煤烟型大气污染的湖泊沉积记录研究

通过阳宗海柱状沉积物中硅藻、介形类研究和磁参数机理解释, 以及对酸性硅藻与湖水瞬时最低pH值的相关性分析和代用标志的综合判别, 确认20世纪50年代湖泊环境优越; 1960年始受煤烟型大气污染危害, 1965~1980年间污染强度最大时湖水瞬时最低pH值可降低至5~6; 1983~1999年间污染强度有减少趋势, 但依然是环境修复的主要障碍. 酸沉降引起的耐酸物种扩展和贝壳生物消亡, 以及水土界面pH-Eh环境变化引起的铁磁性矿物流失, 是导致代用指标垂向变化和进行环境重建的理论依据.     

青海湖近900年来气候环境演化的湖泊沉积记录

通过对青海湖沉积物碳酸盐含量、磁化率、TOC等多环境指标的分析,探讨了青海湖地区近900年来的气候环境演变。结果表明青海湖地区近900年来气候变化属于暖干－冷湿的气候演替类型,经历了5次冷湿期和5次暖干期,中世纪暖期、小冰期以及20世纪以来的升温在该沉积岩芯有清晰的记录。沉积物的磁化率和沉积速率的变化忠实地记录了本世纪以来人类活动的影响。     

近百年来我国西南地区酸沉降背景下湖泊环境变化——来自四面山龙潭湖沉积硅藻证据

大气酸沉降会导致地表水体酸化和富营养化,同时气候变暖也会影响湖泊水体环境,湖泊生态系统如何响应二者相互作用是全球变化研究的热点之一.我国西南地区是全球酸沉降负荷最高的地区之一,然而目前对酸沉降影响下地表水环境变化规律知之甚少.本文以重庆四面山龙潭湖为研究对象,通过沉积岩芯的²¹⁰Pb测年和硅藻分析,并结合流域历史资料数据,揭示龙潭湖过去近百年来水环境变化及其主要驱动因子.结果表明,1926-1968年,龙潭湖以Achnanthidium minutissimum和Encyonema silesiacum占优势;随后,Lindavia bodanica快速增加至峰值后逐渐减少,伴随Aulacoseira alpigena和Aulacoseira ambigua含量上升.硅藻组合中以适应中性和弱碱性水体的属种为主,嗜酸性属种含量很少,表明目前水体总体维持弱碱性,这得益于当地紫色砂页岩和森林土壤对于酸沉降的缓冲作用.尽管目前龙潭湖仍维持弱碱性,1980s以来硅藻推导水体酸碱度下降、中富营养种增加,表明酸沉降降低水体碱度并提高营养水平.气候变暖加剧水体热力分层和营养富集,导致适应扰动、贫营养环境的L.bodanica减少.2010年以来,中富营养属种略有减少反映湖泊富营养化有所减缓.     

内蒙古岱海湖泊沉积记录的小冰期气候环境

通过对岱海深水区沉积柱样有机碳同位素,总有机碳、碳酸盐含量、频率磁化率等环境代用指标的分析,结合剖面的岩性特征和＾２１０Ｐｂ定年,初步探讨了岱海小冰期以来气候环境演化过程,结果表明：在小冰期初期７４０－５４０ａＢＰ,以冷湿气候为主;在５４０－４８０ａＢＰ为寒冷干旱气候,可能为小冰期盛期;４８０－３７０ａＢＰ,气候转温和,以凉偏湿气候为主;３７０－２２０ａＢＰ,凉偏干气候为主;２２０－１３０ａＢＰ,     

