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The published version of this article contains error. The equation (1) lost delta (Δ) before equal sign and five lines from the bottom before “-index”, here needs modification to “Δ-index”.

This paper reports a geochemical study on the mineralogy and major elements of mid-ridge (A), near mountaintop (B), and valley (C) profiles developed in the Lower Cambrian black shale in Northeast Chongqing, China. The primary objective was to understand the elemental mobility, mineralogical transformation, and weathering progression during black shale chemical weathering in a subtropical climate. Profiles A, B, and C are characterized as weak, weak to moderate, and moderate to intense in terms of weathering intensity, respectively, by the Chemical Index of Alteration (CIA). Results indicate that most elements were mobilized by acidic solutions produced during the oxidation of pyrite and organic matter (OM). Among the major elements, Si was slightly enriched in profile A, but depleted through desilication in profile B and C. Al was enriched in the regolith zone in profile A and C, and Fe was enriched at the oxic front because of secondary clay and sesquioxide formation. The addition and depletion of major elements and the depth of the oxic front increased with the degree of weathering. Gypsum and Fe- (hydro-) oxides were observed to form and re-precipitate in the saprock and fractured shale zones. Clay minerals formed from dissolution of plagioclase and the transformation of other labile clay minerals during weathering. The progressive changes in mineralogical composition of weathered material from profile A to C showed the sequence of mineral decomposition with degree of weathering: first, oxidation of pyrite and OM; then Ca and Mg were removed during dissolution of carbonatite; followed by removal of Na from dissolution of plagioclase; lastly, transformation of clay minerals during weathering; meanwhile, desilication occurs at moderate to intense weathering stages.

This work aims to characterize the earthquake-triggered landslides (EQTLs) during the 2017 Jiuzhaigou earthquake and to describe the geological and geomorphological control of landslide hazards. The Jiuzhaigou-EQTLs were studied via field-based investigation and remote sensing techniques during few weeks immediately after the mainshock occurred. The Jiuzhaigou earthquake produced an 11.4-km2 landslide area with 5633 landslides, dominated by shallow disrupted landslides, rock falls, and rockslides/rock avalanche. Statistical analyses show that the Jiuzhaigou-EQTLs had low mobility with a modal apparent friction angle of 40–44°. The Jiuzhaigou-EQTLs mostly occurred at elevations of 2700–3500 m and below 900 m relative relief to the main riverbed, where small-scale landslides were situated at the lower to middle parts of hillslope and large-scale landslides were situated close to the ridge crests. Jiuzhaigou-EQTLs clustered on river valley-side at the upstream of Baihe River (Jiuzhai Paradise and Ganhaizi village), Rize gully, and Danzhu gully on the tectonically active region at the southwest side of seismogenic fault F2. Landslides are prone to failure on the carbonate rocks with anaclinal hillslopes, following the cataclinal and cata-plagioclinal hillslopes. Most Jiuzhaigou-EQTLs preferentially occur on the below low-level break line (L2) in V-shaped valley-side and between first-level (L2) and high-level break line (L1) in U-shaped valley-side formed from long-term paleo-glacier and river incision. We found that landslide frequency is determined by a combination of the earthquake source with ground deformation, slope distribution, and rock strength due to weathering and dissolution along the fractures. Ground surface deformation, rock type (strength), geological structures, and valley-side slope breaks dictated the Jiuzhaigou-EQTL distribution pattern and hazards. This study elucidates the roles that local conditions play in influencing the occurrence, distribution, and frequency of slope failures and provides a better understanding of EQTL phenomenon during the Jiuzhaigou earthquake.

Based on a previous risk calculation study conducted along a road corridor, risk is recalculated using a stochastic simulation by introducing variability into most of the parameters in the risk equation. This leads to an exceedance curve comparable to those of catastrophe models. This approach introduces uncertainty into the risk calculation in a simple way, and it can be used for poorly documented cases to compensate for a lack of data. This approach tends to minimize risk or question risk calculations.

