长江口盐沼土壤有机质分布与矿化的空间差异

在长江口崇明东滩两类植被(互花米草、土著植被)区域分别选择一条纵向剖面,在高潮滩、中潮滩及光滩取得柱状样,利用颗粒有机碳(POC)含量、碳稳定同位素组成、土壤C/N比与颗粒组成等资料,研究盐沼有机质的分布与矿化特征。结果表明,两个纵向剖面的相同高程部位柱样之间,颗粒有机碳δ13C与POC含量的深度特征均存在显著差异;两个柱样的δ13C与POC含量的平均值均相差较大。互花米草对高潮滩柱样有机质的含量与组成均产生了明显影响,对中潮滩柱样有机质组成已有一定影响;土著植被对高潮滩柱样有机质组成的影响显著。盐沼植被对土壤有机质的分布与矿化均产生了明显影响。高潮滩柱样矿化阶段不同的有机质组分混杂,中潮滩柱样有机质的组成相对简单,矿化程度较弱。柱样粘粒含量与含水量在垂向上变化频繁,盐沼原始沉积层序对柱样的物质分布特征具有本底制约。不同高程部位柱样之间,有机质的深度分布特征以及矿化程度差异显著,盐沼碳动态受到潮滩特征性动力沉积过程的显著影响。     

长江口盐沼滩面发育对有机碳深度分布的制约

通过对长江口崇明东滩高潮滩、中潮滩以及光滩柱状样的有机碳含量与碳稳定同位素组成（δ13C）、粒度组成等的测定,研究盐沼有机碳深度分布特征与形成机制。结果表明,盐沼土壤颗粒有机碳（POC）主要赋存于粒径小于0.016 mm的颗粒中,POC含量对粒径在0.002~0.004 mm区间的颗粒含量变化最敏感,说明盐沼POC主要来自长江径流悬移质,这与有机碳稳定同位素结果一致。土壤POC含量与不同粒径区间颗粒含量相关关系表明,高潮滩与中潮滩柱样的泥沙级配较为接近;光滩柱样POC含量与不同粒径区间颗粒含量相关关系特征与高、中潮滩柱样的基本类似,主要不同表现在粒径大于0.016 mm的粗颗粒,这很可能受控于盐沼不同高程部位动力沉积过程。盐沼植被对高、中潮滩柱样POC的贡献相当可观,个别层段高达55.6%;植被对土壤POC的贡献受到滩面过程的明显制约。滩面动力沉积过程形成盐沼垂向上独特的沙、泥纹层构造,其优良的封堵效能显著影响土壤有机碳的垂向分布。盐沼滩面动力沉积过程是塑造有机碳深度分布特征的关键因素。     

An Experimental Evaluation of Dock Shading Impacts on Salt Marsh Vegetation in a New England Estuary

Docks constructed over salt marsh can reduce vegetation production and associated ecosystem services. In Massachusetts, there is a 1:1 height-to-width ratio (H:W) dock design guideline to reduce such impacts, but this guideline’s efficacy is largely untested. To evaluate dock height effects on underlying marsh vegetation and light availability, we deployed 1.2-m-wide experimental docks set at three different heights (low (0.5:1 H:W), intermediate (1:1 H:W), and high (1.5:1 H:W)) in the high and low marsh zones in an estuary in Massachusetts, USA. We measured temperature, light, vegetation community composition, and stem characteristics under the docks and in unshaded control plots over three consecutive growing seasons. Temperature and light were lower under all docks compared with controls; both increased with dock height. Maximum stem height and nitrogen content decreased with available light. In the Spartina patens-dominated high marsh, stem density and biomass were significantly lower than controls under low and intermediate but not high docks. Spartina alterniflora, the dominant low marsh vegetation, expanded into the high marsh zone under docks. S. alterniflora aboveground biomass significantly differed among all treatments in the low marsh, while stem density was significantly reduced for low and intermediate docks relative to controls. Permit conditions and guidelines based on dock height can reduce dock impacts, but under the current guideline of 1:1 H:W, docks will still cause significant adverse impacts to vegetation. Such impacts may interfere with self-maintenance processes (by decreasing sediment capture) and make these marshes less resilient to other stressors (e.g., climate change).     

