磨刀门水道咸潮入侵及其变异分析

随着区域经济及人口的进一步增长,珠江三角洲磨刀门水道已成为江门、中山、珠海、澳门等城市重要的水源地,相应咸潮入侵对供水安全造成的危害也越来越严重。本文依据实测资料和现场调研,对磨刀门水道咸潮入侵的潮相变化、径流—咸潮的响应模式、风对咸潮入侵的影响及咸潮入侵的历史演变趋势及其变异、最小压咸流量及最佳压咸时机等进行了研究。研究结果表明,影响咸潮入侵的主要因素是径流,有利于咸潮入侵的风向为北风～东北风。以思贤滘流量(即马口水文站与三水水文站流量之和)为参照,为保障珠海、澳门供水安全,磨刀门水道最小压咸流量范围为2200-2700m3/s,平均流量为2450m3/s,最佳压咸补淡的时机为大潮转小潮期,也就是朔望(半月)周期的落潮期。     

Sustainability of a Tidal Freshwater Marsh Exposed to a Long-term Hydrologic Barrier and Sea Level Rise

A 115-year-old railroad levee bisecting a tidal freshwater marsh perpendicular to the Patuxent River (Maryland) channel has created a northern, upstream marsh and a southern, downstream marsh. The main purpose of this study was to determine how this levee may affect the ability of the marsh system to gain elevation and to determine the levee’s impact on the marsh’s long-term sustainability to local relative sea level rise (RSLR). Previously unpublished data from 1989 to 1992 showed that suspended solids and short-term sediment deposition were greater in the south marsh compared to the north marsh; wetland surface elevation change data (1999 to 2009) showed significantly higher elevation gain in the south marsh compared to the north (6?±?2 vs. 0?±?2 mm year^?1, respectively). However, marsh surface accretion (2007 to 2009) showed no significant differences between north and south marshes (23?±?8 and 26?±?7 mm year^?1, respectively), and showed that shallow subsidence was an important process in both marshes. A strong seasonal effect was evident for both accretion and elevation change, with significant gains during the growing season and elevation loss during the non-growing season. Sediment transport, deposition and accretion decreased along the intertidal gradient, although no clear patterns in elevation change were recorded. Given the range in local RSLR rates in the Chesapeake Bay (2.9 to 5.8 mm year^?1), only the south marsh is keeping pace with sea level at the present time. Although one would expect the north marsh to benefit from high accretion of abundant riverine sediments, these results suggest that long-term elevation gain is a more nuanced process involving more than riverine sediments. Overall, other factors such as infrequent episodic coastal events may be important in allowing the south marsh to keep pace with sea level rise. Finally, caution should be exercised when using data sets spanning only a couple of years to estimate wetland sustainability as they may not be representative of long-term cumulative effects. Two years of data do not seem to be enough to establish long-term elevation change rates at Jug Bay, but instead a decadal time frame is more appropriate.     

Understanding the Impacts of Climate Change: an Analysis of Inundation,Marsh Elevation,and Plant Communities in a Tidal Freshwater Marsh

Tidal freshwater marshes around the world face an uncertain future with increasing water levels, salinity intrusion, and temperature and precipitation shifts associated with climate change. Due to the characteristic abundance of both annual and perennial species in these habitats, even small increases in early growing season water levels may reduce seed germination, seedling establishment, and late-season plant cover, decreasing overall species abundance and productivity. This study looks at the distribution of tidal freshwater marsh plant species at Jug Bay, Patuxent River (Chesapeake Bay, USA), with respect to intertidal elevation, and the relationship between inundation early in the growing season and peak plant cover to better understand the potential impacts and marsh responses to increased inundation. Results show that 62% of marsh plant species are distributed at elevations around mean high water and are characterized by narrow elevation ranges in contrast with species growing at lower elevations. In addition, the frequency and duration of inundation and water depth to which the marsh was exposed to, prior to the growing season (March 15–May 15), negatively affected peak plant cover (measured in end-June to mid-July) after a threshold value was reached. For example, 36 and 55% decreases in peak plant cover were observed after duration of inundation threshold values of 25 and 36% was reached for annual and perennial species, respectively. Overall, this study suggests that plant communities of tidal freshwater marshes are sensitive to even small systematic changes in inundation, which may affect species abundance and richness as well as overall wetland resiliency to climate change.     

