Coarse–fine and day–night differences of water-soluble ions in atmospheric aerosols collected in Christchurch and Auckland,New Zealand

The water-soluble ions in fine (PM_<2.5) and coarse (PM_2.5−10) atmospheric aerosols collected in Christchurch during winter 2001, spring 2000 and summer 2001, and in Auckland during winter 2001 have been studied in terms of coarse–fine and day–night differences. Although the chemical characteristics of the coarse particles were similar in both cities, those of the fine particles collected in the Christchurch winter were significantly different, as manifested by higher concentrations of nss-K⁺, nss-Cl⁻, nss-Ca²⁺, nss-SO₄²⁻, NO₃⁻ and NH₄⁺. It was found that nighttime PM₁₀ and nss-K⁺ concentrations were much higher than their daytime concentrations in the Christchurch winter but a clear day–night difference was not apparent in the Auckland winter. Moreover, in the winter, sea-salt ions did not show a day–night difference; however, nss-SO₄²⁻ had opposite day–night variation in the two cities. An ion balance calculation has shown that in most samples, coarse particles can be neutral or alkaline, however, fine particles can be neutral or acidic. The possibility of ammonium salts existing in the fine particles collected in the Christchurch winter is discussed and it is concluded that a variety of ammonium salts were present. Equivalent ratios suggest that the fine particles may be significantly aged in the Christchurch winter.The evidence from our soluble ion study strongly suggests that wood and coal burning and secondary aerosols make a significant contribution to fine particulate mass in the Christchurch atmosphere. Thus, home-heating, a sheltered geographic location and relatively calm atmospheric condition are thought to be the major causes for the serious atmospheric particulate pollution in the Christchurch winter.     

Photocatalytic degradation of acetaminophen and caffeine using magnetite–hematite combined nanoparticles: kinetics and mechanisms

Environmental Science and Pollution Research - The increased use of pharmaceutical and personal care products (PPCPs) has contributed to the contamination of water systems and put pressure on the...     

Preparation and evaluation of humic acid–based composite dust suppressant for coal storage and transportation

Environmental Science and Pollution Research - To mitigate environmental pollution caused by the escape of dust during coal storage and transportation, humic acid (HA) and grafted acrylamide (AM)...     

Understanding the patterns and processes underlying water quality and pollution risk in West–Africa River using self-organizing maps and multivariate analyses

Environmental Science and Pollution Research - Rivers are dynamic systems in complex interactions with their surrounding environments. Reliable and fast interpretation of water quality is therefore...     

Comparison of line– and point–source releases of tracer gases

Field measurements were made of greenhouse gas emissions from a wastewater treatment system using open path monitoring with detection by FTIR spectroscopy. Emission rates were determined by the ratio technique using a sulfur hexafluoride tracer gas released from a line source. As a quality control check, a second tracer gas – ethylene – was released from various single point locations. This paper presents a comparison of the line-source and point-source tracer releases for approximating emissions from the area source. The two types of tracer release showed excellent agreement when both release points were two hundred meters from the FTIR beam path. Data for other release points also were comparable, once differences in vertical dispersion as a function of distance are taken into account.     

Separation and remediation of environmental pollutants using metal–organic framework-based tailored materials

Environmental Science and Pollution Research - Metal–organic frameworks (MOFs) are a polymer hybrid family of compounds comprising metal ions that have been deliberately incorporated in...     

Assessing the nexus between COVID-19 pandemic–driven economic crisis and economic policy: lesson learned and challenges

Environmental Science and Pollution Research - This study examines China’s budgetary policy during the COVID-19 pandemic as a result of China’s insufficient ability to deal with a new...     

Pyridinic N–reduced graphene oxide and ZnO composite synergistically enhance photocatalytic performance

Environmental Science and Pollution Research - This paper reports the synthesis of nitrogen-doped reduced graphene oxide (N-rGO)/zinc oxide (ZnO) composite photocatalysts by one-step hydrothermal...     

