NP Concentrations Research Articles

Rate determining step of reduction Np(VI) by organic reagents from 30%TBP/Kerosene to nitrate solution

Abstract A series of single stage trials were conducted using six reducing reagents to investigate the rate determining step during Np(VI) reduction back-extraction from 30%TBP/Kerosene to HNO3 solution under the same conditions. The six reducing reagents included: acetohydroxamic acid, N,N-dimethylhydroxylamine, N,N-diethylhydroxylamine, 2-hydroxyethylhydrazine, methylhydrazine and N,N-dimethylhydrazine. Moreover, the back-extraction of Np(V) from 30%TBP/Kerosene to HNO3 solution without reducing reagent was conducted with the same concentrations of Np and HNO3. The experimental results indicate the rate of Np(VI) reduction in the two-phase system is determined mainly by the rate of Np(V) mass transfer from 30%TBP/Kerosene to HNO3 solution, whose mass transfer kinetics is far slower than previously estimated. The rate determining step is a slow chemical reaction as: NpO2NO3·TBP = NpO2 + + NO3 − + TBP.

Exposure to endocrine disruptor alkylphenols and the occurrence of endometrial cancer

Exposure to environmental chemicals with oestrogenic effects has been associated with the development of endometrial cancer (EMCa). EMCa has become the most commonly diagnosed cancer of the female genital tract. To further understand the potential association between exposure to environmental endocrine disruptors and the occurrence of EMCa, we performed a case-control study between 2011 and 2014. We aimed to detect and compare concentrations of a known hormone disruptor, alkylphenol, between women diagnosed with either EMCa or uterine leiomyoma, and those who did not have either of these. Subjects were women diagnosed with either EMCa or uterine leiomyoma (LM) and healthy controls. A structured questionnaire was administered to collect information on lifestyle and health status. Gas chromatography/mass spectrometry was used to measure urinary NP and OP concentrations in participants. Multiple regression analysis was used to examine the association between exposure and outcomes. Overall, 397 women were recruited, including 49 with EMCa, 247 with LM, and 101 controls. Among them, 73.6% showed detectable levels of NP and 61.0% showed detectable levels of OP. The EMCa group had a significantly higher NP concentration than the control group. Higher OP concentrations were also found in participants with EMCa than those with LM and controls. In addition, women in the upper tertile of the NP group had a significantly increased risk of EMCa occurrence (odds ratio [95% confidence interval] = 4.47 [1.69–11.84] for EMCa vs. control). The same was found in the group of women with more than the median level of OP (odds ratio [95% confidence interval] = 4.32 [2.01–9.30] for EMCa vs. LM). Stratification of pre- and post-menopausal groups resulted in a similar association. The results show that NP/OP exposure is associated with EMCa. Further investigations and exposure minimisation are suggested.

Impact of rainfall on the occurrence, spatiotemporal distribution, and partition trend of micropollutants in Taihu Lake, China: Bisphenol A and 4-nonylphenol as examples

Very limited studies have evaluated the impact of rainfall on the fate of endocrine-disrupting micropollutants in lacustrine systems. This yearlong study investigated monthly fluctuation of bisphenol A (BPA) and 4-nonylphenol (NP) concentrations in both water and sediment samples from Taihu Lake and evaluated the impact of rainfall on their spatiotemporal distribution and partition trends. Results showed that BPA concentration in water was negatively correlated to rainfall while NP concentrations in both phases were positively related to rainfall. The spatial distribution of NP in the lake water was season specific with the lakeshore area higher than the central area during the wet season and a reversed pattern during the dry season. The spatial distributions of sediment-associated NP and BPA in both phases were not significantly different among seasons. Contrary partition tendencies were observed for BPA and NP that BPA tended to desorb from sediment and NP tended to be adsorbed during the wet season while the trends were reversed during the dry season. This study suggests that rainfall could affect the occurrence, distribution and environmental fate of micropollutants and should be considered in the monitoring program and risk assessment.

