青海湖湖滨土壤地表盐分总量及主要河流盐分含量的研究

通过对湖区主要河流和地表盐分总量的研究表明 :湖区盐分积聚主要受到干燥气候、太阳辐射而导致的水分的大量蒸发的影响。在强烈的水分蒸发作用下 ,水体表面盐分有所增高 ,且灌溉不当同样能引起土壤表层盐分的积聚 ,而发生次生盐溃化现象。可见对于湖区的农牧业生产来说 ,加强农田的科学管理、努力减少水分的蒸发 ,保护地表植被、选择适合的地表覆盖物、推广节水灌溉、废除漫灌。

Diagenetic evolution and its effect on reservoir-quality of fan delta sandstones during progressive burial: Evidence from the upper part of the fourth member of Shahejie formation, Bonan sag, Jiyang depression

Petrographic analysis combined with various techniques, such as thin section identification, fluid inclusions, isotopic data, petro-physical property testing and oil testing results, was used to study diagenetic evolution and its effect on reservoir-quality of fan delta reservoirs of Es4s in the Bonan sag. The diagenesis is principally characterized by strong compaction, undercompaction, multi-phase of dissolution and cementation. Compaction played a more important role than cementation in destroying the primary porosity of the sandstones. The reservoirs have experienced complicated diagenetic environment evolution of "weak alkalineacid-alkalinity-acid-weak alkalinity" and two-stage of hydrocarbon filling. The diagenetic sequences are summarized as "early compaction/early pyrite/gypsum/calcite/dolomite cementation→feldspar dissolution/the first stage of quartz overgrowth → early hydrocarbon filling→quartz dissolution/anhydrite/Fe-carbonate cementation→Fe-carbonate dissolution/feldspar dissolution/ the second stage of quartz overgrowth→later hydrocarbon filling→later pyrite cementation. In the same diagenetic context, the diagenetic evolution processes that occurred in different sub/micro-facies during progressive burial have resulted in heterogeneous reservoir properties and oiliness. The braided channel reservoirs in fan delta plain are poorly sorted with high matrix contents. The physical properties decrease continually due to the principally strong compaction and weak dissolution. The present properties of braided channel reservoirs are extremely poor, which is evidenced by few oil layers developed in relatively shallow strata while dry layers entirely in deep. The reservoirs both in the underwater distributary channels and mouth bars are well sorted and have a strong ability to resist compaction. Abundant pores are developed in medium-deep strata because of modifications by two-stage of acidic dissolution and hydrocarbon filling. The present properties are relatively well both in the underwater distributary channels and mouth bars and plenty of oil layers are developed in different burial depth. The present reservoir properties both in interdistributary channel and pre-fan delta are poor caused by extensively cementation. Small amounts of oil layers, oil-water layers and oil-bearing layers are developed in relatively shallow strata while dry layers totally in deep.

The influence of urbanization on karst rivers based on nutrient concentration and nitrate dual isotopes： an example from southwestern China

China is experiencing rapid urbanization that has changed the water quality of rivers, especially nutrient loads. In this study, a typical urban river located in a karst area, Chengguan River, was chosen to explore the influence of urbanization on river ecosystems based on nutrient concentration and nitrate isotopes. The results show monthly variability of water chemistry and nutrient concentration. Nutrient concentration in two tributaries and the mainstem showed significant spatial variability, with heavy N and P pollution in one tributary near a suburban area,indicating a response to different levels of urbanization.Measurements of nitrate dual isotopes suggest thatvolatilization, assimilation, nitrification, and denitrification all occur in the polluted river. Water chemistry and nitrate isotopes show that major nitrogen sources included domestic waste and agricultural input, such as chemical fertilizer and manure. The results suggest that urbanization increases nutrient concentrations and accelerates the riverine nitrogen dynamic, and point to the need to manage point sources of sewage effluents to improve the water quality of urban rivers in southwestern China.

Assessment of the Impact of Developmental Activities on the Estuarine Environments of Mandovi and Zuari Rivers of Goa along the West Coast of India

Physico-chemical and biological data on water and sediments were collected from Mandovi and Zuari Rivers of Goa along the central west coast of India from 2007 to 2008 to understand the impact of developmental activities on the riverine environments. Factor analysis of the data segregated over high and low tides indicated a total of 6 factors each explaining 91% of variance during high tide and 84% of variance during low tide in Mandovi River. In Zuari River, a total of 6 factors explained 83% of variance during high tide and 4 factors explained 78% of variance during low tide. Factor analyses showed the dominance of nitrite and nitrate in Mandovi and of lead and mercury in Zuari. Higher inputs of anthropogenic ammonia and phenols associated with some phosphate were found in both these rivers. Water quality index （WQI） studies showed increasing overall index of pollution （OIP） values especially in the upstream of Zuari River, suggesting slightly polluted water. Increasing developmental activities along the banks of these rivers introduce domestic and anthropogenic nutrients and trace metals in their estuarine region, which flush out to the sea as per tidal currents, which otherwise can hamper the natural environments of these two rivers.