With the aim of alleviating the problems of air pollution, soil desertification, and food shortage in China, the effect of amelioration of salt-affected soil using the by-products of flue gas desulfurization and coal bio-briquette have been studied in Liaoning, Ningxia, and Xinjiang Provinces, as well as Tianjin city in China. Concretely, the changes in soil properties, agricultural production, and safety as a soil amendment have been researched. As a result, soil pH and ESP (exchangeable sodium percentage) decreased and agricultural production increased in all the treated plots. Moreover, the contents of almost all metals (B, Cr, Mn, Ni, Cu, As, Cd, Pb, Se, Hg) in agricultural products were lower than the standard values for human intake and tolerance limit in food. In order to spread this effective technology, an evaluation model for assessing the environmental and economic effects and impact on the health has been developed. As a result, a decrease in SO₂ emissions in provinces and cities and an increase in the area of reclaimed salt-affected soil and agricultural products, as well as decrease in the number of patients could be confirmed. In addition, a reduction in CO₂ emissions in some cases, such as afforestation, biomass utilization, and introduction of energy crops, are examined.

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In the 1960s, the Aral Sea, situated at the lowest reaches of its two main inflows, had a surface area of 68,000 km², a maximum waterlevel of 53.41 m above sea level, a volume of 1,090 km³, and salinity of 10 g L^－1. For the 300 to 400 years before 1960, it was one of the largest lakes in the world. Its influents are Syr Darya, which runs into the Aral Sea from the east, and Amu Darya, which flows from the south. The sea has been continuously shrinking since, the 1960s, and in 1989 it had a surface area of only 37,330 km², a water-level of 39,80 m above sea level, and a volume of 320 km³; and had undergone a sharp salinity increase to 29.60 g L^－1. The total volume of water inflow has decreased over the past 50 years, caused by human activities. In recent years, the Aral Sea has separated into two lakes that connect near the mouth of Syr Darya by a small and shallow channel. These lakes are the Small Aral Sea and the Large Aral Sea. Amu Darya stopped flowing into the Large Aral Sea in 1980. The reduction of the sea had several impacts: fish production ceased, crop production deepened, and salinization of the soil and pollution of drinking water occurred. These impacts as a whole have been generally referred to as the ‘Aral Sea Crisis’.

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Salt stress is manifested primarily as osmotic stress, resulting in the disruption of homeostasis and ion distribution in the cell. Plants resist to salt stress by maintaining their ion homeostasis, accumulating compatible solutes, eliminating the excess salt through salt glands, etc. Resistance to salt stress secondarily causes oxidative stress, and the activity of antioxidant enzymes has a close relationship to salt tolerance. A countermeasure for reconstruction of salt-injured farmland includes the elimination of surface soil, conversion between surface and interlayer soil, saline draining by watering, application of ion-exchange materials, and lime materials. Calcium application to soil is effective in increasing plant salt tolerance; while the amount and timing of application are important for an increased ability to tolerate salt stress. The present review summarized salt-tolerance mechanisms in plants, the recent advances in elucidating stress-response and the possibility of salt removal from salt-damaged soil with the use of plants.

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Chitosan is a polymer which consists of D-glucosamine with β- (1,4) bond, and is generally produced by deacetylation of chitin. Chitin is a main component of the outer shell of shrimp and crab, which are typical waste marine resources. We have paid attention to the effective utilization of such waste marine resources. In this study, a chitosan derivative of the sulfonic acid group was synthesized. Using the chitosan derivative, the adsorption characteristics of metal ions such as precious and transition metals was studied. The precious metals used were Pt and Pd, and the transition metals were Ni, Cu, and Zn. Chitosan was modified chemically with propane sultone, and the product was further crosslinked with ethylene glycol diglycidyl ether. This resin is called PSC. Using PSC, adsorption of the metals was carried out by means of a batch method. From the metal adsorption experiment, it was found that PSC was a superior resin for transition metals to CLC, which is a crosslinked native chitosan resin. On the other hand, PSC was inferior for adsorbing precious metals to CLC. And PSC selectively adsorbed Cu and Pd in a metal coexistence system. The adsorption behavior was explained well by the Langmuir adsorption isotherm.

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