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Environmental Science. Processes & Impacts

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https://www.readbyqxmd.com/read/30014062/modelling-mass-balance-of-cadmium-in-paddy-soils-under-long-term-control-scenarios
#1
Wenli Feng, Zhaohui Guo, Chi Peng, Xiyuan Xiao, Lei Shi, Xiaoqing Han, Hongzhen Ran
A simple mathematical model on the basis of the mass balance principle was developed to simulate the long-term changes of Cd in paddy soils. The model predicted the dynamics of cadmium concentration in soils under six alternative control scenarios, including rice straw incorporation into fields (A), removing straw from fields (B), irrigating paddies with groundwater (C), reducing atmospheric Cd deposition (D), liming (E), and integrating measures (F), which were used for Cd contaminated paddy fields in the central subtropical areas of China...
July 17, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29987291/inter-individual-inter-city-and-temporal-trends-of-per-and-polyfluoroalkyl-substances-in-human-milk-from-swedish-mothers-between-1972-and-2016
#2
Elisabeth Nyberg, Raed Awad, Anders Bignert, Caroline Ek, Gerd Sallsten, Jonathan P Benskin
Inter-individual, inter-city, and temporal trends of 19 per- and polyfluoroalkyl substances (PFASs) were investigated in human milk collected in Stockholm (1972-2016) and Gothenburg (2007-2015), Sweden. The concentrations of perfluorohexane sulfonate (PFHxS), perfluorononanoate (PFNA), perfluorodecanoate (PFDA), perfluoroundecanoate (PFUnDA), and perfluorotridecanoate (PFTrDA) in human milk from Stockholm increased significantly over the entire monitoring periods, whereas branched (Br) and linear (L) isomers of perfluorooctane sulfonamide (FOSA) decreased...
July 10, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29987286/on-the-degradation-pathway-of-glyphosate-and-glycine
#3
Anderson José Lopes Catão, Alejandro López-Castillo
The degradation in water of the most widespread herbicide, glyphosate, is still under debate. Experimental disagreements on this process exist and there are only a few theoretical studies to support any conclusions. Moreover, the relationship between glyphosate and glycine is underestimated. Besides the structural similarity, glycine is a product of glyphosate degradation; hence, their studies are complementary. In this study, two mechanisms for the decomposition of the glyphosate molecule and glycine molecule in water are proposed...
July 10, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29974906/emerging-investigator-series-sunlight-photolysis-of-2-4-d-herbicides-in-systems-simulating-leaf-surfaces
#4
Lei Su, John D Sivey, Ning Dai
Pesticides are commonly applied on foliage, forming dry deposits on the leaf cuticular wax. However, their photochemical transformation in this lipophilic environment is much less understood compared with that in surface water. In this work, sunlight photolysis of six chlorinated phenoxyacetic acid herbicides (i.e., 2,4-D and structural analogues) was evaluated in four organic solvents, on quartz, and on paraffin wax. In solvents of low polarity (i.e., n-heptane and 2-propanol), direct photolysis of 2,4-D herbicides was enhanced due to the relatively high quantum yields in these solvents...
July 5, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29953162/investigation-on-the-hygroscopicity-of-oxalic-acid-and-atmospherically-relevant-oxalate-salts-under-sub-and-supersaturated-conditions
#5
Suresh K R Boreddy, Kimitaka Kawamura
Oxalic acid (OxA) is an end product in the oxidation of many organic compounds, and therefore is ubiquitous in the atmosphere and is often the most abundant organic species in ambient aerosols. To better understand the hygroscopic properties of OxA under sub- and supersaturated conditions in the atmosphere, we investigated the hygroscopic growth and cloud condensation nuclei (CCN) activation ability of pure OxA and its salts using a hygroscopic tandem differential mobility analyzer (HTDMA) and cloud condensation nuclei counter (CCNC), respectively...