Investigation of the Fate of Silver and Titanium Dioxide Nanoparticles in Model Wastewater Effluents via Selected Area Electron Diffraction.

The increasing use of manufactured nanomaterials (MNMs) and their inevitable release into the environment, especially via wastewater treatment plants (WWTPs), poses a potential threat for aquatic organisms. The characterization of MNMs with analytical tools to comprehend their fate and effect on the ecosystem is hence of great importance for environmental risk assessment. We herein report, for the first time, the investigation of physicochemical transformation processes during artificial wastewater treatment of silver (Ag-NPs) and titanium dioxide nanoparticles (TiO2-NPs) via selected area electron diffraction (SAED). TiO2-NPs with an anatase/rutile ratio of ∼80/20 were found to not undergo any physicochemical transformation, as shown via previous energy-dispersive X-ray analysis (EDX) elemental mapping and crystal structure analysis via SAED. In contrast, Ag-NPs were colocalized with substantial amounts of sulfur (Ag/S ratio of 1.9), indicating the formation of Ag2S. SAED ultimately proved the complete transformation of face-centered cubic (fcc) Ag-NPs into monoclinic Ag2S-NPs. The size distribution of both nanomaterials remained virtually unchanged. Our investigations show that cloud point extraction of NPs and their subsequent crystal structure analysis via SAED is another valuable approach toward the comprehensive investigation of wastewater-borne MNMs. However, the extraction procedure needs optimization for environmentally low NP concentrations.

Dietary micronutrient supplementation in low fishmeal based diets for optimum growth and immune status of European sea bass (Dicentrarchus labrax) juveniles

The present study aimed to evaluate the optimal dietary micronutrient supplementation of plant-based diets for juvenile European sea bass. A 90-day feeding trial was performed, where fish were fed a high fishmeal (FM) based diet (62% DM; positive control) or low FM diets (12.5% FM and krill meal), supplemented with increasing levels of a micronutrient mixture (Nutrient Package, NP) consisting of vitamins, minerals and other micronutrients. The supplementation levels ranged from 0% (no supplementation, negative control) to 400%, where 100% supplementation level corresponded to the requirement levels recommended for other fish species. Fish growth and feed performance (SGR, DGI, FCR, PER) were significantly impaired at levels NP0 and NP25 compared to the FM control. Body Fe and Zn concentrations were positively affected by the graded levels of the NP, while Mn and Se concentrations remained stable. Growth parameters were particularly correlated to body Fe and Zn, while immune parameters were mainly correlated to body Zn. Significant immunosuppression was evidenced (concerning the respiratory burst activity) when low FM diets were not supplemented with NP. High inclusion levels of the NP showed a negative impact on lysozyme activity. Histological examinations did not reveal any significant effects on gills, gut and liver morphology. At identical NP supplementation level (50%), fish fed low and high FM diets showed similar growth and innate immunity suggesting that long-term feeding with plant-based diets do not significantly affect the fish when adequate minerals and vitamins supplementation is provided. Quadratic regression analysis showed that the inclusion of the NP between 260 and 300% improves growth and immune parameters of fish fed low-FM diets as well as Zn body incorporation. Overall, the present study suggested the positive impact of NP supplementation of PM-based diets on both fish growth and health but future NP could include less Mn, more Fe, closer to levels obtained in fish fed FM (245 mg·kg−1), and Zn at 122 mg·kg−1.

