Concentration Ratio Method Research Articles

Spatial distribution and quantitative source identification of nutrients and beneficial elements in the soil of a typical suburban area, Beijing.

Source identification and quality monitoring of soil nutrients and beneficial elements (NBEs) are crucial for agricultural production and environmental protection. In this study, grid sampling (223 topsoil samples and 223 subsoil samples) was carried out in the Tongzhou District of Beijing. The concentration level of representative NBEs (N, P, K, Ca, Mg, Se, V, Ge, Mn, Zn) and some typical soil properties representing indicators (total organic carbon, TFe2O3, Al2O3/SiO2, and pH) in soils and their spatial distribution were analyzed. The major sources contributing to these NBEs were assessed by principal component analysis (PCA), redundancy analysis (RDA), and positive matrix factorization (PMF) analysis. The results suggested that the soil parent material contributed 40.09-69.84% to Zn, V, Ge, Mn, F, and K in soils; the local external source contributed 54.89-75.04% to N, Se, and TOC; and the hydrous system contributed 40.67-77.31% to Ca and Mg. The enrichment degree of each NBE was calculated using the standardized concentration ratio method. These indices exhibited the influence and mixing process of different sources on the target NBEs in topsoils. The individual concentrations of the target NBEs and the combined concentrations of N, P, and K were used to evaluate the soil quality. Our study estimated the relative contributions from dominant sources to NBEs in soils from a typical suburban area, providing a basis for agricultural activities and environmental protection.

Source apportionment and health risk assessment of indoor volatile organic compounds

In extremely cold areas with long winter months and exceptionally cold weather, classrooms are inadequately ventilated, resulting in the continuous accumulation of indoor air pollutants that may endanger human health. This article uses adsorption tube sampling-thermal desorption-gas chromatography mass spectrometry to analyze the type and concentration of volatile organic compounds (VOCs) in the classroom. The source analysis and health risk assessment were performed, and the real-time concentration of total volatile organic compounds (TVOC) was computed using the multifunctional ventilation. The result shows that the air in the classroom contains 25 kinds of VOCs. Among them, the carcinogenic risk value of seven kinds of VOCs (3.40 × 10-5) exceeds the acceptable risk value (1 × 10-6) given by the U.S. Environmental Protection Agency (US EPA). There are 17 kinds of VOCs that pose a certain non-carcinogenic risk to the human body. After quantitative analysis by the principal component analysis (PCA) and the characteristic quantity concentration ratio method, human activities, furnishings, outdoor penetration, etc., were found to be main sources of VOCs in the classroom. In addition, TVOC concentration is directly proportional to class time. In winter, classrooms in severely cold areas must take necessary measures to reduce the concentration of VOCs and ensure students' health.

Study on the Single Toxicity of Five Azole Fungicides for Green Algae

Azole fungicides are widely used to control diseases and insect pests of vegetables, fruits and flowers because of their good antibacterial effect and regulating plant growth. However, their extensive use inevitably enters the water environment with rainfall and surface runoff, which leads to potential harm to aquatic organisms. At present, the research on the biological toxicity of azole fungicides mainly focuses on single azole compounds, such as Paclobutrazol, hexaconazole, propiconazole and Difenoconazole. However, the systematic study on the toxic effects of multi-component mixtures of azole fungicides is still very lacking, and it is unable to accurately assess the ecological risk. Therefore, in this paper, five common azole fungicides (imidazole, tebuconazole, triadimefon, tricyclazole and hymexazol) in the environment were taken as target pollutants. Scenedesmus obliquus was used as the toxicity indicator. The mixture system was designed by the equal effect concentration ratio method and linear average ray method. Study the 96h toxicity and interaction of Scenedesmus obliquus under combined stress of azole fungicides. The main research results are as follows:The 96 h toxicity test of five typical azole fungicides to Scenedesmus obliquus was determined by microplate toxicity analysis method. Fitting with Weibull function and taking EC50 as the criterion,the results show that the single toxicity order of the five tested fungicides was:tebuconazole > Triadimefon > oxacillin > Tricyclazole > imidazole.

