不同溶氧条件下九龙江口湿地沉积物一水界面氨氮释放与氧化规律

摘要：沉积物中氨氮（NH4^＋-N）的释放与氧化是河口湿地生态系统氮素生物地球化学循环的关键过程。本文通过室内模拟,构建饱和（BH）、好氧（HY）、缺氧（QY）和厌氧（YY）等四种上覆水溶氧（DO）条件,研究九龙江口湿地两种沉积物（红树林、光滩）中NH4^＋-N在沉积物-水界面的释放与氧化规律。结果表明,不同溶氧条件下,两种沉积物氨氮的释放、氧化存在显著差异。首先,红树林沉积物上覆水NH4^＋-NN的累积释放量是光滩沉积物的1．9-4．5倍,其中红树林沉积物上覆水NH4LN释放量分别达到1．64mg（BH）、2．07mg（HY）、3．47mg（QY）和3．20mg（YY）,而光滩沉积物则分别为0．85mg（BH）、1．00mg（HY）、0．77mg（QY）和1．27mg（YY）。在较高DO条件下两种沉积物NH。’一N均呈低释放状态,而在较低DO条件下则呈高释放状态。另外,四种溶氧条件下红树林沉积物NH4^＋-NN的释放速率（N43．73-78．51mg-m^-2-d^-1）和氧化速率（N26．19-40．68mg-m^-2-d^-1）均高于光滩（分别为N14．50-19．22mg-m^-2-d^-1和N8．89-22．53mg-m^-2-d^-1）,原因可能是红树林沉积物微生物种类丰富,群落多样性更高,矿化和硝化作用强烈。本文明晰了不同溶氧条件下河口红树林湿地沉积物NH4^＋-N的迁移转化过程,可促进滨海湿地的生态保护以及近海水域富营养化的控制。     

滨海沼泽湿地转化为养殖塘对其碳储量的影响

以闽江河口为研究区域,配对采集芦苇(Phragmites australis)湿地、短叶茳芏(Cyperus malaccensis)湿地和互花米草(Spartina alterniflora)湿地的植物、土壤(0～100cm)及由其围垦而成的水产养殖塘沉积物(0～100cm)样品,测定其有机碳含量,计算生态系统碳储量...     

Heavy metal pollution in tidal zones of Bohai Bay using the dated sediment cores

Three sediment cores were collected in November 2003 from Dagu estuary to Qikou estuary. The main polluted heavy metals in the sediment of tidal zones for the Bohai Bay have been found by analyzing the relationship among the contents of heavy metals, the contents of geochemical elements （Fe, AI and Mn） and the size of grain. The dominating contaminative elements in tidal sediments of Bohai Bay are Pb, Zn and Cd. Their contents are higher than the corresponding upper limit of environmental background values and they have very faint correlation with the corresponding contents of geochemical elements and the size of grain, indicating the anthropogenic enrichment. Especially, the preliminary study on the pollution sources and the history of heavy metals in the Dagu estuary has been done using the dated results. The contamination by Zn and Cd also started in the middle 1950s, while the contamination by Pb appeared in the early 1940s. The pollution by Zn and Cd mainly originate from sewage discharge, while the pollution by Pb has many sources, like atmosphere deposition and industrial discharRe.     

长江口污染物累积运移规律的初步研究

对长江口九段沙和崇明东滩潮滩水体及表层沉积物进行分析,结果表明:①南槽水体受到近岸排污的影响,在近岸形成NH4+-N和溶解态总磷(STP)含量很高的污染带,是远岸水域的2～3倍;悬浮颗粒吸附态磷(PP)作为P的主要形态,随着SS的增加,占总磷(TP)的比例从45%左右增加到90%左右。②南槽水体的总重金属分布态势主要取决于水体中SS的浓度,各元素之间及其各元素和SS相关性显著,主要吸附于SS中。③九段沙和崇明东滩在高低潮时受到不同水体的控制,低潮水体中重金属、TP和KN含量是高潮水体1 3～24 7倍,崇明东滩比九段沙变化更加显著。④受排污和水动力作用影响,低潮时悬浮物中重金属含量高于高潮时;悬浮物中重金属含量高于表层沉积物;高潮滩沉积物重金属含量高于低潮滩。      

