Provenance and temporal variations in selected flavonoids in leaves of Cyclocarya paliurus

Cyclocarya paliurus is a well-known multiple function plant in China. To reveal the provenance variation of selected flavonoids in leaves of C. paliurus and changes of their level during the growing season, twelve provenances were grown in a field trial and sampled five times at approximately 1 month intervals. The levels of flavonoids varied significantly in leaves of C. paliurus from different provenances, and isoquercitrin represented the largest component of the selected compounds, followed by kaempferol and quercetin. The growing season also significantly affected the concentration of total flavonoids and its composition. In most cases, the greatest concentration was observed in July and October, showing a bimodal temporal variation pattern. Results not only demonstrated that leaves of C. paliurus exhibited commendably higher levels of quercetin, kaempferol and isoquercitrin, but also provided a basis for breeding strategies, selecting superior provenances, and choosing harvesting time for producing specific flavonoids for the food industry.     

Landscape control of stream water aluminum in a boreal catchment during spring flood

Inorganic aluminum (Al) concentrations are critical for defining the biological effects of acidification. The landscape's role in controlling the spatial variability of Al and its speciation has received only limited attention. We analyzed the speciation of stream Al at 14 sites within a 68 km2 boreal catchment during spring snowmelt, a period of episodic acidity. Three factors that influenced Al at these sites were landscape type (specifically the proportion of wetland areas), stream pH, and dissolved organic carbon (DOC). Forested catchment sites underlain by mineral soils had higher total Al concentrations and greater inorganic Al proportions than catchments with larger wetland areas, despite significantly higher pH. We suggest that this difference results from source limitation of Al in the peat wetlands. The control of Al solubilitywas dominated by organic complexes, with the organic carrying capacity exceeding Al in the majority of samples. When assessing the inorganic phase, only four percent of the samples were oversaturated with regards to commonly forming secondary Al minerals, with no samples showing supersaturation higher than 10 times with respect to any given solid phase. Inorganic Al rarely exceeded biological thresholds, except for short periods during peak flow in forested areas, despite two-thirds of the streams having minimum pH values below 4.9. Streams with a high percentage of wetland area were associated with lower Al:DOC ratios. The Al:DOC ratios were quite stable in each stream before, during, and after snowmelt, with the exception of isolated spikes in the Al:DOC ratio associated with particulate Al at a downstream site during high flow.     

Influence of population density and temporal variations in emissions on the air duality benefits of NOx emission trading

Ozone formation is a complex function of local hydrocarbon and nitrogen oxide emissions. Therefore, trading of NOx emissions among geographically distributed facilities can lead to more or less ozone formation than across-the-board reductions. Monte Carlo simulations of trading scenarios involving 51 large NOx point sources in eastern Texas were used in a previous study by the authors to assess the effects of trading on air quality benefits, as measured by changes in ozone concentrations. The results indicated that 12% of trading scenarios would lead to greater than a 25% variation from conventional across-the-board reductions when air quality benefits are based only on changes in ozone concentration. The current study found that when benefits are based on a metric related to population exposure to ozone, two-thirds of the trading scenarios lead to changes in air quality benefits of approximately 25%. Variability in air quality benefits is not as strongly dependent on the temporal distribution of NOx emissions.     

牛宰后肌肉生物电阻抗值、pH值、失水率的变化及相互关系的研究

对牛宰后骨骼肌肉的生物电阻抗值、pH值、失水率进行测试,结果表明:宰后10 d牛肉样3项指标均有明显的变化,且做出了相应的变化曲线图;电阻抗与pH值、电阻抗与失水率、pH值与失水率之间均呈现相关性,相关系数在α=0.05水平下显著.     

Effects of channel restoration on water velocity, transient storage, and nutrient uptake in a channelized stream

Channel design is an important component of stream restoration, but little is known of the interplay between hydrogeomorphic features and ecosystem processes within designed channels. Water velocity, transient storage, and nutrient uptake were measured in channelized (prerestoration) and naturalized (postrestoration) reaches of a 1-km segment of Wilson Creek (KY) to assess the effects of restoration on mechanisms of nutrient retention. Stream restoration decreased flow velocity and reduced the downstream transport of nutrients. Median travel time was 50% greater in the restored channel due to lower reach-scale water velocity and the longer length of the meandering channel. Transient storage and the influence of transient storage on travel time were largely unaffected except in segments where backwater areas were created. First-order uptake rate coefficients for N and P were 30- and 3-fold higher (respectively) within the restored channel relative to its channelized state. Changes in uptake velocities were comparatively small, suggesting that restoration had little effect on biochemical demand. Results from this study suggest that channel naturalization enhances nutrient uptake by slowing water velocity. Solute injection experiments revealed differences in the functional properties of channelized, restored, and reference streams and provided a means for quantifying benefits associated with restoration of ecosystem services.     

