Impact of Piers on Tidal Marshes： Accumulation of Wood Preservative Metals in Water and Soils

Wood treated with chromated copper arsenate （CCA） is a common material for pier pilings. Research on CCA impacts in estuarine systems indicates that the magnitude of the biological effect is variable and dependent on sediment and water characteristics. To assist environmental agencies in assessing pier impacts a project was conducted in the U.S.A. to investigate the spatial distribution and magnitude of As, Cr, and Cu accumulation in waters and soils near old and new piers. For new piers, soluble metal levels were highest within 2.9 m of the piers. Total As and Cu levels approached background levels at distances of 2.9 m and 1.4 m, respectively. For old piers, total As and Cu approached background levels at a distance of 9.0 m. Total Cr never exceeded background levels. Threshold effects concentrations were exceeded by sedimented As and Cu within 3.6 m of old piers and 2.1 m of new piers. Apparent effects thresholds were never reached. The only water chemistry variable impacted by piers was As with new piers. It was concluded that leachates accumulate only close to piers and at levels below critical biological thresholds, and would be expected to have negligible ecological effects in reasonably flushed areas.

Assessment of Soil Quality of Tidal Marshes in Shanghai City

We take three types of tidal marshes in Shanghai City as the study object:tidal marshes in mainland,tidal marshes in the rim of islands,and shoal in Yangtze estuary.On the basis of assessing nutrient quality and environmental quality,respectively,we use soil quality index(SQI)to assess the soil quality of tidal flats,meanwhile formulate the quality grading standards,and analyze the current situation and characteristics of it.The results show that except the north of Hangzhou Bay,Nanhui and Jiuduansha with low soil nutrient quality,there are not obvious differences in soil nutrient quality between other regions;the heavy metal pollution of tidal marshes in mainland is more serious than that of tidal marshes in the rim of islands;in terms of the comprehensive soil quality index,the regions are sequenced as follows:Jiuduansha wetland>Chongming Dongtan wetland>Nanhui tidal flat>tidal flat on the periphery of Chongming Island>tidal flat on the periphery of Hengsha Island>Pudong tidal flat>Baoshan tidal flat>tidal flat on the periphery of Changxing Island>tidal flat in the north of Hangzhou Bay.Among them,Jiuduansha wetland and Chongming Dongtan wetland have the best soil quality,belonging to class III,followed by Nanhui tidal flat,tidal flat on the periphery of Chongming Island and tidal flat on the periphery of Hengsha Island,belonging to class IV;tidal flat on the periphery of Changxing Island,Pudong tidal flat,Baoshan tidal flat and tidal flat in the north of Hangzhou Bay belong to class V.

Response of gaseous carbon emissions to low-level salinity increase in tidal marsh ecosystem of the Min River estuary,southeastern China

Although estuarine tidal marshes are important contributors to the emission of greenhouse gases into the atmosphere, the relationship between carbon dioxide（CO2）, methane（CH4）emission, and environmental factors, with respect to estuarine marshes, has not been clarified thoroughly. This study investigated the crucial factors controlling the emission of CO2 and CH4from a freshwater marsh and a brackish marsh located in a subtropical estuary in southeastern China, as well as their magnitude. The duration of the study period was November 2013 to October 2014. Relevant to both the field and incubation experiments, the CO2 and CH4emissions from the two marshes showed pronounced seasonal variations. The CO2 and CH4emissions from both marshes demonstrated significant positive correlations with the air/soil temperature（p 〈 0.01）, but negative correlations with the soil electrical conductivity and the pore water/tide water Cl-and SO42- （p 〈 0.01）. The results indicate no significant difference in the CO2 emissions between the freshwater and brackish marshes in the subtropical estuary, whereas there was a difference in the CH4 emissions between the two sites（p 〈 0.01）. Although future sea-level rise and saltwater intrusion could reduce the CH4 emissions from the estuarine freshwater marshes, these factors had little effect on the CO2 emissions with respect to an increase in salinity of less than 5‰. The findings of this study could have important implications for estimating the global warming contributions of estuarine marshes along differing salinity gradients.

