The Effects of Integrated Marsh Management (IMM) on Salt Marsh Vegetation,Nekton, and Birds

An integrated marsh management (IMM) project in an urbanized watershed on Long Island, New York, USA, aimed to mitigate salt marsh degradation and to reduce mosquito production by an innovative combination of restoration and open marsh water management methods. The grid ditch network at two treatment marshes was replaced with naturalized tidal channels and ponds. Effects of the hydrologic alterations were monitored utilizing a before–after–control–impact approach. The treatment marshes experienced a number of beneficial outcomes including a fourfold reduction in the invasive Phragmites australis and increased native vegetation cover in the most degraded portions of the marsh, increased abundance and diversity of marsh killifish and estuarine nekton species, higher shorebird and waterfowl densities, and increased avian species diversity. The successful implementation of IMM concept led to improved marsh health and diminished mosquito production. Therefore, this study may serve as a template for similar large-scale integrated salt marsh restoration projects.     

Sub-Saharan African urbanisation and global environmental change

Scientific evidence for global environmental change in Africa presents a prima facia case for increased human migration and displacement. Closer scrutiny of the evidence on demographic change, however, suggests that migration and displacement are less important variables in explaining the human dimensions of global environmental change on the continent than is commonly projected. Natural population growth in cities is a more important dynamic in the evolving system of human settlement in Africa and this significant shift in where people live, both now and in the future is overlooked by the emphasis on the potential impact of environmentally induced migration. Even without any movement from the countryside, cities represent the fastest growing sector of the sub-Saharan African population. The existing vulnerability of African cities, with their fast growing populations and weak management means any environmental change is likely to have significant consequences for cities. Taking the sub-Saharan African demographic evidence seriously means that the scholarly and policy emphasis currently directed to GEC migration and displacement might be more effectively redirected to questions of the interface between global environmental change and urban areas.     

The long term operation of a biologically based treatment system that removes As, S and Zn from industrial (smelter operation) landfill seepage

Passive treatment systems have a long history in the remediation of mining impacted water. The functioning of these systems is poorly understood, in particular the microbial processes that underpin metal removal. A biologically based engineered wetland treatment system that has operated in Trail, B.C. to treat seepage from a historic Pb and Zn smelter landfill, was investigated. The system has functioned for more than a decade, an unusually long life span for a passive bioreactor design. The study focuses on the 5a of operation from 2003 until 2007. Arsenic is a major contaminant in the ore that is processed in Trail, which has caused high As concentrations in the seepage. In addition to As, Zn and Cd removal were investigated. During the 5-a period, the system sequestered 2990 kg of As, 7700 kg of Zn and 85 kg of Cd. Nearly 90% of these elements were removed in two biochemical reactors (BCRs) that comprise the first two components of the six cell system, with the remainder removed in plant-based polishing cells. Average input concentrations over the 5-a period were 2.3 and 4.1 mM for As and Zn, respectively and 0.45 μM for Cd. Final output concentrations were reduced to 0.01 mM for As, 0.05 mM for Zn and 0.18 μM for Cd. Sulfur removal averaged 34% of input concentration. Analysis of mineral formation in the system using X-ray diffraction and scanning electron microscopy indicated kottigite (Zn₃(AsO₄)₂⋅8H₂O) and sphalerite (ZnS) as the major mineral phases controlling As and Zn sequestration; Cd appears to be immobilized as CdS. Evidence for orpiment was obtained from X-ray absorption spectroscopy (XANES) studies, and arsenopyrite was not detected. Although microbial activity dominates the removal of Zn, As and Cd from the soluble phase, abiotic removal mechanisms contribute including sorption of As and Zn to biosolids and filtration of metal precipitates by the solid matrix. The removal of toxic elements over the period appeared to be relatively consistent. Seasonal fluctuations, a large spike in input element concentrations over a 2-month period, and removal of the two biochemical reactors during a period of reconstruction appeared to have relatively little impact on the system as a whole.     

Solubility and near-equilibrium dissolution rates of quartz in dilute NaCl solutions at 398-473 K under alkaline conditions