Functional and Compositional Responses of Periphyton Mats to Simulated Saltwater Intrusion in the Southern Everglades

Periphyton plays key ecological roles in karstic, freshwater wetlands and is extremely sensitive to environmental change making it a powerful tool to detect saltwater intrusion into these vulnerable and valuable ecosystems. We conducted field mesocosm experiments in the Florida Everglades, USA to test the effects of saltwater intrusion on periphyton metabolism, nutrient content, and diatom species composition, and how these responses differ between mats from a freshwater versus a brackish marsh. Pulsed saltwater intrusion was simulated by dosing treatment chambers monthly with a brine solution for 15 months; control chambers were simultaneously dosed with site water. Periphyton from the freshwater marsh responded to a 1-ppt increase in surface water salinity with reduced productivity and decreased concentrations of total carbon, nitrogen, and phosphorus. These functional responses were accompanied by significant shifts in periphytic diatom assemblages. Periphyton mats at the brackish marsh were more functionally resilient to the saltwater treatment (~?2 ppt above ambient), but nonetheless experienced significant shifts in diatom composition. These findings suggest that freshwater periphyton is negatively affected by small, short-term increases in salinity and that periphytic diatom assemblages, particularly at the brackish marsh, are a better metric of salinity increases compared with periphyton functional metrics due to functional redundancy. This research provides new and valuable information regarding periphyton dynamics in response to changing water sources in the southern Everglades that will allow us to extend the use of periphyton, and their diatom assemblages, as tools for environmental assessments related to saltwater intrusion.     

高密度电阻率法探测海水入侵咸淡水界限初步调查研究——以莱州湾为例

本文从理论上阐述了高密度电阻率法探测海水入侵界限的可行性,对该方法在莱州湾地区实例分析表明,根据高密度电阻率法反演视电阻率断面图勾划出来的咸淡水分界线与水文地质调查结果基本吻合,说明了该方法在莱州湾地区具有较好的有效性和可行性。笔者还利用视电阻率断面图确定了咸淡水水体在平面分布情况和垂向变化情况,为查清海水入侵等环境地质问题提供可靠的基础资料。该方法在探测海水入侵方面具有简单、快速、低廉、无破坏性原位探测等特点,其应用前景可观,值得推广。     

Tidal Freshwater Marshes Harbor Phylogenetically Unique Clades of Sulfate Reducers That Are Resistant to Climate-Change-Induced Salinity Intrusion

Rates of sea level rise associated with climate change are predicted to increase in the future, potentially altering ecosystems at all ecological levels. Sea level rise can increase the extent of brackish water intrusion into freshwater ecosystems, which in turn can affect the structure and function of resident microbial communities. In this study, we performed a year-long mesocosm experiment using intact tidal freshwater marsh sediment cores to examine the effect of a 5-part per thousand (ppt) salinity increase on the diversity and community composition of sulfate-reducing prokaryotes. We used a clone library approach to examine the dsrA gene, which encodes an important catalytic enzyme in sulfate reduction. Our results indicate that tidal freshwater marshes contain extremely diverse communities of sulfate-reducing bacteria. Members of these communities were, on average, only 71 % similar to known cultured sulfate reducers and 81 % similar to previously sequenced environmental clones. Salinity and associated increases in sulfate availability did not significantly affect the diversity or community composition of sulfate-reducing prokaryotes. However, carbon quality and quantity, which correlated with depth, were found to be the strongest drivers of sulfate-reducing community structure. Our study demonstrates that the sulfate-reducing community in tidal freshwater marsh sediments appears resistant to increased salinity in the face of sea level rise. Additionally, the microorganisms that comprise this sulfate-reducing community appear to be unique to tidal freshwater marsh sediments and may represent novel lineages of previously undescribed sulfate reducers.     

