天津地区新近系地热回灌井不同完井工艺应用效果对比

针对新近系地层国内外普遍存在回灌效率低的问题,通过对滤水管和射孔两种不同完井工艺对回灌效果的影响入手,开展两种完井工艺地热回灌的试验研究。研究表明,在地层沉积环境和地层参数相同的情况下,射孔完井工艺回灌量大,回灌持续性好,不易产生堵塞,比滤水管完井工艺效果显著,对提高新近系地热回灌井的回灌效率具有明显的促进作用。     

鄱阳湖地区晚更新世古环境变迁

晚更新世期间鄱阳湖北部地区,九江、湖口、彭泽一带发育风沙-黄土-湖沼相交互地层序列。本文通过对该序列5个露头剖面多环境代用指标分析,研究了该地区晚更新世环境变迁和季风变化过程。研究表明:约147-129.6kaBP,以较强的冬季风控制的气候为主,季风降水很少,气候偏冷干;129.6-76kaBP,早期,夏季风逐渐增强,至120kaBP后,夏季风进入强盛阶段,103kaBP后,夏季风较弱,97kaBP后,夏季风又一次增强,这一时段内古气候阶段性非常清楚,早中期暖湿程度较高,后期较弱,在暖湿的背景上存在110-106、103-92kaBP等冷事件;76-55kaBP,为强盛的冬季风时期,气候冷干;55-25kaBP,夏季风又一次增强,气候温暖湿润,中间有冷波动;25-16kaBP,气候变冷干,后期冬季风有所减弱;16kaBP后,夏季风明显增强,气候变温湿,13.0kaBP后,气候有变干的趋势.      

Constraints on water chemistry by chemical weathering in the Lake Qinghai catchment, northeastern Tibetan Plateau (China): clues from Sr and its isotopic geochemistry

Lake water, river water, and groundwater from the Lake Qinghai catchment in the northeastern Tibetan Plateau, China have been analyzed and the results demonstrate that the chemical components and ⁸⁷Sr/⁸⁶Sr ratios of the waters are strictly constrained by the age and rock types of the tributaries, especially for groundwater. Dissolved ions in the Lake Qinghai catchment are derived from carbonate weathering and part from silicate sources. The chemistry of Buha River water, the largest tributary within the catchment, underlain by the late Paleozoic marine limestone and sandstones, constrains carbonate-dominated compositions of the lake water, being buffered by the waters from the other tributaries and probably by groundwater. The variation of ⁸⁷Sr/⁸⁶Sr ratios with cation concentrations places constraint on the Sr-isotopic compositions of the main subcatchments surrounding Lake Qinghai. The relative significance of river-water sources from different tributaries (possibly groundwater as well) in controlling the Sr distribution in Lake Qinghai provides the potential to link the influence of hydrological processes to past biological and physical parameters in the lake. The potential role of groundwater input in the water budget and chemistry of the lake emphasizes the need to further understand hydrogeological processes within the Lake Qinghai system.     

Sanmenxia Loess and Paleoenvironmental Change

INTRODUCTIONThe Sanmenxia area is located at the SE marginof the Loess Plateau,where a thick-layered loess de-posit developed(Fig.1).Previous research has al-ready been carried out on some loess stratigraphy inthe area(Teng,1988;Xie and Jiang,1987;Yue,1985,1984),which concentrated on petrostratigra-phy and magnetostratigraphy.Further environmentalinvestigation has not yet been pursued.After the ge-ological survey(Zheng et al.,1992;An et al.,1989;Ding and Liu,1989),more integrated str…     

Evidence from isotopic geochemistry as an indicator of eutrophication of Meiliang Bay in Lake Taihu,China