The dissolution-precipitation of quartz controls porosity and permeability in many lithologies and may be the best studied mineral-water reaction. However, the rate of quartz-water reaction is relatively well characterized far from equilibrium but relatively unexplored near equilibrium. We present kinetic data for quartz as equilibrium is approached from undersaturation and more limited data on the approach from supersaturated conditions in 0.1 molal NaCl + NaOH + NaSiO(OH)₃ solutions with pH 8.2-9.7 at 398, 423, 448, and 473 K. We employed a potentiometric technique that allows precise determination of solution speciation within 2 kJ mol⁻¹ of equilibrium without the need for to perturb the system through physical sampling and chemical analysis. Slightly higher equilibrium solubilities between 423 and 473 K were found than reported in recent compilations. Apparent activation energies of 29 and 37 kJ mol⁻¹ are inferred for rates of dissolution at two surface sites with different values of connectedness: dissolution at Q¹ or Q² silicon sites, respectively. The dissolution mechanism varies with ΔG such that reactions at both sites control dissolution up until a critical free energy value above which only reactions at Q¹ sites are important. When our near-equilibrium dissolution rates are extrapolated far from equilibrium, they agree within propagated uncertainty at 398 K with a recently published model by Bickmore et al. (2008). However, our extrapolated rates become progressively slower than model predictions with increasing temperature. Furthermore, we see no dependence of the postulated Q¹ reaction rate on pH, and a poorly-constrained pH dependence of the postulated Q² rate. Our slow extrapolated rates are presumably related to the increasing contribution of dissolution at Q³ sites far from equilibrium. The use of the potentiometric technique for rate measurement will yield both rate data and insights into the mechanisms of dissolution over a range of chemical affinity. Such measurements are needed to model the evolution of many natural systems quantitatively.     

The formation of metastable aluminosilicates in the Al-Si-H2O system: Results from solution chemistry and solid-state NMR spectroscopy

We present the results of a series of experiments designed to probe the interactions between Al and the amorphous silica surface as a function of thermodynamic driving forces. The results from ²⁷Al single pulse magic angle spinning (SP/MAS) and ²⁷Al{¹H} rotational echo double resonance (REDOR) allow us to identify the reaction products and constrain their structure. In all cases, despite low Al and Si concentrations we observe the formation of metastable aluminosilicates. Results from low temperature experiments indicate that despite thermodynamic driving forces for the formation of gibbsite we observe the precipitation of separate octahedrally coordinated Al (Al^[6]) and tetrahedrally coordinated Al (Al^[4]) silicate phases. At higher temperatures the Al^[4] silicate phase dominates the speciation. Structural models derived from the NMR data are also proposed, and the results are discussed as they relate to previous work on Al/Si cycling.     

The role of granites in volcanic-hosted massive sulphide ore-forming systems: an assessment of magmatic�Chydrothermal contributions

Assessment of geological, geochemical and isotopic data indicates that a significant subgroup of volcanic-hosted massive sulphide (VHMS) deposits has a major or dominant magmatic?Chydrothermal source of ore fluids and metals. This group, which is typically characterised by high Cu and Au grades, includes deposits such as those in the Neoarchean Doyon-Bousquet-LaRonde and Cambrian Mount Lyell districts. These deposits are distinguished by aluminous advanced argillic alteration assemblages or metamorphosed equivalents intimately associated with ore zones. In many of these deposits, ??³⁴S_sulphide is low, with a major population below ?3??; ??³⁴S_sulphate differs from coexisting seawater and ??³⁴S_{sulphate?Csulphide}????20?C30??. These characteristics are interpreted as the consequence of disproportionation of magmatic SO₂ as magmatic?Chydrothermal fluids ascended and cooled and as a definitive evidence for a significant magmatic?Chydrothermal contribution. Other characteristics that we consider diagnostic of significant magmatic?Chydrothermal input into VHMS ore fluids include uniformly high (>3 times modern seawater values) salinities or very ¹⁸O-enriched (??¹⁸O?>?5??) ore fluids. We do not consider other criteria [e.g. variable salinity, moderately high ??¹⁸O_fluid (2?C5??), ??³⁴S_sulphide near 0??, metal assemblages or a spatial association with porphyry Cu or other clearly magmatic-hydrothermal deposits] that have been used previously to advocate significant magmatic?Chydrothermal contributions to be diagnostic as they can be produced by non-magmatic processes known to occur in VHMS mineral systems. However, in general, a small magmatic?Chydrothermal contribution cannot be excluded in most VHMS systems considered. Conclusive data that imply minimal magmatic?Chydrothermal contributions are only available in the Paleoarchean Panorama district where coeval seawater-dominated and magmatic?Chydrothermal systems appear to have been physically separated. This district, which is characterised by chloritic and sericitic alteration assemblages and lacks aluminous advanced argillic alteration assemblages, is typical of many VHMS deposits around the world, suggesting that for ??garden variety?? VHMS deposits, a significant magmatic?Chydrothermal contribution is not required. Other than deposits associated with advanced argillic alteration assemblages, the only deposit for which we ascribe a major magmatic?Chydrothermal contribution is the Devonian Neves Corvo deposit. This deposit differs from other deposits in the Iberian Pyrite Belt and around the world in being extremely Sn-rich, with the Sn closely associated with Cu and in having formed from high ¹⁸O-rich fluids (??¹⁸O_fluid ??8.5??). We consider these characteristics, particularly the last, as diagnostic of a significant magmatic hydrothermal contribution. Our analysis indicates that two subgroups of VHMS deposits have a major magmatic?Chydrothermal contribution: Cu/Au-rich deposits with aluminous alteration assemblages and reduced, very Sn-rich deposits in which Sn was introduced in a high-temperature ore assemblage. Comparison with ??normal?? VHMS deposits suggests that these subgroups of VHMS deposits may form in specialised tectonic environments. The Cu/Au-rich deposits appear to form adjacent to magmatic arcs, an environment conducive to the generation of hydrous, oxidised melts by melting metasomatised mantle in the wedge above the subducting slab. This contrasts with the back-arc setting of ??normal?? VHMS deposits in which relatively dry granites (In this contribution, we use the term granite sensu latto) formed by decompression melting drive seawater-dominated hydrothermal circulation. The tectonic setting of highly Sn-rich VHMS deposits such as Neves Corvo is less clear; however, thick continental crust below the ore-hosting basin may be critical, as it is in other Sn deposits.     