Tidal Freshwater Wetlands: Variation and Changes

Tidal freshwater wetlands (TFW) are situated in the upper estuary in a zone bordered upstream by the nontidal river and downstream by the oligohaline region. Here, discharge of freshwater from the river and the daily tidal pulse from the sea combine to create conditions where TFW develop. TFW are often located where human population density is high, which has led to wetland degradation or destruction. Globally, TFW are largely restricted to the temperate zone where the magnitude of annual river discharge prevents saline waters from penetrating too far inland. The constant input of river water delivers high loads of sediments, dissolved nutrients, and other suspended matter leading to high sedimentation rates and high nutrient levels. Prominent biogeochemical processes include the transformation of nitrogen by bacteria and immobilization of phosphate. A diverse, characteristic vegetation community develops which supports a rich fauna. Biotic diversity is highest in the high marsh areas and decreases in the lower levels where tidal inundation is greatest. Benthic fauna is rather poor in diversity but high in biomass compared to other regions of the estuary. Global climate change is a threat for this system directly by sea level rise, which will cause brackish water to intrude into the fresh system, and indirectly during droughts, which reduce river discharge. Salinity will affect the presence of flora and fauna and facilitates sulfate reduction of organic matter in the soil. Increased decomposition of organic matter following saltwater intrusion can result in a lowering of wetland surface elevation. The papers assembled in this issue focus on how these tidal freshwater wetlands have changed over recent time and how they may respond to new impacts in the future.     

2014年长江口咸潮入侵分析及对策

长江口咸潮入侵是枯水期经常发生的一种自然现象,但2014年初的咸潮入侵相比往年尤甚。分析了本次咸潮入侵的基本情况和形成的原因,探讨了长江口咸潮入侵的机理和入侵途径,并结合历史资料,分析了新形势下长江口咸潮入侵出现的新特点。在此基础上,从水源地布局、技术措施、水资源管理和长江流域水量的统一调配等方面研究了如何有效应对长江口咸潮入侵对自来水原水供应的影响。     

Lateral Saltwater Intrusion in the North Channel of the Changjiang Estuary

Saltwater intrusion typically develops in the along-channel direction but exceptions can be found in bifurcated estuaries. Based on the observational data, we found that the saltwater intrusion in the upper reaches of the North Channel (NC) of Changjiang Estuary is dominated by the lateral saltwater intrusion from a small northern outlet (denoted as NONC) of this channel. This phenomenon has severe effects on the freshwater usage in this region. To investigate the underlying mechanisms of this pattern of intrusion, numerical experiments were conducted using a well-validated model. A flux decomposing method was used to decompose the process of saltwater intrusion into several mechanisms. During the neap tide, the saltwater begins to intrude landward into the NONC through shear transport induced by estuarine circulation. During the transition period between the neap tide and the following spring tide, the saltwater that previously reached the NONC further intrudes into the NC via Lagrangian and tidal pumping transports, causing a significant salinity increase in the middle and upper reaches of the NC. During the spring tide and the subsequent middle tide, saltwater intrusion in the NONC retreats. The impacts of the topography of the NONC and the wind stress on this lateral saltwater intrusion were also evaluated in this study.     

Anammox in Tidal Marsh Sediments: The Role of Salinity,Nitrogen Loading,and Marsh Vegetation

Anammox bacteria are widespread in the marine environment, but studies of anammox in marshes and other wetlands are still scarce. In this study, the role of anammox in nitrogen removal from marsh sediments was surveyed in four vegetation types characteristic of New England marshes and in unvegetated tidal creeks. The sites spanned a salinity gradient from 0 to 20 psu. The impact of nitrogen loading on the role of anammox in marsh sediments was studied in a marsh fertilization experiment and in marshes with high nitrogen loading entering through ground water. In all locations, nitrogen removal through anammox was low compared to denitrification, with anammox accounting for less than 3% of the total N₂ production. The highest relative importance of anammox was found in the sediments of freshwater-dominated marshes, where anammox approached 3%, whereas anammox was of lesser importance in saline marsh sediments. Increased nitrogen loading, in the form of nitrate from natural or artificial sources, did not impact the relative importance of anammox, which remained low in all the nitrogen enriched locations (<1%).     

Tidal Marsh Restoration Design Affects Feedbacks Between Inundation and Elevation Change