Lessons from the past:isotopes of an endangered rail as indicators of underlying change to tidal marsh habitats

Introduction:Tidal marsh systems along the Pacific coast of the United States have experienced substantial stress and loss of area and ecosystem function,which we examined by using the endangered California Ridgway’s Rail,Rallus obsoletus obsoletus(‘rail’)as an indicator of its tidal marsh habitat in the San Francisco Estuary.We organized a collection of historical(1885-1940)and modern(2005-2014)rail feathers and analyzed the feather isotope means for delta carbon(δ^(13)C),sulfur(δ^(34)S),and nitrogen(δ^(15)N)by region and time period.Outcomes:Feather isotopes represented the primary foraging habitat during historical then modern time periods.Neither individual nor regional rail feather isotopes suggested freshwater or terrestrial foraging by the rail.Three regions with both historic and modern feather isotopes revealed non-uniform spatial shifts in isotope levels consistent with a marine based food web and significantδ^(15)N enrichment.Discussion:Our results supported the rail’s status as a generalist forager and obligate tidal marsh species throughout the historic record.The variable isoscape trends generated from feather isotope means illustrated a modern loss of the isotopic homogeneity between regions of historical tidal marsh,which correlated with spatially-explicit habitat alterations such as increasing biological invasions and sewage effluent over time.Conclusion:These findings have reinforced the importance of tidal marsh conservation in the face of ongoing underlying changes to these important ecosystems.

Processes of small-scale tidal flat accretion and salt marsh changes on the plain coast of Jiangsu Province,China

Large-scaled reclamation modifies the coastal environment dramatically while accelerating the disappearance of salt marshes,which causes the degradation of the coastal ecosystem and the biodiversity function.In this study,we explored the changes of tidal flat and salt marsh coverage in a small-scale tidal flat with an area of ~160 000 m^2 in the plain coast of Jiangsu Province,China.Human activities（e.g.,the construction of dikes） are a crucial contributor that benefits for the tidal flat accretions and the following changes of salt marsh coverage.Located in the front of the man-made ＂concave coastline＂,the study area is suitable for sediment accretion after the dike construction in the end of 2006.On the basis of the annual tidal surface elevation survey from 2007 to 2012,the sedimentation rates in the human influenced tidal flat varied from a few centimeters per year to 23 cm/a.The study area experienced a rapid accretion in the tidal flat and the expansion of the salt marsh,with the formation of a longshore bar,and a subsequent decline of the salt marsh.Breaking waves during the flooding tide brought much sediment from the adjacent tidal flat to the study area,which caused burial and degeneration of the salt marsh.The vertical grain size changes within a 66 cm long core in the study area also demonstrated the above changes in the tidal environment.This study indicates that the responses of small-scale tidal flat changes to reclamation are significant,and the rational reclamation would benefit for the new salt marsh formation in front of the dikes.Further research about the evolution of small scale tidal flat as well as the spatial planning of the polder dike should be strengthened for the purpose to maintain a healthier coastal environment.

Discovery and features of vertical zonations of tidal salt-marsh foraminifera in Jianchuan, North Jiangsu Province, China

Through densified surface sampling of foraminifera and accurate elevation measurement a-long three transect lines in open-coast tidal salt-marsh of Jianchuan, particular salt-marsh foraminifera assemblages were found. The salt-marsh foraminifera assemblages are distributed in well-defined vertical zonations with respect to elevation and closely parallel marsh floral zonations. At the top of the vertical zonation all foraminifera disappear abruptly which are accurately located at the highest high water datum. This distribution pattern can be used to relocate former sea levels accurately (to an accuracy of within ±5 cm). A modern regional criterion of foraminifera for relocating the former sea levels in high resolution in our country is provided, and deficiencies of studying the vertical zonation only in sheltered coast salt-marsh abroad are filled up.

