We study the focusing intercritical NLS
NLS
i
∂
t
u
+
Δ
x
,
y
u
=
-
|
u
|
α
u
on the semiperiodic waveguide manifold
R
x
d
×
T
y
with
d
≥
5
and
α
∈
(
4
d
,
4
d
-
1
)
. In the case
d
≤
4
, with the ...aid of the semivirial vanishing theory (Luo in Normalized ground states and threshold scattering for focusing NLS on Rd
×
T via semivirial-free geometry, 2022), the author was able to construct a sharp threshold, which being uniquely characterized by the ground state solutions, that sharply determines the bifurcation of global scattering and finite time blow-up solutions in dependence of the sign of the semivirial functional. As the derivative of the nonlinear potential is no longer Lipschitz in
d
≥
5
and the underlying domain possesses an anisotropic nature, the proof in Luo (Normalized ground states and threshold scattering for focusing NLS on Rd
×
T via semivirial-free geometry, 2022), which makes use of the concentration compactness principle, can not be extended to higher dimensional models. In this paper, we exploit a well-tailored adaptation of the interaction Morawetz–Dodson–Murphy (IMDM) estimates, which were only known to be applicable on Euclidean spaces, into the waveguide setting, in order to prove that the large data scattering result formulated in Luo (Normalized ground states and threshold scattering for focusing NLS on Rd
×
T via semivirial-free geometry, 2022) continues to hold for all
d
≥
5
. Together with Tzvetkov–Visciglia (Rev. Mat. Iberoam. 32:1163–1188, 2016) and the author (Luo in Normalized ground states and threshold scattering for focusing NLS on Rd
×
T via semivirial-free geometry, 2022), we thus give a complete characterization of the large data scattering for (NLS) in both defocusing and focusing case and in arbitrary dimension.
Microplastics are emerging persistent contaminants of increasing concern. Although microplastics have been extensively detected in aquatic environments, their occurrence in soil ecosystems remains ...largely unexplored. This review focused on recent progress in analytical methods, pollution characteristics and ecological effects of microplastics in soils. In spite of the presence of microplastics in soils, no standardized methods are available for the quantification. Uniform protocols including microplastic extraction and identification are urgently needed to develop. In soil environments, main sources of microplastics include mulching film, sludge, wastewater irrigation and atmospheric deposition. The fate of microplastics is closely related to soil physio-chemistry and biota. Existing evidence shows that microplastics can influence soil biota at different trophic levels, and even threaten human health through food chains. Therefore, further research is needed to fully reveal the fate and ecological risks of microplastics in soils; and necessary action is required to control microplastic pollution in terrestrial ecosystems.
•Standardized methods need be developed for microplastic extraction/identification in soil.•Main sources of soil microplastics include mulching film, sludge and wastewater irrigation.•Microplastics can have ecological impacts on soil biota and even threaten human health.•Further research is needed to reveal the fate and ecological risks of soil microplastics.
Microplastics may lose buoyancy and occur in deeper waters and ultimately sink to the sediment and this may threaten plankton inhabiting in various water layers and benthic organisms. Here, we ...conduct the first survey on microplastics in the water column and corresponding sediment in addition to the surface water in the Bohai Sea. A total of 20 stations covering whole Bohai Sea were selected, which included 6 stations specified for water column studying. Seawater was sampled every 5 m, with maximal depth of 30 m in the water column using Niskin bottles coupled with a ship-based conductivity, temperature and depth sensor (CTD) system and surface sediment samples were collected using box corer. The results indicated that higher microplastic levels accumulated at a depth range of 5–15 m in the water column in some stations, suggesting the surface water survey was not sufficient to reflect microplastics loading in a water body. Fibers predominated microplastic types in both seawater and sediment of the Bohai Sea, which accounted for 75%–96.4% of the total microplastics. However the relatively proportion of the fibers in the deeper water layers and sediment was lower than that in the surface water. Microplastic shapes are more diverse in the sediment than in the seawater in general. The microplastic sizes changed with depth in the water column and the proportion of the size-fraction < 300 μm increased with depth, probably as a result of rapid biofouling on the small microplastics due to their higher specific surface area. Such depth distribution also implied that sampling with manta net (>330 μm) that commonly used in the oceanographic survey might underestimate microplastics abundance in the water column. Further studies are recommended to focus on the sinking behavior of microplastics and their effects on marine organisms.
