One of the water source areas of the South-to-North Water Diversion Project is the Danjiangkou Reservoir （DJKR）. To understand seasonal variation in phytoplankton composition, abundance and distribution in the DJKR ...One of the water source areas of the South-to-North Water Diversion Project is the Danjiangkou Reservoir （DJKR）. To understand seasonal variation in phytoplankton composition, abundance and distribution in the DJKR area before water diversion, as well as to estimate potential risks of water quality after water diversion, we conducted an investigation on phytoplankton in the DJKR from August 2008 to May 2009. The investigation included 10 sampling sites, each with four depths of 0.5, 5, 10, and 20 m. In this study, 117 taxa belonging to 76 genera were identified, consisting of diatoms （39 taxa）, green algae （47 taxa）, blue-green algae （19 taxa）, and others （12 taxa）. Annual average phytoplankton abundance was 2.01×10^6 ind./L, and the highest value was 14.72 ×10^6 ind/L （at site 3 in August 2008）. Phytoplankton abundance in front of the Danjiangkou Dam （DJKD） was higher than that of the Danjiang Reservoir Basin. Phytoplankton distribution showed a vertical declining trend from 0.5 m to 20 m at most sites in August 2008 （especially at sites of 1, 2, 4 and 10）, but no distinct pattern in other sampling months. In December 2008 and March 2009, Stephanodiseus sp. was the most abundant species, amounting to 55.23% and 72.34%, respectively. We propose that high abundance ofStephanodiscus sp. may have contributed greatly to the frequent occurrence of Stephanodiscus sp. blooms in middle-low reaches of the Hanjiang River during the early spring of 2009. In comparison with previous studies conducted from 1992 to 2006, annual average phytoplankton density, green algae and blue-green algae species, as well as major nutrient concentrations increased, while phytoplankton diversity indices declined. This indicates a gradual decline in water quality. More research should be conducted and countermeasures taken to prevent further deterioration of water quality in the DJKR.展开更多
This article offers a brief description of the water resources situation of the Kingdom of Thailand, a country with a population of over 65 million people and a surface area of 513,120 km^2. The average annual rainfal...This article offers a brief description of the water resources situation of the Kingdom of Thailand, a country with a population of over 65 million people and a surface area of 513,120 km^2. The average annual rainfall is 1,430 mm and the total water resources are estimated at 215,000 Mm^3 （million of m^3）-year^-1. The hydric demand in the country is 70,000 Mm^3.year^-1, 6% of which is groundwater in origin. Over 70% of the water is used for agriculture. Thailand is the world＇s leading exporter of rice. The main problems faced by the Water Authority in Thailand are pollution, floods and droughts, depending on the geographical zone. From the hydrogeological point of view, the Central Plain is the main groundwater reservoir in the nation. Intensive extraction of groundwater over a long period of time has caused three main problems： a decline in groundwater levels, land subsidence, and seawater intrusion. These problems have been especially pressing in the area known as Greater Bangkok.展开更多
基金Supported by the National Basic Research Program of China (973 Program) (No. 2008CB418006)the Knowledge Innovation Program of Chinese Academy of Sciences (No. KZCX-YW-14-1)
文摘One of the water source areas of the South-to-North Water Diversion Project is the Danjiangkou Reservoir （DJKR）. To understand seasonal variation in phytoplankton composition, abundance and distribution in the DJKR area before water diversion, as well as to estimate potential risks of water quality after water diversion, we conducted an investigation on phytoplankton in the DJKR from August 2008 to May 2009. The investigation included 10 sampling sites, each with four depths of 0.5, 5, 10, and 20 m. In this study, 117 taxa belonging to 76 genera were identified, consisting of diatoms （39 taxa）, green algae （47 taxa）, blue-green algae （19 taxa）, and others （12 taxa）. Annual average phytoplankton abundance was 2.01×10^6 ind./L, and the highest value was 14.72 ×10^6 ind/L （at site 3 in August 2008）. Phytoplankton abundance in front of the Danjiangkou Dam （DJKD） was higher than that of the Danjiang Reservoir Basin. Phytoplankton distribution showed a vertical declining trend from 0.5 m to 20 m at most sites in August 2008 （especially at sites of 1, 2, 4 and 10）, but no distinct pattern in other sampling months. In December 2008 and March 2009, Stephanodiseus sp. was the most abundant species, amounting to 55.23% and 72.34%, respectively. We propose that high abundance ofStephanodiscus sp. may have contributed greatly to the frequent occurrence of Stephanodiscus sp. blooms in middle-low reaches of the Hanjiang River during the early spring of 2009. In comparison with previous studies conducted from 1992 to 2006, annual average phytoplankton density, green algae and blue-green algae species, as well as major nutrient concentrations increased, while phytoplankton diversity indices declined. This indicates a gradual decline in water quality. More research should be conducted and countermeasures taken to prevent further deterioration of water quality in the DJKR.
文摘This article offers a brief description of the water resources situation of the Kingdom of Thailand, a country with a population of over 65 million people and a surface area of 513,120 km^2. The average annual rainfall is 1,430 mm and the total water resources are estimated at 215,000 Mm^3 （million of m^3）-year^-1. The hydric demand in the country is 70,000 Mm^3.year^-1, 6% of which is groundwater in origin. Over 70% of the water is used for agriculture. Thailand is the world＇s leading exporter of rice. The main problems faced by the Water Authority in Thailand are pollution, floods and droughts, depending on the geographical zone. From the hydrogeological point of view, the Central Plain is the main groundwater reservoir in the nation. Intensive extraction of groundwater over a long period of time has caused three main problems： a decline in groundwater levels, land subsidence, and seawater intrusion. These problems have been especially pressing in the area known as Greater Bangkok.
