An assessment of variations in mercury deposition to Antarctica over the past 34,000 years

We performed a comparison analysis of the variations .in Mercury ( Hg) concentrations and the precipitation proxies ( e. g. , 18 O values and 10 Be concentrations) in the Dome C ice core. The results showed that there were significant correlations between Hg and δ 10O values, 10Be concentrations, indicating that the accumulation rate in Dome C is one of the key factors controlling the variations of Hg concentrations in the past 34 ,000 years, and implying that Hg concentrations in ice core can be used as another reliable proxy of precipitation rate in Antarctica. Based upon the high-resolution δ 18O values, we estimated the variations in mercury deposition flux to Antarctica over the past 34,000 years. The highest mercury deposition flux is about 3. 80 pg cm-2 yr-1 during the Last Glacial Maxium (LGM) as high as 3. 5 times of the mercury deposition flux ( about 1. 08 pg cm -2 yr -1) in Holocene due to the fluctuations in natural mercury emissions such as the oceanic biological emissions.     

Modeling scenic quality of wetland landscape resources in South Dongting Lake, China

This study introduces a method to quantify the scenic value of wetland landscapes and provides the guidance on the allocation of efforts for the purpose of preserving the most important environments.Dongting Lake,a traditional tourist location,is one of the five largest freshwater lakes in China and a Grade 5A National Scenic Region. This study objectively analyzes the scenic resources of South Dongting Lake,and presents a model based on Quantification TheoryⅠto assess wetland scenic landscapes.Employing a multilinear regression relationship between land-scape factors and their associated scenic value,we built up the Wetland Landscape Quantification Model(WLQM), which was used to classify 221 landscapes into five grades.Finally,some suggestions are proposed regarding quantitative assessment and its use for the sustainable development of wetland environments.     

南水北调东线工程对东平湖水环境的影响

为考察南水北调东线工程对东平湖水环境的影响,为受水区域的用水安全提供保障,于东线工程通水前后分别采集不同水文时期的东平湖湖水样品,分析测定后,采用综合污染指数法、综合营养状态指数法、健康风险评价模型,评价东线工程通水前后东平湖湖水水质级别、营养化水平和健康风险水平的差异。结果表明:东线工程通水后,东平湖湖水综合污染指数由通水前的0.49变为通水后的0.58,水质级别仍为Ⅲ级轻度污染,部分指标超标但不严重;综合营养状态指数由通水前的50.72降为通水后的47.90,表明营养化水平由轻度富营养状态好转为中营养水平;健康风险由通水前的2.91×10~(-4)a~(-1)降为通水后的9.35×10~(-5)a~(-1),即由通水前的中—高风险水平降低为通水后的中风险水平。结论可知,南水北调东线工程的通水有利于东平湖湖水环境的改善,但与其他典型淡水湖泊相比,东平湖湖水的健康风险仍相对偏高,后续需要进一步加强湖区环境保护和污染排放的管控。     

Release of mercury from intertidal sediment to atmosphere in summer and winter

The release of mercury from intertidal sediment to atmosphere was studied based on the simulated experiment. The experiment samples were collected from the Haibo Estuary (S1) and the Licun Estuary (S2) of the Jiaozhou Bay in China,which are seriously polluted with mercury. The results show that the mercury in sediment releases rapidly to atmosphere under solar radiation. After 8 hours of solar radiation,mercury concentrations decrease from 5.62 μg/g and 2.92 μg/g to 2.34 μg/g and 1.39 μg/g in S1 and S2 sediments respectively in summer,and decrease from 5.62 μg/g and 2.92 μg/g to 4.58 μg/g and 2.13 μg/g respectively in winter. The mercury species in the sediment change markedly under solar radiation. The concentrations of mercury bound to organic matter decrease significantly from 2.73 μg/g to 0.31 μg/g in S1 and from 2.07 μg/g to 0.31 μg/g in S2,and the released mercury mainly comes from mercury bound to organic matter. Mercury flux shows distinguishing characteristic of diurnal change,and it increases rapidly in the morning with the rising of solar radiation intensity,but decreases in the afternoon. The mercury flux increases with sediment temperature and solar radiation intensity. The rapid release of mercury in intertidal sediment plays an important role in the regional mercury cycle.     