The Interaction Test of Binary Mixtures of Endocrine-Disrupting Chemicals Using In Vitro Bioassays

Typical environmental endocrine-disrupting chemicals (EDCs) such as estradiol valerate (EV), diethylstilbestrol (DES), di-2-ethylhexyl phthalate (DEHP), mono-2-ethylhexyl phthalate (MEHP), and bisphenol A (BPA) have a strong reproductive and developmental toxicity at low concentrations. However, information on their joint toxicity is scarce. In this study, we evaluated the combined effects of EV and other four EDCs (DES, DEHP, MEHP, and BPA) on the human breast MCF-7 cells by detecting the cell proliferation, intracellular reactive oxygen species (ROS) levels, and estrogen receptor alpha (ERα) protein expression using equal concentration ratio method. The results showed that, after exposure for 24, 48, and 72 h, single EV, DES, and BPA can promote the proliferation of MCF-7 human breast cancer cells, and EV has the strongest effect in inducing cell proliferation. DEHP and MEHP cannot induce MCF-7 cell proliferation for all exposure time, while cell proliferation induced by EV was significantly attenuated by DES, BPA, DEHP, and MEHP when they mixed with EV. For intracellular ROS, single EV, BPA, DES, DEHP, and MEHP elevated intracellular ROS levels for different exposure time. Similar to the cell proliferation, DES and BPA decreased intracellular ROS levels induced by EV when they mixed with EV for 24 h. EV, DES, and BPA exposed alone or combined with EV upregulated the ERα protein expression. However, DEHP and MEHP exposed alone or combined with EV had no effect on ERα protein expression, indicating that DEHP or MEHP could attenuate ERα protein expression upregulated by EV. These results showed that the joint toxicity of binary mixtures of EV and other EDCs do not interact in a synergistic fashion in inducing cell proliferation, intracellular ROS levels, and ERα protein expression. These findings have important implications in the human risk assessments of EV mixed with other EDCs in the environment.

Micrometeorological Methods for Measuring Methane Emission Reduction at Beef Cattle Feedlots: Evaluation of 3-Nitrooxypropanol Feed Additive.

It is highly desirable to test agricultural emission mitigation strategies in a whole-farm environment to ensure that all aspects of management and production operations are included. However, the large spatial scale of commercial operations makes the dual measurements of control and treatment(s) difficult. We evaluated the application of two micrometeorological methods, a novel concentration ratio method and an inverse dispersion method, where both were used to measure methane (CH) emission reductions in cattle fed the compound 3-nitrooxypropanol compared with cattle fed just the basal diet. In total, there were 1344 cattle used that were located in six pens (∼222 animals per pen). Three adjacent pens to the east and three to the west were designated as the treatment and control blocks, respectively. Underlying the emission reduction method was the assumption of site symmetry between the treatment and control pen blocks in the feedlot. There was, on average, a large CH emission reduction of ∼70% (±18%) due to the additive as found by both micrometeorological methods. Both methods also show a change in the diel distribution (peak emissions after initial morning feeding) and seasonal pattern (a decrease in emission reduction of 7.5 and 26.1% over 90 d). The simplicity of the developed concentration ratio method is expected to have applications for evaluating other mitigation strategies at large commercial scales (e.g., the application of manure additives to pens to reduce odors and ammonia emissions).

Validation testing of an ion-specific sensing and control system for precision hydroponic macronutrient management

Ion-specific nutrient management systems would replace conventional electrical conductivity-based management systems for more efficient maintenance of the concentration of each ion in nutrient solutions for closed hydroponic systems. This study reports on the validation testing of a previously developed ion-specific sensing and control system. Specific objectives were to (1) evaluate the ability of the system to maintain the target concentrations of five macronutrients, i.e., NO3−, PO43−, K+, Ca2+, and Mg2+ ions, required for crop growth in closed hydroponic systems based on both real-time measurement of NO3−, K+, and Ca2+ and the use of a concentration ratio method to replenish Mg2+ and PO43−, and (2) investigate the applicability of a cobalt rod-based electrode for hydroponic phosphate sensing. In a lettuce cultivation test conducted with the ebb-and-flow method over 21 days, most of the macronutrient concentrations were successfully maintained at the target levels with RMSE values of 25.2 ± 9.4, 19.1 ± 8.1, and 11.5 ± 6.1 mg∙L−1 for NO3−, K+, and Ca2+, respectively. In the case of Mg2+ and PO43− ions replenished in a proportional ratio to the supply of Ca2+ and NO3− ions, respectively, the Mg2+ concentrations were maintained between 18 and 25 mg∙L−1 at an almost constant level, whereas the PO43− concentrations increased steadily over time with no clear evidence of plant uptake, implying that the use of a concentration ratio method would not be effective in controlling the concentrations of PO43− in hydroponic solutions. As a phosphate sensor, the cobalt electrodes yielded an RMSE result of 10.9 ± 7.1% from a comparison of the electrode method and standard analysis when tested in hydroponic lettuce samples taken once a day during the period of lettuce growing, thereby offering the potential for use in hydroponic phosphate sensing.