Comparative impact of SiO2 and TiO2 nanofillers on the performance of thin‐film nanocomposite membranes

AbstractNanoparticle (NP) additions can substantially improve the performance of reverse osmosis and nanofiltration polyamide (PA) membranes. However, the relative impacts of leading additives are poorly understood. In this study, we compare the effects of TiO2 and SiO2 NPs as nanofillers in PA membranes with respect to permeate flux and the rejection of organic matter (OM) and salts. Thin‐film nanocomposite (TFN) PA membranes were fabricated using similarly sized TiO2 15 nm and SiO2 (10 – 20 nm) NPs, introduced at four different NP concentrations (0.01, 0.05, 0.2, and 0.5% w/v). Compared with PA membranes fabricated without NPs, membranes fabricated with nanofillers improved membranes hydrophilicity, membrane porosity, and consequently the permeability. Permeability was increased by 24 and 58% with the addition of TiO2 and SiO2, respectively. Rejection performance and fouling behavior of the membranes were examined with salt (MgSO4 and NaCl) and OM (humic acid [HA] and tannic acid [TA]). The addition of TiO2 and SiO2 nanofillers to the PA membranes improved the permeability of these membranes and also increased the rejection of MgSO4, especially for TiO2 membranes. The addition of TiO2 and SiO2 to the membranes exhibited a higher flux and lower flux decline ratio than the control membrane in OM solution filtration. TFN membranes' HA and TA rejections were at least 77 and 71%, respectively. The surface change properties of NPs appear to play a dominant role in determining their effects as nanofillers in the composite membrane matrix through a balance of changes produced in membrane pore size and membrane hydrophilicity.

Magneto-Liposomes as MRI Contrast Agents: A Systematic Study of Different Liposomal Formulations.

The majority of the clinically approved iron oxide nanoparticles (IO NPs) used as contrast agents for magnetic resonance imaging (MRI) have been withdrawn from the market either due to safety concerns or lack of profits. To address this challenge, liposomes have been used to prepare IO-based T2 contrast agents. We studied the influence of different phospholipids on the relaxivity (r2) values of magneto-liposomes (MLs) containing magnetic NPs in the bilayer, where a strong correlation between the bilayer fluidity and r2 is clearly shown. Embedding 5-nm IO NPs in the lipid bilayer leads to a significant improvement in their relaxivity, where r2 values range from 153 ± 5 s−1 mM−1 for DPPC/cholesterol/DSPE-PEG (96/50/4) up to 673 ± 12 s−1 mM−1 for DOPC/DSPE-PEG (96/4), compared to “free” IO NPs with an r2 value of 16 s−1 mM−1, measured at 9.4 T MRI scanner. In vitro MRI measurements, together with the ICP-MS analysis, revealed MLs as highly selective contrast agents that were preferentially taken up by cancerous T24 cells, which led to an improvement in the contrast and an easier distinction between the healthy and the cancerous cells. A careful selection of the lipid bilayer to prepare MLs could offer efficient MRI contrast agents, even at very low IO NP concentrations.

Neptunium extraction by N,N-dialkylamides

Abstract Separation of neptunium by solvent extraction has been based on tributylphosphate (TBP) for decades, but TBP is not fully incinerable, which adds to the burden of long-lived radioactive waste. Alternatives to TBP for uranium and plutonium extraction, such as the N,N-diakylamides, previously have been explored in the hopes of transitioning to an extractant that is incinerable. Four N,N-diakylamides, N,N-dihexylhexanamide (DHHA), N,N-dihexyloctanamide (DHOA), N,N-di(2-ethylhexyl)butanamide (DEHBA), and N,N-di(2-ethylhexyl)-iso-butanamide (DEHiBA) were considered in this work for their potential to extract millimolar concentrations of Np(IV), Np(V), and Np(VI) from nitric acid solutions into organic solutions containing 1 M extractant in Exxsol D60. Under these conditions the branching of the alkyl substituents affects the extractability of Np(VI) and Np(IV), causing three of the dialkylamides, DHHA, DHOA and DEHBA, to extract neptunium in the expected order Np(VI) > Np(IV) > > Np(V). In contrast, branched DEHiBA is so poor an extractant for Np(IV) that the extraction order becomes Np(VI) > > Np(V) > Np(IV) between 0.1 and 5.6 M HNO3 due to partial oxidation of the Np(V) in nitric acid.

Response of the Intertidal Microbial Community Structure and Metabolic Profiles to Zinc Oxide Nanoparticle Exposure.

