Shoaling internal waves may reduce gravity current transport

Gravity currents descending along slopes have typically been studied in quiescent environments, despite the fact that in many geophysical settings there is significant externally driven motion. Here we investigate how the head of a gravity current is influenced by interfacial internal waves at the pycnocline of a two-layer ambient water column. Our experimental measurements show that larger amplitude internal waves, interacting with the gravity current, reduce both the mass transport by the gravity current and its thickness. These results suggest that the ambient internal wave field should be considered when estimating transport by gravity currents in geophysical settings with strong internal waves, such as lakes and the coastal ocean.     

Interaction of North Brazil Current rings with the Lesser Antilles Arc and Barbados Island: laboratory experiments and observations

The interaction of North Brazil Current (NBC) rings with the Lesser Antilles Arc (LAA) and the Barbados Island (BI) is addressed by experimental modeling and observations. Our results compare well with previous experimental results and numerical simulations. Several sizes, intensities and two different vorticity profiles (non-isolated and initially isolated vortices) were tested. Three regimes were found namely: (1) the vortex surrounds the BI and its translational motion (TM) stops North of BI; (2) the vortex passes through the corridor between the LAA and the BI by reducing its size; and (3) The vortex stopped at the entrance to the corridor South of the BI. Isolated vortices were prone to stopped North of the BI. Apparently the intensity in the outer vorticity ring has an influence on the fate of the NBC ring. Non-isolated vortices can also stop its TM North of the BI because when in \(\beta\) plane they develop an outer ring similar to the isolated vortices. From these results we conclude that intense and big NBC rings are likely to stop its TM North of the BI. Medium and moderate vortices stops its TM South of the BI and they reduce their size until they are able to pass through the corridor between the LAA and the BI. Mild vortices of all sizes stop South of the corridor, close to the BI and the LAA. Drifter trajectories and Sea Surface Height altimetry confirm the results.     

Multiple source spatial cluster detection via multi-criteria analysis

Multiple data sources are essential to provide reliable information regarding the emergence of potential health threats, compared to single source methods. Spatial Scan Statistics have been adapted to analyze multivariate data sources, but only ad hoc procedures have been devised to address the problem of selecting the most likely cluster and computing its significance. In this work, information from multiple data sources of disease surveillance is incorporated to achieve more coherent spatial cluster detection using tools from multi-criteria analysis. The best cluster solutions are found by maximizing two objective functions simultaneously, based on the concept of dominance. To evaluate the statistical significance of solutions, a statistical approach based on the concept of attainment function is used. The multi-criteria approach has several advantages: the representation of the evaluation function for each data source is clear, and does not suffer from an artificial, and possibly confusing mixture with the other data source evaluations; it is possible to attribute, in a rigorous way, the statistical significance of each candidate cluster; and it is possible to analyze and pick-up the best cluster solutions, as given naturally by the non-dominated set. The methodology is illustrated with real datasets.     

Mycelial culture of wild Inonotus hispidus parasitizing the jujube tree and the cultivation conditions of its fruit body on rice medium北大核心CSCD

Inonotus hispidus is a kind of rare medicinal fungus, and its natural resources are very scarce. Currently, the artificial cultivation technology of I. hispidus is not completely developed, and this reflects on its extremely low biological conversion rate and long cultivation period. In order to improve the bioconversion rate and shorten the production cycle of I. hispidus, we first analyzed the mycelia culture conditions of the collected I. hispidus, and then we further explore the method of domesticated cultivation of its fruiting body in rice medium. During the process of mycelial culture, the suitable temperature, pH, carbon source, and nitrogen source for mycelial growth were selected using the mycelial growth rate as index. During the domesticated cultivation of the fruiting body, the suitable culture medium for its growth was selected using the bioconversion rate as index. Screening results of mycelial culture conditions showed that the optimal culture conditions for the growth of mycelium of the wild I. hispidus were: temperature of 25 °C, initial pH of 6.0, glucose as the carbon source, and yeast extract powder as the source of nitrogen. The results of the domesticated cultivation showed that the biotransformation rate of I. hispidus was higher when using rice as the main medium substrate. The optimal cultivation conditions were: a 0.2% yeast extract content in the nutrient solution, a 1:1.6 ratio of rice to nutrient solution, and a 4 mL inoculum of the liquid strain. Under these conditions, it took about 4 days for the mycelium to grow over the cultivation medium. The time required for the differentiation of the primordium to form fruit bodies was about 20 days, and the bioconversion rate reached 28.70% ± 5.05%. The results of this study indicate the feasibility of using rice as the main substrate for the cultivation of I. hispidus, and it also provide new insights for the finding of new cultivation substrates for other rare medicinal fungi. © 2018 Science Press. All rights reserved.     