COASTAL SALT MARSHES AND MANGROVE SWAMPS IN CHINA

Based on plant specimen data,sediment samples,photos,and sketches from 45 coastal cross-sections,and materials from two recent countrywide comprehensive investigations on Chinese coasts and is-lands,this paper deals with China’s vegetative tidal-flats:salt marshes and mangrove swamps.Thereare now 141700 acres of salt marshes and 51000 acres of mangrove swamps which together cover about30% of the mud-coast area of the country and distribute between 18°N(Southem Hainan Island)and41°N(Liaodong Bay).Over the past 45 years.about 1750000 acres of salt marshes and 49400 acres ofmangrove swamps have been reclaimed.The2.0×10~9 tons of fine sediments input by rivers into the Chinese seas form extensive tidal flats,the soil basis of coastal helophytes.Different climates result inthe diversity of vegetation.The 3～8m tidal range favors intertidal zone development.Of over 20plant species in the salt marshes,native Suaeda salsa,Phragmites australis,Aeluropus littoralis,Zoysiamaerostachys,Imperata cylindrica and

滨海盐沼湿地地貌形态和植被格局的生态-地貌耦合模拟研究

滨海盐沼湿地是重要的海岸带生态系统,其地貌形态和植被格局受潮汐动力、泥沙供给等条件影响显著。近年来,盐沼生态-地貌动力学研究成为前沿研究热点。以我国典型潮滩盐沼的动力环境为原型,建立考虑水动力-泥沙-地貌-植被互馈过程的动态耦合模型,研究了不同潮差、海平面上升速率、泥沙供给与泥沙性质等关键变量影响下的盐沼湿地植被-地貌耦合演变过程。研究结果表明,外部泥沙供给是控制潮滩-盐沼高程和植被范围的关键要素,外海悬沙浓度越大,滩面坡度越缓、滩面高程越高、植被的海向延伸越宽;泥沙沉降速度越小,易形成上凸型剖面,且湿地植被分布范围更宽;潮差同时影响盐沼在潮间带的下部边界和上部边界,更大的潮差、更强的潮汐水动力有助于形成更高的潮沟密度和泥沙向盐沼内部的输送效率。研究结果可为滨海湿地保护和修复工程提供理论参考。

闽江河口淡水、半咸水沼泽土壤碳氮磷分布及计量学特征

以闽江河口区淡水、半咸水短叶茳芏沼泽湿地为研究对象,于2013年11月~2014年8月分季节采集表层土壤样品,研究土壤有机碳（SOC）、总氮（TN）、总磷（TP）含量时空变异格局及其计量学特征,并同步观测相关环境因子.结果表明,淡水、半咸水沼泽土壤SOC、TN、TP含量范围分别为（18.24~28.36,1.44~2.24,0.45~1.01）（14.96~26.19,1.55~2.45,0.67~1.18）g/kg.淡水沼泽土壤各元素含量均具有明显的垂直变化规律;而半咸水沼泽除TN含量垂直变异明显外,其他各指标则表现为波动变化的特征.淡水、半咸水沼泽土壤C/N、C/P、N/P均值分别为12.41±1.22,29.77±6.76,2.40±0.47以及10.89±1.09,24.92±3.80,2.29±0.25.方差分析显示,各指标含量在两个沼泽均存在显著空间差异.两个沼泽土壤SOC、TP、C/N、C/P均与土壤p H和EC呈显著相关关系,而与含水率和容重相关性不显著;土壤C/N均与粉砂粒和砂粒呈极显著相关关系;土壤SOC、TN、TP含量对C/N、C/P、N/P影响显著.淡水、半咸水沼泽土壤营养元素含量分布特征是水动力学作用、外源物质输入、植物生产力和人类活动等多因子综合作用的结果.

长江口潮沼植物对动力沉积过程的影响

为探讨潮沼植物对动力沉积过程的影响 ,在长江口南汇东滩沼泽和邻近的光滩上进行了近底层流速、波浪、悬沙浓度、沉积物粒径和滩面淤积速率等对比实验 ,并在九段沙潮沼中做了两种先锋植物黏附悬沙的实验 .结果表明 ,沼泽和同高程的邻近光滩近底层平均流速的比值为 0 .1 6～ 0 .84;两种环境平均波周期、平均波高和平均悬沙浓度的比值分别为 1 .4,0 .43,和 0 .71 .波浪传入沼泽后 ,一方面波高大大降低 ,另一方面变得规则有序 .海三棱草和草两种先锋植物群落黏附的悬沙分别达到 2 98和40 g/m2 .由于水动力降低和植物的捕沙功能 ,细颗粒泥沙易于在沼泽中沉积下来 ,导致沼泽环境沉积物明显较相邻光滩细 ;沼泽中沉积速率加快 ,侵蚀受到抑制 .