The toxicity of nanomaterials to microorganisms is related to their dose and environmental factors. The aim of this study was to investigate the shifts in the microbial community structure and metabolic profiles and to evaluate the environmental factors in a laboratory scale intertidal wetland system exposed to zinc oxide nanoparticles (ZnO NPs). Microbial assemblages were determined using 16S rRNA high-throughput sequencing. Community-level physiological profiles were determined using Biolog-ECO technology. Results showed Proteobacteria was the predominant (42.6%–55.8%) phylum across all the sediments, followed by Bacteroidetes (18.9%–29.0%). The genera Azoarcus, Maribacter, and Thauera were most frequently detected. At the studied concentrations (40 mg·L−1, 80 mg·L−1, 120 mg·L−1), ZnO NPs had obvious impacts on the activity of Proteobacteria. Adverse effects were particularly evident in sulfur and nitrogen cycling bacteria such as Sulfitobacter, unidentified_Nitrospiraceae, Thauera, and Azoarcus. The alpha diversity index of microbial community did not reflect stronger biological toxicity in the groups with high NP concentrations (80 mg·L−1, 120 mg·L−1) than the group with low NP concentration (40 mg·L−1). The average well color development (AWCD) values of periodically submersed groups were higher than those of long-term submersed groups. The group with NP concentration (40 mg·L−1) had the lowest AWCD value; those of the groups with high NP concentrations (80 mg·L−1, 120 mg·L−1) were slightly lower than that of the control group. The beta diversity showed that tidal activity shaped the similar microbial community among the periodically submerged groups, as well as the long-term submerged groups. The groups with high DO concentrations had higher diversity of the microbial community, better metabolic ability, and stronger resistance to ZnO NPs than the groups with a low DO concentration.

Fluorescence properties of methylene blue molecules coupled with metal oxide nanoparticles

This work deals with the fluorescence properties of the methylene blue (MB) fluorophores loaded on metal oxide nanoparticles, such as TiO2, ZnO, and Al2O3 based on laser-induced fluorescence (LIF) spectroscopy. At first, MB is provoked by diode laser at 665 nm, then the fluorescence emissions are recorded using a Czerny-Turner spectrometer. The lucid red shift appears during the right angle LIF measurements of (MB + TiO2NPs) suspensions, where NP are well distributed among the fluorophores. Despite that, the LIF of (MB + TiO2) demonstrates notable red shift in terms of NP concentrations; however, (MB + ZnO) and (MB + Al2O3) exhibit a negligible one. The larger red shift occurs for the NPs with greater refractive indices due to the optical elongation. Furthermore, the quenching coefficients KTiO2, KZnO, and KAl2O3 are measured according to the linear Stern-Volmer formalism. The quenching effect in a (TiO2+MB) attests to be much stronger than that of other nanoparticles of interest. The discrepancy in the fluorescence emissions of MB at the attendance of different metal oxide NPs is very significant during simultaneous imaging/diagnosis and treatment of tumors.

Landscape pattern at the class level regulates the stream water nitrogen and phosphorus levels in a Chinese subtropical agricultural catchment

The landscape patch amount and configuration at the class level profoundly affect stream nitrogen (N) and phosphorus (P) concentrations in agricultural catchments, but their relationships and contributions to stream NP levels remain unclear. Here, we observed the stream water NP concentrations, stream flow, and landscape pattern at the class level in 11 catchments in a Chinese subtropical agricultural catchment during 2011–2017 to quantify their relationships and contributions. Pearson correlation analysis suggested that landscape patch amount and configuration at the class level significantly affected stream water NP levels, and stepwise multiple linear regression models showed that the landscape pattern of a single land use could effectively predict the NP levels. The determination coefficients (R2) of the total nitrogen (TN) formulas were 0.539–0.811 and smaller than those of the total phosphorus (TP) formulas (0.360–0.672). The best fit was obtained for the TN concentration by using the percentage of land use (PLAND) and fractal dimension index (FRAC) of ponds as independent variables (R2 = 0.811, p < 0.01), while that for the TP concentration was obtained when the edge density (ED) of rivers was used (R2 = 0.672, p < 0.01). Variance partitioning analysis was applied to further quantify the contributions of land use classes to the NP levels. Ponds and tea fields contributed the most to the stream TN and TP levels (30.2 % and 31.1 %, respectively). The PLAND and FRAC of ponds and FRAC of tea fields were the key landscape variables determining stream water NP levels. This study provides detailed instructions and suggestions for reasonable landscape planning to control stream water NP pollution at the practical level.

