旅游活动对洞穴环境的影响及洞穴的自净能力研究——以重庆雪玉洞为例

洞穴空气中的CO2对洞穴次生化学沉积物的沉积和溶蚀有重要的影响.文中基于2010-09-30- 10-08对重庆雪玉洞洞穴CO2浓度、温湿度进行的为期8d的连续监测,并结合“十一”黄金周期间的客流量进行综合分析.结果发现:(1)受旅游活动的影响,洞穴内空气CO2浓度有明显的累积效应;温度变化幅度加大,但没有累积效应;由于地下河和滴水的影响,洞内空气相对湿度一直处于过饱和状态,这是温度没有形成累积效应的一个重要原因.(2)由于洞内外温差的影响,洞口处会形成由洞内向洞外流动的气流,使得近洞口处的空气CO2浓度     

肇庆七星岩风景名胜区开发演变及其规划整治

肇庆七星岩景区作为国内著名的风景名胜区,正面临着生态景观危机.研究显示:七星岩景区的开发演变历经了从1955年前的天然公园,到1956-1978年的农林水利风景区,到1979年后的国家风景名胜区,到近年向城市公园演变的趋势;周边开发程度的不断加强,导致目前风景区存在土地、水面被侵占,水质下降和景观视线遭到破坏等诸多问题.文中提出了景区生长的规划整治策略,即根据肇庆山水城市环境特点,利用古河道, 结合新城市建设,让七星岩景区向东、西向延伸和生长,从而改善景区的环境和景观质量,并提升未来整个肇庆城区的生态     

辽宁暖和洞石笋δ13C对全新世气候变化的生态响应

基于辽宁暖和洞年层石笋NH5的7个230 Th年龄和962个碳同位素数据,建立了10.6～3.5kaBP时段全新世气候及生态演化的δ13 C序列,其长期演化趋势与北大西洋海表温度变化基本一致。该记录表明,10.6～8.8kaBP,δ13 C值逐渐负偏,由-9.4‰降至-10.3‰,气候逐渐转暖湿;8.8～6.7kaBP,δ13 C值负偏显著,平均值为-11.3‰,此时,气候温暖湿润,对应于全新世适宜期,纹层计数显示其持续时间约为1 945a;6.7～3.5kaBP,δ13 C值显著正偏,由-11.3‰升至-8.3‰,干旱化趋势明显。石笋δ18 O时间序列显示出相似的变化趋势。在6.7kaBP前后,δ13 C、δ18 O均快速正偏,纹层计数显示约在40a内完成气候由暖湿到冷干的突变转型,可能是由于北大西洋海表温度降低和植被-大气系统的反馈作用对太阳辐射减少具有放大效应。     

Palaeoenvironmental evolution of Cenote Aktun Ha (Carwash) on the Yucatan Peninsula,Mexico and its response to Holocene sea-level rise

A 61-cm core was obtained from 4 m below the water table in Cenote Aktun Ha, on the Yucatan Peninsula, Mexico. The cenote is 8.6 km from the Caribbean coast and its formation and evolution have been largely affected by sea-level change. The base of the core dates to 6,940–6,740 cal year BP and overlying sediments were deposited rapidly over the subsequent ~200 years. The pollen record shows that the cenote evolved from a marsh dominated by red mangrove (Rhizophora mangle) and fern (Polypodiaceae) to an open-water system. These vegetation changes were controlled by water level and salinity and are thus useful indicators of past sea level. At the base, the δ¹³C_org isotopic ratios reveal the influence of terrestrial vegetation (−29‰ VPDB), but shift to more negative values up-core (−33‰), indicating an influence from particulate matter in the flooded cenote pool. Although microfossil populations were nearly absent through most of the core, the microfossil assemblage in the upper 6 cm of the core is dominated by the juvenile foraminifer Ammonia tepida and the thecamoebian genus Centropyxis. These populations indicate open-water conditions in the cenote and a major environmental shift around 6,600 cal year BP, which is related to sea-level rise in the Caribbean basin. These data fit well with previously established sea-level curves for the Caribbean Sea. Our reconstruction of the environmental history of Cenote Aktun Ha helps elucidate the floral and hydrological history of the region, and highlights the utility of cenote sediments for studying the Holocene sea-level history of the Caribbean Sea.     

An exceptionally strengthened East Asian summer monsoon event between 19.9 and 17.1 ka BP recorded in a Hulu stalagmite

A stalagmite-based isotope record (No. H82) from Nanjing Hulu Cave, spanning from 16.5 to 10.3 ka BP, provided strong evidence for a coherence relation between the East Asian summer monsoon (EASM) and the North Atlantic climates on millennial time scales. Here we extend the high-resolution δ 18O time series back to 22.1 ka BP with additional 7 230Th dates and 573 stable isotope measurements on the lower part of that sample. The new record with a decadal resolution, piecing together with the previous data, p...     