黄河三角洲潮间带不同类型湿地景观格局变化与趋势预测

以1979—2013年7期卫星遥感影像(Landsat TM)为数据源,结合野外实地调查,通过建立黄河三角洲潮间带湿地数据库,探讨不同类型湿地的景观格局以及自然与人为因素对景观格局变化的影响,并基于Markov模型对未来20年三角洲潮间带不同类型湿地的景观格局进行了趋势预测。结果表明,三角洲的潮间带湿地面积在1979—2013年间整体呈先降低后增加变化。其中,1979—2010年的湿地面积持续减少,由1050.28 km^2减少为575.39 km^2,减少率为45.22%;2010—2013年的湿地面积略有增加,由575.39 km^2增加为596.17 km^2,增长率为0.36%。1979—2013年,潮间带主要湿地景观类型随距海远近均呈明显带状分布,但芦苇湿地面积呈明显降低趋势(减少273.53 km^2,减少率为79.68%),盐田养殖池面积呈显著增加趋势(增长12.04km^2,增长率为1584.21%),而光滩、碱蓬湿地、碱蓬-柽柳湿地和柽柳-芦苇湿地等其它类型湿地面积整体均呈波动减少趋势。未来20年,潮间带湿地面积整体将呈降低趋势,其值将由2010年的575.39 km^2减少为2030年的546.98 km^2,减少率为6.60%。芦苇湿地面积将继续减少(减少30.16 km^2,减少率为24.12%),盐田养殖池面积将持续增长(增加3.71 km^2,增长率为38.61%),而光滩、碱蓬湿地、碱蓬-柽柳湿地和柽柳-芦苇湿地等其它类型湿地面积均将呈小幅波动变化。研究发现,尽管自然与人为驱动力的双重作用决定了1979—2013年间潮间带的湿地景观格局及其动态变化,但黄河年输沙量(x_1)、区域GDP(x_2)和水产品产量(x_3)对潮间带湿地面积变化(y)的影响更为重要(y=733.192+35.317 x_1-0.005 x_2-4.085 x_3,P=0.0001<0.05),其对过去30多年间潮间带湿地面积变化的解释贡献高达76.7%。随着黄河三角洲高效生态经济区国家战略的实施,为实现潮间带区域的可持续发展,潮间带湿地的保护与生态保育应给予特别重视。

黄河口新生湿地碱蓬生物量及氮累积与分配对外源氮输入的响应

2014年4—11月,选择黄河入海口北部滨岸高潮滩的碱蓬湿地为研究对象,基于野外原位氮输入模拟试验,研究了不同氮输入梯度下(N0,无氮输入;N1,低氮输入;N2,中氮输入;N3,高氮输入)碱蓬不同器官生物量以及氮累积与分配特征的差异。结果表明,尽管不同氮输入处理并未改变碱蓬地上生物量的季节变化模式,但在不同程度上均促进了地上生物量的增长(平均增幅为19.71%—62.29%)且整体表现为N3>N2>N1>N0;不同氮输入处理亦延长了碱蓬的生长高峰期,N1、N2和N3处理下地上生物量达到最大值的时间相对于N0处理推迟20 d左右。与地上生物量不同,不同氮输入处理改变了地下生物量的季节变化模式,特别是N2和N3处理均对生长初期的地下生物量产生了明显促进作用,且其初期地下生物量达到较高值的时间相对于N1和N0处理提前20—50d。不同氮输入处理下的枯落物量在产生初期和中期均增幅不大,末期则骤然增加且整体表现为N3>N2>N1>N0。不同氮输入处理下碱蓬各器官的全氮(TN)含量总体上均表现为叶>茎>根,叶是氮的主要累积器官。尽管不同氮输入处理并未改变碱蓬不同器官的氮累积与分配格局以及地上与地下之间的养分供给关系,但其为适应不同养分条件而调整自身养分供给与分配的特性在N2处理下表现的尤为明显。研究发现,N2处理下碱蓬种子的发育时间相对于N0、N1和N3处理可能会提前约1个月,原因可能与N2氮输入水平可显著影响碱蓬体内的碳分配比以及碱蓬对适量氮养分输入环境的特殊适应对策有关。随着黄河口新生湿地氮养分供给的不断增加,当未来碱蓬湿地氮养分状况达到较高水平(特别是中等水平)时,其生物量、生长节律(特别是种子发育时间)以及不同器官氮累积与分配状况可能将发生明显改变。