青藏高原东南缘高山湖泊藻类响应气候变化和大气沉降的长期特征

高山湖泊远离人类活动直接影响,通常具有面积小、寡营养、食物网单一等特点,对气候变化和营养输入具有较高的敏感性。我国青藏高原东南缘地区氮沉降通量较高、增温幅度显著,已有研究显示该地区可能受湖泊类型、流域特征等影响存在差异性的湖泊响应模式。本研究选择该区域位于树线以下、具有不同水深的3个小型湖泊(盖公错纳、沃迪错、碧沽天池)开展沉积物调查和对比研究,通过钻孔样品测年、理化特征和藻类(硅藻群落、藻类色素)等多指标分析,结合区域气候定量重建和氮沉降等数据收集,评价了过去300年来藻类演替模式的异同特征及湖泊水深的调节作用。结果显示,3个湖泊中硅藻的优势物种与群落组成差异明显。深水型湖泊盖公错纳(最大水深39.4 m)的硅藻群落以浮游种为主(占比达82%),优势种为眼斑小环藻(Pantocsekiolla ocellata)、科曼小环藻(Pantocsekiella comensis);深水型湖泊沃迪错(最大水深20.7 m)的硅藻群落中浮游种和底栖种约各占50%,优势种为眼斑小环藻(Pantocsekiella ocellata)、连结脆杆藻(Saurosira construens);浅水湖...     

近1800年来云南洱海流域气候变化与人类活动的湖泊沉积记录

对云南洱海湖泊岩芯沉积物进行了多环境指标（年代学、色素、硅藻、有机碳稳定同位素、磁化率、化学元素）的分析,建立了近１８００年来云南洱海流域气候与环境变化的序列,气候演化具有暖干、冷湿交替的组合呈些特征气候阶段如中世纪温暖期、小冰期气候特征在洱海源泊沉积记录中均有反映,洱海湖泊上沉积记录的气候暖干－冷湿交替变化规律,反映了西南委风影响下的气候演化特征,湖泊沉积记录中包含丰富的人类以的信息,磁化率,元     

高山湖泊吉仁错枝角类古生态变化及其对气候环境的响应

高山湖泊吉仁错位于川西高原树线以上,受现代冰川融水补给影响.通过吉仁错沉积钻孔~(210)Pb/~(137)Cs定年和沉积枝角类和多环境代用指标分析,结合主成分分析和冗余分析等方法,高分辨率重建了近200 a来吉仁错枝角类组合和环境变化的过程.结果表明,尽管过去200 a来吉仁错枝角类组合一直以沿岸种为主,但仍经历了3个明显的变化阶段.1850 AD后,枝角类组合中Alonella nana、Chydorus sphaericus和Pleuroxus sp.的增加、以及Alona rustica和Alona guttata丰度的下降指示了水温和水体pH值的上升.1900 AD后枝角类通量的增高并不同步于组合的变化,指示了湖泊营养开始增加,这种不一致的变化分别代表了大气氮沉降和区域气候变暖的影响结果.多指标综合分析得出,过去150 a来,气候变暖和大气污染沉降通过直接和间接作用(流域冰川融水过程和植被土壤过程),较深刻地影响了湖泊物理过程(水温升高和无冰期加长)、营养过程(氮、磷营养升高)和酸碱平衡过程(碱性增强),改变了湖泊生物的生长季节,并通过促进藻类发育,最终引起了湖泊枝角类群落组合的变化和生物量的增加.1945 AD前后吉仁错枝角类与藻类群落结构和湖泊环境的同步变化,响应于持续增温背景下多环境过程的相互作用.     

呼伦湖地区扎赉诺尔晚第四纪湖泊沉积物的磁化率变化及其影响因素

呼伦湖盆地扎赉诺尔晚第四纪湖泊沉积物为砂,泥质碎屑沉,地东露天矿剖面沉积物样品进行了低,高频磁化率测量,粒度分析,磁性矿物成分鉴定和Al2O3 ,Fe2O3含量分析,分析表明,磁铁矿是沉积物磁化率的主要贡献者,全铁含量控制了磁化率值的变化,磁化率与沉积物粒度呈负相关,进一步讨论认为,磁性矿物主要为粉砂－粘土级碎屑,集中分布在细粒沉积物中,因此造成其率较高,砂质沉积物中频率磁化率较高,其原因可能是其中的磁性颗粒比粉砂一粘土级沉积物中的磁性颗粒更细一些。     

