Compared to the shallow-layer vacuum preloading and in situ solidification techniques, the large shell cushion fully utilizes Type III natural sand, which is often considered waste in dredging projects. This makes it an environment-friendly and low-carbon technology, more suitable as a working cushion for equipment in foundation treatment projects in rivers, lakes, seas, and coastal areas with suspended and fluid mud. However, the mechanical behavior during construction and the working mechanism of this type of shell cushion is still unclear, thus hindering its further application. In light of this, based on the strength properties of soils characterized by suspended and fluid mud, this paper starts using numerical simulation to study the mechanical behavior during construction and the bearing deformation characteristics of this shell cushion in depth. Then on this basis, a semi-empirical calculation method for the bearing capacity of this shell cushion is derived using one-dimensional consolidation theory and soil strength theory. Finally, the method is validated by applying it to engineering projects. The results indicate that: (1) the formation of a composite flexible structure in large shell cushions can fully utilize the lateral confinement effect, and the formation of a flat structure can effectively maximize the surface closure effect. The drainage consolidation effect mainly benefits from the drainage function of bagged sand drains. (2) When the underlying layer is suspended mud (water content over 150%), the bearing failure of the soft foundation under the working load of the equipment presents a characteristic of overall shear failure. When the underlying stratum is fluid mud (water content between 85 and 150%), the bearing failure of the soft foundation under the working load of the equipment presents a characteristic of punching shear failure. (3) The formula to calculate the bearing capacity for the shell cushion proposed includes three key technical indicators: stress diffusion coefficient, additional cohesion, and tension. This formula can predict the bearing capacity of the shell cushion effectively, with a calculation error of less than 14% compared to finite element simulation.

Wave-induced liquefaction is a geological hazard under the action of cyclic wave load on seabed. Liquefaction influences the suspended sediment concentration (SSC), which is essential for sediment dynamics and marine water quality. Till now, the identification of liquefaction state and the effect of liquefaction on SSC have not been sufficiently accounted for in the sediment model. In this study, we introduced a method for simulating the liquefaction-induced resuspension flux into an ocean model. We then simulated a storm north of the Yellow River Delta, China, and validated the results using observational data, including significant wave heights, water levels, excess pore water pressures, and SSCs. The liquefaction areas were mainly distributed in coastal zones with water depths less than 12 m, and the simulated maximum potential soil liquefaction depth was 1.39 m. The liquefaction-induced SSC was separated from the total SSC of both liquefaction- and shear-induced SSCs by the model, yielding a maximum liquefaction-induced SSC of 1.07 kg center dot m(-3). The simulated maximum proportion of liquefaction-induced SSC was 26.2% in regions with water depths of 6-12 m, with a maximum significant wave height of 3.4 m along the 12 m depth contour. The erosion zone at water depths of 8-12 m was reproduced by the model. Within 52.5 h of the storm, the maximum erosion thickness along the 10 m depth contour was enhanced by 33.9%. The model is applicable in the prediction of liquefaction, and provides a new method to simulate the SSC and seabed erosion influenced by liquefaction. Model results show that liquefaction has significant effects on SSC and seabed erosion in the coastal area with depth of 6-12 m. The validity of this method is confined to certain conditions, including a fully saturated seabed exhibiting homogeneity and isotropic properties, small liquefaction depth, residual liquefaction dominating the development of pore pressures, no influence by structures, and the sediment composed of silt and mud that experiences frequent wave-induced liquefaction.

Climate change has regulated cryosphere-fed rivers and altered interannual and seasonal sediment dynamics, with significant implications for terrestrial material cycles and downstream aquatic ecosystems. However, there has been a notable scarcity of research focusing on the patterns of water-sediment transport within these permafrost zones. Integrating 6 years (2017-2022) of in-situ observational data from FengHuoShan basin with the partial least squares-structural equation modelling (PLS-SEM) method, we analyse the driving factors, characteristics and seasonal patterns of the water-sediment transport process. We observed a gradual increase in both suspended sediment flux (SSF, Mt/yr) and runoff (Q, km(3)/yr) within the basin, with annual growth rates of 1.34%/yr and 0.75%/yr, respectively. It is worth noting that these growth rates exhibit seasonal variations, with the highest values observed in spring (SSF: 1.76%/yr, Q: 1.71%/yr). This indicates that the response to climate change is more pronounced in spring compared with summer and autumn. Through mathematical statistics and the PLS-SEM model, we found that temperature plays a predominant role in the dynamics of water-sediment in both spring and autumn, whereas rainfall exerts a more significant impact during the summer. Most suspended sediment concentration (SSC, kg/m(3)) peak events throughout the year are primarily driven by rainfall. Affected by the freeze-thaw cycle of permafrost, SSC and discharge (Q, m(3)/s) exhibit distinct seasonality. SSC and Q demonstrate a clockwise trend; both Q and SSC begin to increase from May and peak in August before declining. The insights gleaned from this study hold significant implications for water resource management and soil conservation strategies in the region, particularly in the face of ongoing climatic changes characterized by warming and increased humidity.