Choriogenin transcription in medaka embryos and larvae as an alternative model for screening estrogenic endocrine-disrupting chemicals.

This study assessed the transcription levels of estrogen-responsive genes, such as vitellogenins (Vtg1 and Vtg2), choriogenins (ChgL, ChgH, and ChgHm), cytochrome P450 aromatase (CYP19a1b), and ER subtypes (ERα, ERβ1, and ERβ2), in 7 days-post-fertilization (dpf) embryos and 9 and 12 dpf larvae of medaka (Oryzias latipes) exposed to estrogenic endocrine-disrupting chemicals (EDCs). The <5h-post-fertilization embryos were exposed to EDCs such as 17β-estradiol (E2), p-n-nonylphenol (NP), and bisphenol A (BPA). In E2 (0.10-222nM)-treated 7 dpf embryos and 9 or 12 dpf larvae, ChgL, ChgH, and ChgHm expression was up-regulated in a concentration-dependent manner. By contrast, interestingly, Vtg1 and Vtg2 expression was not induced in E2-treated 7 dpf embryos but was significantly induced in 9 and 12 dpf larvae, suggesting a developmental-stage-specific regulatory mechanism underlying Vtg expression. The maximum concentrations of NP (0.09-1.5μM) and BPA (1.8-30μM) up-regulated Chg expression in 9 or 12 dpf larvae, and the relative estrogenic potencies (REPs) of E2, NP, and BPA were 1, 2.1×10-4, and 1.0×10-5, respectively. Chg messenger RNA (mRNA) in medaka embryos and larvae can be used as a sensitive biomarker for screening potential estrogenic EDCs. Our assay system using embryos and larvae can be used as an in vivo alternative model because independent feeding stages (e.g., embryonic and early larval stages) are suitable alternatives.

Effects of titanium dioxide nanoparticles on leaf cell structure and viability, and leaf elongation in the seagrass Halophila stipulacea

The ecotoxicity of titanium dioxide nanoparticles (TiO2 NPs) is of increasing concern due to their extensive use in a variety of applications. This study aims to achieve a better understanding of TiO2 NP ecotoxicity by assessing for the first time their effects on seagrasses. Changes in leaf cell structure and viability, and leaf elongation in Halophila stipulacea exposed under laboratory conditions to environmentally relevant TiO2 NP concentrations (0.0015–1.5 mg L−1) for 8 days were assessed. Actin filament (AF) disturbance firstly occurred in differentiating cells at 0.0015 mg L−1 on the 8th day, while in meristematic cells at 0.15 mg L−1 on the 6th day, both deteriorating concentration- and time-dependently. Endoplasmic reticulum (ER) appeared aggregated firstly at 0.015 mg L−1 on the 8th day and earlier at the highest concentrations, while microtubules and cell ultrastructure appeared unaffected. Dead cells mainly occurred in older leaves; dead tooth, margin and intercostal epidermal cells exceeded 5% at 0.15–1.5 mg L−1. A significant leaf elongation inhibition occurred at 0.015–1.5 mg L−1 in older leaves and at 1.5 mg L−1 in young apical leaves. AF, ER and leaf elongation impairment in H. stipulacea, being susceptible response parameters, could be used as early warning markers. A risk quotient >1 was calculated, indicating that TiO2 NPs may pose a significant risk to the environment. The data presented underline the need for additional TiO2 NP-seagrasses toxicity information, and could be utilized for the protection of the coastal environment.

