Accumulation and biological cycling of heavy metal in four salt marsh species, from Tagus estuary (Portugal)

Pools of Zn, Cu, Cd and Co in leaf, stem and root tissues of Sarcocornia fruticosa, Sarcocornia perennis, Halimione portulacoides and Spartina maritima were analyzed on a bimonthly basis, in a Tagus estuary salt marsh. All the major concentrations were found in the root tissues, being the concentrations in the aboveground organs neglectable for sediment budget proposes, as seen by the low root-aboveground translocation. Metal annual accumulation, root turnovers and cycling coefficients were also assessed. S. maritima showed the higher root turnovers and cycling coefficients for most of the analyzed metals, making this a phytostabilizer specie. By contrast the low root turnover, cycling coefficient and low root necromass generation makes S. perennis the most suitable specie for phytoremediation processes. Although the high amounts of metal return to the sediments, due to root senescence, salt marshes can still be considered sinks of heavy metals, cycling heavy metals mostly between sediment and root.     

Evaluation of the Impacts of Dock Structures and Land Use on Tidal Creek Ecosystems in South Carolina Estuarine Environments

Tidal creeks and their associated salt marshes are the primary link between uplands and estuaries in the southeastern region. They are also critical nursery and feeding grounds. In addition, the uplands surrounding creeks are preferred sites for homebuilding because of their natural beauty and the ability to access the estuary from a personal dock structure. The objective of this study was to evaluate the cumulative impacts of docks on tidal creek nursery habitats for both small and large tidal creeks. The number of docks was associated with the amount of impervious cover in both small and large creeks. The presence of docks had little measurable effect on sediment metal concentrations at the scale of small and large creeks. In small and large creeks, sediment polycyclic aromatic hydrocarbon (PAH) concentrations were related to the human activity in the upland that includes the presence of docks at the scale of small and large creeks. Some impacts on the benthic community were associated with docks and human activity in small creeks but not in large creeks. Suburban development may reduce fish and crustacean abundances, but the dock may potentially mediate the development effect. Individually, the harm to the marine environment resulting from dock shading, chrominated copper arsenate leachates, and PAH contamination was small at the scale of tidal creeks. However, impacts from dock structures could not be separated from anthropogenic watershed-scale effects. These results demonstrate that suburban development with its accompanying dock construction does represent a major source of environmental degradation to tidal creeks and associated salt marsh habitats.     

黄河口不同恢复阶段湿地土壤N2O产生的不同过程及贡献

采用时空替代法,选择黄河口生态恢复前后未恢复区(R0)、2007年恢复区(R2007)和2002年恢复区(R2002)的芦苇湿地为研究对象,分析了生态恢复工程对湿地土壤N2O产生不同过程与贡献的影响.结果表明,尽管不同恢复阶段湿地土壤N2O总产生量差异明显,但总体均表现为N2O释放.恢复区湿地土壤的N2O产生量大于未恢复区.N2O的产生主要以硝化作用和硝化细菌反硝化作用为主,而反硝化作用对N2O的产生有较大削弱作用,这与不同恢复阶段湿地土壤理化性质密切相关.非生物作用对N2O产生量贡献较大,这与黄河口为高活性铁区,Fe的还原作用关系密切.尽管黄河口不同恢复阶段湿地土壤N2O的产生是生物作用与非生物作用共同作用的结果,但由于非生物作用对N2O产生的影响较大,应受到特别关注.温度和水分对不同恢复阶段湿地土壤N2O产生过程的影响不尽一致,这与土壤微生物活性对温度和水分的响应差异有关.黄河口不同恢复阶段湿地土壤的N2O总产生量介于(0.37±0.08)～(9.75±7.64)nmol·(kg·h)-1,略高于闽江口互花米草湿地的N2O总产生量,但明显低于富氧森林土壤、草原土壤和闽江口短叶茳芏湿地的N2O总产生量.研究发现,黄河口生态恢复工程的长期实施明显促进了N2O的产生,因而下一步生态恢复工程应统筹考虑景观恢复与温室气体削弱这两方面因素.     