SST intraseasonal oscillation and atmospheric forcing system of the South China Sea

ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＳｏｕｔｈＣｈｉｎａＳｅａ (ＳＣＳ)ｉｓａｓｅｍｉ ｅｎｃｌｏｓｅｄｏｃｅａｎｂａｓｉｎｌｏｃａｔｅｄａｔａｓｐｅｃｉａｌｇｅｏｇｒａｐｈｉｃｐｏ ｓｉｔｉｏｎ ,ｏｎｅｏｆｔｈｅｗｏｒｌｄ’ｓｐｒｏｎｏｕｎｃｅｄｍｏｎｓｏｏｎｒｅｇｉｏｎｓ,ｗｉｔｈｎｏｒｔｈｅａｓｔｗｉｎｄｓｐｒｅｖａｉｌｉｎｇｉｎｗｉｎｔｅｒａｎｄｓｏｕｔｈｗｅｓｔｗｉｎｄｓｉｎｓｕｍｍｅｒ,ａｎｄｉｓａｃｒｕｃｉａｌｒｅｇｉｏｎｏｆｉｎｔｅｎｓｉｖｅａｉｒ ｓｅａｉｎｔｅｒａｃｔｉｏｎｏｆｇｒｅａｔ…     

Response of the South China Sea summer monsoon onset to air-sea heat fluxes over the Indian Ocean

We objectively define the onset date of the South China Sea (SCS) summer monsoon, after having evaluated previous studies and considered various factors. Then, interannual and interdecadal characteristics of the SCS summer monsoon onset are analyzed. In addition, we calculate air-sea heat fluxes over the Indian Ocean using the advanced method of CORARE3.0, based on satellite remote sensing data. The onset variation cycle has remarkable interdecadal variability with cycles of 16 a and 28 a. Correlation analysis between air-sea heat fluxes in the Indian Ocean and the SCS summer monsoon indicates that there is a remarkable lag correlation between them. This result has important implications for prediction of the SCS summer monsoon, and provides a scientific basis for further study of the onset process of this monsoon and its prediction. Based on these results, a linear regression equation is obtained to predict the onset date of the monsoon in 2011 and 2012. The forecast is that the onset date of 2011 will be normal or 1 pentad earlier than the normal year, while the onset date in 2012 will be 1-2 pentads later.     

南海北部大陆架短尾大眼鲷生长和死亡参数估计

根据20世纪90年代及60年代的生物学资料,运用体长频率分析法估算短尾大眼鲷的生长和死亡参数.von Bertalanffy生长方程的主要参数L∞=31.5 cm,K=0.60,t0= -0.44 ;体重的生长拐点为1.39龄;瞬时总死亡率(Z)、瞬时自然死亡率(M)和瞬时捕捞死亡率(F)分别为2.94,1.07和1.87.当前开发率为0.64,处于资源过度利用状态.     

青藏高原兹格塘错流域50年来湖泊水量对气候变化响应的模拟研究

运用数值模拟建立青藏高原兹格塘错流域土壤、植被、气候等的空间和属性数据库;接着,借助分布式流域尺度水文模型(SWAT模型),对兹格塘错1956—2006年间的流量进行模拟实验;最后,反演50年来兹格塘错流域水文过程,测试流域温度、降水和蒸发组合的敏感因子对湖泊水量变化的效应,探讨50年来湖泊水量对气候变化的响应。模拟实验的边界条件设置为自然地形、土壤、植被覆盖,其中土壤资料包括有机质含量、粒径等理化参数。模拟结果表明:兹格塘错的年平均流量为6.3m3/s,流量高峰集中在8月至10月,并且由于融雪补给的关系,3月出现另一个流量高峰;模拟结果与遥感解译所得到的结果吻合较好。敏感实验表明:兹格塘错流域内温度、降水和蒸发组合的敏感因子实验具有高原特征,即高原湖泊的水文过程和湖泊流量变化有着较为敏感的响应关系;兹格塘错流量受降水的影响最大,随着降水的增加,流量有所增加;在温度升高的情况下,流域蒸发量增加速度大,兹格塘错流量增加的效应不明显,而在冷湿模式下,流域蒸发量降低,兹格塘错流量增加显著。     

A Multilayer Study of pCO2 in the Surface Waters of the Yellow and South China Seas in Spring and the Sea-Air Carbon Dioxide Flux