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•Microplastics levels in the surface sea were closely related with human activities.•A higher amount of microplastics accumulated in the depth of 5–15 m in the Bohai Sea.•Micropalstics with size <300 μm tended to sinking and presenting in the deeper water.•Microplastics abundance was not consistent between water and corresponding sediment.
Substantial amount of microplastics accumulated in the deeper water rather than the surface water of the Baohai Sea.
•Biochar was used as a carrier for immobilizing Cd-Cu resistant strain NT-2.•Strain NT-2 quickly colonized and secreted EPS on the surface of biochar.•Application of 5% NT-2 loaded biochar decreased ...the bioavailability of Cd and Cu.•Soil enzyme activity markedly recovered in the NT-2 loaded biochar treatment.•NT-2 loaded biochar greatly improved soil microbial community profile.
The application of biochar in the remediation of heavy metal contaminated soil has received increasing global attention during the past decade. Although there has been some review work on the mechanism of heavy metals stabilization by biochar, the effects and mechanisms of interaction between biochar and functional microbes such as heavy metal tolerant, adsorption and transformation microbial strains remains unclear. In this paper, maize biochar and a heavy metal-tolerant strain Pseudomonas sp. NT-2 were selected to investigate the dynamic effects and potential mechanisms of biochar and bacteria loaded biochar on the stabilization of Cd and Cu mixed contaminated soil by a 75-day pot experiment. The results showed that, compared to the single biochar amendment, the application of biochar inoculated with NT-2 strain at the rate of 5% significantly increased the soil pH at the initial stage of incubation, and followed by a slight decline to a neutral-alkaline range during the reaction. The addition of NT-2 loaded biochar could also significantly increase the proportion of residual fraction of Cd and Cu, thus reduce the proportion of exchangeable and carbonate bound species in the soil, which lead to the decreasing of plant and human bioavailability of the metal in the soil indicated by DTPA and simulated human gastric solution extraction (UBM), respectively. Finally, the application of bacterial loaded biochar also markedly enhanced soil urease and catalase activities during the later stage of the incubation, and improved soil microbial community at the end of incubation, which indicates a recovery of soil function after the metal stabilization. The research results may provide some new insights into the development of functional materials and technologies for the green and sustainable remediation of heavy metal contaminated soil by the combination of biochar and functional microorganisms.
The ecological stress of microplastics (MPs) contamination in agroecosystems raise worldwide concerns. However very few studies concentrated on the effects of MPs exposure on soil microbial ...community. The alterations of enzymatic activities and bacterial communities were assayed by spiking 1% and 5% (w/w) of polyethylene (PE) and polyvinyl chloride (PVC) MPs in an acid soil. The results showed that both PE and PVC addition inhibited fluorescein diacetate hydrolase activity and stimulated urease and acid phosphatase activities, and declined the richness and diversity of the bacterial communities. More severe effects were observed in the PE treated soils compared to the PVC treated soils generally. The relative abundances of families Burkholderiaceae increased significantly (p < .05) after MPs addition, suggesting the bacteria associated with nitrogen fixation stimulated by the MPs input. Meanwhile, significant (p < .05) decline of Sphingomonadaceae and Xanthobacteraceae after addition of 5% PVC and 1% PE MPs, respectively implied that MPs might inhibit the biodegradation of xenobiotics in the soil. Mover, the PICRUSt analysis demonstrated that membrane transporter was a sensitive prediction functional gene of microplastics exposure in the soil. Future studies could be focused on the role of MPs on the regulation of nitrogen cycling and organic compounds degradation in soils.
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•PE and PVC MPs inhibited FDAse activity and stimulated urease and acid phosphatase activities.•PE MPs pollution caused a higher OTUs reduction compared to the PVC MPs pollution in the soil.•PE MPs promote the abundance of the bacterial family associated with nitrogen fixation in the soil.•High PVC MPs level significantly reduced the abundance of family Sphingomonadaceae in the soil.
