Effects of Land Use and Sample Location on Nitrate‐Stream Flow Hysteresis Descriptors during Storm Events

The U.S. Geological Survey's New Jersey and Iowa Water Science Centers deployed ultraviolet‐visible spectrophotometric sensors at water‐quality monitoring sites on the Passaic and Pompton Rivers at Two Bridges, New Jersey, on Toms River at Toms River, New Jersey, and on the North Raccoon River near Jefferson, Iowa to continuously measure in‐stream nitrate plus nitrite as nitrogen (NO₃ + NO₂) concentrations in conjunction with continuous stream flow measurements. Statistical analysis of NO₃ + NO₂ vs. stream discharge during storm events found statistically significant links between land use types and sampling site with the normalized area and rotational direction of NO₃ + NO₂‐stream discharge (N‐Q) hysteresis patterns. Statistically significant relations were also found between the normalized area of a hysteresis pattern and several flow parameters as well as the normalized area adjusted for rotational direction and minimum NO₃ + NO₂ concentrations. The mean normalized hysteresis area for forested land use was smaller than that of urban and agricultural land uses. The hysteresis rotational direction of the agricultural land use was opposite of that of the urban and undeveloped land uses. An r² of 0.81 for the relation between the minimum normalized NO₃ + NO₂ concentration during a storm vs. the normalized NO₃ + NO₂ concentration at peak flow suggested that dilution was the dominant process controlling NO₃ + NO₂ concentrations over the course of most storm events.     

轨道交通电连接器国内环境试验标准分析

铁路作为国民经济大动脉、国家重要基础设施和大众化交通工具,在国民经济和社会生活中的作用至关重要。电连接器是铁路车辆设备的关键器件之一,有着很高的安全性和可靠性要求。着重分析了轨道交通电连接器标准中的电性能、机械性能和环境适应性的试验方法,并对这些标准进行了对比总结。经分析发现,更新版本的标准比被替换的标准增加了试验项目,细化了试验条件。然而,目前国内轨道交通电连接器的标准版本相对落后,仅GB/T 25022和GB/T 25023为2010年发布实施。亟需新的标准或试验方法以指导轨道交通电连接器的质量检测和认证。     

Transport infrastructures,environment impacts and tourists' welfare: a choice experiment to elicit tourist preferences in Siena–Italy

Transport infrastructures have been investigated as drivers of tourist demand. Specific attention has been devoted to air transport infrastructure and services. However, the literature on this issue is scanty. Moreover, few studies focus on ex-ante valuation of tourists' preferences for mobility systems. This study contributes to this literature by presenting a case study on the re-organization of the mobility system to access the city of Siena, Italy. A choice experiment is carried out to elicit tourists' preferences for distance, time, cost, travel mode, along with the environmental impact of infrastructure. The latter factor turns out to be particularly relevant in explaining tourists' choices and welfare. Furthermore, the results appear to be robust and not significantly dependent on design settings (specifically the number of alternatives). While these results only refer to a single case study, they seem to suggest that new transportation facilities do not necessarily cause an increase in tourism flows.     

The Structure of the Shear Layer in Flows over Rigid and Flexible Canopies

Flume experiments were conducted with rigid and flexible model vegetation to study the structure of coherent vortices (a manifestation of the Kelvin–Helmholtz instability) and vertical transport in shallow vegetated shear flows. The vortex street in a vegetated shear layer creates a pronounced oscillation in the velocity profile, with the velocity near the top of a model canopy varying by a factor of three during vortex passage. In turn, this velocity oscillation drives the coherent waving of flexible canopies. Relative to flows over rigid vegetation, the oscillation in canopy geometry has the effect of decreasing the amount of turbulent vertical momentum transport in the shear layer. Using a waving plant to determine phase in the vortex cycle, each vortex is shown to consist of a strong sweep at its front (during which the canopy is most deflected), followed by a weak ejection at its rear (when the canopy height is at a maximum). Whereas in unobstructed mixing layers the vortices span the entire layer, they encompass only 70% of the flexibly obstructed shear layer studied here.     

Geochemical and biological controls on trace metal transport in an acid mine impacted watershed

Water samples collected in an acid mine impacted watershed indicated that the concentrations of dissolved trace metals were diurnally influenced by mineral saturation, which is controlled primarily by pH and water temperature. Measurements taken suggested that these variations only occur at sample locations immediately downstream from the confluence of acidic and alkaline waters. It is at these locations where initial mineral precipitation occurred and where subtle changes in solubility were most affected, increasing trace metal removal when both the rate of photosynthesis (influencing pH in headwaters) and water temperature were at a maximum. The role of iron photoreduction (increased midday production of ferrous iron) on overall Cu, Mn, and Zn transport was also evaluated, but found to be inconclusive. Iron photoreduction may however influence adsorption and/or coprecipitation of trace metals through associated changes in oxidation state, solubility, and mineralogy of various iron colloids, which are produced upon the neutralization of acidic, metal enriched water. Furthermore, measured values of copper and zinc were compared to relative USEPA chronic criterion for exposure to continuous concentration (CCC) of metals by the calculation of a “toxicity unit” (TU). It was found that average values of both copper and zinc only exceeded the CCC (TU>1) in the acid mine-impacted Leona Creek. In general, zinc toxicity decreased while copper toxicity increased downstream of the confluence of the mine impacted Leona Creek and background Lion Creek (sampled at Lake Aliso), indicating a significant source of zinc in upstream, non mine-impacted samples.     