Tidal marsh (re)creation on formerly embanked land is increasingly executed along estuaries and coasts in Europe and the USA, either by restoring complete or by reduced tidal exchange. Ecosystem functioning and services are largely affected by the hydro-geomorphologic development of these areas. For natural marshes, the latter is known to be steered by feedbacks between tidal inundation and sediment accretion, allowing marshes to reach and maintain an equilibrium elevation relative to the mean sea level. However, for marsh restoration sites, these feedbacks may be disturbed depending on the restoration design. This was investigated by comparing the inundation-elevation change feedbacks in a natural versus restoration site with reduced tidal exchange in the Scheldt estuary (Belgium). This study analyzes long-term (9 years) datasets on elevation change and tidal inundation properties to disentangle the different mechanisms behind this elevation-inundation feedback. Moreover, subsequent changes in sediment properties that may affect this feedback were explored. In the restoration area with reduced tidal exchange, we found a different elevation-inundation feedback than on natural marshes, which is a positive feedback on initially high sites (i.e., sediment accretion leads to increasing inundation, hence causing accelerating sediment accretion rates) and a gradual silting up of the whole area. Furthermore, there is evidence for the presence of a relict consolidated sediment layer. Consequently, shallow subsidence is less likely to occur. Although short-term ecological development of the tidal marsh was not impeded, long-term habitat development may be affected by the differences in hydro-geomorphological interactions. An increase of inundation frequency on the initially high sites may cause inhibition of habitat succession or even reversed succession. Over time, the climax state of the restoration area may be different compared to natural marshes. Moreover, sediment-related ecosystem services, such as nutrient and carbon burial, may be positively influenced because of continuing sedimentation, although flood water storage potential will decrease with increasing elevation. Depending on the restoration goals, ecosystem trajectories and delivery of ecosystem services can be controlled by adaptive management of the tidal volume entering the restoration area.     

Development of a Multimetric Index for Integrated Assessment of Salt Marsh Ecosystem Condition

Tools for assessing and communicating salt marsh condition are essential to guide decisions aimed at maintaining or restoring ecosystem integrity and services. Multimetric indices (MMIs) are increasingly used to provide integrated assessments of ecosystem condition. We employed a theory-based approach that considers the multivariate relationship of metrics with human disturbance to construct a salt marsh MMI for five National Parks in the northeastern USA. We quantified the degree of human disturbance for each marsh using the first principal component score from a principal components analysis of physical, chemical, and land use stressors. We then applied a metric selection algorithm to different combinations of about 45 vegetation and nekton metrics (e.g., species abundance, species richness, and ecological and functional classifications) derived from multi-year monitoring data. While MMIs derived from nekton or vegetation metrics alone were strongly correlated with human disturbance (r values from ?0.80 to ?0.93), an MMI derived from both vegetation and nekton metrics yielded an exceptionally strong correlation with disturbance (r = ?0.96). Individual MMIs included from one to five metrics. The metric-assembly algorithm yielded parsimonious MMIs that exhibit the greatest possible correlations with disturbance in a way that is objective, efficient, and reproducible.     

Broad Timescale Forcing and Geomorphic Mediation of Tidal Marsh Flow and Temperature Dynamics

Tidal marsh functions are driven by interactions between tides, landscape morphology, and emergent vegetation. Less often considered are the diurnal pattern of tide extremes and seasonal variation of solar insolation in the mix of tidal marsh driver interactions. This work demonstrates how high-frequency hydroperiod and water temperature variability emerges from disparate timescale interactions between tidal marsh morphology, tidal harmonics, and meteorology in the San Francisco Estuary. We compare the tidal and residual flow and temperature response of neighboring tidal sloughs, one possessing natural tidal marsh morphology, and one that is modified for water control. We show that the natural tidal marsh is tuned to lunar phase and produces tidal and fortnight water temperature variability through interacting tide, meteorology, and geomorphic linkages. In contrast, temperature variability is dampened in the modified slough where overbank marsh plain connection is severed by levees. Despite geomorphic differences, a key finding is that both sloughs are heat sinks in summer by latent heat flux-driven residual upstream water advection and sensible and long-wave heat transfer. The precession of a 335-year tidal harmonic assures that these dynamics will shift in the future. Water temperature regulation appears to be a key function of natural tidal sloughs that depends critically on geomorphic mediation. We investigate approaches to untangling the relative influence of sun versus tide on residual water and temperature transport as a function of system morphology. The findings of this study likely have ecological consequences and suggest physical process metrics for tidal marsh restoration performance.     