长江淡水潮汐湿地植物特性和植物群落演替研究——以镇江北固山湿地为例

镇江北固山湿地属于长江近河口段淡水潮汐湿地,植物群落基本保持原生演替的前期状况。根据对该湿地的实地观测研究,描述了河滨湿地植物的生长特性;结合湿地的水文特征刻画了湿地高等水生植物在时间、空间和景观上的生态过程;综合河滨湿地植物的生长特性及湿地的水文特征探讨了镇江淡水潮汐湿地的演变趋势。对湿地面临的问题进行了讨论,从而为长江淡水潮汐湿地的生态修复和增加生物多样性及湿地保护提供参考。     

Global sea-level rise is recognised, but flooding from anthropogenic land subsidence is ignored around northern Manila Bay, Philippines

Land subsidence resulting from excessive extraction of groundwater is particularly acute in East Asian countries. Some Philippine government sectors have begun to recognise that the sea-level rise of one to three millimetres per year due to global warming is a cause of worsening floods around Manila Bay, but are oblivious to, or ignore, the principal reason: excessive groundwater extraction is lowering the land surface by several centimetres to more than a decimetre per year. Such ignorance allows the government to treat flooding as a lesser problem that can be mitigated through large infrastructural projects that are both ineffective and vulnerable to corruption. Money would be better spent on preventing the subsidence by reducing groundwater pumping and moderating population growth and land use, but these approaches are politically and psychologically unacceptable. Even if groundwater use is greatly reduced and enlightened land-use practices are initiated, natural deltaic subsidence and global sea-level rise will continue to aggravate flooding, although at substantially lower rates.     

渤海湾天津段潮间带沉积物柱状样重金属污染特征

2003-11采集了渤海湾天津段北至大沽口,南到岐口海域潮间带3个沉积物柱状样,对沉积物的粒度、有机质、重金属含量进行分析,对渤海湾潮间带沉积物柱状样的地化性质、重金属污染概况以及重金属的空间、垂向分布特点进行了研究.渤海湾潮间带沉积物由北至南逐渐变细,大沽口和独流减河口海域的沉积物主要是极细砂-粉砂-细砂组成,岐口海域潮间带沉积物主要组分是粉砂和极细砂.3个柱状样的垂向粒度分布趋势表明渤海湾潮间带沉积物自下向上有“粗化”的趋势.Fe、Al、Mn3种元素的空间分布与沉积物的粒径呈显著的负相关性,即Fe、Al、Mn含量主要分布在粒度较细的沉积物中.渤海湾潮间带主要重金属污染元素是Pb、Zn、Cd 3种.通过归一化研究,这3类重金属元素在沉积物中有很明显的人为污染痕迹,含量远远高于其相应的环境背景值.     

Restoring coastal wetlands that were ditched for mosquito control: A preliminary assessment of hydro-leveling as a restoration technique

The wetlands surrounding Tampa Bay, Florida were extensively ditched for mosquito control in the 1950s. Spoil from ditch construction was placed adjacent to the wetlands ditches creating mound-like features (spoil-mounds). These mounds represent a loss of 14% of the wetland area in Tampa Bay. Spoil mounds interfere with tidal flow and are locations for non-native plants to colonize (e.g., Schinus terebinthifolius). Removal of the spoil mounds to eliminate exotic plants, restore native vegetation, and re-establish natural hydrology is a restoration priority for environmental managers. Hydro-leveling, a new technique, was tested in a mangrove forest restoration project in 2004. Hydro-leveling uses a high pressure stream of water to wash sediment from the spoil mound into the adjacent wetland and ditch. To assess the effectiveness of this technique, we conducted vegetation surveys in areas that were hydro-leveled and in non-hydro-leveled areas 3 years post-project. Adult Schinus were reduced but not eliminated from hydro-leveled mounds. Schinus seedlings however were absent from hydro-leveled sites. Colonization by native species was sparse. Mangrove seedlings were essentially absent (≈2 m⁻²) from the centers of hydro-leveled mounds and were in low density on their edges (17 m⁻²) in comparison to surrounding mangrove forests (105 m⁻²). Hydro-leveling resulted in mortality of mangroves adjacent to the mounds being leveled. This was probably caused by burial of pneumatophores during the hydro-leveling process. For hydro-leveling to be a useful and successful restoration technique several requirements must be met. Spoil mounds must be lowered to the level of the surrounding wetlands. Spoil must be distributed further into the adjacent wetland to prevent burial of nearby native vegetation. Finally, native species may need to be planted on hydro-leveled areas to speed up the re-vegetation process.     

