Current and future impacts of ultraviolet radiation on the terrestrial carbon balance

One of the most documented effects of human activity on our environment is the reduction of stratospheric ozone resulting in an increase of biologically harmful ultraviolet (UV) radiation. In a less predictable manner, UV radiation incident at the surface of the earth is expected to be further modified in the future as a result of altered cloud condition, atmospheric aerosol concentration, and snow cover. Although UV radiation comprises only a small fraction of the total solar radiation that is incident at the earth’s surface, it has the greatest energy per unit wavelength and, thus, the greatest potential to damage the biosphere. Recent investigations have highlighted numerous ways that UV radiation could potentially affect a variety of ecological processes, including nutrient cycling and the terrestrial carbon cycle. The objectives of the following literature review are to summarize and synthesize the available information relevant to the effects of UV radiation and other climate change factors on the terrestrial carbon balance in an effort to highlight current gaps in knowledge and future research directions for UV radiation research.     

世界地质公园旅游地生命周期影响因素及演变机制——以兴文石海为例

通过使用Butler旅游地生命周期理论,以兴文石海世界地质公园开发最早园区一石海洞乡为研究对象,对景区进行旅游地生命周期划分。同时结合问卷调查数据分析影响该旅游地生命周期演变的主、次因素,以及两者在各阶段的具体演化对旅游地发展的作用,阐明景区主导因素演变机制。研究认为石海洞乡经历了探索期、参与期,现阶段处于发展期,其主导因素分别为：探索期为当地群众,参与期为上级政府、高层官员与专家学者,发展期为当地政府与投资企业。     

测井信息用于层序地层单元划分及对比研究综述

测井曲线是载有地层沉积旋回信息的信号,运用测井信息划分层序地层单元及地层对比研究自开始以来已取得了长足进步,从定性的分析、识别发展到现在可半定量、定量提取不同级别的沉积单元界面及进行层序地层对比,更进一步克服了地质学家手工划分层序中人为因素的影响,进而也推进了层序地层学研究的定量化发展。岩性突变、沉积韵律是影响其测井响应及曲线形态的两个重要因素,测井响应对沉积单元界面上下岩性的类型及粒度的不同而产生的声、放、电性质的变化,是利用测井信息划分沉积单元界面的基础。随着层序地层学研究的深入,沉积单元界面识别及层序地层对比的测井研究将向更深层次、更定量化的方向发展,短周期及超短周期沉积旋回的测井曲线形态内部特征提取及划分、层序地层智能动态匹配对比的方法研究将是今后开展研究的新方向。     

陕甘宁盆地坳陷型湖盆缓坡带三角洲前缘短期基准面旋回与储层成因分析

运用高分辨率层序地层的短期基准面旋回原理,对发育于陕甘宁盆地城华地区长 3油层组缓坡带上的三角洲前缘的储集砂体进行细致分析,按成因将储层砂体详细划分为三大类 6种类型,而这几种类型砂体的成因明显受基准面升降、可容纳空间 (A)和沉积物补给量 (S)之间变化关系两方面的影响。在基准面上升过程中,A/S<1时,以截削式河道砂体为主,A/S >1时,则为完整式河道砂体;在基准面下降过程中,A/S <1时,以孤立式河口坝砂体为主,A/S>1时,则以叠加式河口坝和远砂坝砂体为主;在水下坡折带沉积区,则为复合式坝砂体。基准面升降过程中,短期基准面旋回的规律性变化,影响着不同成因砂体的分布,据此建立了坳陷型湖盆缓坡带三角洲前缘不同砂体类型的成因分布模式     

Tracing anthropogenically driven groundwater discharge into a coastal lagoon from southern Brazil

We investigated the distribution of naturally occurring geochemical tracers (²²²Rn, ²²³Ra, ²²⁴Ra, ²²⁶Ra, CH₄, δ¹⁸O, and δ²H) in the water column and adjacent groundwater of Mangueira Lagoon as proxies of groundwater discharge. Mangueira Lagoon is a large (90 km long), shallow (4–5 m deep), fresh, and non-tidal coastal lagoon in southern Brazil surrounded by extensively irrigated rice plantations and numerous irrigation canals. We hypothesized that the annual, intense irrigation for rice agriculture creates extreme conditions that seasonally change groundwater discharge patterns in the adjacent lagoon. We further supposed that dredging of irrigation canals alters groundwater fluxes.