Assessing endocrine disruption in freshwater fish species from a “hotspot” for estrogenic activity in sediment

Little is known about sediment-bound exposure of fish to endocrine disrupting chemicals (EDC) under field conditions. This study aimed to investigate potential routes of EDC exposure to fish and whether sediment-bound contaminants contribute towards exposure in fish. Tench (Tinca tinca) and roach (Rutilus rutilus) as a benthic and pelagic living fish species, respectively, were sampled at the Luppe River, previously described as a “hotspot” for accumulation of EDC in sediment. A field reference site, the Laucha River, additionally to fish from a commercial fish farm as reference were studied. Blackworms, Lumbriculus variegatus, which are a source of prey for fish, were exposed to sediment of the Luppe River and estrogenic activity of worm tissue was investigated using in vitro bioassays. A 153-fold greater estrogenic activity was measured using in vitro bioassays in sediment of the Luppe River compared the Laucha River. Nonylphenol (NP; 22 mg/kg) was previously identified as one of the main drivers of estrogenic activity in Luppe sediment. Estrogenic activity of Luppe exposed worm tissue (14 ng 17β-estradiol equivalents/mg) indicated that food might act as secondary source to EDCs. While there were no differences in concentrations of NP in plasma of tench from the Luppe and Laucha, vitellogenin, a biomarker for exposure to EDCs, was induced in male tench and roach from the Luppe River compared to both the Laucha and cultured fish by a factor of 264 and 90, respectively. However, no histological alterations in testis of these fish were observed. Our findings suggest that sediments substantially contribute to the overall EDC exposure of both benthic and pelagic fish but that the exposure did not impact gonad status of the fish.

Do predictive environmentally relevant concentrations of ZnO nanoparticles induce antipredator behavioral response deficit in Swiss mice?

The toxicity of zinc oxide nanoparticles (ZnO NPs) has been addressed in several studies; however, their effect on the mammalian group, even at environmentally relevant concentrations, remains poorly understood. The aims of the present study are to expose female Swiss mice to ZnO NP concentrations commonly faced by mammals who enter aquatic systems to perform different ecological functions and to assess the possible effects of such particles on their behavior. The test animals were placed in water added with ZnO NPs for 3 min, 2 times/day, for 21 days. Two experimental groups were set, NP1x, composed of animals subjected to ZnO NP concentration of 760 μg/L; and NP50x (control), which encompassed animals subjected to 38,000 μg/L. Based on field test results (OF), the contact with NPs did not induce locomotor deficits or anxiogenic and anxiolytic effect on the animal models. However, models exposed to NPs were not able to recognize the predatory threat posed by the presence of Pantherophis guttatus and Arapaima gigas; on the other hand, animals in the control group, who were not exposed to ZnO NPs, did not present antipredator behavioral response deficit. Furthermore, mice exposed to NPs were unable to distinguish real predators from plastic copies, and it suggests antipredator behavioral response deficit. High Zn concentrations in blood, liver, brain and skin samples are associated with deficit caused by the exposure to ZnO NPs. To the best of our knowledge, the current study is in the first to evidence that ZnO NPs induce changes in antipredator behavioral responses, even under ephemeral conditions and at low concentrations. However, the exposure to ZnO NPs can be a risk to the health of the assessed individuals and to the dynamics of their populations if the present antipredator behavioral response test results are extrapolated to the ecological context.

