Mccormackblair6999

The digestive tract is an important target organ for microplastics (MPs). However, little is known about the effects of digestive treatment on the intestinal toxicity of MPs. In this study, an in vitro digestive process was applied to transform 100 nm and 5 μm polystyrene microplastics (PS-MPs). Intestinal toxicities of original PS-MPs and transformed PS-MPs (t-PS-MPs) were determined using an in vitro Caco-2 monolayer model. Results showed that the digestive process did not alter the chemical constitution of PS-MPs, but formed a corona on the surface of PS-MPs. The 100 nm PS-MPs showed higher intestinal toxicity than 5 μm PS-MPs. Digestive treatment relieved cytotoxicity and transport function disorder of the Caco-2 monolayer induced by the original PS-MPs. Moreover, the combined toxicities of PS-MPs and arsenic were also decreased by digestive treatment. However, the in vitro digestive process increased the proinflammatory effects of PS-MPs. The formation of a corona on the PS-MP surface, which lead to a change in size, Zeta potential, and adsorbed compounds, might induce the above influence of digestive treatment. Our study suggests that direct cytotoxicity assays of PS-MPs might misestimate their intestinal effects, which provide new lights to the toxicity evaluation of PS-MPs by oral exposure.Microplastic pollution, one of the major global challenges, is a severe threaten to aquatic organisms. The purpose of this study was to investigate the abundance, distribution and characteristics of microplastics in coastal surface waters from eastern Guangdong, south China. We chose pelagic Konosirus punctatus and demersal Mugil cephalus from different sampling sites as candidate monitoring species for the ingestion of marine microplastics, and talked about the relationship between water samples and fish samples. We tried to find out the regulation about microplastics characteristics in fish samples and fish own traits. The mean abundance of microplastics in surface water was 8895 items/m3, small white fragments were dominating character. We need to increase the amount of fish data to further explore. This study would not only provide a detailed reference for a better understanding of microplastic pollution in Guangdong coastal areas, but also shed an insight in prospect of using fish as biomonitoring of microplastic wastes.Nanoplastic exposure could cause toxicity to Caenorhabditis elegans at various aspects. Nevertheless, the effects of chronic exposure to nanoplastics remain largely unclear in nematodes. In this study, we employed C. elegans as an animal model to determine the effects of nanopolystyrene (30 nm) exposure from adult day-1 for 8-day. After the exposure, only 1000 μg/L nanopolystyrene reduced the lifespan. In contrast, nanopolystyrene ≥1 μg/L decreased locomotion behavior and activated oxidative stress. Meanwhile, in 10 μg/L nanopolystyrene exposed nematodes, both expression of SOD-3, a Mn-SOD, and autophagy induction as indicated by LGG-1GFP expression were significantly increased. RNAi knockdown of daf-2 encoding an insulin receptor enhanced the autophagy induction, and RNAi knockdown of daf-16 encoding a FOXO transcriptional factor in insulin signaling pathway suppressed the autophagy induction in 10 μg/L nanopolystyrene exposed nematodes. Moreover, DAF-16 acted upstream of LGG-1, an ortholog of Atg8/LC3, to regulate the toxicity of nanopolystyrene toxicity in inducing ROS production and in decreasing locomotion behavior at adult day-9. Our data implied the potential toxicity of chronic exposure to nanoplastics at predicted environmental concentrations on organisms.Freshwater ecosystems are vulnerable to residual concentrations of chemical agents from anthropogenic activities, and the real impacts of such compounds can only be evaluated accurately using ecotoxicological tests. The assessment of ecotoxicological effects of peracetic acid (PAA) and the active chlorine of calcium hypochlorite (Ca(ClO)2) on the insect Chironomus xanthus Meigen (Diptera Chironomidae) is highly relevant as there are few reports on its effects in fresh water ecosystems. To our best knowledge, this is the first study to assess the chronic toxicity of the compounds to C. xanthus. The toxicity bioassays for C. xanthus included the acute effect (CL50) and the chronic effects based on body length, head width, and cumulative emergence. The results obtained in the acute effect tests indicated that the active chlorine of Ca(ClO)2 is 14 fold more toxic than PAA to C. xanthus. In sublethal evaluations, the active chlorine of Ca(ClO)2 presented higher toxicity than PAA in terms of percentage emergence, body development, and head width. In general, the results showed lower PAA toxicity relative to the active chlorine of Ca(ClO)2, demonstrating that PAA is a promising substitute for chlorinated disinfectants. In addition, the study facilitates the establishment of reference values for the safe release of effluents treated with PAA into water bodies.Seasonal changes in chemical compositions and source apportionment of PM2.5 during clear and hazy days help to develop effective control policy, but limited information is available in megacity Nanjing. In this study, 102 PM2.5 samples were collected during clear and hazy days from 4 seasons in 2014-2015. Their chemical compositions (organic and elemental carbon, 8 water-soluble ions, and 22 inorganic elements) were determined, which were used for PM2.5 source apportionment using the PMF model. The mean PM2.5 concentration was lower during clear days than hazy days (42 vs. 122 μg m-3), so were mean concentrations of metals (0.48 vs. 0.82 