黄河口潮间盐沼湿地生长季净生态系统CO_2交换特征及其影响因素

潮间盐沼湿地生物地球化学过程独特,生态系统CO2交换存在着极大的复杂性和不确定性。利用2012年黄河口潮间盐沼湿地生态系统生长季(4—10月)连续的涡度相关观测数据,分析了潮间盐沼湿地的净生态系统CO2交换(NEE)、总初级生产力(GPP)和生态系统呼吸(Reco)的变化特征及其影响因素。结果表明:生长季,生态系统NEE具有明显的日变化和季节变化。日尺度上,表现为白天CO2净吸收,夜间CO2净释放,NEE日平均值为-0.38 g CO2m-2d-1;月尺度上,平均气温最高的7月生态系统释放CO2最多(15.16 g C/m2),6月生态系统吸收CO2最多(25.07 g C/m2)。潮间盐沼湿地生态系统的CO2交换受到光合有效辐射(PAR)、土壤温度(Ts)、土壤含水量(SWC)和潮汐淹水的共同影响。白天NEE主要受控于PAR,且生态系统表观初始光能利用率(α)和最大光合速率(NEEsat)分别在6月和5月达到最大值,分别为(0.0086±0.0019)μmol CO2μmol-1光子和(4.79±1.52)μmol CO2m-2s-1。夜间NEE随Ts呈指数增加趋势,生态系统呼吸的温度敏感性(Q10)为1.33,且SWC越高,Q10值越大。研究典型晴天(6月19日—6月25日)表明,潮汐淹水增强了生态系统白天对CO2的吸收,同时也增强了夜间CO2释放,研究时段内,潮汐淹水使生态系统净CO2吸收增加了0.76 g CO2m-2d-1。整个生长季,黄河口潮间盐沼湿地生态系统表现为CO2的汇,NEE为-22.28 g C/m2(其中,吸收118.34 g C/m2,释放96.28 g C/m2)。研究结果利于对潮间盐沼湿地源汇功能和影响机制的进一步认识与研究。

某石油污染滩涂沉积物中总石油烃和多环芳烃组成分布特征及源解析

对石油污染滩涂区域不同高程表层沉积物和部分垂直剖面沉积物进行采样分析,分别采用紫外分光光度法和气相色谱质谱联用法测定了沉积物中的TPH（总石油烃）和16种优控PAHs（多环芳烃）,分析其组成分布特征,并进行了源解析。结果表明：中低潮滩表层沉积物中TPH质量比在15.20~63.27 mg/kg,与对照点质量比水平相当,远低于《海洋沉积物质量标准》（1 000 mg/kg）,PAHs均未检出;高潮滩表层沉积物中TPH质量比在1 070.00~46 327.20 mg/kg,显著高于对照点和相应中低潮滩沉积物中污染物质量比,部分点位严重超出《海洋沉积物质量标准》,PAHs质量比在0.60~30.90 mg/kg,多数点位属于重度污染;3号点和7号点高潮滩垂直剖面样品中TPH和PAHs质量比呈现随深度增加而降低的趋势,9号点则相反;高潮滩沉积物中TPH和PAHs质量比之间呈显著正相关关系（Pearson相关系数r为0.985,p〈0.01）,具有同源性;各点位TPH均以C17~C36质量分数最高,其占比为80.15%~94.40%,PAHs组成均以2~3环为主,占比为58.14%~87.70%,低环PAHs以萘、芴和菲为主要污染物。TPH和PAHs组分特征表明,研究区域的滩涂沉积物受到了重油污染影响。