Partial discharge recognition through an analysis of SF6 decomposition products part 2: feature extraction and decision tree-based pattern recognition

The decomposition characteristics of the SF6 under the different kinds of partial discharges (PD) should be understood first when recognizing PD by analyzing SF6 decomposition products in gas insulated switchgear (GIS). Moreover, the characteristic quantities used for recognition must be found. In this paper, the concentration and concentration ratio of SF6 decomposition products were each selected as characteristic quantities. Fuzzy c-means clustering algorithm was adopted to assess the performance of the two types of characteristic quantities, which was based on the data of SF6 decomposition products under the four kinds of PD in Part 1. Concentration ratio had better performance than concentration as a characteristic quantity in PD recognition. The concentration ratio method for PD recognition was established based on the decision tree theory, in which the three concentration ratios, namely c(SOF2)/c(SO2F2), c(CF4)/c(CO2), and c(SOF2 +SO2F2)/c(CO2+CF4), were used as characteristic quantities. The physical significance of the three concentration ratios was also analyzed. Finally, the concentration ratio method was applied to test the performance of PD recognition. The method has a good performance and can successfully recognize different kinds of PD.

Predicting stream N and P concentrations from loads and catchment characteristics at regional scale: A concentration ratio method

We used a concentration ratio method to predict yearly and summer averages of stream total nitrogen, nitrate and total phosphorus concentrations at a regional scale. The ratio of the median daily concentration on the flow weighted annual concentration was used. This ratio characterizes the concentration dynamics of a catchment. We took advantage of the commonly used budget type models applied at a regional scale to relate concentrations to loads instead of directly to land uses, as has previously been done. The relationship was modeled with Boosted Regression Trees using catchment and stream characteristics along with loads and flows obtained from the SPARROW budget model. The ratio modeling approach was compared to a direct approach for concentration prediction, and also to a simple method where the mean ratio was used. The modeling performances of the ratio models were overall satisfying (r2 of 49% to 78%), and a better choice than the two other methods tested. This ratio modeling approach is based on a steady state assumption and largely ignores temporal dynamics. As such, this modeling technique does not replace the more physically-based techniques, but allows for hybrid approaches for improved spatial interpolations. This method could be used to predict effectively the impact (at equilibrium) of land use change and management scenarios on water quality at a regional scale.

Household’s Access to and Affordability of Electricity During Reforms: A Comparative Study of Orissa and West Bengal

Using India’s National Sample Survey data on consumption expenditure by households this paper examines how access to affordability of electricity services have fared under power sector reform programme that was pursued in the of State Orissa (India). To draw a comparative picture of Orissa with a state which did not follow the path of World Bank inspired restructuring of the power sector we use similar data for West Bengal (a proximate State to Orissa). Paper finds that increment in the access to electricity for the bottom 60 percent of the population has remained almost stagnant and the burden of electricity expenditure on the poor households has increased significantly. Compared to west Bengal much larger increase in the expenditure on electricity in Orissa by households having access to electricity clearly signifies that electricity reforms have led to considerable loss in the in consumers’ welfare. Paper uses concentration ratio method to elicit findings.

Uncertainties in Assessing Annual Nitrate Loads and Concentration Indicators: Part 1. Impact of Sampling Frequency and Load Estimation Algorithms

The objectives of this study are to evaluate the uncertainty in annual nitrate loads and concentrations (such as annual average and median concentrations) as induced by infrequent sampling and by the algorithms used to compute fluxes. A total of 50 watershed-years of hourly to daily flow and concentration data gathered from nine watersheds (5 to 252 km) in Brittany, France, were analyzed. Original (high frequency) nitrate concentration and flow data were numerically sampled to simulate common sampling frequencies. Annual fluxes and concentration indicators calculated from the simulated samples were compared to the reference values calculated from the high-frequency data. The uncertainties contributed by several algorithms used to calculate annual fluxes were also quantified. In all cases, uncertainty increased as sampling intervals increased. Results showed that all the tested algorithms that do not use continuous flow data to compute nitrate fluxes introduced considerable uncertainty. The flow-weighted average concentration ratio method was found to perform best across the 50 annual datasets. Analysis of the bias values suggests that the 90th and 95th percentiles and the maximum concentration values tend to be systematically underestimated in the long term, but the load estimates (using the chosen algorithm) and the average and median concentrations were relatively unbiased. Great variability in the precision of the load estimation algorithms was observed, both between watersheds of different sizes and between years for a particular watershed. This has prevented definitive uncertainty predictions for nitrate loads and concentrations in this preliminary work, but suggests that hydrologic factors, such as the watershed hydrological reactivity, could be a key factor in predicting uncertainty levels.