ng m-3 for Co and 2.0 vs. 2.4 μg m-3 for Na), water soluble ions (0.10 vs. 0.16 μg m-3 for Mg2+ and 12 vs. 23 μg m-3 for SO42-), and carbon species (3.2 vs. 5.4 μg m-3 for elemetal C and 20 vs. 35 μg m-3 for organic C). Based on the PMF model, five main sources of PM2.5 were identified including secondary aerosols (31%), coal combustion (27%), road & construction dust (26%), oil combustion (8.5%), and iron & steel industry (5.1%) for all samples. The PM2.5 concentrations from the 5 sources were 0.01-46.5, averaging 9.8 μg m-3 during clear days (PM2.5 less then 75 μg m-3), which increased to 1.83-60.1, averaging 18 μg m-3 during hazy days. However, based on their contributions to PM2.5, only secondary aerosols increased during hazy days compared to clear days in all seasons (11 vs. 42%), indicating its dominant contribution to haze in Nanjing. For different seasons, road & construction dust was a major contributor to PM2.5 in the summer, while oil combustion (4.86 vs.16.8%) contributed more in spring. However, coal combustion became the main source of PM2.5 during the summer (44-85%) due to the pollution controls for the Youth Olympic Games. Tacedinaline HDAC inhibitor Our results suggest that secondary aerosols play an important role in haze formation and season-dependent pollution measures should be implemented for effective control of air pollution.When the nanoscale zero valent iron (nZVI) is used for the reduction of hexavalent chromium (Cr6+) to trivalent chromium (Cr3+) in groundwater, the reduction efficiency is decreased due to the passivation of reactive sites by precipitation. The bimetallic nanoparticle (BNP) can be created with the addition of the second metal to achieve a higher activity and reduce the occurrence of the ferrous/ferric hydroxide precipitation. In this study, the iron-coated aluminum (Fe/Al) BNP and aluminum-coated iron (Al/Fe) BNP systems were designed for remediating Cr6+-contaminated groundwater. The chemical liquid-phase deposition and co-reduction method was applied to produce BNPs. Cr6+ removal rate by Fe/Al BNPs was directly proportional to the saturation concentration and reactive sites, which caused a higher Cr6+ removal rate. The pseudo-first-order kinetic model could be used to describe the Cr6+ adsorption mechanism by Fe/Al BNPs. Results show that Fe/Al BNPs and Al/Fe BNPs could reduce Cr6+ to Cr3+, and the removal efficiencies for Cr6+ were 1.47 g/g BNP and 0.07 g/g BNP, respectively. Detection of Cr3+ in the aqueous phase was observed during the Cr6+ removal process. Results from X-ray diffraction (XRD) analysis confirmed that Cr(OH)3 was present on the surface of BNPs. Main mechanisms caused Cr6+ removal included reduction, precipitation, and adsorption. The reduction of Cr6+ produced OH-, which created alkaline environment and facilitated the formation of chromium hydroxide precipitates [Cr(OH)3]. Thus, the migration of Cr3+ was prevented and the environmental risk was reduced. BNP had a higher activity and stability, and it was applicable for Cr6+-contaminated site remediation.Microcystins released by cyanobacteria affect crop growth and productivity, and even food safety. Plant hormones play a vital role in regulating growth, development and stress response in plants. Therefore, we studied the response of hormones including abscisic acid (ABA), indole-3-acetic acid (IAA), Zeatin (ZT) and gibberellin (GA3) as well as hormone balances (IAA/ABA, ZT/ABA and GA/ABA) to cyanobacterial extract containing microcystins (1, 10, 100 and 1000 μg/L) during stress and recovery periods. Low concentration microcystins (1 μg/L) promoted growth of rice seedlings by increasing levels of IAA, ZT and GA3 and maintaining hormone balances. In addition, the up-regulation of OsYUCCA1 increased IAA level in rice roots by promoting IAA biosynthesis. High concentrations microcystins (10, 100 or1000 μg/L) inhibited growth of rice seedlings by reducing levels of IAA, ZT and GA3 and ratios of IAA/ABA, ZT/ABA and GA/ABA due to increased ABA level. The increase in ABA in rice seedlings induced by high concentrations MCs was resulted from up-regulation of OsNCED1, OsNCED3, OsNCED4 and OsZEP to enhance ABA biosynthesis, and was controlled by up-regulating expression levels of OsABAox1-3 for enhancing ABA catabolism as negative feedback. The highest concentration of MCs (1000 μg/L) caused irreversible damage to metabolisms of IAA and ABA, partly resulting in unrecoverable inhibition on rice growth. All results demonstrate that "low-concentration promotion and high-concentration inhibition" of microcystins was associated with changes in hormone levels and balances by affecting their metabolisms, and could be helpful for guiding agricultural irrigation with microcystin contaminated water.In this study we investigated the bioaccumulation of selected trace elements in lichen samples transplanted for three months in Milan, Italy, with the aim of assessing the main environmental contaminants and the overall pollution load, and of disentangling the main air pollution sources as well as of estimating fluxes of element deposition. The results highlighted Cu and Sb as important contaminants and suggested a common origin for these two elements from railways and non-exhaust sources of vehicular traffic such as brake abrasion. High or very high global air pollution emerged for all study sites. Source apportionment outlined three main factors, that found reliable correlation with distance from major roads and railways, an industrial plant, and soil resuspension. Ranges of estimated mean annual element deposition rates in the study area were similar to those reported for other cities.