Spatial distribution and temporal variability of arsenic in irrigated rice fields in Bangladesh. 1. Irrigation water

Around 38% of the area of Bangladesh is irrigated with groundwater to grow dry season crops, most importantly boro rice. Due to high As concentrations in many groundwaters, over 1000 tons of As are thus transferred to arable soils each year, creating a potential risk for future food production. We studied the reactions and changing speciation of As, Fe, P, and other elements in initially anoxic water during and after irrigation and the resulting spatial distribution of As input to paddy soils near Sreenagar (Munshiganj), 30 km south of Dhaka, in January and April 2005 and February 2006. The irrigation water had a constant concentration of 397 +/- 7 microg L(-1) As (approximately 84% As(III)), 11 +/- 0.1 mg L(-1) Fe, and 2 +/- 0.1 mg L(-1) P. During the fast flow along the longest irrigation channel (152 m) As, Fe, and P speciation changed, but total concentrations did not decrease significantly, indicating that As input to fields was independent of the length of the irrigation channels. In contrast, during slow water flow across the fields, As, Fe, and P concentrations decreased strongly with increasing distance from the water inlet, due to formation and settling of As- and P-bearing Fe aggregates and by adsorption to soil minerals. Total As concentrations in field water were approximately 3 times higher close to the inlet than in the opposite field corner shortly after irrigation, and decreased to below 35 microg L(-1) over the next 72 h. The laterally heterogeneous transfer of As, Fe, and P from irrigation waterto soil has important consequences for their distribution in irrigated fields and needs to be considered in sampling and in assessing the dynamics and mass balances of As fluxes among irrigation water, soil, and floodwater.     

Seasonal variations in concentrations of pharmaceuticals and personal care products in drinking water and reclaimed wastewater in southern California

Southern California imports nearly all of its potable water from two sources: the Colorado River and the California State Water Project (Sacramento-San Joaquin River Basin). Sewage treatment plant effluent (STPE) heavily impacts both of these sources. A survey of raw and treated drinking water from four water filtration plants in San Diego County showed the occurrence of several polar organic "pharmaceuticals and personal care products" (PPCP). These included phthalate esters, sunscreens, clofibrate, clofribric acid, ibuprofen, triclosan, and DEET. Several of these were also found in the finished water, such as di(ethylhexyl) phthalate, benzophenone, ibuprofen, and triclosan. Occurrence and concentrations of these compounds were highly seasonally dependent, and reached maximums when the flow of the San Joaquin River was low and the quantity of imported water was high. The maximum concentrations of the PPCPs measured in the raw water were correlated with low flow conditions in the Sacramento-San Joaquin Delta that feeds the State Water Project. The PPCP concentrations in raw imported water in the summer months approached that of reclaimed nonpotable wastewater.     

Inorganic geochemistry and redox dynamics in bank filtration settings

Bank filtration induces flow of surface water through a hydraulically connected aquifer by excess pumping from a production well in the aquifer. This review presents the four main geochemical processes relevant for inorganic geochemistry, with a focus on iron (Fe) and manganese (Mn), during bank filtration: reduction near the bank, oxidation near the production well, carbonate dissolution, and sorption to aquifer materials. Physical and transport processes affect these geochemical processes and influence the redox state of the infiltrate. The presence of Fe and Mn in bank infiltrate is directly related to its redox status and can necessitate drinking water treatment after extraction. Long-term, in situ sequestration of Fe and Mn requires precipitation of oxide or carbonate solids, since a sorption front can breakthrough at the production well.     

Flux rates of atmospheric lead pollution within soils of a small catchment in northern Sweden and their implications for future stream water quality

It is not well-known how the accumulated pool of atmospheric lead pollution in the boreal forest soil will affect the groundwater and surface water chemistry in the future as this lead migrates through the soil profile. This study uses stable lead isotopes (206Pb/207Pb and 208Pb/ 207Pb ratios) to trace the transport of atmospheric lead pollution within the soil of a small catchment and predict future lead level changes in a stream draining the catchment. Low 206Pb/207Pb and 208Pb/207Pb ratios for the lead in the soil water (1.16 +/- 0.02; 2.43 +/- 0.03) and streamwater (1.18 +/- 0.03; 2.42 +/- 0.03) in comparison to that of the mineral soil (>1.4; >2.5) suggest that atmospheric pollution contributes by about 90% (65-100%) to the lead pool found in these matrixes. Calculated transport rates of atmospheric lead along a soil transect indicate that the mean residence time of lead in organic and mineral soil layers is at a centennial to millennial time scale. A maximum release of the present pool of lead pollution in the soil to the stream is predicted to occur within 200-800 years. Even though the uncertainty of the prediction is large, it emphasizes the magnitude of the time lag between the accumulation of atmospheric lead pollution in soils and the subsequent response in streamwater quality.     

