Table of Content

25 September 2008, Volume 63 Issue 9 Previous Issue    Next Issue

Anomalous Winter Temperature and Precipitation Events in Southern China ZHANG Ziyin, GONG Daoyi, GUO Dong, HE Xuezhao, LEI Yangna 2008, 63 (9):  899-912.  doi: 10.11821/xb200809001 Abstract ( )   PDF (3192KB) ( )   Save This paper analyzed the anomalous low-temperature events, and the anomalous rain-abundant events over southern China for Januaries since 1951 and for winters since 1880, there anomalous events are defined using ±1σ thresholds. And 12 cold temperature Januaries are identified where temperature anomaly is below - 1σ, and 10 wet Januaries are identified where precipitation anomaly is above +1σ.Among these events there are 3 cold-wet Januaries, namely 1969, 1993 and 2008. Using NCEP/NCAR reanalysis data, the authors checked the atmospheric circulation changes in association with the anomalous temperature and precipitation events. The results show that the strong Siberian high (SBH), East Asian Trough (EAT) and East Asian Jet Stream (EAJS) are favorable conditions for low temperature in southern China. While the anomalous south-wind at 850 hPa, the weak EAT at 500 hPa, and the strong Middle East Jet Stream (MEJS) and the weaker EAJS are found to accompany a wetter southern China. The cold-wet winters in southern China, such as January of 2008, are mainly related to a stronger Siberian High, and at the same time the circulation anomalous in middle to upper troposphere is precipitation-favorable. In wet winters, the water vapor below 500 hPa are mainly transported by the anomalous southwesterly flow and the anomalous southern flow over the Indo-China Peninsula and the South China Sea area. The correlation coefficients of MEJS, EAMW (East Asian Meridional Wind), EU (Eurasian pattern) to southern China precipitation in January are +0.65, - 0.59 and - 0.48 respectively, and the correlation for the high-pass filtered data are +0.63, - 0.55 and - 0.44, respectively, their correlations are all significant at the 99% level. MEJS, EAMW and EU together can explain 49.4% of the variance in January precipitation. Explained variance for January and winter temperature by Siberian High, EU, WP (Western Pacific pattern) and AO (Arctic Oscillation) are 47.2% and 51.5%, respectively. There are more precipitation in southern China during El Nino winters, and less precipitation during La Nina winters. And there is no clear evidence that occurrences of anomalous temperature events in winter in southern China are closely linked with ENSO events. References | Related Articles | Metrics

Impact of Spatio- temporal Variation of Precipitation on Severe Acid Rain in Southern China XIE Zhiqing1, DU Yin2, ZENG Yan1, 3, LI Yachun1, WU Jingang1, JIAO Shengming1 2008, 63 (9):  913-923.  doi: 10.11821/xb200809002 Abstract ( )   PDF (2553KB) ( )   Save In this paper, we present the effects of regional precipitation trend change on the frequency, area and intensity of severe acid rain over southern China, where the significant abrupt change in seasonal precipitation has occurred since the 1990s, and based on SO2 and NO2 slant column data retrieved from both SCIAMACHY and GOME, the spatio-temporal distribution characteristics of SO2 and NO2 density are analyzed, too. The results indicate: (1) The emission levels of SO2 and NO2 have reached or passed precipitation scavenging capacity in parts of southern China due to SO2 and NOx total emission amount durative increasing from 1993 to 2004, especially in the region south of the middle and lower Yangtze River. (2) The changes of the severe acid rain city proportion mainly occurred in the region with severe acid rain south of the Yangtze River during 1993 to 2004. With the occurrence of abrupt change in 1999, the severe acid rain mainly moved westwards from 1993 to 1999, and moved eastwards due to the proportion increased in the region with severe acid rain south of the Yangtze River during 2000 to 2004. (3) It is found that the spatial distribution and variation of seasonal precipitation change rate over 10 mm/10a are in a good agreement with those of severe acid over southern China. There occurred a same abrupt period in 1999 for the variation of severe acid rain city proportion and the variation of seasonal precipitation in winter and summer over southern severe acid rain. References | Related Articles | Metrics

