparticulate and bulk ZnO coated fertilizer products (monoammonium phosphate (MAP) and urea) using laboratory-based x-ray techniques and synchrotron-based μ-x-ray fluorescence (μ-XRF) mapping and absorption fine structure spectroscopy (μ-XAFS). Mapping of the soil-fertilizer reaction zones revealed that most of the applied Zn for all treatments remained on the coated fertilizer granule or close to the point of application after five weeks of incubation in soil. Zinc precipitated mainly as scholzite (CaZn2(PO4)2.2H2O) and zinc ammonium phosphate (Zn(NH4)PO4) species at the surface of MAP granules. These reactions reduced dissolution and diffusion of Zn from the MAP granules. Although Zn remained as zincite (ZnO) at the surface of urea granules, limited diffusion of Zn from ZnO-coated urea granules was also observed for both bulk and nanoparticulate ZnO treatments. This might be due to either the high pH of urea granules, which reduced solubility of Zn, or aggregation (due to high ionic strength) of released ZnO nanoparticles around the granule/point of application. The relative proportion of Zn(OH)2 and ZnCO3 species increased for all Zn treatments with increasing distance from coated MAP and urea granules in the calcareous soil. When coated on macronutrient fertilizers, Zn from ZnO nanoparticles (without surface modifiers) was not more mobile or diffusible compared to bulk forms of ZnO. The results also suggest that risk associated with the presence of ZnO NPs in calcareous soils would be the same as bulk sources of ZnO.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Snowmelt runoff is a dominant pathway of phosphorus (P) losses from agricultural lands in cold climatic regions. Soil amendments effectively reduce P losses from soils by converting P to less soluble ...forms; however, changes in P speciation in cold climatic regions with fall‐applied amendments have not been investigated. This study evaluated P composition in soils from a manured field with fall‐amended alum (Al2(SO4)3·18H2O), gypsum (CaSO4·2H2O), or Epsom salt (MgSO4·7H2O) using three complementary methods: sequential P fractionation, scanning electron microscopy with energy‐dispersive X‐rays (SEM‐EDX) spectroscopy, and P K‐edge X‐ray absorption near‐edge structure spectroscopy (XANES). Plots were established in an annual crop field in southern Manitoba, Canada, with unamended and amended (2.5 Mg ha−1) treatments having four replicates in 2020 fall. Soil samples (0–10 cm) taken from each plot soon after spring snowmelt in 2021 were subjected to P fractionation. A composite soil sample for each treatment was analyzed using SEM‐EDX and XANES. Alum‐ and Epsom salt‐treated soils had significantly greater residual P fraction with a higher proportion of apatite‐like P and a correspondingly lower proportion of P sorbed to calcite (CaCO3) than unamended and gypsum‐amended soils. Backscattered electron imaging of SEM‐EDX revealed that alum‐ and Epsom salt‐amended treatments had P‐enriched microsites frequently associated with aluminum (Al), iron (Fe), magnesium (Mg), and calcium (Ca), which was not observed in other treatments. Induced precipitation of apatite‐like species may have been responsible for reduced P loss to snowmelt previously reported with fall application of amendments.
Core Ideas
Soils that received alum or Epsom salt in the preceding fall had P‐enriched microsites, unlike unamended soils.
Alum‐ and Epsom salt‐amended soils had a greater percentage of recalcitrant P than gypsum‐amended and unamended soils.
Both alum‐ and Epsom salt‐amended soils had more apatite‐like P, which reduced P solubility.
Gypsum‐amended and unamended soils had a lower proportion of apatite‐like P.
In unamended and gypsum‐amended soils, P solubility was controlled mostly by P sorbed to calcium carbonate.
Plain Language Summary
Phosphorus (P) losses from agricultural lands can contribute to P enrichment in downstream water bodies and deteriorate water quality. In the Canadian prairies, the spring snowmelt runoff is the dominant pathway of P losses from agricultural lands. Inorganic soil amendments are effective in reducing P losses from soils by converting soil P to less soluble forms. However, information on the effectiveness of amendments for reducing P losses under snowmelt flooding is scarce. We examined the influence of gypsum, alum, and Epsom salt amendments on changes in soil P fractions and species to elucidate the mechanisms responsible for mitigating P losses. Results indicated precipitation of P in alum‐ and Epsom salt‐amended treatments but not in unamended and gypsum‐amended treatments.