PHOSPHORUS ACCUMULATION - DISCHARGE CYCLES IN MARSHES1

ABSTRACT: Artificial and natural marshes were studied to determine changes in quality of polluted water passing through them. Phosphorus removal ranged from zero to 64%. Removals in the 35% range were common, however. Much of the phosphorus went into sediments and unharvestable plant parts. Harvesting vegetation removed 6% of the phosphorus put into the system. Accumulation of phosphorus during the growing season was about 20 g*m^?2, much of which was flushed out after the onset of freezing weather. The amount of phosphorus flushed out can be prevented from entering a lake or stream by handling the marsh discharge in one of three ways; irrigate on land, lagoon to recycle later, treat conventionally if facilities are available.     

WATER BUDGETS FOR SMALL DIKED MARSHES1

ABSTRACT: This paper reports an analysis of the water budgets of 10 small (5–6 ha) diked areas (cells) within the Delta Marsh in southcentral Manitoba, Canada. The important terms in the water budget equation in this study were precipitation (P), water pumped in (SWI), evapotranspiration (ET), seepage in (GWI) and out (GWO), and change in storage (ΔS). P, SWI, and S were measured directly, and the sum of ET and GWO determined by difference. Estimating ET as 0.7 pan evaporation gave a seepage loss of 2.9 mm/day from the most intensively studied cell. Other methods of estimating ET produced estimates of GWO ranging from 2.4 to 3.8 mm/day. Water budgets for less intensively studied cells indicated seepage loss increased as perimeter available for seepage increased, but not proportionately. Efforts to measure seepage directly or estimate it from measured hydraulic gradients and hydraulic conductivity produced estimates much lower than the estimates from the water budget equation. Hydraulic conductivities were very heterogeneous, reflecting the sorting of water deposited sediments. Comparison of the hydraulic conductivities with seepage estimates from the water budget strongly suggests water movement downward as well as laterally from these diked areas.     

Evaluation of tidal marsh restoration: Comparison of selected macroinvertebrate populations on a restored impounded valley marsh and an unimpounded valley marsh within the same salt marsh system in Connecticut,USA

Macroinvertebrates were examined on an impounded valley marsh in Stonington, Connecticut, that has changed from aTypha-dominated system to one with typical salt-marsh vegetation during 13 years following the reintroduction of tidal exchange. Animal populations on this restored impounded marsh were evaluated by comparing them with populations on a nearby unimpounded valley marsh of roughly the same size. Populations of the high marsh snail,Melampus bidentatus Say, were quantitatively sampled along transects that extended from the water-marsh edge to the upland; those of the ribbed mussel,Geukensia demissa Dillwyn, were sampled in low marsh areas on transects along the banks of creeks and mosquito ditches. The occurrence of other marsh invertebrates also was documented, but their abundance was not measured. The mean density ofMelampus was 332±39.6 SE/m² on the restored impounded marsh and 712±56.0 SE/m² on the unimpounded marsh. However, since snails were larger on the restored impounded marsh, the difference in snail biomass was less pronounced than the difference in snail density. MeanMelampus biomass was 4.96±0.52 SE g dry wt/m² on the restored impounded marsh and 6.96±0.52 SE g dry wt/m² on the unimpounded marsh. On the two marshes, snail density and biomass varied in relation to plant cover and other factors. The density and biomass ofGeukensia at the edge of the marsh were comparable on the restored impounded and unimpounded marshes. Mean mussel densities ranged from 80 to 240/m² and mean mussel biomass varied from 24.8–64.8 g dry wt/m² in different low marsh areas. In contrast, below the impoundment dike, meanGeukensia density was 1100±96.4 SE/m² and meanGeukensia biomass was 303.6±33.28 SE g dry wt/m². A consideration of all available evidence leads to the conclusion that the impounded marsh is in an advanced phase of restoration.     