Climatic Characteristics of Rainfall and Rainy Days during the Last 35 Year s over the Qinghai- Xizang Plateau GE Sang, TANG Xiaoping, LU Hongya 2008, 63 (9):  924-930.  doi: 10.11821/xb200809003 Abstract ( )   PDF (2134KB) ( )   Save By using the daily rainy days and rainfall data of 49 stations in 1971-2005 over the Qinghai-Xizang Plateau, the trends of the annual and seasonal rainfall and rainy days are analyzed. The result shows that the trend of the annual rainfall and rainy days increases remarkably in most parts of Tibet, but the trend decreases in most parts of Qinghai. The rainy days are decreasing and the rainfall is increasing in summer half year over the Qinghai-Xizang Plateau, which indicates that the rainfall is centralizing more and more and the rainy intensity has increased. In winter half year, the rainy days and rainfall increase. In summer half year, the spit (0.1-4.9 mm) rainy days decrease, but the rainfall increases. And the rainy days and rainfall of spit and moderate rain (5.0-9.9 mm) increase, the rainy days and rainfall of heavy rain decrease. In winter half year, the rainy days and rainfall of light snow, moderate snow and heavy snow have an increasing trend, while the trend of storm is not obvious. References | Related Articles | Metrics

Ostracodes Assemblages and Their Environmental Significance from Lake Core of Nam Co, Tibetan Plateau XIE Manping1, 2, ZHU Liping1, PENG Ping1, 2, ZHEN Xiaolin1, 2,WANG Yong1, 2, JU Jianting2, 3, A. CHWALB4 2008, 63 (9):  931-944.  doi: 10.11821/xb200809004 Abstract ( )   PDF (3194KB) ( )   Save A 332-cm long lacustrine core was drilled in the middle south of Tibentan Plateau. From the core, 15 species of ostracodes belonging to 6 genera have been identified. According to the changes of the ostracodes assemblage and the ostracodes ecological characters, which are sensitive to the changed of environment, three stages can be distinguished as follows: The early stage was from 8400 to 6800 aBP, during which the temperature descended in fluctuation which matched with the unstable cooling event of earlier Holocene, the climate was cold-humid, and the lake depth changed from shallow to deep. The middle stage was from 6400 to 2500 aBP, during which the climate changed from warm-humid to cold-humid and then became cold-dry, and the lake depth was becoming deep step by step. Weather pattern shifting during this period, from wet-cold to dry-cold, had been modifying and finally built up modern environments in Nam Co. The late stage (2500 aBP- present) showed a trait of lake depth increasing. At the earlier time of this stage, the climate was still cold-dry, which had the same trend of the end of the middle stage, however, the salinity of the lake increased; at the later time of this stage, the climate showed a general tendency toward cold-dry, as well as the hydrological condition of surface flowing water became faint. The concurrence of black shells percentage and the biggest ostracodes content, as well as the increasing of sedimentary hydrodynamic condition, indicated a post-mortem reworking. The abundance of Candona juvenile shells reflected juvenile mortality as a result of the rapid onset of unfavorable conditions such as catastrophic hydrological condition change. References | Related Articles | Metrics

Modern Pollen Assemblages of the Forest Communities and Their Relationships with Vegetation and Climate in Northern China LI Yuecong1, XU Qinghai1, 2, WANG Xueli1, CAO Xianyong1, YANG Xiaolan3 2008, 63 (9):  945-957.  doi: 10.11821/xb200809005 Abstract ( )   PDF (2942KB) ( )   Save In this paper, 53 pollen traps and surface samples were collected in order to detect the characteristics of pollen assemblages and their relationships with vegetation and climate in 16 forest communities located in 10 mountains in northern China. The results show that 72% of the pollen taxa (80 taxa) are the same between the traps and the surface samples. The dominant taxa in the plant communities are consistent with the main pollen taxa in the pollen assemblages at the same sites. In Pinus plant communities, both Pinus pollen influxes and concentrations are higher, indicating its higher pollen product and good pollen preservation ability. In Picea or Abies plant communities, Picea or Abies have lower pollen influx but high concentrations, suggesting their low pollen productivities but good pollen preservation abilities. In Betula or Quercus plant communities, Betula or Quercus have higher pollen influx but low concentrations, revealing their high pollen productivities but poor pollen preservation abilities. The study of the relationships between pollen and vegetation with discriminant analysis shows that pollen assemblages from both trap and surface samples can reflect the characters of different communities and distinguish different ecological areas, but the surface samples reflect the dominant components of communities much better than the traps. The study on the correlations between pollen assemblages and climate with DCCA reveals that significant correlations exist between pollen assemblages and mean temperature of the coldest month (R = 0.84 for trap samples, R = 0.72 for surface samples), and annual mean precipitation as well (R = 0.73 for trap samples, R = 0.71 for surface samples). References | Related Articles | Metrics

