Hesshogan7162

The considerable proportion of Methanomassiliicocales in eutrophic lake implied that methylotrophic methanogenesis might be previously underestimated. These results added new insights towards methanogenesis process in eutrophic freshwater lakes. Pesticides scarcely exist as individual compounds in the water ecosystem, but rather as mixtures of multiple chemicals at relatively low concentrations. In this study, we aimed to explore the mixture toxic effects of fludioxonil (FLU) and triadimefon (TRI) on zebrafish (Danio rerio) by employing different toxicological endpoints. Results revealed that the 96-h LC50 values of FLU to D. rerio at multiple developmental stages ranged from 0.055 (0.039-0.086) to 0.61 (0.33-0.83) mg L-1, which were less than those of TRI ranging from 3.08 (1.84-5.96) to 9.75 (5.99-14.78) mg L-1. Mixtures of FLU and TRI exerted synergistic effects on embryonic zebrafish. Activities of total superoxide dismutase (T-SOD) and catalase (CAT) were markedly altered in most of the individual and pesticide mixture treatments compared with the control. The expressions of 16 genes involved in oxidative stress, cellular apoptosis, immune system and endocrine system displayed that embryonic zebrafish were affected by the individual pesticides and their mixtures, and greater variations of four genes (ERɑ, Tnf, IL and bax) were found when exposed to pesticide mixtures compared with their individual compounds. Therefore, more studies on mixture toxicities among different pesticides should be taken as a priority when evaluating their ecological risk. Zeolite-supported nanoscale zero-valent iron (Z-NZVI) has great potential for metal(loid) removal, but its encapsulation mechanisms and ecological risks in real soil systems are not completely clear. We conducted long-term incubation experiments to gain new insights into the interactions between metal(loid)s (Cd, Pb, As) and Z-NZVI in naturally contaminated farmland soils, as well as the alteration of indigenous bacterial communities during soil remediation. With the pH-adjusting and adsorption capacities, 30 g kg-1 Z-NZVI amendment significantly decreased the available metal(loid) concentrations by 10.2-96.8% and transformed them into strongly-bound fractions in acidic and alkaline soils after 180 d. An innovative magnetic separation of Z-NZVI from soils followed by XRD and XPS characterizations revealed that B-type ternary complexation, heterogeneous coprecipitation, and/or concurrent redox reactions of metal(loid)s, especially the formation of Cd3(AsO4)2, PbFe2(AsO4)2(OH)2, and As0, occurred only under specific soil conditions. Sequencing of 16S rDNA using Illumina MiSeq platform indicated that temporary shifts in iron-resistant/sensitive, pH-sensitive, denitrifying, and metal-resistant bacteria after Z-NZVI addition were ultimately eliminated because soil characteristics drove the re-establishment of indigenous bacterial community. Meanwhile, Z-NZVI recovered the basic activities of bacterial DNA replication and denitrification functions in soils. These results confirm that Z-NZVI is promising for the long-term remediation of metal(loid)s contaminated farmland soil without significant ecotoxicity. This study forms the first basic assessment of microphytobenthos (MPB) dynamics in micro-estuaries and micro-outlets in southern Africa. It examines MPB community responses to environmental variables and further investigates MPB composition qualitatively across different micro-estuaries and micro-outlets over four seasons in a warm temperate region of the subcontinent. Combinations of multivariate analyses were used to explore similarities and differences in MPB communities between systems. Human-induced catchment changes between microsystems ranged from no alteration (rating 0; mostly micro-outlets) to extreme modification (rating 5; mostly micro-estuaries). Two hundred and sixty-seven MPB taxa were identified within all the microsystems, with 247 and 230 MPB taxa being observed in the micro-estuaries and micro-outlets, respectively. The MPB communities differed slightly in terms of microsystem types and seasons, but no significant differences were observed. Multivariate analyses (i.e. Boosted Regression Trely reflect a concomitant change from a complex community dynamic (structure and spatio-temporal attributes) to one that approaches a homogeneous structure (poor spatial zonation, strong taxonomic dominance, low species diversity). Inhalation of size-dependent particle-bound polycyclic aromatic hydrocarbons (PAHs) has been extensively studied, whereas dermal absorption has not been adequately investigated. To address this knowledge gap, dermal absorption of size-dependent particle-bound PAHs was characterized through the collection of indoor air and forearm wipe samples in the setting of an indoor barbecue. NMS-873 The mass of size-fractioned PAHs associated with particulate matter was greater in fine particles (1.8 μm). Gas-particle distribution of specific PAHs from barbecue fume was ascribed to both adsorption and absorption which would probably be close to equilibrium, while that from background air was dominated by absorption. Forearm-deposited amounts of particulate PAHs suggested that removal of coarse and fine particles could minimize exposure to low and high molecular-weight (MW) PAHs, respectively. Besides, the concentrations of particulate PAHs in forearms wipe were significantly correlated to their dry deposition fluxes with coarse particles, but weakly correlated to those with fine particles. This indicated that particle size would influence dermal absorption efficiency of particle-bound PAHs with fine particles prolonging dermal exposure to PAHs. Overall, higher MW particle-bound PAHs derived from barbecue fume may pose higher risk to human health by dermal absorption than lower MW PAHs. Our understanding of colloidal biochar (CB) transport and release is largely unknown in environments with transient chemical conditions, e.g., ionic strength (IS), pH, and especially humic acid (HA). In this study, column experiments were conducted to investigate CB transport and retention in the presence and absence of HA, and CB release under transient IS and pH conditions in saturated sand. Step reductions in solution IS from 25 to 0.01 mM produced significant release peaks of CB due to a reduction in the depth of the primary minima on rough surfaces with small energy barriers. In contrast, step increases of solution pH from 4 to 10 only slightly increased CB release presumably due to the strong buffering capacity of CB. The CB retention was diminished by HA during the deposition phase. However, the release of CB with transients in IS and pH was not influenced much when deposition occurred in the presence of HA. These observations indicate that HA increased the energy barrier during deposition but did not have a large influence on the depth of the interacting minimum during transient release.