Discussion on the Scenario of Salt Accumulation in Yarkand Basin during Late Cretaceous

Large-scale accumulation of salt and formation of potash concentrated in Tethys domain during late Mesozoic to early Cenozoic.These events were typified by the formation of Laos-Thailand and Lanping-Simao

Effect of Irrigation with Saline Water on Soil Water-Salt Dynamics and Maize yield in Arid Northwest China

An experiment was conducted in non-weighing lysimeters to study the effect of irrigation with saline water on water movement and salt accumulation and maize yield. The experiment was carried out in northwest China,both sufficient and insufficient irrigation were applied in the first year,and only sufficient treatments in the second year. Irrigation with solute concentration of 9 g·L-1 and 6 g·L-1 led to salt accumulation about 6-8 dS·m-1 in certain depths,even downwards to 160 cm received about 4 dS·m-1 for 9 g·L-1 and 2 dS·m-1 for 6 g·L-1,which was two times more than initial. Salt-affected water extracted from soil behaved as low evapotranspiration under sufficient irrigation,and more water was left in the soil. Yield of spring maize was not affected when saturated soil paste electrical conductivity did not exceeded 1.2 dS·m-1.

Assessment of major ions and heavy metals in groundwater： a case study from Guangzhou and Zhuhai of the Pearl River Delta, China

Anthropogenic activities in the Pearl River Delta （PRD） have caused a deterioration of groundwater quality over the past twenty years as a result of rapid urbanization and industrial development. In this study, the hydrochemical characteristics, quality, and sources of heavy metals in the groundwater of the PRD were investigated. Twenty-five groundwater samples were collected and analyzed for pH, electrical conductivity （EC）, total dissolved solids （TDS）, δ18O,δ~2H, major ions, and heavy metals. The groundwater was slightly acidic and presented TDS values that ranged from 35.5 to 8,779.3 mg.L-1. The concentrations of the major ions followed the order Cl- 〉 HCO3-〉 Na＋ 〉 SO24- 〉 NO3 〉 NH4＋ 〉 Ca2＋ 〉 K＋ 〉 Mg2＋ 〉 Fe2＋/3＋ 〉 Al3＋. Ca-Mg- HCO3 and Na-K-HCO3 were the predominant types of facies, and the chemical composition of the groundwater was primarily controlled by chemical weathering of the basement rocks, by mixing of freshwater and seawater and by anthropogenic activities. The heavy metal pollution index （HPI） indicated that 64% of the samples were in the low category, 16% were in the medium category and 20% were in the high category, providing further evidence that this groundwater is unsuitable for drinking. Lead, arsenic, and manganese were mainly sourced from landfill leachate; cadmium from landfill leachate and agricultural wastes; mercury from the discharge of leaehate associated with mining activities and agricultural wastes; and chromium primarily from industrial wastes. According to the irrigation water quality indicators, the groundwater in the PRD can be used for irrigation in most farmland without strong negative impacts. However, approximately9 million people in the Guangdong Province are at risk due to the consumption of untreated water. Therefore, we suggest that treating the groundwater to achieve safer levels is necessary.