As an essential component for the transportation of oceanic oil and gas supplies, it is crucial to ensure the efficient operation of submarine pipelines. The fatigue failure of submarine pipelines occurs frequently under the combined effects of currents, waves and soil. Firstly, a pipe-soil interaction suspended pipeline model was developed, which could be used to simulate the mechanical behavior of pipes and the dynamic response of the combined loads of waves and currents. Then, the effects of soil properties, current direction and suspended length on the stress distribution and dynamic mechanical response of submarine suspended pipelines were investigated. In addition, the vibration characteristics of suspended pipelines affected by soil were revealed. At last, according to the vortex-induced resonance evaluation and fatigue life assessment method, the critical length of suspended pipelines for the Bohai sea was determined. The results show that the stress change in the center of the suspended reaches the most significant for the pipeline with a length of less than 20m. When the suspended length exceeds 20m of the pipeline, the connection between the suspended and the buried shows the most dramatic stress fluctuations. Meanwhile, the cumulative damage of the submarine suspended pipeline entering the soil becomes the maximum, and fatigue failure often occurs in this position. The results are expected to provide an important theoretical basis in safe operation and repair decision of submarine pipeline.

Much attention is drawn to polycyclic aromatic hydrocarbons (PAHs) as an air pollutant due to their toxic, mutagenic and carcinogenic properties. Therefore, to understand the levels, seasonality, sources and potential health risk of PAHs in two distinct geographical locations at Karachi and Mardan in Pakistan, total suspended particle (TSP) samples were collected for over one year period. The average total PAH concentrations were 31.5 +/- 24.4 and 199 +/- 229 ng/m(3) in Karachi and Mardan, respectively. The significantly lower concentration in Karachi was attributed to diffusion and dilution of the PAHs by the influence of clean air mass from the Arabian sea and high temperature, enhancing the volatilization of the particle phase PAHs to the gas phase. Conversely, the higher concentration (6 times) in Mardan was due to large influence from local and regional emission sources. A clear seasonality was observed at both the sites, with the higher values in winter and post-monsoon due to higher emissions and less scavenging, and lower values during monsoon season due to the dilution effect. Diagnostic ratios and principal component analysis indicated that PAHs in both sites originated from traffic and mixed combustion sources (fossil fuels and biomass). The average total BaP equivalent concentrations (BaPeq) in Karachi and Mardan were 3.26 and 34 ng/m(3) , respectively, which were much higher than the WHO guideline of 1 ng/m(3) . The average estimates of incremental lifetime cancer risk from exposure to airborne BaPeq via inhalation indicated a risk to human health from atmospheric PAHs at both sites. (C) 2021 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

Under global warming, the permafrost-underlain headwater catchments of the Tibetan Plateau have undergone extensive permafrost degradation and changes in precipitation characteristics, which may substantially alter the riverine suspended sediment and riverine solute fluxes. However, these fluxes and their influencing factors in such catchments are poorly understood. We studied the suspended sediment and solute fluxes in a permafrost-underlain headwater catchment on the northeastern Tibetan Plateau, based on comprehensive measurements of various water types in spring and summer in 2017. The daily flux of suspended sediment in spring was close to that in summer, but heavy rainfall events following a relatively long dry period made the largest contribution to the suspended sediment fluxes in summer. The riverine solute flux (in tons) was 12.6% and 27.8% of the suspended sediment flux (in tons) in spring and summer, indicating the dominating role of physical weathering in total material exportation. The snowmelt mobilized more suspended sediment fluxes and fewer solutes fluxes than summer rain, which may be due to the meltwater erosion and freeze-thaw processes in spring and the thicker thawed soil layer and better vegetation coverage in summer, and the longer contact time between the soil pore water and the soil and rock minerals after the thawing of frozen soil. The input of snowmelt driven by higher air temperatures in spring and the direct input of rainfall in summer would both act to dilute the stream water; however, the supra-permafrost water, with high solute contents, recharged the adjacent streamflow as frozen soil seeps and thus moderated the decrease in the riverine solute content during heavy snowmelt or rainfall events. With the permafrost degradation under future global warming, the solute fluxes in permafrost-underlain headwater catchments may increase, but the suspended sediment flux in spring may decrease due to the expansion of discontinuous permafrost areas and active layer thickness.