Modeling lead input and output in soils using lead isotopic geochemistry

The aim of this study is to model downward migration of lead from the plow layer of an experimental site located in Versailles (about 15 km southwest of Paris, France). Since 1928, samples have been collected annually from the topsoil of three control plots maintained in bare fallow. Thirty samples from 10 different years were analyzed for their lead and scandium contents and lead isotopic compositions. The fluxes are simple because of the well-controlled experimental conditions in Versailles: only one output flux, described as a first-order differential function of the anthropogenic lead pool, was taken into account; the inputs were exclusively ascribed to atmospheric deposition. The combination of concentration and isotopic data allows the rate of migration from the plowed topsoil to the underlying horizon and, to a lesser extent, the atmospheric fluxes to be assessed. Both results are in good agreement with the sparse data available. Indeed, the post-depositional migration of lead appears negligible at the human time scale: less than 0.1% of the potentially mobile lead pool migrates downward, out of the first 25 cm of the soil, each year. Assuming future lead inputs equal to 0, at least 700 yr would be required to halve the amount of accumulated lead pollution. Such a low migration rate is compatible with the persistence of a major anthropogenic lead pool deposited before 1928. Knowledge of pollution history seems therefore to be of primary importance.     

Quality variations in the chain log-board-blank

To achieve a high economic yield in the wood industry it is important to control the grading procedures and to know the quality distribution in different steps. Scots pine (Pinus sylvestris) timber from Sweden has been compared regarding quality variations in the chain log-board-blank caused by biological properties and subjective grading procedures. This study describes the quality distributions in the treatment of trees from harvesting throughout sawing and to the user's judgements, the correlation between the grading procedures in various steps, and the yield in all classes based upon the customer's opinion. The results emphasise that current classification system is very hazardous and seems not be in concordance with the customers' demand. The subjective and visual grading procedures are not sufficiently effective to predict the properties. Three main needs must be satisfied in order to reduce the costs for poor quality; knowledge about the biological variations, new equipment for grading and knowledge about the customers' needs and behaviours     

Determination of mercury evasion in a contaminated headwater stream

Evasion from first- and second-order streams in a watershed may be a significant factor in the atmospheric recycling of volatile pollutants such as mercury; however, methods developed for the determination of Hg evasion rates from larger water bodies are not expected to provide satisfactory results in highly turbulent and morphologically complex first- and second-order streams. A new method for determining the Hg evasion rates from these streams, involving laboratory gas-indexing experiments and field tracer tests, was developed in this study to estimate the evasion rate of Hg from Gossan Creek, a first-order stream in the Upsalquitch River watershed in northern New Brunswick, Canada. Gossan Creek receives Hg-contaminated groundwater discharge from a gold mine tailings pile. Laboratory gas-indexing experiments provided the ratio of gas-exchange coefficients for zero-valent Hg to propane (tracer gas) of 0.81+/-0.16, suggesting that the evasion mechanism in highly turbulent systems can be described by the surface renewal model with an additional component of enhanced gas evasion probably related to the formation of bubbles. Deliberate field tracer tests with propane and chloride tracers were found to be a reliable and practical method for the determination of gas-exchange coefficients for small streams. Estimation of Hg evasion from the first 1 km of Gossan Creek indicates that about 6.4 kg of Hg per year is entering the atmosphere, which is a significant fraction of the regional sources of Hg to the atmosphere.     

Shallow groundwater mercury supply in a Coastal Plain stream

Fluvial methylmercury (MeHg) is attributed to methylation in up-gradient wetland areas. This hypothesis depends on efficient wetland-to-stream hydraulic transport under nonflood and flood conditions. Fluxes of water and dissolved (filtered) mercury (Hg) species (FMeHg and total Hg (FTHg)) were quantified in April and July of 2009 in a reach at McTier Creek, South Carolina to determine the relative importance of tributary surface water and shallow groundwater Hg transport from wetland/floodplain areas to the stream under nonflood conditions. The reach represented less than 6% of upstream main-channel distance and 2% of upstream basin area. Surface-water discharge increased within the reach by approximately 10%. Mean FMeHg and FTHg fluxes increased within the reach by 23-27% and 9-15%, respectively. Mass balances indicated that, under nonflood conditions, the primary supply of water, FMeHg, and FTHg within the reach (excluding upstream surface water influx) was groundwater discharge, rather than tributary transport from wetlands, in-stream MeHg production, or atmospheric Hg deposition. These results illustrate the importance of riparian wetland/floodplain areas as sources of fluvial MeHg and of groundwater Hg transport as a fundamental control on Hg supply to Coastal Plain streams.     

