Consistent inter-annual reduction of rice cadmium in 5-year biannual organic amendment.

Organic fertilizers may contain cadmium (Cd) and the transformation of organic materials in soil also has a role in soil-plant Cd distribution, both of which lead to Cd accumulation in plant edible parts. However, the advisability of applying organic fertilizer to remediate soils that are moderately and slightly contaminated with Cd has not been clarified. In this study, we investigated the impacts of an organic amendment (chicken manure) on the Cd concentration in rice grains (Cd) and the soil chemical properties over a five year period (10 rice seasons) within a slightly contaminated paddy soil in Hunan Province, subtropical China.

Comparison of adsorption behaviors of selected endocrine-disrupting compounds in soil.

Bisphenol-A (BPA), 17α-ethinylestradiol (EE2), and 4-nonylphenol (4NP) are endocrine-disrupting chemicals (EDCs) that are useful models for studying the potential fate and transport of EDCs in soil and water environments. Two alluvial soils with contrasting physicochemical properties were used as adsorbents for this study. The Zook soil material had more organic matter and clay than the sandy loam Hanlon soil material.

Soil labile organic carbon fractions and soil enzyme activities after 10 years of continuous fertilization and wheat residue incorporation.

Labile organic carbon (LOC) fractions and related enzyme activities in soils are considered to be early and sensitive indicators of soil quality changes. We investigated the influences of fertilization and residue incorporation on LOC fractions, enzyme activities, and the carbon pool management index (CPMI) in a 10-year field experiment. The experiment was composed of three treatments: (1) no fertilization (control), (2) chemical fertilizer application alone (F), and (3) chemical fertilizer application combined with incorporation of wheat straw residues (F + R).

Formation of Char-Like, Fused-Ring Aromatic Structures from a Nonpyrogenic Pathway during Decomposition of Wheat Straw.

Fused-ring aromatics, important skeletal components of black carbon (BC), contribute to long-term carbon (C) sequestration in nature. They have previously been thought to be primarily formed by incomplete combustion of organic materials, whereas the nonpyrogenic origins are negligible. Using advanced solid-state C nuclear magnetic resonance (NMR), including recoupled long-range C-H dipolar dephasing, exchange with protonated and nonprotonated spectral editing (EXPANSE), and dipolar-dephased double-quantum/single-quantum (DQ/SQ) spectroscopy, we for the first time identify fused-ring aromatics that formed during the decomposition of wheat ( sp.

Linking chemical structure of dissolved organic carbon and microbial community composition with submergence-induced soil organic carbon mineralization.

Much research has been devoted to investigating how water-extractable organic carbon (DOC) concentration and microbial activity regulate soil organic carbon (SOC) mineralization when soils are saturated with water. However, the relationships of DOC chemical structure and microbial community composition with SOC mineralization, as well as the relative contributions of microbial decomposers and their substrates on the mineralization rate have rarely been examined. In a laboratory experiment, we incubated two typical cropland soils (an Entisol and a Mollisol) of China for 360 days under submerged and non-submerged conditions, and we evaluated the concentration and chemical structure of soil DOC, soil microbial metabolic potential and community composition by using total C/N analysis, solution-state H NMR, Biolog EcoPlates, and 16S rRNA amplicon sequencing, respectively.

Varying redox potential affects P release from stream bank sediments.

Sediments in streams that drain agricultural watersheds may be sinks that can adsorb P from the stream or sources that can release P to the stream. Sediment characteristics and environmental factors, including the oxidation-reduction (redox) potential of the water associated with the sediment, determine whether P will be adsorbed or released by the sediment. We investigated P adsorption and release by four sediments [three Holocene-age sediments (Camp Creek, Roberts Creek and Gunder) as well as Pre-Illinoian-age Till] that occur in Walnut Creek, a second-order stream in Jasper County, Iowa, that is representative of many small streams in the glaciated upper Midwest of the US.

Biochemical stabilization of soil organic matter in straw-amended, anaerobic and aerobic soils.

Crop straw incorporation is a useful approach for increasing the quantity and changing the chemical composition of soil organic matter (SOM). This process is influenced by soil aeration. The present study investigated the stability of whole SOM, particulate organic matter (POM) and mineral-associated organic matter (MinOM) fractions with wheat straw amendment under aerobic and anaerobic conditions over a 12-month incubation period.

