Chemical composition of waters and the phytoplankton of the lakes within the delta of the Selenga river

Field observations showed that the characteristics of chemical composition of waters and the development of plankton algae in the lakes within the delta of the Selenga river are determined by their flowage. The most open Lake Nekipelovskoe communicates with the Selenga outlets throughout a year, and Lake Zavernyaikha only at the period of an open channel. Lake Semenovskoe and Lake Khlystov Zaton are located in the islands and are isolated from the outlets. According to composition of main ions, the lakes under investigation refer to the hydrocarbonate class, the calcium group. The sum of ions in the water of Lake Nekipelovskoe approaches the one in the Selenga (86?221 mg/dm³), and the highest sums of ions were recorded in the wintertime in the lakes isolated from the outlets (446?743 mg/dm³). The lakes of the delta are characterized by a high trophicity. The maximum concentrations of total phosphorus in Lake Nekipelovskoe and Lake Zavernyaikha were 68 and 122 μg mg/dm³, and in Lake Semenovskoe and Lake Khlystov Zaton ?0.8 and ?0.63 μg mg/dm³, respectively. The most intense development of algae is observed in Lake Zavernyaikha, which is due to the high population of Baikal endemics. Lake Zavernyaikha showed a close negative correlation between the concentration of NO ₃ ^? , mineral phosphorus and phytoplankton biomass; the correlation coefficient was ?0.8 and ?0.63, respectively. The lakes exhibited increased contents readily hydrolysable organic matter, and a decrease in dissolved oxygen concentration in winter; hydrogen sulfide was repeatedly recorded in Lake Khlystov Zaton. The water quality in the lakes during the springtime varies from “quite clean” to “weakly polluted”; at low-water periods, especially in winters, it can drop to the category of “exceedingly dirty”. The water quality of the Selenga can be influenced by the lakes during spring floods when material accumulated during the wintertime is transported to the river outlets and further to Lake Baikal.     

Changes in the summertime atmospheric circulation over East Asia and formation of long-lasting low-water periods within the Selenga river basin

We examine the formation patterns of the low-water periods 1976?C1982 and 1996?C2011 for the Selenga river. One of the immediate reasons for the low-water periods under consideration is the attenuation of the circulation in the zone of convergence of monsoon flows and mid-latitude flows over Mongolia and North China. Unlike the low-water periods of the preceding decades, a decrease in precipitation amounts during the current low-water period is taking place concurrently with large-scale climatic changes.     

Chemical composition characteristics of water and phytoplankton development in Lake Zavernyaikha

Based on long-term observations, we examine the seasonal and interannual dynamics of the phytoplankton and chemical composition of the water in Lake Zavernyaikha located in the delta of the Selenga river. The study revealed an intense development of five kinds of phytoplankton under the ice, dominated by dynophytes: Baikal’s endemics G. baicalense and P. baicalense. The main factors for massive algae development under the ice are: the favorable gaseous regime and relationship of nutrients, high content of readily hydrolizable organic matter (RHOM), isolatedness of the water body, and high division rate of dinophytes.     

Seasonal and spatial distribution of heavy metals in the Selenga River Delta

In order to estimate the present-day pollution levels in the ecosystem of the Se-lenga River Delta and to monitor the changes caused by the discharge of household refuse and industrial wastes, as well as the functioning of the agricultural and stock farming, a comprehensive study of the water and bottom sediments in the main branches of the Selenga River Delta was carried out. This study has determined the concentrations of heavy metals in river water and bottom sediments in its delta.     

色楞格河三角洲重金属季节和空间分布

In order to estimate the present-day pollution levels in the ecosystem of the Selenga River Delta and to monitor the changes caused by the discharge of household refuse and industrial wastes,as well as the functioning of the agricultural and stock farming,a comprehensive study of the water and bottom sediments in the main branches of the Selenga River Delta was carried out.This study has determined the concentrations of heavy metals in river water and bottom sediments in its delta.     