连通域标识法在FMI图像溶洞信息定量拾取中的应用

溶蚀孔洞在碳酸盐岩储层中是重要的流体储集空间,研究成像测井(FMI)图像孔洞连通域标记及信息定量拾取很有意义.全井眼微电阻率成像测井(FMI)经数据处理后可得到全井壁高分辨率的彩色图像,经图像灰度化、中值滤波处理后,通过阈值分割得到能够反映井壁溶蚀孔洞特征的二值图像,孔洞表现为黑色暗斑.基于等价对处理的图像连通域标记算法具有快速、不重复标记的优点,利用该算法,可准确地从二值图像中标记溶蚀孔洞连通域,进而可对每个连通域进行目标信息拾取,包括孔洞尺寸、连通域面积、圆度等.利用反映溶蚀孔洞发育程度的面孔率曲线对图像进行分层,在此基础上可拾取每一层段溶蚀孔洞面孔率、分选系数及溶洞密度值的分布等非均质信息,能够定量地评价溶蚀孔洞发育、非均质性强的碳酸盐岩储层,也是FMI图像应用于岩石孔洞结构信息定量表征新的尝试.     

Shared microsporidian profiles between an obligate (Niphargus) and facultative subterranean amphipod population (Gammarus) at sympatry provide indications for underground transmission pathways

Only sparse knowledge exists on amphipod-infecting microsporidians in subterranean waters. Here, we DNA barcoded two sympatric amphipod populations (obligate subterranean Niphargus schellenbergi, facultative Gammarus fossarum) and their microsporidian parasites. Parasite prevalence was assessed by diagnostic PCR assays. Overall prevalence was 82.7 %. Both amphipod populations shared all four identified parasite species (Nosema granulosis, Microsporidium sp. I, Orthosomella sp., Microsporidium sp. BPAR3). Hence, we postulate underground transmission pathways of microsporidians mediated by subterranean amphipod hosts.     

北京石花洞石笋微层层面有机物质的形成时间及机理初探

通过对北京石花洞滴水水溶性有机碳(DOC)近一个水文年的观测,发现不同点滴水DOC浓度均表现出明显的季节性变化,7月中旬均有一个大的主峰出现。初步说明中国北方石笋微层的层面物质沉积于7月雨季,主要来源于大的雨量对土壤中有机质的淋溶;洞穴顶板较薄的滴水点在5月和8月有明显的DOC次峰,可能与石笋亚年层形成有关。     

Insights into Wasatch fault vertical slip rates using the age of sediments in Timpanogos Cave, Utah

Timpanogos Cave, located near the Wasatch fault, is about 357 m above the American Fork River. Fluvial cave sediments and an interbedded carbonate flowstone yield a paleomagnetic and U–Th depositional age of 350 to 780 ka. Fault vertical slip rates, inferred from calculated river downcutting rates, range between 1.02 and 0.46 mm yr^− 1. These slip rates are in the range of the 0–12 Ma Wasatch Range exhumation rate ( 0.5–0.7 mm yr^− 1), suggesting that the long-term vertical slip rate remained stable through mid-Pleistocene time. However, the late Pleistocene (0–250 ka) decelerated slip rate ( 0.2–0.3 mm yr^− 1) and the accelerated Holocene slip rate ( 1.2 mm yr^− 1) are consistent with episodic fault activity. Assuming that the late Pleistocene vertical slip rate represents an episodic slowing of fault movement and the long-term (0–12 Ma) average vertical slip rate, including the late Pleistocene and Holocene, should be  0.6 mm yr^− 1, there is a net late Pleistocene vertical slip deficit of  50–75 m. The Holocene and late Pleistocene slip rates may be typical for episodes of accelerated and slowed fault movement, respectively. The calculated late Pleistocene slip deficit may mean that the current accelerated Wasatch fault slip rate will extend well into the future.     

芙蓉洞洞穴水离子浓度和元素比值变化特征及其环境意义

通过对芙蓉洞2006年3月—2009年2月期间泉水和洞穴滴水、池水的地球化学指标监测,结合当地的器测数据,初步认为洞穴滴水的Sr2+、Ca2+、Mg2+浓度及其比值既取决于环境降水和温度的变化,也受到上覆岩土作用的影响。芙蓉洞外山上的6#泉水Ca2+平均浓度为45.81mg/L,洞内1#、3#滴水Ca2+的平均浓度64.59mg/L,2#和4#池水中由于Ca2+沉积,浓度下降到24.74mg/L,下降了大约61.7%。Mg2+和Sr2+的浓度在泉水、滴水和池水中的变化规律与Ca2+基本一致。各种水体中Cl-的浓度变化幅度较小,平均浓度为1.72±0.2mg/L。岩溶水与基岩作用时间长短以及运移过程中Ca2+的前期沉积作用对各元素与离子含量变化具有重要作用。旱季Ca2+的前期沉积作用和雨季基岩的溶蚀及雨水的稀释作用主导着岩溶水中Mg/Ca与Sr/Ca的变化,这些指标能对干旱和洪涝等极端气候事件做出响应。