A multilayer study of pCO2 for the Yellow and South China Seas in the surface waters was conducted based on data from four cruises sponsored by the China SOLAS Project in 2005 and 2006, including data for the surface microlayer (SML), sub- surface layer (SSL) and surface layer (SL). The carbon fluxes across the air-sea interface were calculated. The results showed that the pCO2 values in the surface waters of the study area decreased in the following order: pCO2 SML pCO2 SSL pCO2 SL. The highest val- ues were found in March for all SML, SSL and SL, followed by those in April, and the lowest were in May. The pCO2 values had a significant positive correlation with temperature or salinity. While there was no relationship between pCO2 and longitude, there was a significant negative correlation between it and latitude, i.e., 'high latitude low pCO2'. By using four calculation models, the carbon dioxide fluxes ( FCO2 ) in spring in the Yellow and South China Seas, which were found to act as a 'sink' of atmospheric CO2, were preliminarily estimated on the basis of the pCO2 data in the SML to be -7.00×106t C and -22.35×106t C, respectively. It is suggested that the FCO2 calculated on the basis of pCO2 data in the SML is more reliable than that calculated on the basis of those in the SL.     

Movements of the Western Pacific Warm Pool Centroid and Their Relationship to Sea Surface Temperature Changes in Ni(n)o Regions

By using monthly historical sea surface temperature (SST) data for the years from 1950 to 2000, the Western Pacific Warm Pool (WPWP) climatology and anomalies are studied in this paper. The analysis of WPWP centroid (WPWPC) movement anomalies and the Nino-3 region SST anomalies( SSTA) seems to reveal a close, linear relation between the zonal WPWPC and Nino-3 region SSTA, which suggests that a 9' anomaly of the zonal displacement from the climatological position of the WPWPC corresponds to about a 1 ℃ anomaly in the Nino-3 region area-mean SST. This study connects the WPWPC zonal displacement with the Nino-3 SSTA, and it may be helpful in better understanding the fact that the WPWP eastward extension is conducive to the Nino-3 region SST increase during an El Nino-Southern Oscillation (ENSO) event.     

基于光学与雷达影像变化检测的2020年鄱阳湖洪灾评估与分析

利用遥感对地观测技术对2020年夏季鄱阳湖地区发生的洪水灾情进行评估和分析,分别选取Landsat 8卫星4月和Sentinel-1A雷达卫星7月的影像作为洪水发生前、后的影像,利用遥感专题信息提取、随机森林分类和变化检测技术揭示洪水淹没范围,以及被淹没的主要土地覆盖类型面积,同时结合水文气象和地形数据进行灾情和受灾原因分析。研究结果表明,鄱阳湖2020年洪灾的淹没面积为1961.95 km²,共造成区内110.83 km²建筑用地、760.54 km²耕地、71.59 km²林地、992.02 km²草地和26.97 km²裸地被淹,其中尤以鄱阳县受灾最为严重,其总受灾面积达到514 km²,其次为新建区与余干县,分别达到了330 km²和310 km²。持续2个月的强降雨使得鄱阳湖流域的水位超过了其1998年特大洪水的水位,加上长江水倒灌,湖区地势北高南低,积水不能及时排出,圩堤决口等诸...     

ORIGIN OF CARBONATE MATERIALS IN THE NORTHERN BASIN OF LAKE BAIKAL AND ITS RELATIONSHIP TO HOLOCENE PALEOCLIMATE

Fine-grained disseminated carbonate was found in Holocene sediments in a core taken from the northern basin of Lake Baikal. The core had two distinct facies. a terrigenous blue-clay overlain by a diatomaceous silt. Oxygen and carbon stable isotope analyses, combined with SEM , X-ray diffraction and .palynology, show that the carbonate in the blue-clay layer is pedogenic in origin, rather than biogenic or authigenic . The S C values in the blue clay suggest that the carbonate is derived from a single source , while the carbonate in the diatom-rich layer might be transported by winds from different sources. On the assumption that the carbonate was formed during the post-glacial age and was transported primarily by river runoff, the 18O isotopic values suggest that the annual temperature in the northern Baikal drainage area was about 3℃ warmer during the middle Holocene (8500-7000 a, B. P.) than during the early Holocene (11 000-8 500a, B.P.) when the blue clay was being deposited . This interpretation is     