HNO3 analyzer by scrubber difference and the NO–ozone chemiluminescence method

A fast response analyzer for HNO₃ in highly polluted air is described. The time resolution attainable was 12 s. The method is based on the difference in a technique for HNO₃-scrubbed and non-scrubbed air and the reduction of HNO₃ to NO with the use of a line of catalytic converters and a method for the subsequent NO-ozone chemiluminescence. A sample air stream, in which particulates are removed with a Teflon filter, is divided into two channels. CH-1 is directly connected to the converter line, and CH-2 contains a HNO₃ scrubber packed with a nylon fiber that goes to another converter line. Each converter line is composed of a hot quartz-bead converter (QBC) and a molybdenum converter (MC) in a series. A QBC reduces HNO₃ to (NO+NO₂), which is called NO_x. The MC reduces the NO_x to NO.For CH-1, the analyzer detects most compounds that typically comprise NO_y (J. Geophys. Res. 91 (1986) 9781). These CH-1 compounds are called NO_y′ hereafter (NO_y-particulate nitrate) because the particulates are removed by the filter. A difference in the detector signal for the two channels indicates HNO₃. For a blank test, atmospheric air in which HNO₃ was pre-scrubbed by an extra nylon fiber was introduced to the analyzer. Variations in the blank value were 0.38±0.42 and 0.34±0.55 ppb during the high readings (NO_y′-HNO₃ ) (called NO_y^* hereafter) (111±12 ppb, N=180), and low NO_y^* readings (62±8 ppb, N=180), respectively, indicating that the lowest detection limit of the analyzer is 1.1 ppb (2σ). When the data obtained with the analyzer is compared to the data using the denuder method, a linear correlation with the regression of Y=0.973X+0.077 (r²=0.916 (N=20)) in the range of 0–6.5 ppb HNO₃ is obtained, which is an excellent agreement. Atmospheric monitoring was carried out at Kobe. Although the average concentration of HNO₃ was 2.6±1.3 ppb, ca.10 ppb for a HNO₃ concentration was occasionally observed when the NO_y^* concentration was high, i.e., more than 100 ppb.     

Seed treatments containing neonicotinoids and fungicides reduce aquatic insect richness and abundance in midwestern USA–managed floodplain wetlands

Agrochemicals including neonicotinoid insecticides and fungicides are frequently applied as seed treatments on corn, soybeans, and other common row crops. Crops grown from pesticide-treated seed are often directly planted in managed floodplain wetlands and used as a soil disturbance or food resource for wildlife. We quantified invertebrate communities within mid-latitude floodplain wetlands and assessed their response to use of pesticide-treated seeds within the floodplain. We collected and tested aqueous and sediment samples for pesticides in addition to sampling aquatic invertebrates from 22 paired wetlands. Samples were collected twice in 2016 (spring [pre-water level drawdown] and autumn [post-water level flood-up]) followed by a third sampling period (spring 2017). Meanwhile, during the summer of 2016, a portion of study wetlands were planted with either pesticide-treated or untreated corn seed. Neonicotinoid toxic equivalencies (NI-EQs) for sediment (X??=?0.58 μg/kg), water (X??=?0.02 μg/L), and sediment fungicide concentrations (X??=?0.10 μg/kg) were used to assess potential effects on wetland invertebrates. An overall decrease in aquatic insect richness and abundance was associated with greater NI-EQs in wetland water and sediments, as well as with sediment fungicide concentration. Post-treatment, treated wetlands displayed a decrease in insect taxa-richness and abundance before recovering by the spring of 2017. Information on timing and magnitude of aquatic insect declines will be useful when considering the use of seed treatments for wildlife management. More broadly, this study brings attention to how agriculture is used in wetland management and conservation planning.

     

The photochemical formation and gas–particle partitioning of oxidation products of decamethyl cyclopentasiloxane and decamethyl tetrasiloxane in the atmosphere

Decamethyl cyclopentasiloxane (D₅) and decamethyl tetrasiloxane (MD₂M) were injected into a smog chamber containing fine Arizona road dust particles (95% surface area <2.6 μM) and an urban smog atmosphere in the daytime. A photochemical reaction – gas–particle partitioning reaction scheme, was implemented to simulate the formation and gas–particle partitioning of hydroxyl oxidation products of D₅ and MD₂M. This scheme incorporated the reactions of D₅ and MD₂M into an existing urban smog chemical mechanism carbon bond IV and partitioned the products between gas and particle phase by treating gas–particle partitioning as a kinetic process and specifying an uptake and off-gassing rate. A photochemical model PKSS was used to simulate this set of reactions. A Langmuirian partitioning model was used to convert the measured and estimated mass-based partitioning coefficients (K_P) to a molar or volume-based form. The model simulations indicated that >99% of all product silanol formed in the gas-phase partition immediately to particle phase and the experimental data agreed with model predictions. One product, D₄TOH was observed and confirmed for the D₅ reaction and this system was modeled successfully. Experimental data was inadequate for MD₂M reaction products and it is likely that more than one product formed. The model set up a framework into which more reaction and partitioning steps can be easily added.     

Pharmacological implications of ipriflavone against environmental metal–induced neurodegeneration and dementia in rats

Environmental Science and Pollution Research - Long-term exposure to environmental neurotoxic metals is implicated in the induction of dementia and cognitive decline. The present study aims to...     