June 28, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29922797/cr-vi-uptake-and-reduction-by-biogenic-iron-oxyhydr-oxides
#6
Andrew H Whitaker, Jasquelin Peña, Mathilde Amor, Owen W Duckworth
The mobility and toxicity of chromium (Cr) in soil and water systems are largely controlled by its oxidation state and interactions with solid phases. Relative to abiotic minerals, biogenic iron (Fe) (oxyhydr)oxides (BIOS) may enhance Cr(vi) adsorption and reduction due to their poorly ordered structures, large surface areas, and incorporation of cell derived organic matter. To determine the extent and mechanisms of the reaction between Cr(vi) and BIOS, sorption isotherm and kinetic studies were conducted using two-line ferrihydrite, BIOS, and BIOS amended with 0...
June 20, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29901671/reaction-of-bisphenol-a-with-synthetic-and-commercial-mno-x-s-spectroscopic-and-kinetic-study
#7
Nabil Shaikh, Huichun Zhang, Kowsalya Rasamani, Kateryna Artyushkova, Abdul-Mehdi S Ali, José M Cerrato
The reaction of bisphenol A (BPA) using laboratory synthesized (Syn-MnOx) and commercially available (Com-MnOx) MnOx(s) media was investigated using spectroscopic and aqueous chemistry methods. The surface area of Syn-MnOx (128 m2 g-1) and Com-MnOx (13.6 m2 g-1) differed by an order of magnitude. The impurities were less than 1% by weight for Syn-MnOx while Com-MnOx contained 29% impurity by weight, mainly Al, Si and Fe. The removal of 99.7% BPA was observed applying Syn-MnOx, while 71.2% BPA removal was observed applying Com-MnOx after 44 hours of reaction of 10 mM MnOx(s) media with 1 mM BPA at pH 5...
June 14, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29900462/occurrence-impact-variables-and-potential-risk-of-ppcps-and-pesticides-in-a-drinking-water-reservoir-and-related-drinking-water-treatment-plants-in-the-yangtze-estuary
#8
Cong Xu, Lei Chen, Luhua You, Zheng Xu, Long-Fei Ren, Karina Yew-Hoong Gin, Yiliang He, Weizhi Kai
PPCPs and pesticides have been documented throughout the world over the years, yet relatively little is known about the factors affecting their spatial distribution and temporal change in order to know their potential risk to the ecosystem or human health in the future. In our study, 5 PPCPs and 9 pesticides were selected to study their occurrence, impact variables and potential risk in a drinking water reservoir in Yangtze Estuary and related drinking water treatment plants (DWTPs) in China. The detection results showed the presence of PPCPs and pesticides reflected in a large part of croplands and urban and built-up land in the adjacent basin...
June 14, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29897369/emerging-investigator-series-determination-of-biphasic-core-shell-droplet-properties-using-aerosol-optical-tweezers
#9
Kyle Gorkowski, Neil M Donahue, Ryan C Sullivan
We present a new algorithm for the analysis of whispering gallery modes (WGMs) found in the cavity enhanced Raman spectra retrieved from optically tweezed droplets. Our algorithm improves the computational scaling when analyzing core-shell droplets (i.e. phase-separated or biphasic droplets) in the aerosol optical tweezers (AOT), making it computationally practical to analyze spectra collected at a few Hz over hours-long experiments. This enables the determination of the size and refractive index of both the core and shell phases with high accuracy, at 0...
June 13, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29897361/occurrence-and-source-analysis-of-selected-antidepressants-and-their-metabolites-in-municipal-wastewater-and-receiving-surface-water
#10
Luo-Dan Ma, Jian Li, Jia-Jun Li, Min Liu, Dong-Zhi Yan, Wen-Yan Shi, Gang Xu
Seven commonly utilized antidepressants (amitriptyline, fluoxetine, sertraline, citalopram, paroxetine, venlafaxine, and bupropion) and three of their metabolites were detected in four wastewater treatment plants (WWTPs) and corresponding receiving waters including the mainstream and three of the tributaries of Huangpu River, Shanghai. The concentration levels of selected antidepressants in wastewater and receiving water were both at ng L-1 level, but those antidepressants that were found in wastewater were typically in a range of one and even two orders of magnitude higher than those that were present in the receiving water except for the concentration levels of paroxetine, norfluoxetine, and nortriptyline...