Escherichia coli attachment to model particulates: The effects of bacterial cell characteristics and particulate properties.

E. coli bacteria move in streams freely in a planktonic state or attached to suspended particulates. Attachment is a dynamic process, and the fraction of attached microorganisms is thought to be affected by both bacterial characteristics and particulate properties.

Allelic Variation in Outer Membrane Protein A and Its Influence on Attachment of to Corn Stover.

Understanding the genetic factors that govern microbe-sediment interactions in aquatic environments is important for water quality management and reduction of waterborne disease outbreaks. Although chemical properties of bacteria have been identified that contribute to initiation of attachment, the outer membrane proteins that contribute to these chemical properties still remain unclear. In this study we explored the attachment of 78 environmental isolates to corn stover, a representative agricultural residue.

Surface Properties Differ between Stream Water and Sediment Environments.

The importance of as an indicator organism in fresh water has led to numerous studies focusing on cell properties and transport behavior. However, previous studies have been unable to assess if differences in cell surface properties and genomic variation are associated with different environmental habitats. In this study, we investigated the variation in characteristics of obtained from stream water and stream bottom sediments.

Characterization and quantification of biochar alkalinity.

Lack of knowledge regarding the nature of biochar alkalis has hindered understanding of pH-sensitive biochar-soil interactions. Here we investigate the nature of biochar alkalinity and present a cohesive suite of methods for its quantification. Biochars produced from cellulose, corn stover and wood feedstocks had significant low-pK organic structural (0.

Phosphorus source-sink relationships of stream sediments in the Rathbun Lake watershed in southern Iowa, USA.

The surface waters of Rathbun Lake watershed in southern Iowa are impacted by agricultural sources of sediments and nutrients, including phosphorus (P). Because stream sediments often play an important role in regulating P concentrations in stream water, we investigated sediment-water column P relationships in four creeks within the watershed and then evaluated the relationship between sediment properties and indicators of the risk of P loss. Based on Mehlich-3-extractable P (17 to 68 mg kg(-1)) and degree of P saturation (2 to 12 %), stream bank and bed sediments at the four sites were unlikely to serve as major sources of P.

Decomposition Dynamics and Changes in Chemical Composition of Wheat Straw Residue under Anaerobic and Aerobic Conditions.

Soil aeration is a crucial factor that regulates crop residue decomposition, and the chemical composition of decomposing crop residues may change the forms and availability of soil nutrients, such as N and P. However, to date, differences in the chemical composition of crop straw residues after incorporation into soil and during its decomposition under anaerobic vs. aerobic conditions have not been well documented.

Successful recanalization for acute ischemic stroke via the transbrachial approach.

The recent development of revascularization devices, including stent retrievers, has enabled increasingly higher revascularization rates for arterial occlusions in acute ischemic stroke. Patient-specific factors such as anatomy, however, may occasionally limit endovascular deployment of these new devices via the conventional transfemoral approach. We report three cases of acute ischemic stroke where a transbrachial endovascular approach to revascularization was used, resulting in successful recanalization.

Reduction of estrone to 17 β-estradiol in the presence of swine manure colloids.

Land application of animal manure and municipal biosolids to improve soil fertility carries the risk of adding to aquatic ecosystems contaminants that can disrupt the endocrine systems of aquatic organisms. This study explored the fate of two estrogens, 17 β-estradiol (E2) and estrone (E1), in the presence of organic colloids derived from swine manure. Most reports concerning environmental estrogens indicate a degradation/transformation pathway that leads to decreased estrogenicity, that is, E2 is transformed to E1 and potentially to other daughter products.

Evaluation of modified boehm titration methods for use with biochars.

The Boehm titration, originally developed to quantify organic functional groups of carbon blacks and activated carbons in discrete pK ranges, has received growing attention for analyzing biochar. However, properties that distinguish biochar from carbon black and activated carbon, including greater carbon solubility and higher ash content, may render the original Boehm titration method unreliable for use with biochars. Here we use seven biochars and one reference carbon black to evaluate three Boehm titration methods that use (i) acidification followed by sparging (sparge method), (ii) centrifugation after treatment with BaCl (barium method), and (iii) a solid-phase extraction cartridge followed by acidification and sparging (cartridge method) to remove carbonates and dissolved organic compounds (DOC) from the Boehm extracts before titration.