Coastal groundwater quality significantly affects the regional sustainable development, due to the water resource shortage in coastal zone. Current studies on coastal groundwater have mainly focused ...on saline water intrusion and over-extraction. Information on the heavy metal pollution of coastal groundwater with salinization trend is limited. This study investigated heavy metals in groundwater from a typical coastal region with intensive anthropogenic activities and saline water intrusion. The southwestern coastal plains of the study area showed significant groundwater salinization trend. Heavy metals in the coastal groundwater mainly originated from anthropogenic activities and groundwater salinization according to principal component analysis. Relative high concentrations of As, Co, Cr, Cu, Fe, Mn, and Ni occurred in the southwestern coast of the study area with high TDS level, indicating that the concentrations of these heavy metals in shallow aquifer of the study area might be influenced by the groundwater salinization. Average concentrations of heavy metals in groundwater of the study area ranged from 0.03 (Cd) to 686.92 (Fe) μg/L. Fe was the dominant heavy metal in groundwater with the maximal concentration of 2333.76 μg/L and exceeding-standard rate reaching 98.23%. Approximately 13.27% of sampling sites showed moderate or higher heavy metal pollution of groundwater based on heavy metal pollution index. Heavy metals in groundwater exerted low ecological risks. Elements Fe, Ni, and As were the main contributors for ecological risks. Cancer risks of heavy metals for both adults and children were high at all sampling sites. Non-cancer risks for adults and children were unacceptable at 4.42% and 17.70% of sampling sites, respectively. The salinization of the coastal groundwater could also lead to the increase in the ecological and health risks of heavy metals in coastal groundwater. These findings provide initial and important information on heavy metals pollution in coastal aquifer with saline water intrusion.
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•Southwestern coastal plains of study area showed significant groundwater salinization.•About 13.27% of sampling sites showed moderate or more serious heavy metal pollution.•Heavy metals in groundwater exerted low ecological risks.•Heavy metals in groundwater exerted high cancer risks for adults and children.•Salinization of coastal groundwater caused the increase in pollution and risks.
The concentrations of six priority phthalic acid esters (PAEs) in intensively managed suburban vegetable soils in Nanjing, east China, were analyzed using gas chromatography–mass spectrometry ...(GC–MS). The total PAE concentrations in the soils ranged widely from 0.15 to 9.68 mg kg−1 with a median value of 1.70 mg kg−1, and di-n-butyl phthalate (DnBP), bis-(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DnOP) were the most abundant phthalate esters. Soil PAE concentrations depended on the mode of use of plastic film in which PAEs were incorporated as plasticizing agents and both the plastic film and poultry manure appeared to be important sources of soil PAEs. Vegetables in rotation with flooded rice led to lower concentrations of PAEs in soil. The results indicate that agricultural plastic film can be an important source of soil PAE contamination and further research is required to fully elucidate the mechanisms of PAE contamination of intensive agricultural soils with different use modes of use of plastic film.
•Phthalate esters in soils from suburban intensive vegetable production systems were investigated.•Phthalate levels and risks of the vegetable soils with different plastic film use modes were examined.•Sources of phthalate esters in vegetable production soils were analyzed.
PAE contamination of intensively managed vegetable soils varied widely depending on the mode of use of plastic film in different production systems.
Soil particulate organic matter (POM) has rapid turnover and metal enrichment, but the interactions between organic matter (OM) and metals have not been well studied. The present study aimed to ...investigate changes in the OM concentration and composition of the POM fraction and their corresponding effects on metal distribution and extractability in long-term polluted paddy soils. Soil 2000–53 μm POM size fractions had higher contents of C–H and C=O bonds, C–H/C=O ratios and concentrations of fulvic acid (FA), humic acid (HA), cadmium (Cd) and zinc (Zn) than the bulk soils. Cadmium and Zn stocks in soil POM fractions were 24.5–27.9% and 7.12–16.7%, respectively, and were more readily EDTA-extractable. Compared with the control soil, the 2000–250 μm POM size fractions had higher organic carbon concentrations and C/N ratios in the polluted soils. However, there were no significant differences in the contents in C–H and C=O bonds or C–H/C=O ratios of POM fractions among the control, slightly and highly polluted soils. In accordance with the lower contents of C=O bonds and FA and HA concentrations, the Cd and Zn concentrations in 250–53 μm POM size fractions were lower than those in 2000–250 μm POM size fractions. Enrichment of Cd in POM fractions increased with increasing soil pollution level. These results support the view that changes in the OM concentration and the size and composition of POM fractions play a key role in determining the distribution of Cd and Zn in paddy soils.