湖泊沉积物的磁化率、频率磁化率及其古气候意义—以青海湖、岱海近代沉积为例

湖泊沉积物的磁性参数是古气候、古环境的重要代用指标。通过对青海湖QI_5孔和岱海DH_(32)孔短岩心的磁化率、频率磁化率的研究,并与地球化学参数等其它资料对比,探讨了以上两个湖区历史时期古气候变化规律;论证了用磁化率、频率磁化率作为古气候、古环境指标的可靠性和敏感性;并对其变化机制进行了初步探讨。     

湖泊沉积物的磁化率、频率磁化率及其古气候意义—以青海湖、岱海近代沉积为例

湖泊沉积物的磁性参数是古气候、古环境的重要代用指标。通过对青海湖QI₅孔和岱海DH₃₂孔短岩心的磁化率、频率磁化率的研究,并与地球化学参数等其它资料对比,探讨了以上两个湖区历史时期古气候变化规律;论证了用磁化率、频率磁化率作为古气候、古环境指标的可靠性和敏感性;并对其变化机制进行了初步探讨。     

The lacustrine sedimentary records of coal-burning atmospheric pollution

With the acceleration of industrialization, coal- burning atmospheric pollution is getting more and more serious in many regions in China. However, there are only about ten odd years literature records about pollution in some large and mid-sized cities, where the atmosphere has perhaps been polluted for several decades, and therefore it is difficult to know the process and characteristic of pollution, and diffi-cult to evaluate its damage to environment. Lacustrine sediment, a natural record w…     

长江中下游地区湖泊沉积物杀生剂污染特征及生态风险

杀生剂作为抑菌活性成分,广泛应用于药物、个人护理品、食品、农业及其他多种领域中。大量杀生剂会直接或者随污水处理厂出水进入地表水环境中,威胁人体健康和生态安全。本研究通过对长江中下游地区61个湖泊进行调查,共检出11种杀生剂,包括5种杀菌剂、1种防污剂、3种尼泊金酯类防腐剂和2种消毒剂,总浓度达103 ng/g。其中,多菌灵和尼泊金甲酯的检出率大于50%,分别为100%和96.2%。多菌灵和尼泊金甲酯的平均浓度分别为（1.79±2.76）和（11.4±8.19） ng/g,其他杀生剂的平均浓度均低于1.0 ng/g。与国外许多河流湖泊相比,长江中下游地区湖泊沉积物中杀生剂污染处于中等偏低水平,总杀生剂浓度的平均值为（16.7±14.5） ng/g。氟康唑、咪康唑、三氯生和三氯卡班可能主要来自生活污水,多菌灵和涕必灵主要来自面源污染。尼泊金酯类防腐剂在沉积物中的分布特征与沉积物总有机碳含量密切相关。采用风险商值法对湖泊沉积物中杀生剂的生态风险进行了评价,发现多菌灵、尼泊金甲酯和三氯卡班在部分采样点具有高风险。有必要重点关注高风险污染物和高风险区域,并采取适当的措施来减少杀生剂对湖泊生态环境...     

The Global Atmospheric Electrical Circuit and Climate

Evidence is emerging for physical links among clouds, global temperatures, the global atmospheric electrical circuit and cosmic ray ionisation. The global circuit extends throughout the atmosphere from the planetary surface to the lower layers of the ionosphere. Cosmic rays are the principal source of atmospheric ions away from the continental boundary layer: the ions formed permit a vertical conduction current to flow in the fair weather part of the global circuit. Through the (inverse) solar modulation of cosmic rays, the resulting columnar ionisation changes may allow the global circuit to convey a solar influence to meteorological phenomena of the lower atmosphere. Electrical effects on non-thunderstorm clouds have been proposed to occur via the ion-assisted formation of ultra-fine aerosol, which can grow to sizes able to act as cloud condensation nuclei, or through the increased ice nucleation capability of charged aerosols. Even small atmospheric electrical modulations on the aerosol size distribution can affect cloud properties and modify the radiative balance of the atmosphere, through changes communicated globally by the atmospheric electrical circuit. Despite a long history of work in related areas of geophysics, the direct and inverse relationships between the global circuit and global climate remain largely quantitatively unexplored. From reviewing atmospheric electrical measurements made over two centuries and possible paleoclimate proxies, global atmospheric electrical circuit variability should be expected on many timescales.     