Dynamics of the Selenga river network and delta structure

The results of investigations for the Selenga river basin and delta are presented. The causes for the changes in the channel network structure are considered. The study revealed tendencies of erosion activity and plane deformations within the delta. An analysis is made of the distribution of water flow rate and sediment loads for the channel network, based on field measurements and existing research material.     

2010年夏季白令海小型底栖动物丰度与生物量初步研究

2010年7月12—18日, 中国第4次北极科考队在白令海以箱式或多管取样器采集7站位10 cm长度的表层沉积物芯样, 并在现场进行了分层处理。室内分析时共检出14个小型底栖动物类群：自由生活海洋线虫(free-living Nematoda)、底栖桡足类(Copepoda)、多毛类(Polycheata)、动吻类(Kinorhyncha)、端足类(Amphipoda)、双壳类(Bivalvia)、涟虫(Cumacea)、介形类(Ostracoda)、原足类(Tanaidacea)、腹足类(Gastropoda)、等足类(Isopoda)、海蛇尾(Ophiura)、缓步类(Tardigrada)以及其它类(Others)。平均丰度和平均生物量分别为2 658.89±2 452.86 ind/10 cm²和1 587.56±1 452.65 μg?dwt/10 cm², 最高值皆出现在白令海北部陆架浅水区, 分别为7 135.12±429.43 ind/10 cm²和4 056.42±721.33 μg?dwt/10 cm², 最低值皆出现在白令海盆西部深水区, 分别仅为56.04±39.38 ind/10 cm²和87.91±85.60 μg?dwt/10 cm²。线虫为丰度的最优势类群, 占平均丰度比例的94.81％, 桡足类为第二优势类群, 占3.60％。表层0—6 cm芯样的取样效率为93.44％。基于各站丰度的类群相似性分析, 浅水区与深水区的小型底栖动物群落的相似性系数仅为30.72%, 最大的差别在于深水区的丰度比浅水区小了一个数量级。白令海陆架浅水区比白令海盆深水区和中国海域具有明显更高的小型底栖动物丰度和生物量。Pearson相关性分析显示, 白令海小型底栖动物丰度和生物量与水深、营养盐及多个粒径参数呈负相关, 其中生物量对环境变化的响应可能比丰度更敏感。     

Hydrologo-morphological approach to regionalization of the Selenga river basin

We examine the evolutionary stages of scientific views on the formation history of the delta plain of the Selenga river and adjacent territories, based on cartographic material and national investigations spanning the period 1701?C2009. We suggest the regionalization of the Selenga river from hydromorphometric attributes of erosion-accumulation, abrasion-accumulation and neotectonic processes. The study is based on comparing topographic maps, guides for navigation and space images (1898?C2009) as well as on experimental data obtained by the authors.     

Flood Hazard on the Rivers of the Baikal Region

A comprehensive characterization of the flood hazard on the rivers of the Baikal region is presented, which was obtained by investigating the streams within the basins of the Angara, Upper Lena (with the Vitim and Olekma), Lower Tunguska (headwaters), Upper Amur and Lake Baikal (including the entire Selenga basin). The main flood indicators for the period 1985–2017 are estimated: the genesis, recurrence, duration, flooded area and the force of impact. The influence of changes in the river runoff characteristics on the flood risk is shown by results of correlation analysis and analysis of integro-differential curves. An assessment is made of the changes in the flood frequency at gauging stations during the period of pronounced climatic changes (from 1981 to 2014), compared with the earlier period. The flood hazard within the spatial context for municipalities in the rank of administrative districts is determined on the basis of the dual (socio-economic and natural) nature of floods. It has been confirmed that the most dangerous in the Baikal region are rainfall floods in the southern areas of Irkutsk oblast, the Republic of Buryatia and Zabaikalskii krai. They have the highest frequency, and the largest flooding areas and force of impact and are characterized by the greatest damage and by the largest number of victims and evacuated people. At the same time, the frequency of floods at gauging stations in recent years has decreased compared to the earlier period against the background of the observed low-water period, which is most pronounced on the rivers of South Baikal and in the Selenga river basin.     

Influence of water management activity on the state of streams within the Selenga River basin

A water management assessment for the Selenga basin is made. The territorial-sectoral utilization of water for separate areas of the basin is considered. The influence of discharged waste waters on the river runoff is demonstrated.     