This study analyzes the leaching behavior of elements from red mud (bauxite residue) at pH values ranging from 2 to 13. The leaching characteristics of metals and contaminated anions in five red mud samples produced by Bayer and combined processes were analyzed using the batch leaching technique following the US Environmental Protection Agency (USEPA) Method 1313. In addition, the geochemical model of MINTEQ 3.1 was used to identify the leaching mechanisms of metals. The results showed that Ca, Mg, and Ba follow the cationic leaching pattern. Al, As, and Cr show an amphoteric leaching pattern. The leaching of Cl− is unaffected by the pH. The maximum leaching concentration of the proprietary elements occurs under extremely acidic conditions (pH = 2), except for As. The leaching concentration of F− reaches 1.4–27.0 mg/L in natural pH conditions (i.e., no acid or base addition). At the same pH level, the leaching concentrations of Pb, As, Cr, and Cu are generally higher from red mud produced by the combined process than that those of red mud from the Bayer process. The leaching concentration of these elements is not strongly related to the total elemental concentration in the red mud. Geochemical modeling analysis indicates that the leaching of metal elements, including Al, Ca, Fe, Cr, Cu, Pb, Mg, Ba, and Mn, in red mud are controlled by solubility. The leaching of these elements depended on the dissolution/precipitation of their (hydr)oxides, carbonate, or sulfate solids.

A nationwide investigation was carried out to evaluate the geochemical characteristics and environmental impacts of red mud and leachates from the major alumina plants in China. The chemical and mineralogical compositions of red mud were investigated, and major, minor, and trace elements in the leachates were analyzed. The mineral and chemical compositions of red mud vary over refining processes (i.e., Bayer, sintering, and combined methods) and parental bauxites. The main minerals in the red mud are quartz, calcite, dolomite, hematite, hibschite, sodalite, anhydrite, cancrinite, and gibbsite. The major chemical compositions of red mud are Al, Fe, Si, Ca, Ti, and hydroxides. The associated red mud leachate is hyperalkaline (pH > 12), which can be toxic to aquatic life. The concentrations of Al, Cl−, F−, Na, NO32−, and SO42− in the leachate exceed the recommended groundwater quality standard of China by up to 6637 times. These ions are likely to increase the salinization of the soil and groundwater. The minor elements in red mud leachate include As, B, Ba, Cr, Cu, Fe, Ni, Mn, Mo, Ti, V, and Zn, and the trace elements in red mud leachate include Ag, Be, Cd, Co, Hg, Li, Pb, Sb, Se, Sr, and Tl. Some of these elements have the concentration up to 272 times higher than those of the groundwater quality standard and are toxic to the environment and human health. Therefore, scientific guidance is needed for red mud management, especially for the design of the containment system of the facilities.

This paper aims to characterize the EQ (earthquake)-triggered landslides and to assess the EQ-triggered landslide susceptibility in moderate-minor earthquake prone areas at the southern margin of Sichuan Basin, China. 284 EQ-triggered landslides were inventoried from field-based investigation and dominated by rockfall, soil slide, and rock avalanche. Statistical analyses show that the volume of EQ-triggered landslides ranges from 20 to 1,510,000 m 3 with concentrations in the range of 20–10,000 m 3 , corresponding to 90% of the total amount of landslides. Among these EQ-triggered landslides, 38.4% occurred in the areas seriously affected by the mining in terms of causing factors and 89.8% occurred in the carbonate rock distribution areas lithologically. The geological conditions with widely developed karst and goaf amplified the influence of moderate-minor earthquakes. 14 key conditioning factors are selected to construct landslide susceptibility map by weighted information value method (E-IV), weighted certainty factor method (E-CF), and support vector machine (SVM) methods. The results show that the AUC values of E-IV, E-CF, and SVM are 0.867, 0.857, and 0.884, respectively, indicating three methods present good prediction accuracy, while the SVM has the highest accuracy. Landslides mostly clustered in the coal mining and carbonate rock area, which are widely affected by karstification (dissolution void or fissures) and goaf. Meanwhile, the very high landslide susceptibility areas are mainly distributed in the Gongchang Anticline tectonic area with 652 km 2 from the best SVM method. This study can provide insights into EQ-triggered landslides in frequent moderate-minor EQ-impacted regions.