Recent advances in offshore geotechnics for deep water oil and gas developments

The paper presents an overview of recent developments in geotechnical analysis and design associated with oil and gas developments in deep water. Typically the seabed in deep water comprises soft, lightly overconsolidated, fine grained sediments, which must support a variety of infrastructure placed on the seabed or anchored to it. A particular challenge is often the mobility of the infrastructure either during installation or during operation, and the consequent disturbance and healing of the seabed soil, leading to changes in seabed topography and strength. Novel aspects of geotechnical engineering for offshore facilities in these conditions are reviewed, including: new equipment and techniques to characterise the seabed; yield function approaches to evaluate the capacity of shallow skirted foundations; novel anchoring systems for moored floating facilities; pipeline and steel catenary riser interaction with the seabed; and submarine slides and their impact on infrastructure. Example results from sophisticated physical and numerical modelling are presented.     

Projecting uncertainty onto marine megafauna trajectories

In this study, a method is proposed for estimating the uncertainty of a Lagrangian pathway calculated from an undersampled ocean surface velocity field. The primary motivation and application for this method is the differentiation between active and passive movements for sea turtles whose trajectories are observed with satellite telemetry. Synthetic trajectories are launched within a reconstructed surface velocity field and integrated forward in time to produce likely trajectories of an actual turtle or drifter. Uncertainties in both the initial conditions at launch and the velocity field along the trajectory are used to yield an envelope of possible synthetic trajectories for each actual trajectory. The juxtaposition of the actual trajectory with the resulting cloud of synthetic trajectories provides a means to distinguish between active and passive movements of the turtle. The uncertainty estimates provided by this model may lead to improvements in our understanding of where and when turtles are engaged in specific behaviors (i.e. migration vs. foraging)—for which potential management efforts may vary accordingly.     

Comprehensive Utilization of Vanadium–Titanium Magnetite Deposits in China Has Come to a New Level

There are two production areas for vanadium-titanium magnetite deposits in China:the Panzhihua area in Sichuan Province and the Chengde area in Hebei Province. The Panzhihua vanadium titanomagnetite iron ore deposits are hosted by a mafic-ultramafic intrusive complex,and belong to late magmatic differentiation condensation of crystalline iron deposits.The rock mass is characterized by good differentiation,clear and differentiated facies zones and rhythm.The rock assemblage can be divided into the following rock facies combination:gabbro,gabbro-norite,gabbro troctolite,gabbro-plagioclase,gabbro-eclogite-olivine pyroxenite,and diabase types.The orebodies occur mostly as close-bedded,distributed in the dark facies zone in the bottom layers of the middle or lower part of the stratiform rock mass.The main ore minerals are granular ilmenite,magnetite,ilmenite spar,and magnesium aluminum spinel,with small amounts of pyrrhotite,pyrite and cobalt,nickel and copper sulfide.The ores have siderite and mosaic textures and occur as compact massive,banded and disseminated structures;they consist of TFeO 20％-45％,TiO2 3％-16％,V2O50.15％-0.5％,Cr2O30.1％-0.38％,associated with trace amounts of Cu,Co,Ni,Ga,Mn,P,Se,Te,Sc and Pt group elements.     

Aftershock of the Wenchuan Earthquake in Sichuan Triggers Large Earthquake in Minxian County, Gansu

Because of the confining compression of the Pacific,Eurasian and Indian plates,the Chinese mainland is frequently stricken with earthquakes,especially in the Qinghai-Tibet Plateau and surrounding areas and along the NS-trending tectonic zone from Yinchuan to Lanzhou,Chengdu,and finally to the Kunming tectonic belt (Fig.1).Historical records show that there are 14 earthquakes of＞Ms 8 occurring in the two regions,eight of which occurred along the latter tectonic belt.The 2008 Wenchuan earthquake located on both the NS tectonic zone and the Longmenshan fault zone along the eastern margin of the Qinghai-Tibet Plateau.