Redox Chemistry in the Root Zone of a Salt Marsh Sediment in the Tagus Estuary,Portugal

Measurements of O₂, Fe(II), Mn(II)and HS₅ in salt marshsediments in the Tagus Estuary, Portugal, made with a voltammetric microelectrode, reveal strong seasonal differences in pore water composition within the 20~cm deep root zone. In spring, oxygen was below detection limit except close to the sediment surface. Fe(II) was present below 5 cm in concentrations ranging from detection limit to 1700 M. In summer, oxygen was present in the pore water almost to the bottom of the root zone in concentrations ranging from detection limit to more than 100 M. The spatial variability was intense: O₂ concentrations as high as 78 M and as low as 25 M existed within 2~mm of each other. Fe(II) was below detection limit except towards the bottom of the root zone. In late fall, oxygen was found to 8 cm depth, but in concentrations lower than in summer, and Fe(II) was present below 9 cm. Mn(II) was found at levels declining from typical values of 200 M in spring to less than 20 M in late fall. With one exception, sulfide was below the detection limit in all measurements. During periods when dissolved Fe(II) is available in the pore water at the same time as ₂ is delivered by roots, iron-rich concretions can form on roots. These conditions, which lead to precipitation of iron oxide in the sediment adjacent to roots, exist in spring, when new roots infiltrate anoxic Fe(II) containing sediment. They do not exist in summer, when dissolved Fe(II) is unavailable, or in winter, when oxygen is unavailable. The seasonal redox pattern revealed by the pore water chemistry is driven by the annual cycle of growth and decay of roots.     

Influence of Physical Manipulations on Short-Term Salt Marsh Morphodynamics: Examples from the North and Mid-Atlantic Coast,USA

Along the mid- and north Atlantic coasts of the USA, over 90 % of salt marshes have been ditched. Ditching was largely abandoned by the mid-twentieth century; however, techniques that create permanent shallow water pools for mosquito control and bird habitat are increasingly being applied to marshes of the USA and elsewhere. Salt marshes in Plum Island Sound, Massachusetts, and Barnegat Bay, New Jersey, were used to examine differences between areas that have been ditched and those altered to increase the density of shallow pools in water table dynamics, salinity, soil and porewater chemistry, as well as short-term sedimentation, accretion, and elevation change rates. We found that the area with plugged ditches, berms, and pools in Plum Island had less drainage, higher salinity and porewater sulfide and ammonium concentrations, and higher soil organic matter than the adjacent ditched area. Despite averaging 8 cm lower in elevation, the Plum Island ditched area had less sediment deposition and was composed of higher elevation plant species than the area with plugged ditches, berms, and shallow pools. Elevation increased in the ditched area at a rate of 3.2 ± 0.5 mm/year, but elevation change was variable in the area with pools. In Barnegat Bay, the marsh area with pools and ditches had less sediment deposition and surface accretion than the ditch-only area, associated, in part, with the higher elevation. An average elevation difference of 4.5 cm was associated with a sixfold difference in mineral sediment deposition. Temporal sediment deposition and surface accretion was important in the ditch-only area but was absent or muted in the area with numerous pools. Elevation increased in both marsh areas at an average rate of 1.8 ± 0.8 mm/year, less than half the long-term average local rate of sea-level rise. Our results illustrate how physical manipulations including changes to tidal hydrology and surface topography interact with elevation to influence short-term biophysical feedbacks.     

长江口可能最高潮位研究

以长江口高桥站为研究对象,根据历史资料,用经验分析和统计结合起来的方法,建立风暴潮增水模式,依据流体动力学原理建立二维风暴潮天文潮综合水位模式,尔后以极值气象因子为基础,利用因子组合法及台风位移法分别设计极端台风模型,推算高桥站最大增水及可能最高潮位,并以水文统计频率分析成果作为研究确定长江口ＰＭＴ的佐证。     

The Air-Coastal Sea Chemical Exchange: A Case Study on the New Jersey Coast

The coastal marine atmosphere adjacent to large urban and industrial centers is in general strongly impacted by pollution emissions, resulting in high loading of pollutants in the ambient air. Among the airborne substances are certain trace elements from a variety of emission sources that can serve as micronutrients to marine organisms in coastal waters. High concentrations of such elements in coastal air can result in enhanced air-to-sea deposition fluxes to coastal waters. They could also be transported over the open ocean, affecting the composition of the remote marine atmosphere and then ocean ecosystems. To provide better understanding of the extent of air-to-sea deposition processes on the New Jersey coast, a heavily polluted coastal region on the US East Coast, a synthesis of observation data was carried out for selected trace elements, including Fe, Cd, Cr and Cu, derived from measurements of both size-segregated and bulk aerosol particles, as well as precipitation around the New Jersey coast. The atmospheric input of Hg was also estimated based on measurement data. Results indicated that the total deposition fluxes of most trace elements were higher in Northern coastal NJ compared to Southern coastal NJ, reflecting the differences in the source strengths of these element emissions between the two coastal regions. Dry deposition processes were more significant for common dust-derived elements, particularly Fe and Al, compared with their wet deposition fluxes. However, the processes of precipitation scavenging appeared to be more important for the elements that were often enriched in fine particles including Zn, Cu, Pb and Ni. The removal of Hg from the ambient air was overwhelmingly dominated by atmospheric wet deposition. In the future, atmospheric measurements at more sites on the NJ coast should be performed simultaneously to reduce the spatial and temporal uncertainties associated with atmospheric deposition fluxes estimated in this study.     