This work addresses the integrated assessment of rockfall (including landslides) hazards and risk for S301, Z120, and Z128 highways, which are important transportation corridors to the world heritage site Jiuzhai Valley National Park in Sichuan, China. The highways are severely threatened by rockfalls or landslide events after the 2017 Ms 7.0 Jiuzhaigou earthquake. Field survey (September 14–18th, 2017, May 15–20th, 2018, and September 9–17th, 2018), unmanned aerial vehicle (UAV), and satellite image identified high-relief rockfalls and road construction rockfalls or landslides along the highway. Rockfall hazard is qualitatively evaluated using block count, velocity, and flying height through a 3D rockfall simulation at local and regional scales. Rockfall risk is quantitatively assessed with rockfall event probability, propagation probability, spatial probability, and vulnerability for different block volume classes. Approximately 21.5%, 20.5%, and 5.3% of the road mileage was found to be subject to an unacceptable (UA) risk class for vehicles along S301, Z120, and Z128 highways, respectively. Approximately 20.1% and 3.3% of the road mileage belong to the UA risk class for tourists along Z120 and Z128 highways, respectively. Results highlighted that high-relief rockfall events were intensively located at K50 to K55 (Guanmenzi to Ganheba) and K70 to K72 (Jiudaoguai to Shangsizhai Village) road mileages along S301 highway and KZ18 to KZ22 (Five Flower Lake to Arrow Bamboo Lake) road mileages, KZ30 (Swan Lake to Virgin Forests), and KY10.5 kilometers in Jiuzhai Valley. Rockfalls in these locations were classified under the UA risk class and medium to very high hazard index. Road construction rockfalls were located at K67 (Jiuzhai Paradise) and K75–K76 kilometers along S301 highway and KZ12 to KZ14 (Rhino Lake to Nuorilang Waterfall), KZ16.5 to KZ17.5 (Golden Bell Lake), KY5 (Lower Seasonal Lake), and KY14 (Upper Seasonal Lake) kilometers along Z120 and Z128 highway in Jiuzhai Valley. Rockfalls in these areas were within a reasonable practicable risk to UA risk class and very low to medium hazard index. Finally, defensive measures, including flexible nets, concrete walls, and artificial tunnels, could be selected appropriately on the basis of the rockfall hazard index and risk class. This study revealed the integration between qualitative rockfall hazard assessment and quantitative rockfall risk assessment, which is crucial in studying rockfall prevention and mitigation.

Numerical simulations are carried out to investigate the effect of cloud condensation nuclei（CCN） concentrations on microphysical processes and precipitation characteristics of hailstorms. Two hailstorm cases are simulated, a spring case and a summer case, in a semiarid region of northern China, with the Regional Atmospheric Modeling System. The results are used to investigate the differences and similarities of the CCN effects between spring and summer hailstorms. The similarities are：（1） The total hydrometeor mixing ratio decreases, while the total ice-phase mixing ratio enhances, with increasing CCN concentration;（2） Enhancement of the CCN concentration results in the production of a greater amount of small-sized hydrometeor particles, but a lessening of large-sized hydrometeor particles;（3） As the CCN concentration increases, the supercooled cloud water and rainwater make a lesser contribution to hail, while the ice-phase hydrometeors take on active roles in the growth of hail;（4） When the CCN concentration increases, the amount of total precipitation lessens,while the role played by liquid-phase rainfall in the amount of total precipitation reduces, relatively, compared to that of icephase precipitation. The differences between the two storms include：（1） An increase in the CCN concentration tends to reduce pristine ice mixing ratios in the spring case but enhance them in the summer case;（2） Ice-phase hydrometeor particles contribute more to hail growth in the spring case, while liquid water contributes more in the summer case;（3） An increase in the CCN concentration has different effects on surface hail precipitation in different seasons.

In order to study the effect of excess sludge ozonation, a continuous experiment in lab scale process was carried out. During the treatment process, a high level of ozone was produced by the electrolysis-type ozone generator, and various parameters, such as Soluble Chemical Oxygen Demand （SCOD）, Mixed Liquor Suspended Solids （MLSS）, Mixed Liquor Volatile Suspended Solids （MLVSS）, pH and so on, which char- acterize sludge were investigated. A substantial reduction in the volume of sludge and the release of intracellular materials were observed： SCOD proliferated as a consequence of extending the ozone feeding time; MLSS and MLVSS, especially the ratio of MLVSS to MLSS, dwindled as the action time rose. Through analyzing the effluent quality and excess sludge activity, the sludge-water volume mixture ratio of 1 ： 20 with 50 -60 minutes＇ oxidation treatment was found to be the optimal condition for ozonic disintegration of excess sludge. A remarkable sludge reduction rate of 57% could be achieved under the ozone feeding time of 40 minutes, which revealed the optimal action time.