黄河口潮滩湿地土壤CH4氧化潜力及其对有机物输入的响应

2010年11月,采集了黄河口北部滨岸高潮滩、中潮滩、低潮滩和光滩表层土壤样品,基于短期培养实验,研究了不同潮滩土壤CH4氧化潜力及其对有机物输入的响应.结果表明,尽管4种湿地土壤的CH4氧化潜力存在一定差异（P＞0.05）,但整体变化规律相似.12～60 h,CH4氧化潜力均呈先增加后降低变化;60～132 h,CH4氧化潜力均呈迅速增加趋势.4种湿地土壤CH4氧化潜力整体表现为光滩（2.37 μg/g·d）＞低潮滩（2.29 μg/g·d）＞中潮滩（1.70 μg/g·d）＞高潮滩（1.47 μg/g· d）.甲醇输入整体抑制了湿地土壤的CH4氧化潜力,抑制程度表现为光滩＞中潮滩＞低潮滩＞高潮滩.4种湿地土壤的CH4氧化潜力分别为1.27,0.49,0.67和0.38 μg/（g·d）,较对照组降低13.56％,70.98％,70.65％和83.83％;酵母膏输入对高潮滩、中潮滩和光滩土壤的CH4氧化潜力表现为促进作用,促进程度表现为中潮滩＞高潮滩＞光滩.3种湿地土壤的CH4氧化潜力分别为2.89,2.41和2.96μg/（g·d）,较对照组增加69.38％,64.01％和24.76％.与之相比,酵母膏对低潮滩土壤的CH4氧化潜力表现为弱抑制作用,其氧化潜力为2.14 μg/（g·d）,较对照组降低6.67％.可见,不同有机物对潮滩湿地土壤CH4氧化潜力的影响差异较大,在当前外源有机物为黄河入海主要污染物情况下,潮滩湿地CH4的源/汇功能将会发生明显变化,这就使得在估算黄河口潮滩CH4排放清单时应特别关注不同有机物输入对CH4释放的影响.

黄河口滨岸潮滩湿地土壤碳、氮的空间分异特征

2009年5月,运用地统计学方法研究了黄河口滨岸潮滩湿地土壤碳、氮的空间分布格局。结果表明,潮滩湿地土壤的TC、TN和C/N含量具有明显的水平变异性,自表层向下均呈显著降低趋势,总体表现为TN>C/N>TC。潮滩湿地土壤不同土层TN和C/N含量的水平分布空间结构明显,分别符合不同的变异函数理论模型,且具有强烈/中等程度的空间相关性,其空间变异性均以向低潮滩延伸且受潮汐涨落影响较大的方向为最大,自然结构因素在引起TN和C/N空间异质性中的贡献占优,随机因素的影响相对较小。潮滩湿地土壤不同土层TN和C/N具有明显的空间分布格局,表层土壤的TN含量向低潮滩延伸方向形成明显斑块低值区,边缘则形成斑块高值区,而不同土层的C/N以及亚表层的TN则与之相反。研究发现,微地貌特征和潮汐微域物理扰动强度是导致空间异质性的重要随机因素,而水盐条件、土壤类型和潮汐物理扰动是重要结构因素。湿地有机质来源以陆源为主,且越靠近海的方向,潮滩湿地土壤中的有机质受陆源的影响越大。

外源氮持续输入对相应氮梯度下碱蓬残体分解及硫养分释放的影响

以黄河口北部滨岸高潮滩的碱蓬残体为研究对象,将第一年度野外原位氮输入试验(N0:无额外氮处理;N1:低氮处理;N2:中氮处理;N3:高氮处理)获得的不同基质质量残体(NL0,NL1,NL2和NL3),原位投放至来源样区,并通过第二年度的持续输氮,探讨外源氮持续输入条件下残体基质质量改变对其分解速率和硫养分释放的影响。结果表明,随着氮输入量的增加,不同基质质量残体的分解速率整体表现为NL1>NL3>NL2>NL0,说明外源氮持续输入条件下基质质量改变促进了残体的分解,且该促进作用在低氮处理下表现的最为明显,原因主要与其在残体分解过程中C/N比的改变程度最为明显有关。不同基质质量残体中的TS含量均呈不同程度波动变化特征,且其与相应的C/S比均呈相反规律变化,说明C/S比是调控不同氮持续输入条件下残体分解过程中硫含量变化的主控因素。不同基质质量残体的硫养分在分解期间均发生不同程度的净释放,且释放强度整体表现为NL3>NL1>NL2>NL0,说明外源氮持续输入条件下残体基质质量改变促进了其硫养分释放,且该促进作用在高氮处理下表现的最为明显。研究发现,未来黄河口氮养分负荷增加的情况下,碱蓬残体的基质质量(C/N和C/S)将发生改变,而持续增强的氮负荷又会促进不同基质质量残体的硫养分归还,从而加速硫的生物循环速率。