Salt Marsh and Fringing Oyster Reef Transgression in a Shallow Temperate Estuary: Implications for Restoration,Conservation and Blue Carbon

The importance of intertidal estuarine habitats, like salt marsh and oyster reef, has been well established, as has their ubiquitous loss along our coasts with resultant forfeiture of the ecosystem services they provide. Furthering our understanding of how these habitats are evolving in the face of anthropogenic and climate driven changes will help improve management strategies. Previous work has shown that the growth and productivity of both oyster reefs and salt marshes are strongly linked to elevation in the intertidal zone (duration of aerial exposure). We build on that research by examining the growth of marsh-fringing oyster reefs at yearly to decadal time scales and examine movement of the boundary between oyster reef and salt marsh at decadal to centennial time scales. We show that the growth of marsh-fringing reefs is strongly associated to the duration of aerial exposure, with little growth occurring below mean low water and above mean sea level. Marsh-shoreline movement, in the presence or absence of fringing oyster reefs, was reconstructed using transects of sediment cores. Carbonaceous marsh sediments sampled below the modern fringing oyster reefs indicate that marsh shorelines within Back Sound, North Carolina are predominantly in a state of transgression (landward retreat), and modern oyster-reef locations were previously occupied by salt marsh within the past two centuries. Cores fronting transgressive marsh shorelines absent fringing reefs sampled thinner and less extensive carbonaceous marsh sediment than at sites with fringing reefs. This indicates that fringing reefs are preserving carbonaceous marsh sediment from total erosion as they transgress and colonize the exposed marsh shoreline making marsh sediments more resistant to erosion. The amount of marsh sediment preservation underneath the reef scales with the reef’s relief, as reefs with the greatest relief were level with the marsh platform, preserving a maximum amount of carbonaceous sediments during transgression by buffering the marsh from erosional processes. Thus, fringing oyster reefs not only have the capacity to shelter shorelines but, if located at the ideal tidal elevation, they also keep up with accelerating sea-level rise and cap carbonaceous sediments, protecting them from erosion, as reefs develop along the marsh.     

Tsunami Waves with an Initial Negative Wave on the Chilean Coast

This work describes the characteristics of a tsunami with an initial negative wave in the Pacific Ocean. These tsunamis fall into two classes; one class is produced by strong earthquakes and the other by earthquakes of moderate size. The relationship between the run-up probability occurrence is determined for both classes of tsunami and the mechanisms by which the tsunamis are generated is considered with reference to the keyboard model of tsunamigenic earthquakes. Tsunamis in the Arica region of northern Chile were analysed in more detail and these analyses suggest that a catastrophic tsunami is likely to occur in the Arica region in the next 10–20 years.     

长江口潮流速垂线分布规律研究

河道中流速沿垂线的分布规律是研究许多河床动力学问题的关键.长江口潮流河段涨、落潮流垂线流速分布有其特殊规律,因此根据长江口实测水流流速资料,分析流速垂线分布的规律性具有重要意义.本文通过对长江口的实例运用对数线性扩展分布模式计算分析,并与传统的对数分布模式进行比较,结果表明,对数线性扩展分布模式在各层数据上都与实测数据具有更好的相关性.     