Species composition and seasonal density dynamics of ciliated Protozoa in Baoan Lake with particular reference to the submerged macrophytes

ＩＮＴＲＯＤＵＣＴＩＯＮＣｉｌｉａｔｅｓ,ａｌｗａｙｓｄｏｍｉｎａｔｉｎｇａｌｌｔｈｅｐｒｏｔｏｚｏａｎｓ,ａｒｅｔｈｅｃｏｍｍｏｎａｎｄｉｍｐｏｒｔａｎｔｍｅｍｂｅｒｓｏｆｆｒｅｓｈｗａｔｅｒｚｏｏｐｌａｎｋｔｏｎｃｏｍｍｕｎｉｔｉｅｓ.Ａｓｍａｉｎｃｏｎｓｕｍｅｒｓｏｆｂａｃｔｅｒｉａ,ｐｉｃｏｐｌａｎｋｔｏｎａｎｄｎａｎｎｏｐｌａｎｋｔｏｎ(Ｆｉｎｌａｙ,1978;Ｐｏｒｔｅｒｅｔａｌ.,1985;Ｔａｙｌｏｒ,1984,1987;Ｓｉｍｅｋｅｔａｌ.,1996)ｃｏｍｐｒｉｓｅａｎｉｍｐｏｒｔａｎｔｔｒｏｐｈｉｃｌｉｎｋａ…     

Seasonal dynamics of crustacean zooplankton community structure in Erhai Lake,a plateau lake,with reference to phytoplankton and environmental factors

The seasonal dynamics of a crustacean zooplankton community in Erhai Lake was investigated from May 2010 to April 2011. In total, 11 species were recorded, including six （6 genera） cladoceran and five （5 genera） copepod species. The crustacean zooplankton densities ranged from 24.3 to 155.4 ind./L. In winter and spring, the large-bodied cladoceran Daphnia galeata dominated the crustacean plankton community. In summer and autumn, when the colonial or filamentous algae dominated the phytoplankton communities, the small-bodied species （e.g. Bosminafatalis, Ceriodaphnia quadrangular, and Mesocyclops leuckarti） replaced the large-bodied ones. One-way ANOVA and redundancy analysis revealed that community structure was dependent upon total nitrogen, total phosphorus, water temperature, transparency, and the biomass of small algae. The variation in both phytoplankton structure and environmental variables were important factors in the seasonal succession of crustacean zooplankton structure in Erhai Lake.     

Comparison between BCR sequential extraction and geo-accumulation method to evaluate metal mobility in sediments of Dongting Lake,Central China

The form in which a metal exists strongly influences its mobility and thus, the effects on the environment. Operational methods of speciation analysis, such as the use of sequential extraction procedures, are commonly applied. The Dongting Lake, the second largest fresh-water lake in China, contains three China wetlands of international importance, the East Dongting Lake, South Dongting Lake, and West Dongting Lake. In this work, an optimized BCR sequential extraction procedure was used to assess the environmental risk of Cd, Cr, Cu, Ni, Pb and Zn in contaminated sediment of the Dongting Lake. The procedure was evaluated by using a certified reference material, BCR701. The results of the partitioning study indicated that in the lake sediments, more easily mobilized forms （acid exchangeable） were predominant for Cd, particularly in the samples from the East Dongting Lake. In contrast, the largest amount of Pb was associated with the iron and manganese oxide fractions and Cu, Zn, Cr, and Ni analyzed were mainly distributed in residual phase at an average percentage greater than 60% of the total metals. The potential risk to the lake＇s water contamination was highest in the East Dongting Lake based on the calculated contamination factors. On the other hand, the total metal content was determined as well by inductively coupled plasma and mass spectrometry （ICP-MS） and assessed by using geo-accumulation index. The assessment results using geo-accumulation index were compared with the information on metal speciation. Both were correspondent with each other.     