While the activities of ²²²Rn in shallow groundwater were 2–3 orders of magnitude higher than in surface water, CH₄ and radium isotopes were only 1 order of magnitude higher. Therefore, ²²²Rn appears to be the preferred groundwater tracer in this system. Radon concentrations and conductivities were dramatically higher near the pump house of rice irrigation canals, consistent with a groundwater source. Modeling of radon inventories accounting for total inputs (groundwater advection, diffusion from sediments, and decay of ²²⁶Ra) and losses (atmospheric evasion, horizontal mixing and decay) indicated that groundwater advection rates in the irrigation canals (25 cm/d) are over 2 orders of magnitude higher than along the shoreline (0.1 cm/d). Nearly 75% of the total area of the canals is found in the southern half of the lagoon, where groundwater inputs seem to be higher as also indicated by methane and stable isotope trends. In spite of the relatively small area of the canals, we estimate that they contribute nearly 70% of the total (57,000 m³/d) groundwater input into the entire Mangueira Lagoon. We suggest that the dredging of these canals cut through aquitards which previously restricted upward advection from the underlying permeable strata. The irrigation channels may therefore represent an important but previously overlooked source of nutrients and other dissolved chemicals derived from agricultural practices into the lagoon.     

Links between global CO<Subscript>2</Subscript> variability and climate anomalies of biomes

The global rate of fossil fuel combustion continues to rise, but the amount of CO₂ accumulating in the atmosphere has not increased accordingly. The causes for this discrepancy are widely debated. Particularly, the location and drivers for the interannual variability of atmospheric CO₂ are highly uncertain. Here we examine links between global atmospheric CO₂ growth rate (CGR) and the climate anomalies of biomes based on (1986–1995) global climate data of ten years and accompanying satellite data sets. Our results show that four biomes, the tropical rainforest, tropical savanna, C₄ grassland and boreal forest, and their responses to climate anomalies, are the major climate-sensitive CO₂ sinks/sources that control the CGR. The nature and magnitude by which these biomes respond to climate anomalies are generally not the same. However, one common influence did emerge from our analysis; the extremely high CGR observed for the one extreme El Niño year was caused by the response of the tropical biomes (rainforest, savanna and C₄ grassland) to temperature.     

Wave characteristics and tectonic-sedimentation evolution of foreland thrust fault of Micang Mountain

In this paper,the technology of wave process method for sedimentation is first adopted in the research of the foreland thrust fault of Micang Mountain with respect of oil and reservoir’s formation and tectonic and sedimentary evolution. From the fluctuation characteristics,we could make conclusions in the foreland thrust belt of Micang Mountain that,there existed 2 first-order sedimentary cycles (220 Ma),corresponding to Caledonian-Hercynian and Indo-Chinese-Yanshan-Himalayan tectonic cycles respec-tively; there existed 4 second-order sedimentary cycles (10 Ma),corresponding to two sedimentation peak period and two denudation peak periods in research zone; there existed 12 third-order sedimen-tary cycles (35 Ma) and 21 fourth-sedimentary cycles (20 Ma). These 33 cycles in the research zone corresponded to the sedimentation-denudation process in different periods,furthermore,their fluctua-tion characteristics bore the genetic relationship with the development law of source,reservoir and cap rocks: the source rock had the tendency to develop at the turning part between wave crest and wave trough,or at the superposition of wave turning part in different periods,presenting like "X"; most res-ervoir rocks developed at the place of wave peak; the development of cap rock was located in the wave trough on the right of sedimentation-denudation datum line. As a result,through the application of wave process method for sedimentation,we could rediscover the understanding of the tectonic and sedimentary evolution from another prospective,meanwhile,it enables to make prediction about the development rule of source,reservoir and cap rocks,which means a significant importance to the re-search of oil and reservoir’s forming condition.     