夏季南海西北部海域由外海至近岸表层海水浮游植物群落结构的空间变化

依托2013年夏季科技基础专项南海珊瑚礁海域调查航次,主要研究了南海西北部海域由外海到近岸表层海水内浮游植物叶绿素（Chl a）质量浓度和群落结构,以及微微型浮游植物（聚球藻、微微型真核生物）丰度。研究结果显示：1）调查期间,从外海到近岸总Chl a质量浓度由0.024逐渐增至19.1 μg/L;同时,小型浮游植物（Micro-,＞20 μm）所占比例由6.0%增至81%,微型浮游植物（Nano-,3~20 μm）所占比例（9%~24%）的空间变化不明显,而微微型浮游植物（Pico-,＜3 μm）所占比例由85%降至5.1%。2）从外海到近岸聚球藻和微微型真核生物丰度分别由（2.58±0.21）×106和（1.62±0.91）×105 cells/L升高至（2.29±0.10）×108和（1.83±0.46）×107 cells/L,而且二者呈显著正相关关系（R2＝0.68,p＜0.05）。3）调查海域总浮游植物生物量空间变化主要受微微型浮游植物丰度空间变化的调控。     

菲尔德斯半岛南部邻近海域石油污染的初步研究

本文首次报道了菲尔德斯半岛南部邻近海域的水样和生物样石油污染状况。表层水样的测定结果表明 ,调查海域已受到明显的石油污染。在所调查的各站位 ,中国长城站前海湾受油污最轻 ,水样油的浓度略高于中国《海水水质标准》规定的第三类水质最高容许浓度 ,为 5 1 2 .2 5 μg/L;智利站前和海豹湾受油污最重 ,分别达 41 49.2 3 μg/L和 41 6 9.72 μg/L,约比长城站前海水含量高 8倍。几种海洋生物受污染程度不一 ,潮间带生物受油污明显高于鱼类。鉴于调查海域已受到明显的油污染 ,且进入南极水域后消除不易 ,为保护南极生态环境 ,很有必要开展油的净化规律 ,以及石油污染对生态系统影响等的研究。     

Sedimentary Steryl Chlorin Esters (SCEs) and Other Photosynthetic Pigments as Indicators of Paleolimnological Change Over the Last 28,000 Years from the Buguldeika Saddle of Lake Baikal

Detailed depth profiles of photosynthetic pigments in a sediment core (G-12) collected at the BDP93 site, the Buguldeika saddle, of south Lake Baikal, along with depth profiles of total organic carbon (TOC) and biogenic silica, were studied to elucidate the temporal changes of phytoplankton assemblages in the lake during the past 28 kyr. In addition to the quantification of carotenoids by high-performance liquid chromatography with photodiode-array detection (HPLC-PDA), steryl chlorin esters (SCEs) were analyzed by HPLC-PDA, HPLC-mass spectrometry (LC-MS) and sterols in SCEs by gas chromatography–mass spectrometry (GC–MS) to enrich the taxonomical information on the phytoplankton composition. Allochthonous input of organic matter from the Selenga River resulted in the higher TOC contents in core G-12 than in a previously reported core (G-6) collected at another site from the southern basin. The poorer correlation in core G-12 than in G-6 between TOC and chlorophyll-a-originating pigments, which are indicative of autochthonous production, also indicated a significant allochthonous input at the site. The abundance of lutein among the carotenoids detected, and the good correlation of total chlorophyll a and b shows that green algae represented a significant portion of the phytoplankton, accompanying the diatoms at the G-12 site, after the last glacial period. The presence of cryptomonads and cyanobacteria were confirmed from marker carotenoids in the sediment core. GC–MS analysis of sterols in SCEs detected marker sterols of diatoms, green algae, chrysophytes and dinoflagellates. The depth profiles of the measured indicators gave consistent features for temporal changes in phytoplankton assemblage at the G-12 site of Lake Baikal after the last glacial maximum. Notably, the profile of a chrysophyte-specific sterol in SCEs was consistent with the reported distribution of chrysophyte cysts during the Holocene. The presence of phytoplankton, such as green algae, diatoms and chrysophytes, in Lake Baikal during the late last glacial period was indicated by the analysis of sterols in SCEs. Sedimentary carotenoids and sterols in SCEs were found to give complementary information about phytoplankton composition. These molecular indicators allow us to reconstruct past lake phytoplankton assemblages responding to environmental changes with a time resolution as high as age–depth relationship in sediments attainable at present.     

