In China and East Asia,the long-term continuous observational data at daily resolution are insufficient,and thus there is a lack of good understanding of the extreme climate variation over the last 100 years plus.In t...In China and East Asia,the long-term continuous observational data at daily resolution are insufficient,and thus there is a lack of good understanding of the extreme climate variation over the last 100 years plus.In this study,the extreme temperature indices defined by ETCCDI(Expert Team on Climate Change Detection and Indices)and local meteorological administrations were analyzed for Changchun City,Northeast China,by using the daily maximum temperature(Tmax)and daily minimum temperature(Tmin)over 1909?2018.The results showed that extreme cold events,such as cold days,cold nights,frost days,icing days,and low temperature days,decreased significantly at rates of?0.41 d(10 yr)^?1,?1.45 d(10 yr)^?1,?2.28 d(10 yr)^?1,?1.16 d(10 yr)?1 and?1.90 d(10 yr)^?1,respectively.Warm nights increased significantly at a rate of 1.71 d(10 yr)^?1,but warm days decreased slightly and the number of high temperature days decreased at a rate of?0.20 d(10 yr)?1.The frequency of cold surge events increased significantly at a rate of 0.25 d(10 yr)^?1,occurring mainly from the mid-1950s to late-1980s.The average Tmax,average Tmin and extreme Tmin increased at rates of 0.09℃(10 yr)^?1,0.36℃(10 yr)^?1 and 0.54℃(10 yr)^?1,respectively;and extreme Tmax decreased significantly at a rate of?0.17℃(10 yr)^?1.In 1909?2018,1951?2018 and 1979?2018,the indices related to cold events decreased,while the trends of the indices related to warm events were different for different periods.展开更多
The metamorphic conditions of the Upper Permian Yangjiagou Formation in eastern Changchun, China, were evaluated based on the mineral assemblage, illite crystallinity, illite polytypism,the b dimension of illite, and ...The metamorphic conditions of the Upper Permian Yangjiagou Formation in eastern Changchun, China, were evaluated based on the mineral assemblage, illite crystallinity, illite polytypism,the b dimension of illite, and the chemical composition of chlorite. The pelitic rocks in the Yangjiagou Formation are characterized by illite + kaolinite + chlorite ± mixed-layer chlorite/smectite and detrital quartz + plagioclase. Illite in the formation has a crystallinity of 0.38-0.55 and comprises mixed 2 Mand1 Mpolytypes, indicating a metamorphic temperature of >200℃. Based on the chemical composition of chlorite and the chlorite geothermometer, we estimated diagenetic to very low-grade metamorphic conditions with temperatures of 185℃～204℃. The b dimension of illite varies from 8.992 A to 9.005 A.We used a mathematical algorithm to extend Guidotti and Sassi’s(1986) diagram relating illite b dimension with temperature and pressure, and used this diagram, together with illite crystallinity and chlorite chemical composition, to semi-quantitatively estimate the formation pressure at<1.2 kbar. These reveal that the Yangjiagou Formation has experienced very low-grade metamorphism.展开更多
A databank designed for wetland studies has been established and put into operation by scientists at the Changchun Institute of Geography, CAS, as a result of many years of hard work.……
Pb in the farmland surface soil of Changchun suburb was taken as the main research object. The field research and laboratory analysis were used to investigate Pb content, spatial distribution characteristics and its e...Pb in the farmland surface soil of Changchun suburb was taken as the main research object. The field research and laboratory analysis were used to investigate Pb content, spatial distribution characteristics and its ecological risk in different farmland soils. The results showed that Pb content was during 18.85 - 41.34 mg/kg in farmland soil of Changchun suburb, and was higher than the background value of Jilin Province at 90% of the sampling sites. The spatial distribution of Pb content in farmland soil had obvious geographical features, and Pb content in southwest and northeast soils was higher. The high-content areas were relatively concentrated, and Pb content gradually reduced from the high-content island- shape center to its surrounding. The soil Pb contents in paddy field, dry field and vegetable field had insignificant difference with the background value, indicating that Pb accumulations in dry field, paddy field and vegetable field were not significant. The order of Pb content in different land use types was showed as follows： vegetable field 〉 dry field 〉 paddy field. Pb pollution of all samples belonged to light pollution. The average potential ecological risk of soil Pb in different land use types presented the following order： vegetable field 〉 dry field 〉 paddy field.展开更多
基金the National Key R&D Program of China(Grant No.2018YFA0605603).