June 13, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29876570/an-experimental-methodology-to-measure-the-reaction-rate-constants-of-processes-sensitised-by-the-triplet-state-of-4-carboxybenzophenone-as-a-proxy-of-the-triplet-states-of-chromophoric-dissolved-organic-matter-under-steady-state-irradiation-conditions
#11
Marco Minella, Lorenzo Rapa, Luca Carena, Marco Pazzi, Valter Maurino, Claudio Minero, Marcello Brigante, Davide Vione
By a combination of transient absorption spectroscopy and steady-state irradiation experiments, we investigated the transformation of phenol and furfuryl alcohol (FFA) sensitised by irradiated 4-carboxybenzophenone (CBBP). The latter is a reasonable proxy molecule to assess the reactivity of the excited triplet states of the chromophoric dissolved organic matter that occurs in natural waters. The main reactive species for the transformation of both phenol and FFA was the CBBP triplet state, despite the fact that FFA is a commonly used probe for 1O2...
June 7, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29869654/spatial-variation-in-the-atmospheric-deposition-of-perfluoroalkyl-acids-source-elucidation-through-analysis-of-isomer-patterns
#12
Jana H Johansson, Yali Shi, Matthew Salter, Ian T Cousins
To evaluate the relevance of different proposed sources of perfluoroalkyl acids (PFAAs) to air, their isomer patterns were analyzed in deposition samples collected from five geographical locations: two urban sites in China (>360 km from known operational fluorochemical manufacturing facilities), one remote marine site in the Azores archipelago and two Swedish sites representing urban and background conditions. Despite variable contributions from linear perfluorooctanoic acid (PFOA) in the samples, the pattern of branched PFOA isomers was similar to those of technical standards manufactured using electrochemical fluorination (ECF)...
June 5, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29790879/exploring-matrix-effects-and-quantifying-organic-additives-in-hydraulic-fracturing-associated-fluids-using-liquid-chromatography-electrospray-ionization-mass-spectrometry
#13
Marika Nell, Damian E Helbling
Hydraulic fracturing (HF) operations utilize millions of gallons of water amended with chemical additives including biocides, corrosion inhibitors, and surfactants. Fluids injected into the subsurface return to the surface as wastewaters, which contain a complex mixture of additives, transformation products, and geogenic chemical constituents. Quantitative analytical methods are needed to evaluate wastewater disposal alternatives or to conduct adequate exposure assessments. However, our narrow understanding of how matrix effects change the ionization efficiency of target analytes limits the quantitative analysis of polar to semi-polar HF additives by means of liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS)...
May 23, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29877524/the-cycle-of-nitrogen-in-river-systems-sources-transformation-and-flux
#14
REVIEW
Xinghui Xia, Sibo Zhang, Siling Li, Liwei Zhang, Gongqin Wang, Ling Zhang, Junfeng Wang, Zhihuang Li
Nitrogen is a requisite and highly demanded element for living organisms on Earth. However, increasing human activities have greatly altered the global nitrogen cycle, especially in rivers and streams, resulting in eutrophication, formation of hypoxic zones, and increased production of N2O, a powerful greenhouse gas. This review focuses on three aspects of the nitrogen cycle in streams and rivers. We firstly introduce the distributions and concentrations of nitrogen compounds in streams and rivers as well as the techniques for tracing the sources of nitrogen pollution...
June 20, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29863203/density-functional-theory-characterization-of-the-structures-of-h-3-aso-3-and-h-3-aso-4-adsorption-complexes-on-ferrihydrite
#15
Nelson Y Dzade, Nora H de Leeuw
Reactions occurring at ferric oxyhydroxide surfaces play an important role in controlling arsenic bioavailability and mobility in natural aqueous systems. However, the mechanism by which arsenite and arsenate complex with ferrihydrite (Fh) surfaces is not fully understood and although there is clear evidence for inner sphere complexation, the nature of the surface complexes is uncertain. In this work, we have used periodic density functional theory calculations to predict the relative energies, geometries and properties of arsenous acid (H3AsO3) and arsenic acid (H3AsO4), the most prevalent form of As(iii) and As(v), respectively, adsorbed on Fh(110) surface at intermediate and high pH conditions...