淮河中上游浮游植物时空分布特征及关键环境影响因子识别

浮游植物是水生态系统的初级生产者,直接影响着水生态系统的结构、功能与稳定性。基于2012-2014年淮河流域沙颍河—淮干中游浮游植物和水质4次汛期和非汛期采集数据,利用物种优势度和多样性指数对浮游植物的时空分布进行表征,并利用冗余度分析、偏相关性分析等方法探索了淮河中上游流域的多种水环境因子对浮游植物时空分布的影响。结果表明,从时间变化上看,2012-2014年浮游植物密度呈现逐年递减趋势;从空间变化上看,物种丰度呈现从上游至下游逐渐减少趋势。从时空变化的影响因素上看,非汛期总磷和电导率影响最大,其解释度分别为：10.96%和8.36%;汛期总磷、总氮和氨氮影响最大,其解释度分别为9.47%、8.08%和6.96%。     

北极拉普捷夫海春季冰藻和浮游植物群落结构及生物量分析

对1999年春季采集于北极拉普捷夫海东南部的冰藻和冰下浮游植物群落的种类组成进行了分析,并对丰度和生物量进行了统计和对比。藻种以硅藻占绝对优势,其中又以羽纹硅藻为主。优势种集中,主要包括海洋拟脆杆藻(Fragilariopsisoceanica)、圆柱拟脆杆藻(F.cylindrus)、寒冷菱形藻(Nitzschiafrigida)、普罗马勒菱形藻(N. promare)、带纹曲壳藻(Ach nanthestaeniata)、新寒冷菱形藻(Nitzschianeofrigida)、大洋舟形藻(Naviculapelagica)、范氏舟形藻(N. vanhoeffenii)、北极直链藻(Melosiraarctica)、北方舟形藻(N. septentrionalis)、新月细柱藻(Clindrothecaclosterium)和绿藻门的塔形藻(Pyramimonassp. )。微藻主要集中在冰底10cm,丰度为14. 6-1562. 2×104 cells·L-1,平均为639. 0×104 cells·L-1;生物量为7. 89-2093. 5μgC·L-1,平均为886. 9μgC·L-1,总体上比次冰底高1个数量级,比冰下表层水柱高2个数量级。冰底20cm冰柱的累计丰度和生物量平均分别为冰下20m水柱累计量的7. 7和12. 2倍,显示冰藻在春季海冰融化前在近岸生态系统中的重要作用。尽管各站位冰底和冰下表层水柱藻类群落的相似性普遍不高,但整个调查海域冰底和冰下水柱优势种极为相似,春季期间冰藻对冰下浮游植物群落的影响明显。由于     

华侨城湿地浮游生物调查

2014年7月,对华侨城湿地浮游生物进行调查。共鉴定浮游植物4门17种,浮游动物3门12种。叶绿素a含量值较大,以及耐污浮游生物成为优势种群,表明华侨城湿地正受较严重污染。同时,淡水藻类成为水体优势藻种,表明华侨城湿地水体正逐步淡化。     

Assessing the Influence of the Mining Operations on the State of Streams in the Northern Part of the Red River Basin (Viet Nam)