Spatial variability in soil water and salinity in Tamarix community in a semiarid saline region of the upper Yellow River北大核心CSCD

Tamarix is widely distributed in semiarid saline regions of the upper Yellow River. The community of Tamarix affects the spatial distribution of soil water and salinity. It is important to explore the dynamic response relationship of Tamarix community and spatial distribution of soil water and salinity in order to evaluate the effects of vegetation community construction and ecological restoration in this region. The natural Tamarix community in the secondary saline-alkali land of the Ningxia Yellow River Irrigation Area was investigated in July 2016. Classical statistics and geostatistics were used to analyze the spatial distribution characteristics of soil water and salinity. The results showed that the soil water content was relatively low (1.98%-7.55%), whereas the soil salinity was high (average conductivity 10.28-25.38 mS/cm) in the study area. The variability coefficient range of soil water and salinity was 36.1%-83.7%, both with moderate variations. Furthermore, the variation degree of soil salinity decreased with the increase in soil depth. The soil water and salinity had obvious spatial structure characteristics, which was mainly affected by structural factors or structural factors associated with stochastic factors. The coefficients of nugget were 0.04%-49.88%, indicating the strong spatial correlation. The spatial distribution of soil water and salinity in Tamarix community showed a patchy pattern; the soil water and salinity distribution in the areas with high Tamarix growing density were considerably high. The correlation analysis showed that there was a positive correlation between soil water and salinity in the study area. In conclusion, soil water and salinity restrict the distribution and growth of Tamarix. Furthermore, the distribution and growth of Tamarix enhanced the spatial variability of soil water and salinity. Keywords. © 2018 Science Press. All rights reserved.     

Fate of imidacloprid in soil and plant after application to cotton seeds

This study aimed to investigate the persistence of imidacloprid in soil after application to cotton seeds and to obtain a complete picture on the mass balance of this compound in soil and cotton plants. The study was carried out as a pot culture experiment under laboratory conditions using a Gaucho formulation containing ¹⁴C-labeled imidacloprid. Three treatments of cotton seeds were made in sandy loamy soil: live seeds grown in autoclaved soil, dead seeds put in live soil and live seeds grown in live soil. Results showed that total ¹⁴C recoveries decreased by time ranging 93.8–96.2, 77.1–88.4 and 53.5–62.4% of the applied radioactivity at 7, 14, and 21 d after application, respectively. The reduction in the extracted ¹⁴C from soil coincided with the increase of non-extracted ones. Levels of bound ¹⁴C was always less in autoclaved soil than in live ones. Results revealed also that only 1.8–6.8% of the applied ¹⁴C was taken up by the plants and fluctuated within the test period. ¹⁴C levels were higher in plants grown in autoclaved soil than those in live ones and the radioactivity tended to accumulate on the edges of cotton leaves. Most of the radioactivity in the soil extracts was identified as unchanged ¹⁴C-imidacloprid.     