X荧光能谱技术鉴别淡水珍珠和海水珍珠的应用

采用X荧光能谱技术研究珍珠中微量元素的种类及其质量分数,以达到无损鉴别淡水珍珠和海水珍珠的目的。利用X射线荧光能谱仪优选适合的激发工作条件,通过设定相同的工作条件,获得珍珠主量元素和微量元素的能量色散图谱,定性分析其主量元素和微量元素的组合关系。其中,Mn的特征峰与Sr/Ca计数比率对鉴别珍珠品种有重要的指示意义。研究表明,在电压为30～35kV、电流为0.50～0.80mA、滤光片PdThick的测试条件下,淡水珍珠一般具有Ca＋Sr＋Mn的组合关系,海水珍珠具有Ca＋Sr的组合关系;淡水珍珠中的Sr/Ca介于0.14～0.37,海水珍珠中的Sr/Ca介于0.46～0.71。综合利用元素的组合关系和Sr/Ca计数比率,可快捷、无损地鉴别珍珠品种。     

Importance of Biogeomorphic and Spatial Properties in Assessing a Tidal Salt Marsh Vulnerability to Sea-level Rise

We evaluated the biogeomorphic processes of a large (309 ha) tidal salt marsh and examined factors that influence its ability to keep pace with relative sea-level rise (SLR). Detailed elevation data from 1995 and 2008 were compared with digital elevation models (DEMs) to assess marsh surface elevation change during this time. Overall, 37 % (113 ha) of the marsh increased in elevation at a rate that exceeded SLR, whereas 63 % (196 ha) of the area did not keep pace with SLR. Of the total area, 55 % (169 ha) subsided during the study period, but subsidence varied spatially across the marsh surface. To determine which biogeomorphic and spatial factors contributed to measured elevation change, we collected soil cores and determined percent and origin of organic matter (OM), particle size, bulk density (BD), and distance to nearest bay edge, levee, and channel. We then used Akaike Information Criterion (AICc) model selection to assess those variables most important to determine measured elevation change. Soil stable isotope compositions were evaluated to assess the source of the OM. The samples had limited percent OM by weight (<5.5 %), with mean bulk densities of 0.58 g cm^-3, indicating that the soils had high mineral content with a relatively low proportion of pore space. The most parsimonious model with the highest AICc weight (0.53) included distance from bay's edge (i.e., lower intertidal) and distance from levee (i.e., upper intertidal). Close proximity to sediment source was the greatest factor in determining whether an area increased in elevation, whereas areas near landward levees experienced subsidence. Our study indicated that the ability of a marsh to keep pace with SLR varied across the surface, and assessing changes in elevation over time provides an alternative method to long-term accretion monitoring. SLR models that do not consider spatial variability of biogeomorphic and accretion processes may not correctly forecast marsh drowning rates, which may be especially true in modified and urbanized estuaries. In light of SLR, improving our understanding of elevation change in these dynamic marsh systems will play a crucial role in forecasting potential impacts to their sustainability and the survival of these ecosystems.     

Hydrologic Versus Biogeochemical Controls of Denitrification in Tidal Freshwater Wetlands

Tidal freshwater wetlands (TFW) alter nitrogen concentrations in river water, but the role of these processes on a river’s downstream nitrogen delivery is poorly understood. We examined spatial and temporal patterns in denitrification in TFW of four rivers in North Carolina, USA and evaluated the relative importance of denitrification rate and inundation on ecosystem-scale N₂ efflux. An empirical model of TFW denitrification was developed to predict N₂ efflux using a digital topographic model of the TFW, a time series of water level measurements, and a range of denitrification rates. Additionally, a magnitude-frequency analysis was performed to investigate the relative importance of storm events on decadal patterns in N₂ efflux. Spatially, inundation patterns exerted more influence on N₂ efflux than did the range of denitrification rate used. Temporal variability in N₂ efflux was greatest in the lower half of the tidal rivers (near the saline estuary) where inundation dynamics exerted more influence on N₂ efflux than denitrification rate. N₂ efflux was highest in the upper half of the rivers following storm runoff, and under these conditions variation in denitrification rate had a larger effect on N₂ efflux than variability in inundation. The frequency-magnitude analysis predicted that most N₂ efflux occurred during low flow periods when tidal dynamics, not storm events, affected TFW inundation. Tidal hydrology and riparian topography are as important as denitrification rate in calculating nitrogen loss in TFW; we present a simple empirical model that links nitrogen transport in rivers with loss due to denitrification in TFW.     

Fertilization Effects on Elevation Change and Belowground Carbon Balance in a Long Island Sound Tidal Marsh

We report the results of a 5-year fertilization experiment in a central Long Island Sound salt marsh, aimed at understanding the impacts of high nutrient loads on marsh elevational processes. Fertilization with nitrogen led to some significant changes in marsh processes, specifically increases in aboveground primary production and in CO₂ fluxes from the soil. However, neither nitrogen nor phosphorus fertilization led to elevation loss (relative to controls), reduced soil carbon, or a decrease in belowground primary production, all of which have been proposed as links between elevated nutrient loads and marsh drowning. Our data suggest that high nutrient levels increase gross carbon loss from the sediment, but that this is compensated for by other processes, leading to no net deleterious effect of nutrient loading on carbon storage or on marsh stability with respect to sea level rise.     