Uptake, translocation and ligand of silver in Lactuca sativa exposed to silver nanoparticles of different size, coatings and concentration

The broad use of silver nanoparticles (AgNPs) in daily life products enhances their possibilities to reach the environment. Therefore, it is important to understand the uptake, translocation and biotransformation in plants and the toxicological impacts derived from these biological processes. In this work, Lactuca sativa (lettuce) was exposed during 9 days to different coated (citrate, polyvinylpyrrolidone, polyethylene glycol) and sized (60, 75, 100 nm) AgNPs at different concentrations (1, 3, 5, 7, 10, 15 mg L−1). Total silver measurements in lettuce roots indicated that accumulation of AgNPs is influenced by size and concentration, but not by nanoparticle coating. On the other hand, nanosilver translocation to shoots was more pronounced for neutral charged and large sized NPs at higher NP concentrations. Single particle inductively coupled plasma mass spectrometry analysis, after an enzymatic digestion of lettuce tissues indicated the dissolution of some NPs. Ag K-edge X-ray absorption spectroscopy analysis corroborated the AgNPs dissolution due to the presence of less Ag-Ag bonds and appearance of Ag-O and/or Ag-S bonds in lettuce roots. Toxicological effects on lettuces were observed after exposure to nanosilver, especially for transpiration and stomatal conductance. These findings indicated that AgNPs can enter to edible plants, exerting toxicological effects on them.

Effect of Al2O3 nanoparticle on viscoelastic and filtration properties of a salt-polymer-based drilling fluid

ABSTRACT Conventional bentonite-based drilling fluids have associated problems while drilling troublesome or high-temperature zone due to degradation of rheological properties and excessive fluid loss. Clay particles present in the drilling fluid tend to block the pore throats and cause blockage to hydrocarbon flow. Similarly, polymers along with the filtrate loss, in the invaded zone, alter the wettability due to which there is a reduction in relative permeability to oil. All of these factors collectively cause a fall in production rates and demand stimulation jobs. The use of nondamaging drilling fluids, a particle-free salt-polymer-based drilling fluid, has addressed these problems by yielding a substantially less filtrate loss. However, at moderately high depths with high temperatures, this drilling fluid fails to maintain rheological properties and hence sagging, carrying, and fluid loss problems remerge. Sagging increases the equivalent circulation density which eventually decreases rate of penetration and induces formation damages. Hence, a need to further improve its properties is much required. This study has investigated the effect of aluminum oxide nanoparticles (Al2O3 NP) on these salt-polymer-based drilling fluids. A significant change was observed in rheological and fluid loss properties of drilling fluid (DF) when doped with different concentrations (0.5%, 0.8%, and 1%) of Al2O3 NP compared to the Base DF. Steady shear (rotational) tests were conducted to study the degree of shear thinning behavior of all the drilling fluids. It was observed that shear thinning behavior of the DF was increased with the addition of Al2O3 NP. Rotational measurements at 30°C showed a decrease in viscosity and shear stress of Al2O3 NP DF with an increase in concentration. However, at elevated temperatures of 60°C and 80°C, the reduction in viscosity of Al2O3 NP DF was substantially less than Base DF. One percent Al2O3 NP DF showed higher viscosity as compared to 0.5%, 0.8% Al2O3 NP, and Base DF at these conditions. To investigate the viscoelastic properties, oscillation tests were performed. Amplitude sweep tests showed an increase in storage modulus (G’) with an increase in Al2O3 NP concentration. While Base and 0.5% Al2O3 NP DF showed viscoelastic liquid in nature, 0.8% and 1% Al2O3 NP DF showed dominant storage properties indicating its viscoelastic solid nature at 30°C, 60°C, and 80°C. From the frequency sweep tests at higher temperatures, 0.8% and 1% Al2O3 NP DF, unlike Base and 0.5% Al2O3 NP DF, showed increase in complex viscosity at lower frequencies indicating structural build-up. Both rotational and thixotropic tests showed less structural regain time for 1% Al2O3 NP DF compared to other drilling fluid. Lastly, fluid loss control property of all the drilling fluids was investigated by measuring the filtrate loss volume in an API filter press apparatus. One percent Al2O3 NP DF showed a greater reduction in filtrate volume with Base DF showing the highest.