Established methods for using standardized dust wipes to collect and measure total lead in household dust are readily available but the use of dust wipes to measure bioaccessible lead (BaPb) is less ...clear. This study compared two in vitro methods for estimating the proportion of BaPb in dust collected into dust wipes including the US-EPA's in-vitro bioaccessible assay (IVBA) method at two pH (1.5 and 2.5) values; and the physiologically based extraction test (PBET 2.5 pH). Two types of simulated household dust samples (Pb-soil contaminated and Pb-paint contaminated) each with three Pb concentrations were created. Equal amounts of simulated dust were applied to a smooth surface and collected following the standard EPA dust wipe protocol and were analyzed for BaPb and total Pb (ASTM-E1644-17, ICP-OES). Estimated BaPb levels differed significantly by the method of extraction. Mean percent BaPb were IVBA pH 1.5, > 90% (Pb-paint) and 59-63% (Pb-soil); IVBA pH 2.5 78-86% (Pb-paint) and 45-50% (Pb-soil); PBET pH 2.5 56 to 61% (Pb-paint) and 41-50% Pb-soil). Particularly for lead-paint contaminated dust, PBET showed significantly greater discrimination as suggested by the broader range of BaPb values and closer approximation to total lead concentrations in simulated household dust samples.
•High quality calcium phosphate recovered from swine waste using lime addition.•Total alkalinity removal by acid addition and aeration improved P-product quality.•Amorphous calcium phosphate with ...11.8 wt% P recovered at 2/1 Ca/P molar ratio.•Up to 97% P removal achieved with 10/1 M Ca/P dose in the altered permeate.•Additional removal of residual COD during flocculation improved effluent quality.
The aim of this study is the sustainable recovery of phosphorus as high-quality calcium phosphate from anaerobic membrane bioreactor treated swine permeate for targeted use as fertilizer or raw material for the fertilizer industry. Phosphorus removal efficiencies from treated swine permeate were evaluated by adding various calcium/phosphorus molar ratios ranging from 1/1 to 12/1. Results showed that removal efficiencies were inconsistent in duplicate trials at the same calcium doses (maximum P removal 93 % in Trial 1 and <20 % removal in Trial 2). The variability in P removal was due to the high bicarbonate alkalinity of the swine permeate, which buffered the system and thereby prevented it from reaching alkaline pH conditions ideal for P removal. Total alkalinity and initial solution pH had the greatest impact on P removal and caused unintended precipitation of non-specific calcium minerals (Calcite). The carbonate alkalinity from the permeate was removed using process modifications that included acid addition and aeration for removal as CO2. Carbonate removal resulted in 97 % P removal with increased total P content (11.8 % P) in the final product and better solubility. Additional COD removal was also observed during the flocculation process.
To understand the biogeochemistry of nutrients and contaminants in environmental media, their speciation and behavior under different conditions and at multiple scales must be determined. Synchrotron ...radiation‐based X‐ray techniques allow scientists to elucidate the underlying mechanisms responsible for nutrient and contaminant mobility, bioavailability, and behavior. The continuous improvement of synchrotron light sources and X‐ray beamlines around the world has led to a profound transformation in the field of environmental biogeochemistry and, subsequently, to significant scientific breakthroughs. Following this introductory paper, this special collection includes 10 papers that either present targeted reviews of recent advancements in spectroscopic methods that are applicable to environmental biogeochemistry or describe original research studies conducted on complex environmental samples that have been significantly enhanced by incorporating synchrotron radiation‐based X‐ray technique(s). We believe that the current focus on improving the speciation of ultra‐dilute elements in environmental media through the ongoing optimization of synchrotron technologies (e.g., brighter light sources, improved monochromators, more efficient detectors) will help to significantly push back the frontiers of environmental biogeochemistry research. As many of the relevant techniques produce extremely large datasets, we also identify ongoing improvements in data processing and analysis (e.g., software improvements and harmonization of analytical methods) as a significant requirement for environmental biogeochemists to maximize the information that can be gained using these powerful tools.
Core Ideas
SR‐based techniques have revolutionized the field of environmental biogeochemistry.
Improvements to light sources will provide SR with extreme brightness and coherence.
This should be met with similar advances to synchrotron‐related hardware and software.
Environmental biogeochemists can drive the new advances in the synchrotron science.
Advances in SR will enable future breakthroughs in environmental biogeochemistry.
Organic amendments often reduce the bioaccessibility of soil lead (Pb) but not that of soil arsenic (As). The effect of Pb on As bioaccessibility is rarely studied in co‐contaminated soils. In a ...field study, we assessed the effect of mushroom compost, leaf compost, noncomposted biosolids, and composted biosolids amendments on As speciation in a co‐contaminated (As and Pb) soil at 7, 349, and 642 days after amending soils and the change of As speciation during an in vitro bioaccessibility extraction (gastric solution, pH 2.5) using bulk X‐ray absorption near‐edge structure spectroscopy. Soil was contaminated by coal combustion and other diffuse sources and had low As bioaccessibility (7%–12%). Unamended soil had As(III) sorbed onto pyrite (As(III)‐pyrite; ∼60%) and As(V) adsorbed onto Fe oxy(hydr)oxides (As(V)‐Fh; ∼40%). In amended soils, except in composted biosolids‐amended soils, at 7 days, As(V)‐Fh decreased to 15%–26% and redistributed into As(III)‐Fh and/or As(III)‐pyrite. This transformation was most pronounced in mushroom compost amended soil resulting in a significant (46%) increase of As bioaccessibility compared to the unamended soil. Composted biosolids‐amended soils had relatively stable As(V)‐Fh. Lead arsenate formed during the in vitro extraction in amended soils, except in composted biosolids‐amended soils. Arsenic speciation and bioaccessibility were similar in 349‐ and 642‐day in all the amended and unamended soils. Reduction of As(V)‐Fh to As(III) forms in the short term in three of the amended soils showed the potential to increase As bioaccessibility. The formation of stable lead arsenate during the in vitro extraction would counteract the short‐term increase of As bioaccessibility in those amended soils.