Behavior of Cu, Ni and Cd during nutrient depletion in a spring bloom in Funka Bay

The concentrations of Cu, Ni and Cd were determined in Funka Bay during a spring phytoplankton bloom, consisting of diatoms. Just after the bloom, both dissolved Cd and nutrients were removed in the euphotic zone. However, the removal ratio of Cd to phosphate was very different from that in seawater. The removal of Cd took place at a Cd/phosphate ratio of 0.07×10⁻³, which was lower than in seawater before the bloom (0.25×10⁻³), leading to an increase in this ratio in seawater exceeding 0.7×10⁻³ at the end of the bloom. Elevated concentrations of Cd and phosphate were observed in the deeper layer after the bloom due to the decomposition of detrital materials produced in the bloom. The ratio of Cd/phosphate in the regeneration step was 0.24×10⁻³ which was different from the removal ratio of 0.07×10⁻³. These observations suggest that the high Cd/phosphate ratio in the regeneration would reflect a relatively high regeneration rate of Cd than that of phosphate. No significant decrease in Cu and Ni concentrations was observed during the development of the bloom, suggesting that biological removal of these metals was not so significant during the spring bloom. The concentrations of Cd, Cu and silicate in surface waters increased after the bloom with decreasing salinity due to the influence of a spring thaw.     

杭州湾沿岸平原晚第四纪沉积特征和沉积过程

本文采用层序地层学基本原理,以海平面升降旋回为主线,根据３００口钻井,静力触探井和分析化验等资料。探讨了杭州湾地区晚第四纪地层层序,沉积特征,控制沉积的主要地质作用及沉积层的形成过程。结果表明,该区晚第四纪地层底界面为区域不整合面,是末次冰期海面下降时形成的。     

Palaeoclimatic cycles, global environmental changes and new glacial periods induced by the impact of extraterrestrial bodies

In terms of Earth-Sun geometry, the Milankovitch theory has successfully explained most of the cyclic palaeoclimatic variations during the history of the Earth, especially in the Quaternary. In this paper, the authors suggest that the impact of extraterrestrial bodies on the Earth may be another mechanism to cause palaeoclimatic cycles, global environmental changes and new glacial periods. Based on geological and geochemical records in the boundary layers produced by six huge Cenozoic bolide-impact events (65, 34, 15, 2.4, 1.1, 0.73 Ma B.P.), including those at 34, 15, 1.1 and 0.73 Ma B. P. which are represented by four famous tektite-strewn fields, the process and mechanics of palaeoclimatic cycles and global environmental catastrophes induced by extraterrestrial impact are discussed in detail. Impact-generated dust, soot and aerosol floating in the stratosphere could result in short-term (<1 year), rapid drop in temperature immediately after impact. Through self-regulation of the Earth’s climate system, the temperature at the surface slowly went up within 100a and maintained stable for a long time at 250K. If there were no other factors leading to the break-down of the newly-established equilibrium, a new glacial pound would be initiated. Estimating from the thickness of δ¹³C and δ¹⁸O anomalies in sediments across the impact boundary layer and deposition rate, the duration of two stages of the palaeoclimate cycle in the form of cold weather—greenhouse effect—normal weather was 10⁴ – 10⁵a, respectively. The conclusion deduced from the above model is supported by palaeotemperature change recorded by oxygen isotope in sediments across the impact boundary layer. The study was granted by the Scientific and Technological Bureau of Resources and Environment, Chinese Academy of Sciences (KZ952-J1-031) and the National Natural Science Foundation of China.