Experimental study and comparative analysis of modified solar paraboloidal dish–thermoelectric generator systems

Environmental Science and Pollution Research - Solar energy is one of the major sources of renewable energy which contributes for environmental protection and pollution reduction. Methods and...     

Use of 2–methoxyethyl ether and nitromethane as oxygenated additives for performance improvement and emission reduction of CI engine: experimental investigation and numerical simulation

Environmental Science and Pollution Research - Diesel engines are playing a vital responsibility in the field of automobile, agriculture, construction, and power generation. In the present world,...     

Particulate matter–bound organic compounds: levels,mutagenicity, and health risks

Environmental Science and Pollution Research - Increased industrialization and consumption of fossil fuels in the Metropolitan Region of São Paulo (MRSP), Brazil, have caused a growth of the...     

Solar light–driven photocatalytic degradation and mineralization of beta blockers propranolol and atenolol by carbon dot/TiO2 composite

Herein improved solar light–driven photocatalytic degradation and mineralization of two emerging pollutants as well as recalcitrant beta blockers propranolol (PR) and atenolol (AT) have been demonstrated by metal-free carbon dot/TiO₂ (CDT) composite. Hydrothermally synthesized TiO₂ has been decorated with electrochemically synthesized carbon dots (CDs) and was well characterized by various analytical techniques viz. XRD, FTIR, Raman, XPS, UV–visible DRS, FESEM, and TEM. The optimized CDT composite, 2CDT (2 mL carbon dot/TiO₂), showed?~?3.45- and?~?1.75-fold enhancement in the photodegradation rate as compared to pristine TiO₂ for PR and AT respectively in 1 hour of irradiation along with complete degradation of PR and AT after 3 hours of irradiation. 2CDT exhibited 76% and 80% mineralization of PR and AT in contrast with 62% and 47% observed by pristine TiO₂. Further, the major reaction intermediates formed after degradation have been identified by HPLC/MS analysis, confirming more than 99% reduction of the parent compound for both PR and AT. Reusability of the optimized catalyst also showed successful degradation up to 3 cycles, showing reduction abilities of 97%, 95%, and 94% for 1st, 2nd, and 3rd cycle respectively. The enhanced degradation and mineralization efficiency of the 2CDT composite could be attributed to the excellent photosensitizer and electron reservoir properties of the CD along with upconverted photoluminescence behavior. The present study unlocks the possibility of using metal-free, facile CDT composite for effective degradation and mineralization of widely used beta blockers and other pharmaceuticals.

     

Dose–response relationships between urinary cobalt concentrations and obesity,insulin resistance,and metabolic-related disorders in the general population

Environmental Science and Pollution Research - Excessive cobalt exposure has been shown to induce various adverse health effects in animal and human toxicity studies. However, the relationships...     

Air–land exchanges of CO2, CH4 and N2O measured by FTIR spectrometry and micrometeorological techniques

Micrometeorological flux-gradient and nocturnal boundary layer methods were combined with Fourier transform infrared (FTIR) spectroscopy for high-precision trace gas analysis to measure fluxes of the trace gases CO₂, CH₄ and N₂O between agricultural fields and the atmosphere. The FTIR measurements were fully automated and routinely obtained a precision of 0.1–0.2% for several weeks during a measurement campaign in October 1995. In flux-gradient measurements, vertical profiles of the trace gases were measured every 30 min from the ground to 22 m. When combined with independent micrometeorological measurements of water vapour fluxes, trace gas fluxes from the underlying surface could be determined. In the nocturnal boundary layer method the rate of change in mass storage in the 0–22 m layer was combined with fluxes measured at 22 m to estimate surface fluxes. Daytime fluxes for CO₂ were −0.78±0.40 (1σ) mg CO₂ m⁻² s⁻¹. Daytime fluxes of N₂O and CH₄ were very small and difficult to measure reliably using the flux-gradient technique, despite the high precision of the concentration measurements. Mean daytime flux for N₂O was 17±48 ng N m⁻² s⁻¹, while the corresponding flux for CH₄ was 47±410 ng CH₄ m⁻² s⁻¹. The mean nighttime flux of CO₂ estimated using the nocturnal boundary layer method was +0.15±0.05 mg CO₂ m⁻² s⁻¹, in good agreement with chamber measurements of respiration rates. Nighttime fluxes of CH₄ and N₂O from the nocturnal boundary layer method were 109±69 ng CH₄ m⁻² s⁻¹ and 2±3.2 ng N m⁻² s⁻¹, respectively, in good agreement with chamber measurements and inventory estimates based on the sheep and cattle stocking rates in the region. The suitability of FTIR-based methods for long term monitoring of spatially and temporally averaged flux measurements is discussed.