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•The OC and FA contents and C/N in POM (2000–250 μm) increased in polluted soil.•Enrichment of Cd and Zn decreased with decreasing POM size.•No significant change in content of C=O group in POM was observed in polluted soil.•Changes in the size and composition of soil POM affected the Cd and Zn distribution.
Interactions between soil organic matter and metals.
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•The content of antibiotics and ARGs on PE was decreased with salinity.•PE MPs can selectively enrich antibiotics, ARGs and microbe in various waters.•Bacterial community on PE MPs ...differed from surrounding water by antibiotics.•ARGs and bacterial diversity on PE MPs increased in river water.•Bacteria on PE MPs were more susceptible to antibiotics in marine water.
The partition of antibiotics and antibiotic resistant genes (ARGs) between the microplastics (MPs) and the surrounding water with various salinity are still unclear. In this study, we hypothesized that adsorption of antibiotics on MPs might cause a significant change of the structure of microbial communities, diversity and abundance of ARGs on MPs and this might be further affected by change of salinity. In this study, we investigated adsorption of four common antibiotics (sulfamerazine, tetracycline, chloramphenicol and tylosin) to polyethylene (PE) MPs in river, estuary and marine waters, and the differences of antibiotic resistant genes (ARGs) and bacterial communities on MPs and in the three waters. The results showed that MPs can enrich antibiotics, ARGs and microbes from the surrounding water. Elevated salinity could reduce adsorption of antibiotics to MPs and the abundance of ARGs. For example, MPs can concentrate more antibiotics and ARGs in the fresh river water than in the estuary and the marine waters. In addition, ARGs and bacterial communities on MPs at various salinity were significantly different under the pressure of four antibiotics. On MPs, sul1, sulA/folP-01, tetA, tetC, tetX and ermE increased significantly but a few new ARGs such as sulA/folP-01 and tetA appeared. The structure of the bacterial communities on MPs was different from the surrounding water since some bacteria species found on MPs were barely detected in the surrounding water while some genera on MPs vanished after exposure to antibiotics. As the antibiotics adsorbed and the ARGs on MPs decreased with the water salinity, the structure of the communities on MPs thus varied with salinity change. These findings are important to understand the effects of MPs on the transport, fate and ecological risk of antibiotics and ARGs in different aquatic environments.
The effects of microbial colonization and biofilm formation on microplastics in the marine and coastal environments have aroused global concern recently. However, the simultaneous influences of ...exposure time and depth on biofilm formation, and subsequently on the properties variations of microplastics is less studied. In this study, polyethylene (PE) film was exposed at three depths (2 m, 6 m, and 12 m) for three time periods (30 days, 75 days, and 135 days) in the coastal seawater of Yellow Sea, China. The results show that the total amount of biofilms markedly increased with exposure time, but decreased with water depth. Typical morphologies and compositions of biofilms such as coccus-, rod-, disc-shaped bacteria and filaments, as well as a dense layer of extracellular polymeric substances were observed on the surfaces of the PE microplastics. Biofilm formation could decrease the hydrophobicity of PE microplastics, and increase the abundances of hydrophilic C−O and CO groups on the surface of PE. Alphaproteobacteria, Gammaproteobacteria and Bacteroidia were identified as the core microbiome of the PE associated biofilms, while the dominant bacteria families vary from the early to the late phases of the biofilm formation. Our results indicate that microplastics associated biofilms could affect the environmental processes and fates of microplastics in the marine and coastal environment.
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•Biofilm formation and its influences on PE properties were investigated.•The thickness of biofilms on PE increases with exposure time but decreases with depth.•Biofilms could decrease the hydrophobicity and change the functional groups of PE.•The dominant PE colonizing microbial community varies during the biofilm formation.
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