In this paper, Lake Taihu, a large shallow freshwater lake in China, is chosen as an example of reconstruction of eutrophication through the comparison between stable isotopes from dissolved nutrients and plants and water column nutrient parameters and integration of multiple proxies in a sediment core from Meiliang Bay including TN, TP, TOC, C/N, δ ¹⁵N, δ ¹³C, etc. Differences in aquatic plant species and trophic status between East Taihu Bay and Meiliang Bay are indicated by their variations in δ ¹³C and δ ¹⁵N of aquatic plants and δ ¹⁵N of NH₄ ⁺. A significant influence of external nutrient inputs on Meiliang Bay is reflected in temporal changes in δ ¹⁵N of NH₄ ⁺ and hydro-environmental parameters. The synchronous change between δ ¹³C and δ ¹⁵N values of sedimented organic matter (OM) has been attributed to elevated primary production at the beginning of eutrophication between 1950 and 1990, then recent inverse correlation between them has been caused by the uptake of ¹⁵N-enriched inorganic nitrogen by phytoplankton grown under eutrophication and subsequent OM decomposition and denitrification in surface sediments, indicating that the lake has suffered from progressive eutrophication since 1990. Based on the use of a combination of stable isotopes and elemental geochemistry, the eutrophication of Meiliang Bay in Lake Taihu could be better traced. These transitions of the lake eutrophication respectively occurring in the 1950s and 1990s have been suggested as a reflection of growing impacts of human activities, which is coincident with the instrumental data.

     

岱海湖泊沉积物频率磁化率对历史时期环境变化的反映*

在探讨封闭湖泊沉积物频率磁化率的环境意义的基础上,根据岱海DH₃₂孔湖泊沉积物磁化率的测量结果,结合粒度、孢粉、历史资料和硅藻分析结果,对岱海历史时期的环境变化进行了探讨。研究认为:历史时期内陆封闭湖泊沉积物频率磁化率高值段指示气候偏湿阶段;低值段指示气候干旱阶段;DH₃₂孔湖泊沉积物频率磁化率反映的近300年来岱海气候变化可划分七个阶段,并与粒度、孢粉、硅藻和历史资料的分析结果基本一致。湖泊沉积物频率磁化率是恢复历史时期环境变化的重要环境指标之一。     

A high-resolution climatic change since the Late Glacial Age inferred from multi-proxy of sediments in Qinghai Lake

The study of climatic changes since the Late Glacial Age has become one of the hotspots of the PAGES in recent years.Deep-sea cores from the high-latitude area show that the climate was very unstable during the transitional period from the Late Glacial Age to the Holocene[1,2],which has also been testified by the geological records from ocean sediments,ice cores and terrestrial sections in different latitudes of the earth[3—8].What’s more,climatic instability also ex-isted in the Holoce…     

九江—澎泽一带沙山研究存在问题探讨

依据ＴＬ和＾１４Ｃ测年数据及各项环境指标分析，对九江－红光澎泽一带沙册剖面进行了研究和对比，讨论了１４７ｋａＢ．Ｐ．至晚冰期的年代地层序列和古气候环境，同时对沙山在、古湖沼形机制进行了深入探讨。该区沙山地貌并非新的构造运动所致，属差异侵蚀作用的结果，泥炭层由风积地区沙丘间湖沼沉积形成。     

近8kaBP来云南洱海地区气候演化的有机碳稳定同位素记录

根据洱海湖泊沉积有机碳稳定同位素记录,结合硅藻分析资料,恢复了近８ｋａ来云南洱海地区的气候演化序列。结果表明：８．１ｋａＢ．Ｐ．来的气候演化分为９个阶段,伴随湖泊水位波动变化。     

Molecular structure parameters and thermal stabilities of benzocarbazoles

The distance between 4-H and adjacent H on the substitutional benzene ring in benzo[c]carbazole was calculated in terms of molecular structure parameters. The result showed that the distance is shorter than the sum of van der Vaals＇ radii of two hydrogen atoms. This means that there is a steric hinderance between them. This effect will make the bond angle stretch and the bond length extend, or cause the molecule to distort, thus making benzo[c]carbazoles become unstable in thermodynamics. On the contrary there is no such effect for benzo[a]carbazoles. This conclusion has been confirmed by the result of calculation of the distance between the same two atoms with software GaussView. So the skeleton of benzo[c]carbazoles in sediments may be breached or isomerized with increasing maturity. It is consistent with the decrease of the ratio of benzo[c]carbazole to benzo[a]carbazole in hydrocarbon migration, suggesting that [c]/[a] not only changes with the distance of migration, but also may be influenced by maturity.