Mercury (Hg) released by melting glaciers is likely to bind to suspended particles in meltwater runoff, posing potential risks to downstream ecosystems. The rapidly receding glaciers on the Tibetan Plateau promote the export of total suspended particles (TSP), increasing the uncertainty of Hg export released by glacier melting. To investigate the relationships between TSP and Hg, a multimedia sampling campaign was conducted in July 2020 in the Kuoqionggangri glacier region of the Lhasa River Valley No. 1 glacierized basin located in the inland Tibetan Plateau. Samples from glacier snow/ice, supraglacial rivers, subglacial rivers, proglacial lakes, and meltwater runoff were obtained, and the relationships between TSP and Hg and their transport in glacier meltwater runoff in the context of glacier retreat were explored. The average TSP concentration of different environmental samples ranged from 9.51 mg/L to 399. 27 mg/L, showing significant differences. The average total Hg (THg) concentrations ranged from 0.52 ng/L to 58.81 ng/L and decreased in the order of snow/ice >runoff> subglacial river > proglacial lake > supraglacial river. Both TSP mass concentration and number concentration have an impact on the diurnal variation in meltwater runoff Hg, and the influence of TSP number concentration is stronger than that of concentration. Sites with high TSP concentrations and quantities tended to have higher Hg concentrations, while TSP particle size had no significant effect on Hg concentration or spatial distribution. Our study further divided the glacier recharge basin into the glacier cover zone, the periglacial zone, and the downstream zone and discussed the potential impact of TSP on Hg transport in each zone. Our analysis highlights that the periglacial zone will expand and activate the resuspension process of river sediments in the warming future, which may increase the export of TSP and Hg downstream.

The present study examines the effect of Diwali festival (17-21 October 2017; 19th October was the Diwali day) on aerosol characteristics over Patiala, northwestern part of India. Diwali being one of the major festivals of India that falls between mid-October and mid-November is celebrated with full enthusiasm by burning crackers, fireworks, etc. During this period, the study site also is engulfed with high aerosol loading because of extensive paddy residue burning emission. During Diwali event, a particulate matter (PM10) concentration varies from 132 to 155 mu gm(-3), while a mass concentration of black carbon aerosols varies from 6 to 9 mu gm(-3) with the maximum concentration on post-Diwali day. Aerosol optical depth (AOD(500)) was maximum (0.852) on post-Diwali day indicating the additional loading of submicron particles due to burning of crackers and fireworks. The magnitude of single scattering albedo (SSA(500)) decreases to a minimum value around 0.864 showing abundance of absorbing aerosols on Diwali affected days (19th and 20th October). A sudden jump of +12.9Wm(-2) in atmospheric radiative forcing resulting in a heating rate of up to 1.4Kday(-1) on next day of Diwali shows the warming state of the lower and middle atmosphere.

The measurement of black carbon (BC) and organic carbon (OC), dust in total suspended particulates (TSP) was carried out at Yulong Snow Mountain (Mt. Yulong) and Ganhaizi Basin, in the Mt. Yulong region, southwestern China. TSP samples were analyzed using a thermal/optical reflectance carbon analyzer. Results show that average BC and OC concentrations in TSP in the Mt. Yulong region were 1.61 +/- 1.15 mu g/m(3) and 2.96 +/- 1.59 mu g/m(3), respectively. Statistical results demonstrated that there were significant differences in mean BC and OC contents between Ganhaizi Basin and Mt. Yulong at the 0.05 level. Strong correlations between BC and OC indicate their common dominant emission sources and transport processes. Temporal variations of BC, OC, and optical attenuation (ATN) values were consistent with each other in carbonaceous aerosols. The ratios of OC/BC in monsoon season were significantly higher than in non-monsoon in aerosols from Ganhaizi, which is closely related to the formation of secondary organic carbon (SOC) and extensive motor vehicle emissions from tourism activities. The temporal variations of BC, OC and ATN in carbonaceous aerosols in Ganhaizi and Mt. Yulong were totally different, probably due to elevation difference and diverse tourism activity intensity between the two sites. Time-averaged aerosol optical depth (AOD) at the wavelength of 550 nm in Mt. Yulong was higher than that of the inland of the Tibetan Plateau (TP). Source apportionment indicated that intensive exhaust emissions from tourism vehicles were the main local sources of atmospheric pollutant in the Mt. Yulong region. Biomass-burning emissions released from South Asia could penetrate into the inland of the TP under the transport of summer monsoon. Further study is needed to assess light absorption and radiative forcing of carbonaceous aerosols, and modeling research in combination with long-term in-situ observations of light-absorbing particulates (LAPs) in the TP is also urgently needed in future work.