Impacts of Engineering Measures for Water Conservancy on Annual Runoff in the Chaohe River Basin Based on an Empirical Statistical Model LI Zijun1, LI Xiubin2 2008, 63 (9):  958-968.  doi: 10.11821/xb200809006 Abstract ( )   PDF (2841KB) ( )   Save Time series contrasting method is used to analyze the variation of precipitation, runoff, water consumption, water conservancy projects and soil and water conservation measures of the Chaohe River Basin from 1961 to 2005. The results show: (1) The annual precipitation in the drainage basin tends to decrease while the runoff has declined markedly since the 1960s, the mean annual runoff during 1991-2000 is only 90.9% in proportion to that of the period from 1961 to 1970. (2) The annual runoff variation in the drainage basin is significantly related to human activities such as soil and water conservation and hydraulic projects. The influence degree of engineering measures for water conservancy on runoff reduction is calculated by using the rainfall-runoff statistical model. The results show that during 1981-1990, 1991-2000, 2001-2005 and 1981-2005, the average annual runoff reduction amounts are 1.15 ×108, 0.28 ×108, 1.10 ×108 and 0.79 ×108 m3 respectively and the average annual runoff-reducing effects are 31.99% , 7.13% , 40.71% and 23.79% accordingly. Runoff-reducing effects by engineering measures for water conservancy are more prominent in the low water period. References | Related Articles | Metrics

River Network Change and Its Ecological Effects in Shenzhen Region in Recent 30 Years ZHOU Hongjian1, 2, SHI Peijun3, 4, 5, WANG Jing'ai1, 2, 3,GAO Lu2, ZHENG Jing5, YU Deyong6 2008, 63 (9):  969-980.  doi: 10.11821/xb200809007 Abstract ( )   PDF (2887KB) ( )   Save Based on the topographic map data (in the late of the 1960s and 1980s), rivers general investigation data (in 2003) and remote sensing data (MMS in 1980; TM in 1988, 2005) of Shenzhen region, the temporal and spatial changes of river networks and the relationship between river networks and urbanization ratio were analyzed. According to the above results, ecological effects of river networks change in Guanlan River basin, based on the four indicators of vegetation coverage (Vc), biological resources value (Br), ecosystem services value (Es) and ecological capital (Ec), were discussed. The results showed that: (1) the river network structure appeared as a trend from comprehension to simplicity, and the development of river branches were restricted strongly in recent 30 years. The length was shortened by 355.4 km, and the number of rivers reduced 378, while the drainage density decreased from 0.84 km/km2 to 0.65 km/km2. The major area, where the river networks decreased or disappeared, is located in the circle area with the town as the center and the radius of 1-2 km. There were 4 different types of change characteristics of river networks in all 9 drainages of Shenzhen according to urbanization ratio in the main drainage and whether or not it flows into sea directly. (2) There was significant correlation between urban expansion and river networks reduction, especially with river branches decreasing when the urban land ratio was less than 30% ; while it was above 30% , the effects became weak. (3) The ecological functions of Guanlan River basin became weaker remarkably, of which Br decreased most (about 41%), Vc was second (24%). The ecological capital per unit area decreased from 22.79 million yuan/km2 to 2.34 million yuan/km2, while total capital reduced 3136 million yuan in 2000-2005. (4) Changing river networks and urbanization were the main reasons for the degradation of ecological functions, and they had different contribution ratios for decline of the four indexes, of which they were respectively 23.1% and 35.8% for Vc, 25.1% and 32.7% for Br, 7.7% and 56.2% for Es, and 10.6% and 52.2% for Ec. The paper provided an empirical case to recover river networks in the last several periods, and a quantitative expression of river networks change. References | Related Articles | Metrics

