Contribution of Spartina maritima to the reduction of eutrophication in estuarine systems

Salt marshes are among the most productive ecosystems in the world, performing important ecosystem functions, particularly nutrient recycling. In this study, a comparison is made between Mondego and Tagus estuaries in relation to the role of Spartina maritima in nitrogen retention capacity and cycling. Two mono-specific S. maritima stands per estuary were studied during 1 yr (biomass, nitrogen (N) pools, litter production, decomposition rates). Results showed that the oldest Tagus salt marsh population presented higher annual belowground biomass and N productions, and a slower decomposition rate for litter, contributing to the higher N accumulation in the sediment, whereas S. maritima younger marshes had higher aboveground biomass production. Detritus moved by tides represented a huge amount of aboveground production, probably significant when considering the N balance of these salt marshes. Results reinforce the functions of salt marshes as contributing to a reduction of eutrophication in transitional waters, namely through sedimentation processes.     

CHemical and Biological Assessment of an Urban, Estuarine marsh in Northeastern New Jersey USA

Oritani Marsh in the Hackensack Meadowlands of urbanized northeastern New Jersey USA was assessed in 2000 for vegetation, soil/sediment chemistry, abundance/diversity of benthic invertebrates, and bird and mammal usage. Vegetatively, both marsh and uplands are dominated by tall, dense Phragmites australis. Small patches (less than 2 hectares total) dominated by Spartina spp. were found at the lowest elevations. Soil/sediment cores were sliced into 5 intervals and analyzed for metals, pesticides and volatile/semivolatile organic compounds. Thirteen locations had at least one chemical above Long et al.’s [Environmental Management, 19, 1995, 81--97] “Effects Range-Median” (ERM). Seven metals and nine organics exceeded ERM in at least one sample, with mercury showing the most exceedances. The surface 15 cm interval was generally more contaminated with metals than the 15 to 30 cm interval; the reverse was true for semivolatile organic compounds. Twenty taxa of benthic macroinvertebrates were collected, with each location producing from 1 to 9 taxa. Abundance ranged from 11 to 3,889 individuals/m². Number of taxa was moderately (r ² between 0.40 and 0.70) negatively correlated with zinc, beryllium, nickel and arsenic concentrations; no other chemical’s r ² was above 0.25. Diversity was moderately negatively correlated with arsenic and beryllium. These correlations were unexpected: zinc, beryllium, nickel and arsenic were not the chemicals found at the highest concentrations relative to benchmarks. Number of taxa, abundance and diversity were moderately (negatively) correlated with elevation; organic carbon was moderately (positively) correlated with abundance. All other correlations were weak (r ² < 0.35). Live traps captured only one mammal species, the meadow jumping mouse. Bird observations revealed 39 species, dominated by a few common species.     

Effect of field exposure to 38-year-old residual petroleum hydrocarbons on growth, condition index, and filtration rate of the ribbed mussel, Geukensia demissa

In September 1969, the Florida barge spilled 700,000 L of No. 2 fuel oil into the salt marsh sediments of Wild Harbor, MA. Today a substantial amount, approximately 100 kg, of moderately degraded petroleum remains within the sediment and along eroding creek banks. The ribbed mussels, Geukensia demissa, which inhabit the salt marsh creek bank, are exposed to the spilled oil. Examination of short-term exposure was done with transplantation of G. demissa from a control site, Great Sippewissett marsh, into Wild Harbor. We also examined the effects of long-term exposure with transplantation of mussels from Wild Harbor into Great Sippewissett. Both the short- and long-term exposure transplants exhibited slower growth rates, shorter mean shell lengths, lower condition indices, and decreased filtration rates. The results add new knowledge about long-term consequences of spilled oil, a dimension that should be included when assessing oil-impacted areas and developing management plans designed to restore, rehabilitate, or replace impacted areas.     

长江口地区的盐水入侵灾害及变化趋势

本文在总结长江口地区现状盐水入侵时空变化规律的基础上,着重分析了在未来海平面上升、长江东线南水北调和三峡水利枢纽工程以及长江口北支综合整治等因素影响下,南支河段盐水入侵强度的变化趋势。     

植物对沼泽湿地生态系统N2O排放的影响

利用静态暗箱/气相色谱法连续3个生长季(2003-2005年)对三江平原小叶章草甸和毛果苔草沼泽N2O排放通量进行野外对比观测试验.结果表明,植物不同生长阶段对湿地生态系统N2O排放通量的影响不尽相同.植物的参与促进了湿地生态系统N2O的排放,2003-2005年生长季小叶章草甸土壤-植物系统N2O排放通量分别是土壤表观N2O排放通量的1.58倍、2.09倍和2.34倍,同期毛果苔草沼泽土壤-植物系统N2O排放通量分别是土壤表观N2O排放通量的1.86倍、1.50倍和1.33倍.3个生长季小叶章草甸N2O排放通量均大于毛果苔草沼泽,这主要是由土壤理化性质的空间变异性以及水文情况的差异造成的.     