Effects of Steady‐State Assumption on Hydraulic Conductivity and Recharge Estimates in a Surficial Aquifer System

AbstractThe ability of a calibrated flow model to predict the behavior of a surficial aquifer system is governed by the quality of the hydraulic conductivity and recharge estimates used. Reasonable lateral and vertical hydraulic conductivities can be estimated by steady‐state simulations driven by effective recharge rates that approximate the net effects of evapotranspiration, and water released from storage during periods of recession. Results from a hypothetical, transient, cross‐sectional model indicated that most of the water was contributed uniformly from storage from five to 25 days after a recharge event. Results also showed that a steady‐state, snapshot calibration approach can be used on aquifers in a humid climate with diffusivities between 20 and 500 m2/d. Most estimates of the lateral and vertical hydraulic conductivities of the hypothetical aquifer system were within 30% of the actual values. Estimates of hydraulic conductivity from the transient cases were similar to those from the snapshot calibration cases. The long‐term recharge rate could be identified by calibrating to multiple synoptic surveys that were sampled over the range of drier to wetter conditions. The effective recharge rates estimated for the driest and wettest conditions bracketed the long‐term recharge rate. Results suggested that the effective recharge rate estimated for the synoptic survey with the lowest water level root‐mean‐square (RMS) error was the best estimate of the long‐term recharge rate. A field application of the snapshot calibration approach simulated the surficial aquifer system beneath Cecil Field Naval Air Station well and provided reasonable estimates of the long‐term recharge rate (0.4 mm/d) relative to the range of recharge rates that were independently estimated by the chloride concentration ratio method (0.2 to 0.6 mm/d).

Developments in the Concentration Ratio Method

Developments in the Concentration Ratio Method

Concentration Ratio Method to Determinethe Rate Constant for the Special Case when ka = ke

Concentration Ratio Method to Determinethe Rate Constant for the Special Case when ka = ke

シルミン中のナトリウムの定量分光分析

On the quantitative determination of sodium contained in the silumin alloys, the characteristics of Fuji Panchromatic Process plates were examined by the spectrum exposure, because the ordinary spectral lines in the ultra range were not available in this purpose. The A.C. intermittent arc source was applied so as to secure the steady and reproducible analyses sensitivity. As a sampling device, the solutions method was adopted using a porous cup electrode, and for processing the standard sample series, copper was selected as an internal standard. A series of standard sample solutions having a known content ratios of Na to Al and several metal-specimens were prepared. With these solutions, the spectral lines were photographed on the same plates, and the Na quantity in the standard metal electrode was determined by the concentration ratio method. It was confirmed that the quantitative analysis is limit of Na in the silumin alloys by spectrography was 0.005%. The standard deviation percentage of this method was 8.10%.

The spectrographs determination of trace elements in the cathode layer ARC by the variable internal standard method

AbstractThe use of iron as the variable internal standard for the determination of trace elements in the cathode layer are, when the iron varies from two to one hundred per cent of ferric oxide, is discussed. Davidson and Mitchell's method, which requires one trace element working curve of fixed iron content and a correction curve for variation of iron content, is examined. Straight line working curves, of slope approximately unity up to at least five hundred parts per million, are obtained for most of the trace element lines when log intensity ratio, corrected for background, is plotted against log concentration, the curves for different iron contents being parallel but vertically displaced. Straight line correction curves are obtained by plotting this separation of the working curve, due to variation in iron content, against log concentration of iron. Two shortened methods for the derivation of the curves are proposed: in the first, the working and correction curves fan be prepared from a standard material by a single determination of the log intensity ratio of the trace element and internal standard lines, corrected for background; the second employs an observed working curve and an arbitrary correction curve. In the concentration ratio method, in which the working curve itself makes allowance for the variation in internal standard content, the log intensity ratio is plotted against the log concentration ratio and this method has similar limitations to the first shortened method.