Occurrence and pathways of manure-borne 17beta-estradiol in vadose zone water.

The hormone 17beta-estradiol (E2) can cause endocrine disruption in sensitive species at part per trillion concentrations. The persistence and transport pathways of manure-borne E2 in agricultural soils were determined by comparing its occurrence with the transfer of water and the transport of non-sorbing fluorobenzoic acid (FBA) tracers. This comparison was done using capillary wick lysimeters installed 0.

Interactions among K+-Ca2+ exchange, sorption of m-dinitrobenzene, and smectite quasicrystal dynamics.

The fate of organic contaminants in soils and sediments is influenced by sorption of the compounds to surfaces of soil materials. We investigated the interaction among sorption of an organic compound, cation exchange reactions, and both the size and swelling of smectite quasicrystals. Two reference smectites that vary in location and amount of layer charge, SPV (a Wyoming bentonite) and SAz-1 were initially Ca- and K-saturated and then equilibrated with mixed 0.

Fate, transport, and biodegradation of natural estrogens in the environment and engineered systems.

Natural steroidal estrogen hormones, e.g., estrone (E1), 17beta-estradiol (E2), estriol (E3), and 17alpha-estradiol (17alpha), are released by humans and livestock in the environment and are the most potent endocrine disrupters even at nanogram per liter levels.

Keratoameloblastoma: a tumor sui generis or a chimera?

The term keratoameloblastoma has been used to describe a histologically heterogeneous group of ameloblastoma variants which have in common the formation of keratin by the ameloblastomatous epithelium. The English language literature contains reports of only 12 cases of keratoameloblastoma, of which 4 cases exhibited a papilliferous component. We report a unique tumor that we believe falls within the broad histopathologic spectrum of keratoameloblastoma.

Cosorption of atrazine and a lauryl polyoxyethylene oxide nonionic surfactant on smectite.

Commercial atrazine formulations commonly contain nonionic surfactants that serve as solubilizing and wetting agents for enhancing the stability and efficacy of the herbicide. The fate of atrazine in soils has been extensively investigated; yet, few studies have considered the effects of formulation components on the fate of atrazine in soils. In this study, we investigated the influence of the nonionic surfactant, Brij 35 (Brij), on the sorption of atrazine on Ca- and K-saturated samples of a reference smectite, Panther Creek (PC).

Influence of smectite hydration and swelling on atrazine sorption behavior.

Smectites, clay minerals commonly found in soils and sediments, vary widely in their ability to adsorb organic chemicals. Recent research has demonstrated the importance of surface charge density and properties of exchangeable cations in controlling the affinity of smectites for organic molecules. In this study, we induced hysteresis in the crystalline swelling of smectites to test the hypothesis that the extent of crystalline swelling (or interlayer hydration status) has a large influence on the ability of smectites to adsorb atrazine from aqueous systems.

Plant-available zinc and lead in mine spoils and soils at the mines of Spain, Iowa.

To investigate the forms of Zn and Pb and their plant availability in mine spoil long after its abandonment, we studied seven sites in the Mines of Spain, near Dubuque, IA. Ores of Zn and Pb were mined from dolomitic limestone primarily during the 19th century, and there had been no subsequent remediation of metals-contaminated spoil. From both mine spoil and undisturbed areas, we collected root-zone soil samples as well as samples of the dominant ground-level, native plants, aniseroot [Osmorhiza longistylis (Torr.

Impact of dissolved organic matter on copper mobility in aquifer material.

Naturally occurring dissolved organic matter (DOM) and biosolids-derived DOM have been implicated in the mobility of metals in soils and aquifer materials. To investigate the effect of DOM on copper mobility in aquifer material, DOM derived from sewage biosolids was separated into two apparent molecular-weight (MW) fractions, 500 to 3500 Da (LMW) and > 14 000 Da (HMW). In each MW fraction, the DOM was further fractionated into hydrophilic, hydrophobic acid, and hydrophobic neutral compounds by an XAD-8 chromatography technique.

Sorption and transport behavior of naphthalene in an aggregated soil.

Soil solution chemistry influences the sorption and transport behavior of hydrophobic organic compounds (HOCs) in soil. We used both batch and column studies to investigate the influence of ionic strengths (0.03 and 1.