Effects of salinity on soil bacterial and archaeal community in estuarine wetlands and its implications for carbon sequestration: verification in the Yellow River Delta

Soils from two typical tidal salt marshes with varied salinity in the Yellow River Delta wetland were analysed to determine possible effects of salinity on soil carbon sequestration through changes in soil microbiology. The mean soil respiration (SR) of the salt water–fresh water mixing zone (MZ) was 2.89 times higher than that of the coastal zone (CZ) (4.73 and 1.63?μmol?m^?2?s^?1, respectively, p?Pseudomonas sp. and Limnobacter sp. that might have led to its higher dehydrogenase activity and respiratory rates. Additionally, the CZ possessed more Halobacteria and Thaumarchaeota with the ability to fix CO₂ than the MZ. Significantly lower soil salinity in MZ (4.25?g?kg^?1) was suitable for β-Proteobacteria, but detrimental for Halobacteria compared with CZ (7.09?g?kg^?1, p?相似文献   

Energy-Based Land Use Predictors of Proximal Factors and Benthic Diatom Composition in Florida Freshwater Marshes

The Landscape Development Intensity index (LDI), which is based on non-renewable energy use and integrates diverse land use activities, was compared to other measures of LU (e.g., %agriculture, %urban) to determine its ability for predicting benthic diatom composition in freshwater marshes of peninsular Florida. In this study, 70 small, isolated herbaceous marshes located along a human disturbance gradient (generally agricultural) throughout peninsular Florida were sampled for benthic diatoms and soil and water physical/chemical parameters (i.e., TP, TKN, pH, specific conductance, etc.). Landscape measures of percent agriculture, percent urban, percent natural, and LDI index values were calculated for a 100 m buffer around each site. The strongest relationships using Mantel's r statistic, which ranges from −1 to 1, were found between benthic diatom composition, the combined soil and water variables, and LDI scores (r=0.51, P<0.0001). Although similar, soil and water variables alone (r=0.45, P<0.0001) or with percent agriculture or percent natural were not as strongly correlated (both Mantel's r=0.46, P<0.0001). Little urban land use was found in the areas surrounding the study wetlands. Diatom data were clustered using flexible beta into 2 groups, and stepwise discriminant analysis identified specific conductance, followed by LDI score, soil pH, water total phosphorus, and ammonia, as cluster-separating variables. The LDI explained slightly more of the variation in species composition than either percent agriculture or percent natural, perhaps because the LDI can combine disparate land uses into a single quantitative value. However, the ecological significance of the difference between land use metrics and diatom composition is controvertible, and additional tests including more varied land uses appear warranted.     

植物N/P与土壤pH值对湿地植物物种丰富度的影响

通过人工控制模拟试验,研究了植物中全氮与全磷之比(植物N/P)和土壤pH值与湿地植物物种丰富度的关系.结果表明,湿地物种丰富度与植物N/P之间呈单峰变化关系,当2.09.5时,氮、磷供应平衡系统可能被破坏,湿地物种逐渐减少.物种丰富度与土壤pH值表现为显著的正相关关系(R²=0.526),当pH值为5.6～6.8时,物种丰富度随着土壤pH值增加而增加.通过方差分析,土壤pH值和植物N/P对物种丰富度的影响分别为37.96%和15.29%.     

北京市某垃圾卫生填埋场堆山及覆盖工程实例

填埋场堆山及覆盖工程是指垃圾从地面向上填埋作业,至设计标高或填埋场停止使用高度的过程。为避免堆体沉降过大对堆体的稳定造成影响,根据勘察报告对垃圾填埋区进行的沉降分析,利用陈腐垃圾对沉降最大区域进行压实、垫高,保证垃圾堆体压实密度大于0.9;为减少渗沥液的产生保证渗沥液、沼气收集及导排系统安全有效的运行,采用基础构建的方式减少填埋作业面,从而减少雨季雨水的渗入;待堆体形成后,通过在堆体顶部及边坡铺设防渗及导排层对渗沥液和沼气进行疏导和收集,降低渗沥液和沼气对堆体稳定以及周边环境造成的影响,并铺设生态恢复层,美化环境。     

Environmental chemical study on the marsh of Fatimid cemetery at Aswan City,Egypt

ＩｎｔｒｏｄｕｃｔｉｏｎＡｓｗａｎｇｏｖｅｒｎｏｒａｔｅ ,Ｅｇｙｐｔ ,ｉｓｆａｍｏｕｓｆｏｒｂｙｍｏｎｕｍｅｎｔｓ (Ａｎｃｉｅｎｔ,ＣｏｐｔｉｃａｎｄＩｓｌａｍｉｃ) .Ｔｈｅｆｏｕｎｄａｔｉｏｎａｒｅｏｆｔｈｅｆｉｒｓｔｉｍｐｏｒｔａｎｃｅａｎｄｃａｒｅｓｈｏｕｌｄｂｅｔａｋｅｎｔｏｓｅｅｔｈａｔｔｈｅｙａｒｅｃｏｎｓｏｌｉｄａｔｅｄａｎｄｐｒｏｔｅｃｔｅｄａｓｆｏｒａｓｐｏｓｓｉｂｌｅｆｒｏｍｔｈｅｉｎｆｉｌｔｒａｔｉｏｎｏｆｗａｔｅｒ.Ｗａｔｅｒｉｓａｍａｊｏｒｃａｕｓｅｏｆｄａｍａｇｅ ,ｎｏ…