Transport of atmospheric fine particulate matter: part 2--findings from recent field programs on the intraurban variability in fine particulate matter

Air quality field data, collected as part of the fine particulate matter Supersites Program and other field measurements programs, have been used to assess the degree of intraurban variability for various physical and chemical properties of ambient fine particulate matter. Spatial patterns vary from nearly homogeneous to quite heterogeneous, depending on the city, parameter of interest, and the approach or method used to define spatial variability. Secondary formation, which is often regional in nature, drives fine particulate matter mass and the relevant chemical components toward high intraurban spatial homogeneity. Those particulate matter components that are dominated by primary emissions within the urban area, such as black carbon and several trace elements, tend to exhibit greater spatial heterogeneity. A variety of study designs and data analysis approaches have been used to characterize intraurban variability. High temporal correlation does not imply spatial homogeneity. For example, there can be high temporal correlation but with spatial heterogeneity manifested as smooth spatial gradients, often emanating from areas of high emissions such as the urban core or industrial zones.     

Effect of climate change on flux of N and C: air-land-freshwater-marine links: synthesis

Projected climate change might increase the deposition of nitrogen by about 10% to seminatural ecosystems in southern Norway. At Storgama, increased precipitation in the growing season increased the fluxes of total organic carbon (TOC) and total organic nitrogen (TON) in proportion to the water flux. In winter, soil temperatures near 0 degrees C, common under a snowpack, induced higher runoff of inorganic nitrogen (N) and lower runoff of TOC. By contrast, soil temperatures below freezing, caused by little snow accumulation (expected in a warmer world), reduced runoff of inorganic N, TON, and TOC. Long-term monitoring data showed that reduced snowpack can cause either decreased or increased N leaching, depending on interactions with N deposition, soil temperature regime, and winter discharge. Seasonal variation in TOC was mainly climatically controlled, whereas deposition of sulfate and nitrate (NO3) explained the long-term TOC increase. Upscaling to the river basin scale showed that the annual flux of NO3 will remain unchanged in response to climate change projections.     

Laccase mediated biodegradation of 2,4-dichlorophenol using response surface methodology

The effects of different environmental parameters, i.e., pH, temperature, time and enzyme concentration on the biodegradation of 2,4-dichlorophenol (2,4-DCP) in aqueous phase was evaluated with laccase from Pleurotus sp. using response surface methodology (RSM) in the present investigation. The Box-Behnken design of experiments was used to construct second order response surfaces with the investigated parameters. It was observed that the maximum degradation efficiency of approximately 98% was achieved at pH 6, temperature of 40 degrees C, time 9h and an enzyme concentration of 8IUml(-1). The adequacy of the model was confirmed by the coefficient of multiple regression, R(2) and adjusted R(2) which were adjudged to be 87.9% and 73.6%, respectively indicating a reasonably good model for practical implementation. Despite the fact that many successful attempts have been taken in the past for biodegradation of 2,4-DCP using whole cells, the present study emphasizes the fastest biodegradation of 2,4-DCP, a potent xenobiotic compound.     

Levels and trends of HBCD and BDEs in the European and Asian environments, with some information for other BFRs

In this paper, we review recent data for brominated flame retardants (particularly BDEs, HBCD and TBBP-A) in samples from the European and Asian environments, including recent temporal trend studies. Research is active and we cite over 100 studies published during 2005-2007. Environmental compartments studied comprise the atmosphere, indoor and outdoor air, sewage sludges, soils and sediments and a variety of biological samples and food chains. Findings include that the lack of reference materials for use in analytical quality control and method validation identified earlier has been addressed, and certified concentrations are now available for a number of BDE congeners in six pre-existing and one new reference materials. BDE209 was certified in three samples of indoor dust. The analysis of BDE209 remains problematic, but suitable methods for its determination are available and need to be applied. The contamination of indoor environments with BFRs has been recognised as representing a significant uptake pathway, particularly via dust. Additional data for TBBP-A are needed from areas, where it is produced and used, primarily Asia, as the worst-case scenario. As a reactive flame retardant it is less likely to leach from finished products. Also, issues regarding the importance of e-waste recycling as a source of BFRs to the local populations and the local environment require urgent study, certainly in China and possibly elsewhere. Generally, trends show a levelling in concentrations of BDEs and increases in concentrations of HBCD wherever determined and BDE209 in Asia.