June 20, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29850698/bacterial-bioreporter-detection-of-arsenic-associated-with-iron-oxides
#16
Case M van Genuchten, Amanda Finger, Jan R van der Meer, Jasquelin Peña
Bacterial bioreporters are engineered microorganisms that have found recent application as a low-cost method of detecting arsenic (As) in environmental systems. However, no assessment exists of bioreporter detection of particle-bound As. We applied an Escherichia coli-based bioreporter to assess the bioavailability of As(v) adsorbed by goethite (α-FeOOH), 2-line ferrihydrite and As(v) co-precipitated with Fe(iii). We found that As(v) bound to the surface of crystalline goethite was not detected by the bioreporters, which contrasted sharply the 50% detection of As(v) adsorbed by ferrihydrite...
June 20, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29790534/evidence-for-the-natural-origins-of-anomalously-high-chromium-levels-in-soils-of-the-cecina-valley-italy
#17
Eliana Tassi, Martina Grifoni, Fabrizio Bardelli, Giuliana Aquilanti, Sonia La Felice, Antonella Iadecola, Pierfranco Lattanzi, Gianniantonio Petruzzelli
The problem of high levels of chromium is one of the most important issues in soils of the Mediterranean area, in particular those deriving from ophiolitic parent materials. Very often the chromium concentration is greater than the threshold values of legislation on soil pollution and the knowledge of the origin of contamination (natural or anthropogenic) is important to formulate risk characterization. This study evaluated the soils from three coastal areas of the Cecina Valley (Tuscany, Italy) to understand the origin of chromium in the soils, where high levels of hexavalent chromium were found in well and spring waters of the areas...
June 20, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29774347/effect-of-humic-acid-bacterial-exudates-on-sorption-desorption-interactions-of-90-sr-with-brucite
#18
Hollie Ashworth, Liam Abrahamsen-Mills, Nick Bryan, Lynn Foster, Jonathan R Lloyd, Simon Kellet, Sarah Heath
One of the nuclear fuel storage ponds at Sellafield (United Kingdom) is open to the air, and has contained a significant inventory of corroded magnox fuel and sludge for several decades. As a result, some fission products have also been released into solution. 90Sr is known to constitute a small mass of the radionuclides present in the pond, but due to its solubility and activity, it is at risk of challenging effluent discharge limits. The sludge is predominantly composed of brucite (Mg(OH)2), and organic molecules are known to be present in the pond liquor with occasional algal blooms restricting visibility...
June 20, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29774338/trace-metals-in-oysters-molecular-and-cellular-mechanisms-and-ecotoxicological-impacts
#19
REVIEW
Wen-Xiong Wang, Jie Meng, Nanyan Weng
Oysters are important benthic bivalves in coastal and estuarine environments. They are widely farmed due to their rapid growth and taste; they are also widely applied in environmental monitoring of coastal pollution due to their accumulation of contaminants. Most importantly, oysters are among the few marine organisms that are considered to be hyper-accumulators of many toxic metals, such as cadmium, copper and zinc. As such, there is a tremendous call to study the interactions between metals and oysters, especially due to the increasing metal pollution in many coastal and estuarine waters...
June 20, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29761198/kinetics-of-cd-ii-adsorption-and-desorption-on-ferrihydrite-experiments-and-modeling
#20
Yuzhen Liang, Lei Tian, Yang Lu, Lanfang Peng, Pei Wang, Jingyi Lin, Tao Cheng, Zhi Dang, Zhenqing Shi
The kinetics of Cd(ii) adsorption/desorption on ferrihydrite is an important process affecting the fate, transport, and bioavailability of Cd(ii) in the environment, which was rarely systematically studied and understood at quantitative levels. In this work, a combination of stirred-flow kinetic experiments, batch adsorption equilibrium experiments, high-resolution transmission electron microscopy (HR-TEM), and mechanistic kinetic modeling were used to study the kinetic behaviors of Cd(ii) adsorption/desorption on ferrihydrite...
June 20, 2018: Environmental Science. Processes & Impacts
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