Temporal dynamics of periphyton exposed to tetracycline in stream mesocosms

Significant amounts of antibiotics enter the environment via point and nonpoint sources. We examined the temporal dynamics of tetracycline exposure to stream periphyton and associated organisms across a logarithmically dosed-series of experimental mesocosms, designed to mimic natural conditions. Target in-stream tetracycline exposures were based on environmentally relevant concentrations in aquatic ecosystems throughout the United States (<1-100 μg L(-1)). Significant changes in the stream biotic community were observed within 7 days with in-stream tetracycline concentrations as low as 0.5 μg L(-1), including significant changes in antibiotic resistance, bacteria abundance and productivity, algae biomass, cyanobacteria, organic biomass, and nematodes. These effects were magnified with increased exposure time and dosing concentration. Recovery of the periphyton community after 28 days of exposure was dependent upon the tetracycline dose. At the highest doses, 10 and 100 μg L(-1), bacteria productivity recovered; however, bacteria, algae, and nematode abundance did not recover at the same rate and remained low even after a 28-day recovery period (of nondosing). This study demonstrates that tetracycline exposure under near-natural conditions and at concentrations currently observed in aquatic environments may have important consequences for the structure and function of stream periphyton and, potentially, public health via increasing resistance of naturally occurring bacteria.     

湍流气体中短纤维运动学模拟

亚琛工业大学纺织技术研究所（ITA）研发了能够模拟纤维运动学的数字模型,如预测纤维的运动轨迹及变形。通过计算流体动力学（CFD）技术可以分析不同加工过程中纤维的运动。     

Speciation of selenium in stream insects using X-ray absorption spectroscopy

Selenium contamination in the environment is a widespread problem affecting insects and other wildlife. Insects occupy a critical middle link and aid in trophic transfer of selenium in many terrestrial and freshwater food chains, but the mechanisms of selenium uptake through the food chain are poorly understood. In particular, biotransformation of selenium by insects into different chemical forms will greatly influence how toxic or benign the selenium is to that organism or to its predators. We have used X-ray absorption spectroscopy (XAS) to identify the chemical form of selenium in insects inhabiting selenium contaminated streams near Hinton, Alberta (Canada). Selenium K near-edge spectra indicate a variability of selenium speciation among the insects that included mayflies (Ephemeroptera), stoneflies (Plecoptera), caddisflies (Trichoptera), and craneflies (Diptera). Higher percentages of inorganic selenium were observed in primary consumers, detritivores, and filter feeders than in predatory insects. Among the organic forms of selenium, organic selenides constituted a major fraction in most organisms. A species modeled as trimethylselenonium was observed during the pupal stage of caddisflies. These results provide insights into how the insects cope with their toxic cargo, including how the selenium is biotransformed into less toxic forms and how it can be eliminated from the insects. More broadly, this study demonstrates the strengths of XAS to probe the effects of heavy elements at trace levels in insects from the field.     

Sources and variations of mercury in tuna

While the bulk of human exposure to mercury is through the consumption of marine fish, most of what we know about mercury methylation and bioaccumulation is from studies of freshwaters. We know little of where and how mercury is methylated in the open oceans, and there is currently a debate whether methylmercury concentrations in marine fish have increased along with global anthropogenic mercury emissions. Measurements of mercury concentrations in Yellowfin tuna caught off Hawaii in 1998 show no increase compared to measurements of the same species caught in the same area in 1971. On the basis of the known increase in the global emissions of mercury over the past century and of a simple model of mercury biogeochemistry in the Equatorial and Subtropical Pacific ocean, we calculate that the methylmercury concentration in these surface waters should have increased between 9 and 26% over this 27 years span if methylation occurred in the mixed layer or in the thermocline. Such an increase is statistically inconsistent with the constant mercury concentrations measured in tuna. We conclude tentatively that mercury methylation in the oceans occurs in deep waters or in sediments.     

Redox processes controlling manganese fate and transport in a mountain stream

The biogeochemical processes controlling the speciation and transport of manganese in a Colorado mountain stream were studied using a conservative tracer approach combined with laboratory experiments. The study stream, Lake Fork Creek, receives manganese-rich inflows from a wetland contaminated by acid mine drainage. A conservative tracer experiment was conducted on a 1300-m reach of the stream. Results indicate that manganese was progressively removed from the stream, resulting in a loss of 64 +/- 17 micromol day(-1) m(-1). Laboratory experiments using streamwater, mine effluent, and rocks from the stream showed the importance of surface-catalyzed oxidation and photoreduction on the speciation of manganese. The field and modeling results indicate that light generally promotes oxidation and removal of manganese from the stream, presumably through a photosynthetically enhanced oxidation process. Differences in Mn speciation within the stream suggest that reductive processes affect Mn speciation within the water column. These results identify the rapid oxidation and precipitation of MnOx as a dominant process within this freshwater stream.