SPECIES COMPOSITION, HORIZONTAL DISTRIBUTION AND SEASONAL SUCCESSION OF PHYTOPLANKTON IN THE CHANNEL FROM DONGTING LAKE TO THE CHANGJIANG RIVER, CHINA

The species composition, horizontal distribution and seasonal succession of the phyto-plankton at five sampling stations in the channel between Dongting Lake and the Changjiang River, China were studied from May 1995 to December 1997. A total of 416 taxa were observed; diatoms comprised the most diverse taxonomic group representing 58.2 % of the total species. The β-mezotrophic indicators were 92 taxa or 22 % of the total, the a-mezotrophic or α, β-eutrophic indicators decreased distinctly to 20 taxa or 4.8 % of the total. The species number and composition of various phyla were approximately similar at Stations 1, 2, 3 and 4, but at Station 5 the number of species was the minimum and the ratio of diatoms to total phytoplankton in the number of species was the highest. In seasonal succession of the phytoplank-ton species, the number was the highest in May and June, lower in December, January, March and July in the channel. The dominant species were different in different months. The ratio of diatoms species number to blue green algae and green algae species number diminished gradually from winter to summer and autumn, and then increased gradually from autumn to winter and early spring in the annual cycle. Margalef, Simpson and Shannon—Weaver diversity indices changed in different months, their values were higher in winter, lower in summer. Nygaard‘s diatoms quotients were lower in winter, then in spring and autumn, higher in summer. These results indicated that the water quality was the best in winter, better in spring and autumn than in summer. The relationship between the structure of the phytoplankton communi-ty and the water environmental quality was discussed.     

基于MODIS数据的太湖浮游植物物候变化及其对水表温度的响应

浮游植物物候能够反映浮游植物的生长变化与湖泊生态系统的变化,水温、营养盐浓度等因素对物候有重要影响。太湖富营养化程度较高,水温的影响作用日趋显著,物候与水温关系的研究对理解、控制和改善太湖生态系统具有重要意义。本研究利用2003—2018年MODIS遥感数据计算浮游植物物候指标和湖泊水表温度（Temperature of Water Surface,LSWT）,通过分析太湖浮游植物物候时空变化特点探究了不同区域的物候特征,并结合LSWT揭示了浮游植物物候对LSWT变化的响应关系。结果表明：① 不同浮游植物物候指标具有不同空间分布特点,水华发生次数、峰值叶绿素a（Chla）浓度和水华总持续时间呈现由西部沿岸向湖心区递减的趋势;浮游植物生长开始时间和峰值Chla发生时间分布复杂但在沿岸区域相对较早;② 太湖可被划分为4种具有不同物候特征的区域,Ⅰ类区域主要位于贡湖湾、东部沿岸以及太湖中部开阔水域,该区Chla浓度范围为50~60 μg/L,且波动平缓,水华发生次数最少、开始最晚、持续时间最短;Ⅱ类区域主要分布于太湖西部沿岸,Chla浓度范围为50~90 μg/L且变化剧烈,该区水华发生次数最多、开始最早、持续时间最长;Ⅲ和Ⅳ类属于过渡区域,前者主要分布于梅梁湾、竺山湾及入湾口,后者主要位于南部沿岸以及太湖中部;③ 浮游植物物候对LSWT变化的响应受营养水平影响,当营养水平较高时,浮游植物的生长受LSWT的促进作用显著,LSWT年际变化的升高趋势对浮游植生长物候提前、生物量增加的影响明显,反之,则LSWT变化对浮游植物生长的影响减弱。     

A multilayer study of pCO2 in the surface waters of the Yellow and South China Seas in spring and the sea-air carbon dioxide flux

A multilayer study of pCO₂ for the Yellow and South China Seas in the surface waters was conducted based on data from four cruises sponsored by the China SOLAS Project in 2005 and 2006, including data for the surface microlayer (SML), subsurface layer (SSL) and surface layer (SL). The carbon fluxes across the air-sea interface were calculated. The results showed that the pCO₂ values in the surface waters of the study area decreased in the following order: pCO_{2 SML} > pCO_{2 SSL} > pCO_{2 SL}. The highest values were found in March for all SML, SSL and SL, followed by those in April, and the lowest were in May. The pCO₂ values had a significant positive correlation with temperature or salinity. While there was no relationship between pCO₂ and longitude, there was a significant negative correlation between it and latitude, i.e., ‘high latitude low pCO₂’. By using four calculation models, the carbon dioxide fluxes ( ) in spring in the Yellow and South China Seas, which were found to act as a ‘sink’ of atmospheric CO₂, were preliminarily estimated on the basis of the pCO₂ data in the SML to be −7.00×10⁶t C and −22.35×10⁶t C, respectively. It is suggested that the calculated on the basis of pCO₂ data in the SML is more reliable than that calculated on the basis of those in the SL.