Impact of Fertilization on a Salt Marsh Food Web in Georgia

We examined the response of a salt marsh food web to increases in nutrients at 19 coastal sites in Georgia. Fertilization increased the nitrogen content of the two dominant plants, Spartina alterniflora and Juncus roemerianus, indicating that added nutrients were available to and taken up by both species. Fertilization increased Spartina cover, height, and biomass and Juncus height, but led to decreases in Juncus cover and biomass. Fertilization increased abundances of herbivores (grasshoppers) and herbivore damage, but had little effect on decomposers (fungi), and no effect on detritivores (snails). In the laboratory, herbivores and detritivores did not show a feeding preference for fertilized versus control plants of either species, nor did detritivores grow more rapidly on fertilized versus control plants, suggesting that changes in herbivore abundance in the field were driven more by plant size or appearance than by plant nutritional quality. Community patterns in control plots varied predictably among sites (i.e., 17 of 20 regression models examining variation in biological variables across sites were significant), but variation in the effects of fertilization across sites could not be easily predicted (i.e., only 6 of 20 models were significant). Natural variation among sites was typically similar or greater than impacts of fertilization when both were assessed using the coefficient of variation. Overall, these results suggest that eutrophication of salt marshes is likely to have stronger impacts on plants and herbivores than on decomposers and detritivores, and that impacts at any particular site might be hard to distinguish from natural variation among sites.     

Salt Marsh Accretion and Storm Tide Variation: an Example from a Barrier Island in the North Sea

We reconstruct past accretion rates of a salt marsh on the island of Sylt, Germany, using measurements of the radioisotopes ²¹⁰Pb and ¹³⁷Cs, as well as historical aerial photographs. Results from three cores indicate accretion rates varying between 1 and 16 mm year⁻¹. Comparisons with tide gauge data show that high accretion rates during the 1980s and 1990s coincide with periods of increased storm activity. We identify a critical inundation height of 18 cm below which the strength of a storm seems to positively influence salt marsh accretion rates and above which the frequency of storms becomes the major factor. In addition to sea level rise, we conclude that in low marsh zones subject to higher inundation levels, mean storm strength is the major factor affecting marsh accretion, whereas in high marsh zones with lower inundation levels, it is storm frequency that impacts marsh accretion.     

中国盐湖锂资源的产业化现状——以西台吉乃尔盐湖和扎布耶盐湖为例

锂对国民经济和国家安全具有重要意义,是21世纪的能源金属.近10年,中国主要从国外进口碳酸锂产品.中国是一个多盐湖的国家,盐湖锂占锂资源工业总储量的85%.现代第四纪盐湖主要分布在我国西北的青海、西藏、新疆和内蒙古四省区,具有很好的开发前景.经过多年科研后,目前国内已经在西台吉乃尔和扎布耶两个盐湖建立了卤水提锂产业.本文对比研究了这两个盐湖资源状况和地理气候条件,以及由此而决定的盐湖资源开发工艺流程,探讨了其工艺优化方向.并指出这两个盐湖具有锂资源储量大,品位高的优势,但是受盐湖类型或地理气候条件限制,工艺上有待改善.建议继续加强对盐湖开发技术优化和对盐湖提锂产业的扶持.     

The Identification of an Alkaline Salt Lake:A Case Study from the Permian Fengcheng Formation in Hashan-Wuxia Area

正The study area is located in the northwest of Junggar basin which was in the relaxation stage of foreland basin accompanied by momentary extend volcanic activities when the Fengcheng Formation developed in early     

Effects of Docks on Salt Marsh Vegetation: an Evaluation of Ecological Impacts and the Efficacy of Current Design Standards

Private docks are common in estuaries worldwide. Docks in Massachusetts (northeast USA) cumulatively overlie ~ 6 ha of salt marsh. Although regulations are designed to minimize dock impacts to salt marsh vegetation, few data exist to support the efficacy of these policies. To quantify impacts associated with different dock designs, we compared vegetation characteristics and light levels under docks with different heights, widths, orientations, decking types and spacing, pile spacing, and ages relative to adjacent control areas across the Massachusetts coastline (n = 212). We then evaluated proportional changes in stem density and biomass of the dominant vegetation (Spartina alterniflora and Spartina patens) in relation to dock and environmental (marsh zone and nitrogen loading) characteristics. Relative to adjacent, undeveloped habitat, Spartina spp. under docks had ~ 40% stem density, 60% stem biomass, greater stem height and nitrogen content, and a higher proportion of S. alterniflora. Light availability was greater under taller docks and docks set at a north-south orientation but did not differ between decking types. Dock height best predicted vegetation loss, but orientation, pile spacing, decking type, age, and marsh zone also affected marsh production. We combined our proportional biomass and stem elemental composition estimates to calculate a statewide annual loss of ~ 2200 kg dry weight of Spartina biomass (367 kg per ha of dock coverage). Managers can reduce impacts through design modifications that maximize dock height (> 150 cm) and pile spacing while maintaining a north-south orientation, but dock proliferation must also be addressed to limit cumulative impacts.     