Transport,deposition and biodegradation of particle bound polycyclic aromatic hydrocarbons in a tidal basin of an industrial watershed

Polycylic aromatic hydrocarbons (PAHs) are commoncontaminants in industrial watersheds. Their origin,transport and fate are important to scientists,environmental managers and citizens. The Philadelphia NavalReserve Basin (RB) is a small semi-enclosed embayment nearthe confluence of the Schuylkill and Delaware Rivers inPennsylvania (USA). We conducted a study at this site todetermine the tidal flux of particles and particle-boundcontaminants associated with the RB. Particle traps wereplaced at the mouth and inside the RB and in the Schuylkilland Delaware Rivers. There was net particle deposition intothe RB, which was determined for three seasons. Spring andfall depositions were highest (1740 and 1230 kg ofparticles, respectively) while winter deposition wasinsignificant. PAH concentrations on settling particlesindicated a net deposition of 12.7 g PAH in fall and 2.1 gPAH in spring over one tidal cycle. There was nosignificant PAH deposition in the winter. Biodegradationrates, calculated from ¹⁴C-labeled PAH substratemineralization, could attenuate only about 0.25% of the PAHdeposited during a tidal cycle in fall. However, in thespring, biodegradation could be responsible for degrading50% of the settling PAHs. The RB appears to be a sink forPAHs in this watershed.     

Identifying the European Fossil Fuel Plumes in the Atmosphere Over the Northeast Atlantic Region Through Isotopic Observations and Numerical Modelling

As part of the Danish NEAREX project the origin and variability of anthropogenic atmospheric CO₂ over the Northeast Atlantic Region (NEAR) has been studied. The project consisted of a combination of experimental and modelling activities. Local volunteers operated CO₂ sampling stations, built at University of Copenhagen, for ¹⁴C analysis at four locations (East Denmark, Shetland Isles, Faroe Isles and Iceland). The samples were only collected during winter periods of south-easterly winds in an attempt to trace air enriched in fossil-fuel derived CO₂ due to combustion of fossil fuels within European countries. In order to study the transport and concentration fields over the region in detail, a three-dimensional Eulerian hemispheric air pollution model has been extended to include the main anthropogenic sources for atmospheric CO₂. During the project period (1998–2001) only a few episodes of transport from Central Europe towards NEAR arose, which makes the data set for the evaluation of the method sparse. The analysed samples indicate that the signal for fossil CO₂, as expected, is largest (up to 3.7±0.4% fossil CO₂) at the Danish location closest to the European emissions areas and much weaker (up to ∼1.5±0.6% fossil CO₂) at the most remote location. As the anthropogenic signal is weak in the clean atmosphere over NEAR these numbers will, however, be very sensitive to the assumed background ¹⁴CO₂ activity and the precision of the measurements. The model simulations include the interplay between the driving processes from the emission into the boundary layer and the following horizontal/vertical mixing and atmospheric transport and are used to analyse the meteorological conditions leading to the observed events of high fossil CO₂ over NEAR. This information about the history of the air masses is essential if an observed signal is to be utilised for identifying and quantifying sources for fossil CO₂.     

Direct measurements of the tile drain and groundwater flow route contributions to surface water contamination: From field-scale concentration patterns in groundwater to catchment-scale surface water quality

Enhanced knowledge of water and solute pathways in catchments would improve the understanding of dynamics in water quality and would support the selection of appropriate water pollution mitigation options. For this study, we physically separated tile drain effluent and groundwater discharge from an agricultural field before it entered a 43.5-m ditch transect. Through continuous discharge measurements and weekly water quality sampling, we directly quantified the flow route contributions to surface water discharge and solute loading. Our multi-scale experimental approach allowed us to relate these measurements to field-scale NO₃ concentration patterns in shallow groundwater and to continuous NO₃ records at the catchment outlet. Our results show that the tile drains contributed 90-92% of the annual NO₃ and heavy metal loads. Considering their crucial role in water and solute transport, enhanced monitoring and modeling of tile drainage are important for adequate water quality management.     

Detection of fullerenes (C60 and C70) in commercial cosmetics

Detection methods are necessary to quantify fullerenes in commercial applications to provide potential exposure levels for future risk assessments of fullerene technologies. The fullerene concentrations of five cosmetic products were evaluated using liquid chromatography with mass spectrometry to separate and specifically detect C₆₀ and C₇₀ from interfering cosmetic substances (e.g., castor oil). A cosmetic formulation was characterized with transmission electron microscopy, which confirmed that polyvinylpyrrolidone encapsulated C₆₀. Liquid-liquid extraction of fullerenes from control samples approached 100% while solid-phase and sonication in toluene extractions yielded recoveries of 27-42%. C₆₀ was detected in four commercial cosmetics ranging from 0.04 to 1.1 μg/g, and C₇₀ was qualitatively detected in two samples. A single-use quantity of cosmetic (0.5 g) may contain up to 0.6 μg of C₆₀, demonstrating a pathway for human exposure. Steady-state modeling of fullerene adsorption to biosolids is used to discuss potential environmental releases from wastewater treatment systems.     

Combined effects of titanium dioxide and humic acid on the bioaccumulation of cadmium in Zebrafish

The combined effects of titanium dioxide (TiO₂) nanoparticles and humic acid (HA) on the bioaccumulation of cadmium (Cd) in Zebrafish were investigated. Experimental data on the equilibrium Cd bioaccumulation suggest that only the dissolved Cd effectively contributed to Cd bioaccumulation in HA solutions whereas both the dissolved and TiO₂ associated Cd were accumulated in TiO₂ or the mixture of HA and TiO₂ solutions, due likely to the additional intestine uptake of the TiO₂-bound Cd. The equilibrium Cd bioaccumulation in the mixed system was comparable to that in the corresponding HA solutions, and significantly lower than that in the corresponding TiO₂ solutions (n = 3, p < 0.05). The presence of either HA or TiO₂ (5-20 mg L⁻¹) in water slightly increased the uptake rate constants of Cd bioaccumulation whereas combining HA and TiO₂ reduced the uptake rate constants.