Risk Factor s and Autocor r elation Char acter istics on Sever e Acute Respir atory Syndrome in Guangzhou CAO Zhidong1, 2, WANG Jinfeng1, GAO Yige1, 2,HAN Weiguo3, FENG Xiaolei4, ZENG Guang5 2008, 63 (9):  981-993.  doi: 10.11821/xb200809008 Abstract ( )   PDF (3297KB) ( )   Save Most of the traditional epidemiological studies are based on the classic statistical analysis instead of spatial information. Spatial analysis of risk factor and autocorrelation characteristics of epidemic can guide scientific prevention and control measures. Spatio-temporal data of 1277 cases of infected persons in 2003 in Guangzhou are studied. Map of incidence rate based on 1 km×1 km grids is gained by kriging and kernel methods. Nine spatial risk factors, such as population density, traffic net, hospital, shopping mall, school, etc., are explored, results show that these risk factors are significantly correlated to incidence rate of SARS. Strict control measures to these risk factors can effectively prevent and control SARS epidemic. Global and local spatial autocorrelation characteristics are quantitatively measured with Moran's I and LISA statistics. Spatial cluster of incidence rate has experienced a weak-strong-weak process. High-high cluster areas are mainly in the center of Guangzhou city, where have high population density, economically active, and well-developed traffic net. The focus of high-high cluster areas did not transfer in the whole SARS epidemic process. The Government has taken successfully the prevention and control measures to prevent the further spread of SARS; however, the strategy of taking infectors to the nearest hospital contributed to the result that the spread risk has been high in the city centre. SARS incidence emerged in Guangzhou provides a sample for studying SARS and other unexpected new epidemics emerged in urban areas. Spatial autocorrelation analysis of SARS in Guangzhou provides a scientific basis for the emergency plan of the outbreak of SARS or other unexpected new epidemics in urban areas. References | Related Articles | Metrics

Heavy Metal Concentr ations of Agr icultur al Soils and Vegetables from Dongguan, Guangdong Province, China CAI Limei1, 2, MA Jin1, 2, ZHOU Yongzhang1, 2, HUANG Lanchun1, 2,CHEN Feixiang1, 2, XIE Xiaohua1, 2, YANG Xiaoqiang1, 2 2008, 63 (9):  994-1003.  doi: 10.11821/xb200809009 Abstract ( )   PDF (2536KB) ( )   Save A total of 118 of agricultural soil and 43 of vegetable samples were collected from Dongguan, Guangdong Province. The spatial distribution, sources, accumulation characteristics and potential risk of heavy metals in the agricultural soils and vegetables were depicted in details by three different approaches, including total contents of 8 metal elements in soils and vegetables, GIS maps and multivariate analysis of heavy metals in soils in the study. The results show that there are higher accumulation of heavy metals such as Cu, Zn, Ni, Pb, Cd and Hg in agricultural soils, and the contents of Pb (65.38 mg kg-1) and Hg (0.24 mg kg-1) are 1.82 and 2.82 times of background contents of the corresponding heavy metals in soils of Guangdong Province, respectively. There are about 3.4% of Cu, 5.9% of Ni, 1.7% of Cd and 28% of Hg in all collected soil samples from all investigated sites which have overran the contents for heavy metals of China Environmental Quality Standard for Soils (GB15618-1995, Grade II). The pollution characteristics of multi-metals in soils are mainly reflected by Hg. There are different sources to 8 metal elements in soils, Cu, Zn, Ni, Cr and As are predominantly derived from parent materials, and Pb, Hg and Cd are affected by anthropogenic activity. The spatial distribution shows that Cu, Zn, Ni, Cr, Pb, As and Hg contents of agricultural soils are high in west and low in east, and Cd contents are high in northwest, southeast and low in southwest in Dongguan. The ratios of vegetable samples with Ni, Pb and As concentrations higher than the Maximum Levels of Contaminants in Foods (GB2762-2005) are 4.7% , 16.3% and 48.8% , respectively. The order of bioconcentration factors (BCF) of heavy metals in vegetables is: Cd > Zn > Cu > As > Ni > Hg > Cr > Pb. References | Related Articles | Metrics