Core Ideas
Sources of soil arsenic (As) and lead (Pb) were coal burning and other diffuse sources.
Soil As speciation: 60% As(III) sorbed onto pyrite and 40% As(V) adsorbed onto Fe oxy(hydr)oxides.
Three amendments temporarily reduced sorbed As(V) into As(III) forms.
Lead arsenate formed during the in vitro bioaccessibility extraction.
Lead may counteract temporarily increased As bioaccessibility in amended soils.
Plain Language Summary
Lead and arsenic in soils can be transferred to humans by ingesting soil accidentally, especially when children play outdoors. Organic amendments such as compost change the chemical forms of arsenic in the field and affect arsenic release from ingested soils within the digestive system. We assessed four organic amendments on their effects on chemical form of soil arsenic in the field and in a simulated gastric system. Within 7 days, three of the amendments temporarily changed the chemical form of arsenic in the field to more bioavailable forms. We could not tell the exact time duration that the temporary change of As form persisted in soils, but we have evidence that it was less than 1 year. Arsenic and lead in the amended soils reacted and formed an insoluble precipitate, called lead arsenate. This transformation would reduce the negative effect of both soil arsenic and lead on humans. The use of organic amendments is beneficial for urban agriculture.
Population growth and technical and social changes have always exerted pressure on environmental quality. However, we are experiencing unprecedented change in the rate and scale of human impacts on ...the environment. The One Health Initiative recognizes that improving the quality of life for humans and other animal species requires a holistic and integrated framework to seek multidisciplinary solutions to global environmental quality challenges. This special section is designed to elucidate the connections among soil health, environmental quality, food safety and security, and human health. Soil chemistry is defined as the field of soil science that deals with the chemical constituents, properties, and reactions of soils. Soil chemistry plays a central role in food production and the protection of human health. Chemical reactions between nutrients or contaminants and soil solids, and the composition of the soil solution and the atmosphere, influence crop growth as well as the quality of our food, air, and water. This collection of nine papers brings together studies that highlight how soil chemical constituents, properties, and reactions can be examined or managed using a multidisciplinary approach to move toward a more efficient, sustainable, nutrient‐rich, and low‐contaminant food production system that affords protection of soil, water, and human and animal health. We believe that studies such as these are needed to maintain and enhance environmental quality through interdisciplinary scientific approaches for human, animal, and environmental health outcomes.
Core Ideas
One Health Initiative links soils to human, animal, and environmental health.
Interdisciplinary soil chemistry studies protect and enhance environmental quality.
Environmental quality will benefit from a holistic view of environmental processes.
Urban gardening has been experiencing increased popularity around the world. Many urban gardens are located on sites that may be contaminated by trace elements or organic compounds due to previous ...use. The three main exposure pathways to the human body for soil contaminants are (a) ingestion of soil directly, (b) consumption of produce containing or superficially contaminated with a contaminant, (c) and inhalation of soil dust. The first two modes have received much attention; however, the contribution of the inhalation route has not been investigated adequately. Two inhalation risk studies were carried out in urban gardens located in Kansas City, MO, by collecting dust while 25‐m2 plots were rototilled. Microclimatic variables were monitored, and total inhalable dust mass was determined using a personal sampling train including a small pump and air filter. Soil lead (Pb) concentration was assessed at both sites. For Study 1, particle size distribution of collected particles was estimated through analysis of scanning electron microscope images of filters. Little dust was collected at either site. Most particles captured, however, appeared to be <4 μm in diameter. The amount of dust emitted was correlated with soil moisture. Tilling reduced soil aggregate size and blended soil, resulting in a more homogeneous distribution of Pb. Dust inhalation while tilling is likely not a major Pb exposure risk for gardeners, but given the preponderance of very small particles in what was captured, care should be taken to prevent dust from entering the respiratory system.
Core Ideas
The inhalation exposure route of soil Pb for urban gardeners has not been adequately investigated.
Rototilling activity‐based inhalation risk studies were conducted in two urban garden sites.
Short‐term dust exposure from rototilling is not a major Pb exposure pathway for the person conducting the rototilling.
Rototilling under dry conditions presents the greatest risk.
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