Zizania aquatica–duck ecosystem with recycled biogas slurry maintained crop yield

The Chinese government recently adopted the concept of ecological circular agriculture in a bid to increase recycling of agricultural waste and reduce chemical fertilizer input. Field experiments were conducted in 2015 and 2016 to determine the effects of a Zizania aquatica–duck ecosystem supplemented with recycled biogas slurry and no chemical fertilizers on Z. aquatica yield, plant nitrogen (N) and phosphorus (P) uptake, and NP concentrations in the surface water. Compared with Z. aquatica monoculture plus chemical fertilizer (Zcf treatment), the Z. aquatica–duck ecosystem with biogas slurry and no chemical fertilizer (Zbs–D treatment) maintained yield (approximately 24.48 t ha−1) and N and P uptake (approximately 3.15 and 0.98 g plant−1, respectively). Although N and P concentrations in the surface water were approximately 3.11 times higher under Zbs–D than Zcf treatment, concentrations in the draining surface water (4.54 mg N L−1 and 0.74 mg P L−1) met the discharge standard (5.00 mg N L−1 and 1.00 mg P L−1). These findings suggest that the Zbs–D ecosystem could be used to completely substitute chemical fertilizers in Z. aquatica production without yield losses via safe application of biogas slurry. In turn, this system would also increase the sustainability of Z. aquatica crop production in an environmentally-friendly manner. Simple and efficient methods for determining the NP content of biogas slurry are now required in addition to further long-term monitoring.

Distribution and ecological risk assessment of PEDCs in the water, sediment and Carex cinerascens of Poyang Lake wetland, China

Phenolic endocrine disrupting chemicals (PEDCs), such as 4-nonylphenol (NP), 4-t-octylphenol (OP), bisphenol A (BPA), and nonylphenol-di-ethoxylate (NP2EO), can cause feminization and carcinogenesis. This study assessed the distributions of NP, OP, BPA, and NP2EO in the water, sediment, and Carex cinerascens of Poyang Lake wetland. The four PEDCs were ubiquitous. The concentrations of NP and OP in the water and sediment of the wetland were significantly lower than those in other regions of China. Average BPA concentrations in the water, sediment, and Carex cinerascens samples were 40.49 ± 18.42 ng/L, 9.840 ± 3.149 ng/g, and 3.25 ± 1.40 ng/g, respectively; the BPA concentration in the water was similar to that of other rivers in China. Average NP2EO concentrations in the wetland were 3125.9 ± 478.1 ng/L, 650.0 ± 209.9 ng/g, and 275.8 ± 59.0 ng/g in the water, sediment, and Carex cinerascens samples, respectively. The predicted no-effect concentrations in sediment for NP, OP, BPA, and NP2EO were estimated to be 75.41, 45.25, 8.22, and 237.5 ng/g, respectively. The risk quotient (RQ) method was used to characterise the ecological risk from these PEDCs. A high ecological risk (RQ ≥ 1) from BPA was observed for 0%, 57.69%, and 5.00% of water, sediment, and C. cinerascens samples, respectively, while a high risk from NP2EO was observed for 71.43%, 96.15%, and 55.00% of samples. Ecological risk varied spatially. The high ecological risk from NP2EO in Poyang Lake wetland may be a result of non-point pollution from rural areas and sewage from Poyang Lake basin.

Seryum Oksit Nanopartiküllerinin Bakteriler Üzerindeki Ekotoksik Etkileri

In this study, the ecotoxic effects of cerium oxide nanoparticles (CeO2 NPs) on both gram positive Bacillus subtilis and gram negative Escherichia coli bacteria were investigated. CeO2 NPs were prepared in synthetic water solutions having different water contents (low, median and high ionic strength and conductivity, pH 5.5 and 6.5). Bacteria were exposed to CeO2 NP solutions in absence and presence of light conditions for 1 h. Different NP concentrations (10, 100, 500 and 1000 mg/L) were used, and environmental scanning electron microscopy imaging was performed for morphological examination of the bacteria. Results showed an aggregation of NPs relating to both high NP concentrations and high ionic strength of the water solutions. Regardless of the test condition, CeO2 NPs highly inhibited the bacterial growth.