Vegetation Dynamics in a Tidal Freshwater Wetland: A Long-Term Study at Differing Scales

Tidal freshwater wetlands are complex, species-rich ecosystems located at the interface between tidal estuaries and nontidal rivers. This study conducted on the Patuxent River estuary in Maryland was designed to assess vegetation dynamics over several decades to determine if there were directional changes in the dominant communities. Aerial photographs (1970, 1989, and 2007) documented broad-scale spatial changes in major plant communities. The coverage of areas dominated by Nuphar lutea and Phragmites australis expanded; mixed vegetation and scrub–shrub habitats were essentially unchanged; and Typha and Zizania aquatica communities fluctuated in coverage. Data collected between 1988 and 2010 from permanent plots and transects were used to examine fine-scale changes. Shifts in the importance of some species through time were observed, but there were no directional changes in community species composition. The lack of directional change as measured at a fine scale is characteristic of tidal freshwater wetlands in which variations in the abundance of individual species, especially annuals, are responsible for most short-term change in species composition. Changes in the composition of plant communities are interpreted as responses to variations in vertical accretion, stability of habitat types, invasive plant species, and herbivores. In the future, vegetation changes are likely to occur as a result of the intrusion of brackish water and increased flooding associated with global climate change and sea level rise. This long-term study establishes a baseline from which potential future changes to tidal freshwater wetlands can be better understood.     

咸淡水界面位置确定的综合方法(TEcG)及其应用

准确确定咸淡水界面位置是评价咸水入侵范围的前提。对于咸淡水界面位置的确定,传统研究以水化学法和物探法为主。为克服单一使用传统方法造成的人力、物力和财力的大量浪费,以莱州湾西南岸广饶县小清河以南咸水入侵区为研究对象,在综合分析研究区地下水开采现状、水化学监测结果的基础上,选择3个典型断面,采用水化学法中的野外现场电导率法,快速判断咸淡水界面大致位置（某两眼监测井之间）;再在一咸一淡的两眼监测井之间,采用高密度电阻率法快速、准确地确定咸淡水界面的空间分布。结果表明：该地区的地下水电导率若大于1.61 mS/cm,即可认为此处受到咸水入侵;咸淡水界面位置的视电阻率特征值为11~13 Ω·m,咸淡水界面附近咸水体呈舌状入侵并主要发生在地表以下13 m内的浅层地下水中。     

Comparative Study of Hydrogen and Carbon Isotopic Composition of Gases Generated from the Pyrolysis of a Peat under Saltwater and Freshwater Conditions

To understand the influence of the diagenetic water medium on the isotopic compositions of thermogenic coalbed gas, both hydrous and anhydrous closed-system pyrolyses were performed at temperatures of 250°C to 650°C on an herbaceous marsh peat. Compared to the results of anhydrous pyrolysis, the hydrocarbon gases generated from hydrous pyrolyses have very different hydrogen isotopic compositions. However, the carbon isotopic compositions of the hydrocarbon gases became only slightly heavier in hydrous pyrolysis, compared to that from anhydrous pyrolysis. With the progress of thermal evolution from peat to a more advanced thermal maturity of vitrinite reflectance values (Ro) of 5.5% during the pyrolysis, the difference in the average δD value increased from 52‰ to 64‰ between the hydrous pyrolysis with saltwater and anhydrous pyrolysis and increased from 18‰ to 29‰ between the hydrous pyrolysis with freshwater and anhydrous pyrolysis, respectively. The difference in the average δ13C value was only 1‰–2‰ between the hydrous and anhydrous pyrolysis. The relationships between the δD values of the generated hydrocarbon gases and Ro values as well as among δD values of the hydrocarbon gas species are established. The close relationships among these parameters suggest that the water medium had a significant effect on the hydrogen isotopic composition and a minimal effect on the carbon isotopic composition of the hydrocarbon gases. The results of these pyrolyses may provide information for the understanding of the genesis of coalbed gas from herbaceous marsh material with the participation of different diagenetic water media.