文摘In China and East Asia,the long-term continuous observational data at daily resolution are insufficient,and thus there is a lack of good understanding of the extreme climate variation over the last 100 years plus.In this study,the extreme temperature indices defined by ETCCDI(Expert Team on Climate Change Detection and Indices)and local meteorological administrations were analyzed for Changchun City,Northeast China,by using the daily maximum temperature(Tmax)and daily minimum temperature(Tmin)over 1909?2018.The results showed that extreme cold events,such as cold days,cold nights,frost days,icing days,and low temperature days,decreased significantly at rates of?0.41 d(10 yr)^?1,?1.45 d(10 yr)^?1,?2.28 d(10 yr)^?1,?1.16 d(10 yr)?1 and?1.90 d(10 yr)^?1,respectively.Warm nights increased significantly at a rate of 1.71 d(10 yr)^?1,but warm days decreased slightly and the number of high temperature days decreased at a rate of?0.20 d(10 yr)?1.The frequency of cold surge events increased significantly at a rate of 0.25 d(10 yr)^?1,occurring mainly from the mid-1950s to late-1980s.The average Tmax,average Tmin and extreme Tmin increased at rates of 0.09℃(10 yr)^?1,0.36℃(10 yr)^?1 and 0.54℃(10 yr)^?1,respectively;and extreme Tmax decreased significantly at a rate of?0.17℃(10 yr)^?1.In 1909?2018,1951?2018 and 1979?2018,the indices related to cold events decreased,while the trends of the indices related to warm events were different for different periods.
基金funded by the Natural Science Foundation of China (Grants 41172039,41372042)
文摘The metamorphic conditions of the Upper Permian Yangjiagou Formation in eastern Changchun, China, were evaluated based on the mineral assemblage, illite crystallinity, illite polytypism,the b dimension of illite, and the chemical composition of chlorite. The pelitic rocks in the Yangjiagou Formation are characterized by illite + kaolinite + chlorite ± mixed-layer chlorite/smectite and detrital quartz + plagioclase. Illite in the formation has a crystallinity of 0.38-0.55 and comprises mixed 2 Mand1 Mpolytypes, indicating a metamorphic temperature of >200℃. Based on the chemical composition of chlorite and the chlorite geothermometer, we estimated diagenetic to very low-grade metamorphic conditions with temperatures of 185℃～204℃. The b dimension of illite varies from 8.992 A to 9.005 A.We used a mathematical algorithm to extend Guidotti and Sassi’s(1986) diagram relating illite b dimension with temperature and pressure, and used this diagram, together with illite crystallinity and chlorite chemical composition, to semi-quantitatively estimate the formation pressure at<1.2 kbar. These reveal that the Yangjiagou Formation has experienced very low-grade metamorphism.
文摘 A databank designed for wetland studies has been established and put into operation by scientists at the Changchun Institute of Geography, CAS, as a result of many years of hard work.……
基金Supported by Science Technology Development Plan Item in Jilin,China(20110403)Key Item of Water Pollution Control and Treatment,China(2012ZX07201-001)
文摘Pb in the farmland surface soil of Changchun suburb was taken as the main research object. The field research and laboratory analysis were used to investigate Pb content, spatial distribution characteristics and its ecological risk in different farmland soils. The results showed that Pb content was during 18.85 - 41.34 mg/kg in farmland soil of Changchun suburb, and was higher than the background value of Jilin Province at 90% of the sampling sites. The spatial distribution of Pb content in farmland soil had obvious geographical features, and Pb content in southwest and northeast soils was higher. The high-content areas were relatively concentrated, and Pb content gradually reduced from the high-content island- shape center to its surrounding. The soil Pb contents in paddy field, dry field and vegetable field had insignificant difference with the background value, indicating that Pb accumulations in dry field, paddy field and vegetable field were not significant. The order of Pb content in different land use types was showed as follows： vegetable field 〉 dry field 〉 paddy field. Pb pollution of all samples belonged to light pollution. The average potential ecological risk of soil Pb in different land use types presented the following order： vegetable field 〉 dry field 〉 paddy field.