试论植物在潮滩发育演变中的作用

根据1985—1991年对长江三角洲和苏北潮滩-潮沼系统中潮流和波浪观察、滩面高程量算、沉积物分析和人工海草试验，研究植物对潮滩动力和沉积的影响。结果表明，（1）植物可使底层流速降低20％-60％，使波浪能量大部分被吸收。（2）沼泽前缘存在侵蚀机制，而沼泽的主体则有明显的促淤现象；沼泽中的沉积速率可达光滩的9倍以上。（3）沼泽前缘沉积物有粗化现象，沼泽主体则是细化环境；沼泽是孢粉相对富集的场所；沼泽中各种物理沉积构造不易形成和保存。

外源氮输入对黄河口碱蓬湿地土壤碳氮含量动态的影响

2014年4—11月,选择黄河入海口北部滨岸高潮滩的碱蓬湿地为研究对象,基于野外原位氮输入模拟试验,研究了不同氮输入梯度下(N0,无氮输入;N1,低氮输入;N2,中氮输入;N3,高氮输入)湿地土壤碳氮含量动态特征及其差异。结果表明,不同氮输入处理下土壤的SOC、TN、NH_4^+—N和NO_3^-—N含量整体上均随着土层深度的增加而逐渐降低,各土层的SOC和NO_3^-—N含量在N2处理最高,而TN和NH_4^+—N含量在N3处理最高。尽管不同氮输入处理并未改变湿地土壤中TN和NH_4^+—N含量的动态变化模式,但随氮负荷增强二者含量均呈增加趋势。不同的氮输入处理明显改变了土壤中SOC和NO_3^-—N的动态变化模式,适量氮输入(N1和N2)明显提高了土壤中的NO_3^-—N含量,过量氮输入(N3)则不利于NO_3^-—N的累积;不同氮输入处理下(特别是N2和N3处理)湿地表层土壤(0—20cm)的SOC含量在7月中旬后远大于N0处理(P<0.05),说明持续的氮输入可能不利于表层土壤中SOC的转化。研究发现,当未来黄河口湿地氮养分达到N1和N2水平时将有利于土壤氮矿化,而这将使得土壤氮养分的供给更为充足;但氮负荷持续增强可能使土壤表层的SOC转化受到抑制,而这将有助于提升土壤的储碳功能。

外源氮输入对黄河口新生湿地植物-土壤系统硫分布特征的影响

选择黄河口北部滨岸高潮滩的碱蓬湿地为研究对象,基于野外原位氮(N)输入模拟试验,研究了不同氮输入梯度下(N0,无氮输入;N1,低氮输入,9.0 gN m^(-2)a^(-1);N2,中氮输入,12.0 gN m^(-2)a^(-1);N3,高氮输入,18.0 gN m^(-2)a^(-1))碱蓬湿地植物-土壤系统全硫(TS)分布特征的差异。结果表明,外源N输入明显改变了湿地土壤TS含量的分布状况。随着N输入量的增加,除表层TS含量变化不明显外,其他土层均呈增加趋势。不同氮输入处理下植物各器官的TS含量整体均表现为叶>茎>根,叶是硫的主要累积器官。尽管氮输入处理并未改变植被的硫分配格局以及其地上与地下之间的硫养分供给关系,但其为适应不同养分环境可进行自身生长特性及养分分配的调整,且这种调整在N2处理下表现的尤为明显。随氮输入量的增加,不同氮处理下植物-土壤系统的S储量整体呈增加趋势,但土壤S储量的增幅远低于植物亚系统S储量的增幅以及N供给的增幅,说明N、S之间的养分供给存在不同步性。研究发现,未来黄河口N养分负荷增加情况下,碱蓬湿地植物-土壤系统的S生物循环速率不但可能会加速,而且N、S养分之间也可能形成一个正反馈机制,并将有利于维持新生湿地的稳定与健康。