Effects of increased elevation and macro- and micronutrient additions onSpartina alterniflora transplant success in salt-marsh dieback areas in Louisiana

Spartina alterniflora was transplanted into dieback areas of a salt marsh in southeast Louisiana at two elevations (ambient and +30 cm) with and without macro- (N, P, and K) and micronutrient (Fe, Mn, Cu, and Zn) additions to determine if transplant success is dependent on increasing elevation or nutrients.Spartina alterniflora transplanted into elevated plots had more than twice the above- and belowground biomass as compared to nonelevated plots after three months of growth. Additionally, there was significantly more vegetative reproduction (greater culm density and number of newly produced culms) in elevated plots as compared to plots at ambient elevation. Macronutrient additions increased culm densities only in elevated plots.Spartina alterniflora transplanted into nonelevated plots had lower survival rates even when transplants received nutrient additions. These results suggest thatS. alterniflora may be transplanted successfully into degraded salt-marsh areas if elevation is increased. The addition of nutrients without a concomitant increase in elevation is not sufficient for transplant success.     

Coastal Flood Inundation Monitoring with Satellite C‐band and L‐band Synthetic Aperture Radar Data

Satellite Synthetic Aperture Radar (SAR) was evaluated as a method to operationally monitor the occurrence and distribution of storm‐ and tidal‐related flooding of spatially extensive coastal marshes within the north‐central Gulf of Mexico. Maps representing the occurrence of marsh surface inundation were created from available Advanced Land Observation Satellite (ALOS) Phased Array type L‐Band SAR (PALSAR) (L‐band) (21 scenes with HH polarizations in Wide Beam [100 m]) data and Environmental Satellite (ENVISAT) Advanced SAR (ASAR) (C‐band) data (24 scenes with VV and HH polarizations in Wide Swath [150 m]) during 2006‐2009 covering 500 km of the Louisiana coastal zone. Mapping was primarily based on a decrease in backscatter between reference and target scenes, and as an extension of previous studies, the flood inundation mapping performance was assessed by the degree of correspondence between inundation mapping and inland water levels. Both PALSAR‐ and ASAR‐based mapping at times were based on suboptimal reference scenes; however, ASAR performance seemed more sensitive to reference‐scene quality and other types of scene variability. Related to water depth, PALSAR and ASAR mapping accuracies tended to be lower when water depths were shallow and increased as water levels decreased below or increased above the ground surface, but this pattern was more pronounced with ASAR. Overall, PALSAR‐based inundation accuracies averaged 84% (n = 160), while ASAR‐based mapping accuracies averaged 62% (n = 245).     

氮输入对三江湿地小叶章不同生长阶段土壤产生CH4能力的影响

在小叶章(Deyeuxia angustifolia)不同生长阶段,用室内鲜土培养法对土壤CH4的产生能力进行了研究.结果表明,氮输入后,植物各生长阶段的土壤CH4产生率均随时间的推移发生了明显的波动.从生长季(6月7日～8月24日)CH4产生率均值来看,不同氮输入水平对土壤CH4产生起促进作用;不同氮输入水平对植物不同生长阶段CH4产生率影响明显.第一(6月7日～7月2日)、第二(7月2日～7月20日)阶段适量的氮输入(6g.m-2)对CH4产生起促进作用,但过量氮输入(12g.m-2)会对CH4产生起抑制作用;而第三(7月20日～8月7日)、第四(8月7日～8月24日)阶段不同氮输入均对CH4产生起促进作用;氮输入后,土壤微生物量碳(MBC)、土壤微生物量氮(MBN)、土壤基础呼吸(BR)、土壤代谢熵(qCO2)、土壤诱导呼吸(SIR)、铵态氮(NH4+-N)、硝态氮(NO3--N)和植物地上生物量与土壤CH4产生的动态关系存在差异.土壤CH4产生与qCO2呈显著正相关(p0.01),与土壤MBN、TOC和地上生物量呈显著正相关(p0.05).     

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pH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.