Although the Chinese people have, through continuous efforts, built the constantly improving Yellow River flood control system, and created a miracle which has been tranquil for over 50 years, the tendency for the downstream watercourse of the Yellow River to uplift every year has not been fundamentally curbed, and the aboveground river is still the “scourge” of the sons and daughters of the Yellow River. By the use of a variety of modern investigation and survey methods, the geological environment characteristics of the downstream of the Yellow River have been identified basically, including the environmental and geological factors affecting the stability of aboveground rivercourse of the lower Yellow River such as the active fracture of the lower Yellow River, crustal uplift, land subsidence, seismic activity, geological conditions of dike foundation engineering, hydrodynamic conditions of rivers, and geomorphology of watercourses. After a comprehensive analysis of the inability mode of aboveground river on the downstream of the Yellow River and its corresponding impact factors, by using the fuzzy comprehensive evaluation method, we have evaluated the crustal stability of the aboveground river, dike foundation stability, watercourse landform stability and overall stability. The results of comprehensive results show that the stability of downstream aboveground rivercourse of the Yellow River can be divided into four grades and 11 sections, i e. “basically stable, unstable, very unstable and extremely unstable”. On the basis of the stability segmentation, we consider the influence of integrally the future structural faults, earthquakes, the difference of watercourse between forward and backward heights of dikes, river regime and river type, historical crevasses, foundation soil liquefaction and seepage deformation, and find out 17 most unstable danger points. Finally, from 17 danger points, we select 7 danger points which are most prone to instability including Wuzhi, Zhongmou, Kaifeng, Fengqiu, Dongming, Changyuan and Dong’e. The calculation and analysis of the range and area inundated by 7 danger points, area, and number of people threatened, possible economic loss, and environmental damage, the inability caused by any one of 7 points could bring disastrous consequences to the downstream.

The chemical weathering can consume atmosphere/soil CO₂. Human activities such as pollution, fertilization and acid precipitation have exerted a large impact on CO₂ intake by carbonate weathering. Thus, based on the analysis on chemical component change of the karst groundwater in the karst ridge watershed of Conglin Village, Fuling District of Chongqing City, the influence of human activities such as fertilization, sewage discharges from mustard tuber processing, breeding industry and acid rain precipitation on carbonate weathering and CO₂ intake in 1980, 2003 and 2006 was studied. The results showed that CO₂ intake by carbonate rock declined with year. Because H⁺ derived from acid sewage discharge, fertilization and acid precipitation reacted with carbonate rock when mustard tuber production and swine breeding were developed fleetly after 2000 as well as the burning amount of high-sulfur coal augmented persistently, which led to the increase of (Ca²⁺+Mg²⁺)/HCO₃^-. The difference on charge between Ca²⁺+Mg²⁺ and HCO₃^- was balanced by NO₃^-+SO₄^2-. The control on pollution and acid rain, especially the pre-neutralization of acid waste water, would rejuvenate the atmospheric CO₂ intake strength of carbonate weathering besides the protection of water and soil environment.

Adsorption behavior of Cr (Ⅵ) in vadose zone, which is silty clay and clayey soil, was studied through kinetics experiments, isothermal adsorption experiments under various conditions, including different ph, temperature and organic contents. The results from kinetics experiments showed that the sorption progress of Cr (Ⅵ) has clear features in different stages, and adsorption equilibrium showed at 30 min, the adsorption rate of silty clay and clayey soil were 60%. The isothermal adsorption curve of Cr (Ⅵ) fitted closely with Freundlich equation model. When pH is 3-5 a plateau were seen, thereafter with increase in pH the adsorption rate of Cr (Ⅵ) dropped sharply and the minimum achieved at pH 10, the adsorption rate were only 35%. Adsorption rate of Cr (Ⅵ) increased gradually with the increase of temperature, the temperature of vadose zone is 14.7 ℃, according to the experimental results, the adsorption rate of Cr (Ⅵ) is about 40%. The use of organics represents an important contribution to the sorption of Cr (Ⅵ), sorption rate up to 100% when 30% of organic content. These studies will provide basis for manager to minimize the impacts, and provide basic data for pollution prevention and remediation of vadose zone.

A much improved understanding of how farmyard manure application may affect carbonate rock dissolution is needed in order to predict possible feedbacks between the rock carbon cycle and the global climate system. Two carbonate mineral rock tablets; dolomite and limestone were buried at six depths between 0 and 110 cm in a soil typical of the subtropical karst area in Guiyang City, Guizhou Province. The extent of tablet dissolution, soil CO₂, soil pH, soil water content, soil mineral and chemical composition, and chemical composition of soil water were tested in order to assess the degree of dissolution under manure application over the course of one year. The results show that manure addition decreases the dissolution rate of carbonate rocks; limestone and dolomite by between 11.7%-116.9% and 25.0%-65.69% respectively, with the dissolution rate of limestone consistently exceeding that of dolomite under the same conditions. Our data indicates that the rate of pedogenesis of the dolomite and limestone rocks is decreased as much as 35.77% and 59.41% respectively, as a result of manure application. Moreover, the results suggest that manure application accelerated the generation of soil CO₂, with soil CO₂ concentration increasing on average by 93.94%, and the CO₂ flux increasing by 67.64% compared with the control profile. Finally, the data also indicates that manure decreases CO₂ uptake by dissolution of carbonate rocks by 25.50%-39.45% on a Guiyang city scale. The counteraction of the CO₂ sink contributed by karst water due to farmyard manure utilization in general karst area (both dolomite and limestone) however was 59.41%-62.72%, indicating the application of manure successfully reduces both dissolution and CO₂ release to the atmosphere.