A study was made of the influence of extraction of lead and zinc ores in the northern part of Vietnam (the Red river basin, Chodon district of Bac Can Province, and the basins of the Dai, Ban Thi, Ta Dieng and Cau rivers). Background concentrations of macro- and microelements and biogenic elements are determined in the river waters and water extracts from bottom sediments of small streams of the study area. A significance exceedance of background concentrations was revealed in stretches of the headwaters of the Ban Thi and Dai rivers caused by a combination of natural and anthropogenic factors. It is established that the river waters near the pollution sources contain increased (compared with the geochemical background) concentrations of Zn, Pb, Fe, Ni, Co, As, Bi, Cd, Cs, Sb, Ag,NO₂^? and SO₄^2?. The waters are estimated as moderately and heavily polluted, and at the other points as minimally polluted. It is determined that the level of accumulation of matter in water extracts from bottom sediments with respect to the geochemical background in the vicinity of the ore dressing factories corresponds to weakly and heavily polluted bottom sediments, and further downstream, to thy minimum level of pollution. It is shown that the influence of extraction of lead and zinc ores on the state of small streams is observed in stretches as long as 11–12 km (with a maximum in stretches of up to 4.5 km). The mathematical model of Pb and Zn distribution in the river waters of the study area has been developed and tested.     

黑河甘肃段浮游植物群落结构演变趋势

为探究西北干旱区内陆河流域水生态系统时空演变规律,2017年7月对黑河甘肃段进行了浮游植物的采样调查,并收集1981、1997、2008年浮游植物夏季调查数据,分析黑河上中下游浮游植物物种、生物多样性和优势种等群落结构的演变特征,同时提出生物活动力指标以表征河流生物的活动能力和活跃程度。结果表明：在空间分布上,黑河中游在各年份都具有最为丰富稳定的浮游植物群落结构,物种数（61属）、生物多样性指数（2.87）和生物活动力指数（0.194万cells·hm^-2）均高于上下游。在时间尺度上,上游浮游植物群落变得持续丰富;中游从1981年持续衰落到2008年后出现反转并快速恢复到2017年更为丰富和活跃的水平;下游则呈现出持续衰落的态势。以1981年为基准,黑河中游水域面积到2010年减小5.2%,浮游植物生物活动力降低了16.5%,到2017年水域面积增加1.2%,浮游植物生物活动力增加了4.3%。黑河浮游植物对流域天然湿地及水域的变化具有强烈的敏感性和依赖性,浮游植物演变特征与湿地水域面积变化趋势一致。     

海南博螯沿岸地貌与人类活动的潜在影响

The Boao coastal system along the eastern coast of Hainan Island is a dynamic delta-tidal inlet-barrier formed during the late Holocene. The delta developed inside a shallow lagoon barred by a sandy barrier with a narrow, shallow tidal inlet opening. Two major distributary channels separated by small islands characterize the delta. The lagoon is silting up receiving and trapping sediments from both the river and, in minor measure during storms, through the tidal inlet opening and barrier washovers. The barrier at the tidal inlet is highly dynamic and changes its form, accreting (migrating spit) against the inlet during fair-weather conditions and being eroded during storms and river floods.The delta has almost completely filled the lagoon and major concerns exist on the effect that ongoing large development plans may have on the environment. These concerns include the effect on floods and rate of siltation once banks of the islands have been stabilized and floodwater and sediment load are impeded from spreading over the lowlands, and the effect of increasing pollutant loads from the new facilities on the ecosystems of the increasingly restricting lagoon water and on the seashores.     

Geomorphology of the Boao coastal system and potential effects of human activities - Hainan Island, South China

The Boao coastal system along the eastern coast of Hainan Island is a dynamic delta-tidal inlet-barrier formed during the late Holocene. The delta developed inside a shallow lagoon barred by a sandy barrier with a narrow, shallow tidal inlet opening. Two major distributary channels separated by small islands characterize the delta. The lagoon is silting up receiving and trapping sediments from both the river and, in minor measure during storms, through the tidal inlet opening and barrier washovers. The barrier at the tidal inlet is highly dynamic and changes its form, accreting (migrating spit) against the inlet during fair-weather conditions and being eroded during storms and river floods. The delta has almost completely filled the lagoon and major concerns exist on the effect that ongoing large development plans may have on the environment. These concerns include the effect on floods and rate of siltation once banks of the islands have been stabilized and floodwater and sediment load are impeded from spreading over the lowlands, and the effect of increasing pollutant loads from the new facilities on the ecosystems of the increasingly restricting lagoon water and on the seashores.