31 research outputs found
Enrofloxacin Induces Intestinal Microbiota-Mediated Immunosuppression in Zebrafish
The immunosuppressive effects of antibiotics and the potential associations with the intestinal microbiota of the host have been increasingly recognized in recent years. However, the detailed underlying mechanisms of immune interference of antibiotics in environmental organisms remain unclear, particularly at the early life stage of high sensitivity. To better understand the gut microbiome and immune function interactions, the vertebrate model, zebrafish, was treated with environmentally relevant concentrations of a frequently detected antibiotic, enrofloxacin (ENR), ranging from 0.01 to 100 μg/L. 16S ribosomal RNA sequencing indicated diminished diversity, richness, and evenness of intestinal flora following ENR treatment. Twenty-two taxa of gut bacteria including Rickettsiales, Pseudomonadales, and Flavobacteriales were significantly correlated with immunosuppressive biomarkers, including a significant decrease in the abundance of macrophages and neutrophils. To validate the immunomodulatory effects due to altered intestinal microbial populations, zebrafish reared under sterile and non-sterile husbandry conditions were compared after ENR treatment. A significant inhibitory effect was induced by ENR treatment under non-sterile conditions, while the number of macrophages and neutrophils, as well as biomarkers of immunosuppressive effects, were significantly salved in zebrafish under sterile conditions, confirming for the first time that immunosuppression by ENR was closely mediated through alterations of the intestinal microbiome in fish.publishedVersio
Satellite-Observed Decreases in Water Turbidity in the Pearl River Estuary:Potential Linkage With Sea-Level Rise
Effect of Calcium Hydroxide on the Pyrolysis Behavior of Sewage Sludge: Reaction Characteristics and Kinetics
The effect of calcium
hydroxide (Ca(OH)<sub>2</sub>), a promising
additive to control the pollutants released during sludge pyrolysis,
on the pyrolysis behavior and kinetics of sewage sludge was investigated
in detail in this study. The obtained thermograms of Ca(OH)<sub>2</sub>-blended sludge showed that the addition of Ca(OH)<sub>2</sub> influenced
the thermogravimetric characteristics of sludge, especially in the
temperature range of 340–700 °C where the decomposition
of Ca(OH)<sub>2</sub> happens. An increasing addition of Ca(OH)<sub>2</sub> improved the pyrolysis conversion of sludge at temperatures
of more than 600 °C, which was verified by the increase of the
process heat flow. Importantly, the transformation of elements in
sludge was promoted, resulting in a lesser content of impurities,
which existed mostly in the thermally stable forms, in the remaining
char. Kinetic analysis revealed that the pyrolysis behavior of sludge
was influenced by the addition of Ca(OH)<sub>2</sub> and reaction
temperature. At low temperatures, Ca(OH)<sub>2</sub> acted as the
source of nuclei required for the establishment of reaction interface
and then induced the secondary cracking of the pyrolytic compounds
in the sludge matrix when the reaction came to high temperatures.
A retrofitted kinetic model, overcoming the drawback faced by most
Arrhenius-derived models that the integral of temperature-induced
item was resolved by approximation, is developed and exhibits superiority
in describing the reaction characteristics of sludge pyrolysis
Novel Calcium Oxide-Enhancement Phosphorus Recycling Technique through Sewage Sludge Pyrolysis
Municipal sewage
sludge is abundant and rich in phosphorus, making
it a promising alternative phosphorus reserve. A good knowledge of
the phosphorus transformation during pyrolysis will underlie the industrial
phosphorus recycling and reclamation of sewage sludge. This work first
advanced a novel calcium oxide (CaO)-enhancement phosphorus-recycling
technique based on pyrolysis of sewage sludge, by regulating the transformation
of phosphorus in sewage sludge during pyrolysis through the CaO addition.