Influence of a Drought Event on Hydrological Characteristics of a Small Estuary on the Amazon Mangrove Coast

The effects of atypical climatic conditions, such as those of a drought event, are remarkably accentuated in minor estuaries filled with sediments and with reduced or sporadic freshwater input, where the salinity intrusion is pronounced. To understand these effects, hydrological and hydrodynamic parameters were evaluated during a drought period in a small estuary located on the eastern Amazon coast in northern Brazil. Five campaigns were conducted between June 2012 and June 2013. Samples were collected from the surface and bottom layer every 3 h over a 25-h period at three stations of the Taperaçu Estuary. To compare drought and post-drought periods, in terms of salinity and chlorophyll-a, data was recorded until June 2015. Taperaçu is a relatively shallow estuary of the Amazon coastal zone, which is characterized by the absence of any direct fluvial discharge, although it does receive freshwater input from adjacent wetlands, as well as less saline waters from the Caeté Estuary through the Taici Creek. Hydrological variables were controlled by rainfall levels and the tidal range, and the water became more saline and more oxygenated, with reduced dissolved nutrient and chlorophyll-a concentrations when precipitation decreased. A significant variation was found between the months of June 2012 (most intense drought) and 2013 (less intense drought). The connection to the neighboring Caeté Estuary and adjacent mangroves and wetlands contributed to the influx of nutrient-enriched waters. Overall, then, it is hoped that the results of this study can contribute to the understanding of the effects of drought events in other minor estuaries on the highly indented Amazon coast, as well as in other areas of the equatorial zone with similar environmental characteristics.     

长江口环境用水量计算方法探讨

环境用水在水资源配置中不能忽视，但环境用水问题的研究在理论上和具体计算方法上，目前国内外尚未有系统的成果。以长江口为例，以维持长江口水盐平衡并兼顾水沙平衡为目标，分析了长江口所必需的环境用水量。     

Living on the Edge: Increasing Patch Size Enhances the Resilience and Community Development of a Restored Salt Marsh

Foundation species regulate communities by reducing environmental stress and providing habitat for other species. Successful restoration of biogenic habitats often depends on restoring foundation species at appropriate spatial scales within a suitable range of environmental conditions. An improved understanding of the relationship between restoration scale and environmental conditions has the potential to improve restoration outcomes for many biogenic habitats. Here, we identified and tested whether inundation/exposure stress and spatial scale (patch size) can interactively determine (1) survival and growth of a foundation species, Spartina alterniflora and (2) recruitment of supported fauna. We planted S. alterniflora and artificial mimics in large and small patches at elevations above and below local mean sea level (LMSL) and monitored plant survivorship and production, as well as faunal recruitment. In the first growing season, S. alterniflora plant survivorship and stem densities were greater above LMSL than below LMSL regardless of patch size, while stem height was greatest in small patches below LMSL. By the third growing season, S. alterniflora patch expansion was greater above LMSL than below LMSL, while stem densities were higher in large patches than small patches, regardless of location relative to LMSL. Unlike S. alterniflora, which was more productive above LMSL, sessile marine biota recruitment to mimic plants was higher in patches below LMSL than above LMSL. Our results highlight an ecological tradeoff at ~LMSL between foundation species restoration and faunal recruitment. Increasing patch size as inundation increases may offset this tradeoff and enhance resilience of restored marshes to sea-level rise.     

贵州拉丁晚期扬子台地边缘地表暴露带的特征及裂隙中微型钟乳石的成因

贵州中三叠世拉丁晚期扬子台地边缘地表暴露带,经历的时间长,约1 Ma(233~232 Ma);形成的厚度大(一般100~150 m左右,最厚可达180 m左右).暴露特征清楚,渗流豆石、窗格(鸟眼)构造、中-大型帐篷构造、喀斯特化角砾岩非常发育,这显然是潮湿-半潮湿气候条件下,在古隆起区形成的钙质风化壳.暴露带裂隙中的微型钟乳石,有覆水石、滴水石、流水石3种类型.其18O同位素组成一般在-10‰(PDB)左右,13C的同位素组成一般在1.5‰~2‰(PDB)左右.18O同位素组成表明,钟乳石是淡水成因的,但13C的同位素组成为略高于淡水成因的沉积物的值,这可能是不饱和的大气降水溶解了基岩,而获得13C的缘故.上述3种形态的微型钟乳石的岩石学特征也表明,是典型的淡水成因形成.由此可见,暴露带裂隙中的微型钟乳石为淡水成因的产物.