The effects of small water bodies on the atmospheric heat and water budgets over the MacKenzie River Basin

The effects of small water bodies or lakes on the surface sensible and latent heat fluxes and the transport of heat and water vapour in the atmospheric boundary layer (ABL) over the Mackenzie River Basin (MRB) are studied from two cases, which occurred on 2 and 8 June 1999 during the warm season. The synoptic condition for the cases is representative of about 33% of the synoptic situation over the MRB. The two events are simulated using the Canadian mesoscale compressible community (MC2) model. A one‐way nesting grid approach is employed with the highest resolution of 100 m over a domain of 100 km². Experiments were conducted with (LAKE) and without (NOLAKE) the presence of small water bodies, whose size distribution is obtained through an inversion algorithm using information of their linear dimension determined from aircraft measurement of surface temperature during MAGS (the Mackenzie GEWEX (Global Energy and Water Cycle Experiment) Study) in 1999. The water bodies are assumed to be distributed randomly in space with a fractional area coverage of 10% over the MRB. The results show that, in the presence of lakes, the domain‐averaged surface sensible heat flux on 2 June 1999 (8 June 1999) decreases by 9·3% (6·6%). The surface latent heat flux is enhanced by 18·2% (81·5%). Low‐level temperature advection and the lake surface temperature affect the air–land/lake temperature contrast, which in turn controls the sensible heat flux. In the absence of lakes the surface wind speed impacts the latent heat flux, but in the presence of lakes the moisture availability and the atmospheric surface layer stability control the latent heat flux. The enhancement is smaller on 2 June 1999 as a result of a stable surface layer caused by the presence of colder lake temperatures. The domain‐averaged apparent heat source and moisture sink due to turbulent transports were also computed. The results show that, when lakes are present, heating and drying occur in the lowest 100 m from the surface. Above 100 m and within the ABL, there was apparent cooling. However, the apparent moistening profiles reveal that lakes tend to moisten the ABL through transfer of moisture from the lowest 50–100 m layer. Copyright © 2004 John Wiley & Sons, Ltd.     

长江中下游不同湖泊沉积物中重金属污染物的累积及其潜在生态风险评价

利用富集因子和Hakanson潜在生态风险指数法,结合年代学结果,对长江中下游湖泊太白湖、龙感湖、巢湖和西氿沉积物中重金属元素Co、Cr、Cu、Ni、Pb、Zn的富集程度进行了评价,并比较分析了上述重金属的潜在生态风险.结果表明,太白湖和龙感湖沉积物中各重金属富集程度均较低;巢湖沉积物中Co、Cr、Ni的富集程度接近中等水平,而Cu、Pb、Zn的富集已经达到中等水平;西氿沉积物中Co的富集非常低,Cr、Ni富集水平较低,Pb达到中等富集,Cu、Zn达到较高的富集水平.对4个湖泊沉积物中重金属的综合污染程度进行比较:巢湖西氿龙感湖太白湖.各湖泊沉积物中单一元素的潜在生态风险都较低,但是,根据多元素潜在生态评价指数,各湖泊沉积物中重金属存在明显不同的潜在生态风险:巢湖西氿龙感湖太白湖.总体上看,太白湖和巢湖沉积物重金属污染以及潜在生态风险自1965年以来一直在加重,而龙感湖和西氿沉积物在表层有下降的趋势.这种差异与各个湖泊流域内人类活动的方式和强度密切相关.巢湖和西氿流域内城市化、工业化发展迅速,人类活动导致大量重金属元素进入湖泊,给湖泊带来明显的污染;而龙感湖和太白湖流域人类活动主要以农业活动为主,人类活动对重金属的贡献相对较小.