The obtained results indicated that CaO addition promoted the formation
of hydroxylapatite, which is a desirable phosphorus species for plant
growth. The factors of pyrolysis temperature and inherent composition
of sewage sludge both influenced the fraction of hydroxylapatite during
pyrolysis. An increase in pyrolysis temperature and a sludge with
a high content of ash and a low content of volatile matters potentially
promoted the transformation of P from organic phosphorus to the inorganic
species during pyrolysis with the addition of CaO, particularly for
the formation of hydroxylapatite. Increasing CaO addition significantly
increased the fraction of hydroxylapatite in the obtained char, and
the maximum content of 25 wt % hydroxylapatite over total phosphorus
was attained. This enhanced transformation of hydroxylapatite may
be potentially attributed to the interaction between CaO and the polyphosphate
with the aid of the inherent minerals that appeared to benefit the
immobilization of phosphorus during sludge pyrolysis. As the formation
of hydroxylapatite was enhanced, this facile technology of CaO-enhancement
sewage sludge pyrolysis could be used for the direct recycling of
P as well as the disposal of sewage sludge
High-Resolution Mapping of Ice Cover Changes in Over 33,000 Lakes Across the North Temperate Zone
More than 50% of global lakes periodically freeze, and their lake ice phenology is sensitive to climate change. However, spatially detailed quantification of the changes in lake ice at the global scale is not available. Here, we map ice cover in >33,000 lakes throughout the North Temperate Zone (23.5°–66.5°N) using 0.55 million Landsat images from 1985 to 2020. Over this period, we found a remarkable reduction in median ice cover occurrence (ICO) (61% to 43%), which was strongly related to warming terrestrial mean surface temperatures (R2 = 0.94, p < 0.05). Lakes in Europe showed the most pronounced ice loss (median ICO decreased from 50% to 24%), and extensive lake ice losses were also detected in the northern US, and central and eastern Asia. An overall increase in ice cover was identified from P2 (1999–2006) to P3 (2007–2014) due to regional decreased temperatures associated with the “global warming hiatus.” Thehigh-resolution mapping of lake ice here provides essentialbaseline information whichcan be used to elucidate ice loss-induced environmental and societal impacts
Study on Microscopic Pore Structure Classification for EOR of Low Permeability Conglomerate Reservoirs in Mahu Sag
The microscopic pore structure controls the fluid seepage characteristics, which in turn affect the final recovery of the reservoir. The pore structures of different reservoirs vary greatly; therefore, the scientific classification of microscopic pore structures is the prerequisite for enhancing the overall oil recovery. For the low permeability conglomerate reservoir in Mahu Sag, due to the differences in the sedimentary environment and late diagenesis, various reservoir types have developed in different regions, so it is very difficult to develop the reservoir using an integrated method. To effectively solve the problem of microscopic pore structure classification, the low permeability conglomerate of the Baikouquan Formation in Well Block Ma18, Well Block Ma131, and Well Block Aihu2 are selected as the research objects. The CTS, HPMI, CMI, NMR, and digital cores are used to systematically analyze the reservoir micro pore structure characteristics, identify the differences between different reservoir types, and optimize the corresponding micro pore structure characteristic parameters for reservoir classification. The results show that the pore types of the low permeability conglomerate reservoir in the Baikouquan Formation of the Mahu Sag are mainly intragranular dissolved pores and residual intergranular pores, accounting for 93.54%, microfractures and shrinkage pores that are locally developed, accounting for 5.63%, and other pore types that are less developed, accounting for only 0.83%. On the basis of clear pore types, the conglomerate reservoir of the Baikouquan Formation is divided into four types based on the physical properties and microscopic pore structure parameters. Different reservoir types have good matching relationships with lithologies. Sandy-grain-supported conglomerate, gravelly coarse sandstone, sandy-gravelly matrix-supported conglomerate, and argillaceous-supported conglomerate correspond to type I, II, III, and IV reservoirs, respectively. From type I to type IV, the corresponding microscopic pore structure parameters show regular change characteristics, among which, porosity and permeability gradually decrease, displacement pressure and median pressure increase, maximum pore throat radius, median radius, and average capillary radius decrease, and pore structure becomes worse overall. Apparently, determining the reservoir type, clarifying its fluid migration rule, and formulating a reasonable development plan can substantially enhance the oil recovery rate of low permeability conglomerate reservoirs
Enrofloxacin Induces Intestinal Microbiota-Mediated Immunosuppression in Zebrafish
The immunosuppressive effects of antibiotics and the potential associations with the intestinal microbiota of the host have been increasingly recognized in recent years. However, the detailed underlying mechanisms of immune interference of antibiotics in environmental organisms remain unclear, particularly at the early life stage of high sensitivity. To better understand the gut microbiome and immune function interactions, the vertebrate model, zebrafish, was treated with environmentally relevant concentrations of a frequently detected antibiotic, enrofloxacin (ENR), ranging from 0.01 to 100 μg/L. 16S ribosomal RNA sequencing indicated diminished diversity, richness, and evenness of intestinal flora following ENR treatment. Twenty-two taxa of gut bacteria including Rickettsiales, Pseudomonadales, and Flavobacteriales were significantly correlated with immunosuppressive biomarkers, including a significant decrease in the abundance of macrophages and neutrophils. To validate the immunomodulatory effects due to altered intestinal microbial populations, zebrafish reared under sterile and non-sterile husbandry conditions were compared after ENR treatment. A significant inhibitory effect was induced by ENR treatment under non-sterile conditions, while the number of macrophages and neutrophils, as well as biomarkers of immunosuppressive effects, were significantly salved in zebrafish under sterile conditions, confirming for the first time that immunosuppression by ENR was closely mediated through alterations of the intestinal microbiome in fish
Global mapping reveals increase in lacustrine algal blooms over the past decade
Algal blooms constitute an emerging threat to global inland water quality, yet their spatial and temporal distribution at the global scale remains largely unknown. Here we establish a global bloom database, using 2.91 million Landsat satellite images from 1982 to 2019 to characterize algal blooms in 248,243 freshwater lakes, representing 57.1% of the global lake area. We show that 21,878 lakes (8.8%) spread across six continents have experienced algal blooms. The median bloom occurrence of affected lakes was 4.6%, but this frequency is increasing; we found increased bloom risks in the 2010s, globally (except for Oceania). The most pronounced increases were found in Asia and Africa, mostly in developing countries that remain reliant on agricultural fertilizer. As algal blooms continue to expand in scale and magnitude, this baseline census will be vital towards future risk assessments and mitigation efforts