长江口潮滩湿地大型底栖动物群落的生态学特征

长江口潮滩湿地共有大型底栖动物68种，河口低盐种、半咸水种和淡水种共存，反映了咸、淡水过渡环境的特点。沿着河口梯度，随着盐度的升高，底栖动物物种数增多。沿潮滩高程梯度，从低位盐沼到高位盐沼，随着海三棱面草密度和生物量的增加，以及沉积物特性的变化，底栖动物物种丰度和多样性呈上升趋势。从潮沟底、潮沟边滩到草滩，潮沟系统小尺度生境变化导致底栖动物种类组成的生态系列变化。就长江口潮滩湿地来讲，不同尺度的空间异质性特点各异、主导因素亦有差别，河口盐度梯度、高程梯度、盐沼植被、潮沟系统对淤泥质河口潮滩湿地不同等级尺度的空间异质性起着主要的决定作用。正是这种不同尺度的异质性，维持着淤泥质河口潮滩湿地底栖动物群落结构的多样性和稳定性，使其表现出特大型河口淤泥质潮滩湿地底栖动物群落的独特性。尤其是沿高程分布的盐沼植被、潮沟系统、微地貌结构对潮滩湿地的底栖动物群落起着主要的调控作用。因此，在制订河口湿地恢复和重建计划时，对影响底栖动物群落的盐沼植被、高程、地形(尤其是潮沟变化)应予以特别关注。     

螃蟹对闽江河口湿地土壤碳氮磷含量及其生态化学计量学特征影响

为阐明螃蟹活动对湿地土壤碳、氮、磷含量及其生态化学计量学特征的影响,对闽江河口湿地不同潮滩螃蟹干扰下的土壤碳、氮、磷含量及其生态化学计量学特征进行了测定和分析.结果表明:高潮滩有螃蟹(GP)和高潮滩无螃蟹(GD)组土壤碳、氮、磷含量的平均值分别为(13.32±0.66)、(1.51±0.05)、(0.70±0.05)g·kg~(-1)和(13.25±0.53)、(1.52±0.04)、(0.75±0.04)g·kg~(-1),螃蟹组与对照组之间的碳、氮、磷含量差异不显著(p0.05);中潮滩有螃蟹(ZP)和中潮滩无螃蟹(ZD)组土壤碳、氮、磷含量的平均值分别为(13.85±0.61)、(1.64±0.08)、(0.77±0.07)g·kg~(-1)和(13.10±0.43)、(1.52±0.08)、(0.79±0.04)g·kg~(-1),螃蟹组土壤碳、氮含量显著高于对照组(p0.05),但磷含量差异不显著(p0.05).GP和GD组土壤C/N、C/P、N/P的平均值分别为(8.80±0.26)、(19.38±1.34)、(2.17±0.16)和(8.70±0.28)、(17.78±0.42)、(2.04±0.13),螃蟹组养分比与对照组差异不显著(p0.05);ZP和ZD组土壤C/N、C/P、N/P的平均值分别为(8.57±0.27)、(18.41±0.68)、(2.11±0.18)和(8.52±0.35)、(16.72±0.32)、(2.01±0.19),螃蟹组养分比与对照组差异不显著(p0.05).总体来看,土壤碳、氮、磷及其生态化学计量学特征的变化是环境因子综合作用的结果,其生态化学计量学特征对土壤碳、氮、磷固持及限制性养分具有一定的指示作用.