养殖水中总有机碳与化学需氧量和生化需氧量相关性的研究

总有机碳能较全面地反映水体有机物的污染程度,总有机碳的测定具有操作简单、分析快速、结果准确等特点。研究了养殖水中的总有机碳与化学需氧量和生化需氧量相关性,总有机碳与化学需氧量的相关系数为０.９９１８,总有机碳与生化需氧量的相关系数为０.９３６２,可以用总有机碳来估算和衡量水体的污染情况。     

Biological Oxygen Demand in Soils and Litters

Biological oxygen demand (BOD) in mineral and organic horizons of soddy-podzolic soils in the forest-park belt of Moscow as an indicator of their microbial respiration and potential biodestruction function has been studied. The BOD of soil samples has been estimated with a portable electrochemical analyzer after incubation in closed flasks under optimum hydrothermal conditions. A universal gradation scale of this parameter from very low (<2 g O₂/(m³ h)) to extremely high (>140 g O₂/(m³ h)) has been proposed for mineral and organic horizons of soil. A physically substantiated model has been developed for the vertical distribution of BOD in the soil, which combines the diffusion transport of oxygen from the atmosphere and its biogenic uptake in the soil by the first-order reaction. An analytical solution of the model in the stationary state has been obtained; from it, the soil oxygen diffusivity and the kinetic constants of O₂ uptake have been estimated, and the profile-integrated total BOD value has been calculated (0.4–1.8 g O₂/(m² h)), which is theoretically identical to the potential oxygen flux from the soil surface due to soil respiration. All model parameters reflect the recreation load on the soil cover by the decrease in their values against the control.     

Chemical Oxygen Demand (COD) Reduction in Domestic Wastewater by Fly Ash and Brick Kiln Ash

The potential of fly ash, brick kiln ash and commercial activated carbon is determined for the reduction of chemical oxygen demand (COD) from domestic wastewater. Laboratory experiments are conducted for investigating the effect of treatment time, adsorbent dose, pH of the media, initial COD concentration, agitation speed and particle size of adsorbents on the COD reduction from the domestic wastewater. Starting with an initial COD concentration of 1080 mg/l the maximum COD reduction achieved for fly ash was 87.84%, brick kiln ash was 83.22% and commercial activated carbon was 99.35 %. These values were achieved when the wastewater was treated with activated carbon for 180 min, fly ash 250 min and brick kiln ash 300 min and the adsorbent dose was kept respectively at 40 g/l, 60 g/l and 45 g/l for activated carbon, fly ash and brick kiln ash. Agitation speed was kept constant at 600 rpm and the pH was maintained at 2 for activated carbon and fly ash and 5 for brick kiln ash. The maximum percent reduction is for 0.053 mm or smaller size of the particles. Though the adsorption capacity of the ash for reducing the COD is lower than that of the commercial activated carbon, the low material cost can make it an attractive option for the treatment of domestic wastewater.     

Chemical Oxygen Demand and Ammonia Nitrogen Removal in a Non-saturated Layer of a Strengthened Constructed Rapid Infiltration System

A strengthened constructed rapid infiltration (SCRI) system is a sewage treatment system derived from a constructed rapid infiltration (CRI) system. The SCRI tank structure primarily includes saturated and non-saturated layers. The degradation of the chemical oxygen demand (COD) and the conversion of ammonia nitrogen (NH₄ ⁺-N) are primarily performed in a non-saturated layer. To study the COD and NH₄ ⁺-N removal process in a non-saturated layer, two organic glass columns with a radius of 2.5 cm and a height of 70 cm were loaded with layers of soil from the Shunyi district of Beijing. The primary goal of this research is to quantify the removal effect factors and the relationship of the COD and NH₄ ⁺-N in the non-saturated layer. The SCRI system functioned successfully under a wetting-drying ratio of 1:5 with hydraulic loading at 1.0 m³/ (m²·d) for over 2 months. Our results show that the removal rate of NH₄ ⁺-N is approximately 69.11%, and the removal efficiency of COD is approximately 90.46%. The removal of COD is only slightly affected by pH, while the removal of NH₄ ⁺-N is greatly influenced by pH.     

Biochemical Oxygen Demand Relationships in Typical Agricultural Effluents

Understanding the variables controlling biochemical oxygen demand (BOD) of effluents from agricultural systems is essential for predicting and managing the water quality risks associated with agricultural production. In this study, short- and long-term oxygen demand behaviors of waters from primarily agricultural sources and their relationships with other parameters were evaluated. A total of 46 water samples were generated from diverse organic sources commonly associated with agricultural activities and analyzed for BOD and other various water quality parameters. Short-term BOD (BOD₂ and BOD₅) were significantly correlated with total organic carbon (TOC), particulate organic carbon (POC), and dissolved organic carbon (DOC) (R ²?=?0.62–0.77, p?<?0.001), likewise to total nitrogen, total Kjeldahl nitrogen, and nitrite–nitrogen (NO₂–N) (R ²?=?0.40–0.55, p?<?0.001). Long-term BOD (BOD₆₀) was generally poorly correlated with these C and N fractions. Phosphate (PO₄–P) exhibited a positive and linear relationship with both short- and long-term BOD, whereas chloride (Cl) tended to inhibit oxygen demand. Multivariate combinations of each of TOC, POC, and DOC with NO₂–N, and Cl or PO₄–P improved the predictions of both short- and long-term BOD. The ultimate BOD (BOD_u) derived from the first-order kinetics was highly correlated with BOD₆₀ (R ²?=?0.81, p?<?0.001) whereas BOD₆₀ was correlated with BOD₅ (R ²?=?0.60, p?<?0.001). Overall the results indicated that C and N forms along with PO₄–P and Cl were the dominant factors controlling the oxygen demand behaviors of agricultural effluents.     

Oxygen Demand of Aircraft and Airfield Pavement Deicers and Alternative Freezing Point Depressants

Aircraft and pavement deicing formulations and other potential freezing point depressants were tested for biochemical oxygen demand (BOD) and chemical oxygen demand (COD). Propylene glycol-based aircraft deicers exhibited greater BOD₅ than ethylene glycol-based aircraft deicers, and ethylene glycol-based products had lower degradation rates than propylene glycol-based products. Sodium formate pavement deicers had lower COD than acetate-based pavement deicers. The BOD and COD results for acetate-based pavement deicers (PDMs) were consistently lower than those for aircraft deicers, but degradation rates were greater in the acetate-based PDM than in aircraft deicers. In a 40-day testing of aircraft and pavement deicers, BOD results at 20°C (standard) were consistently greater than the results from 5°C (low) tests. The degree of difference between standard and low temperature BOD results varied among tested products. Freshwater BOD test results were not substantially different from marine water tests at 20°C, but glycols degraded slower in marine water than in fresh water for low temperature tests. Acetate-based products had greater percentage degradation than glycols at both temperatures. An additive component of the sodium formate pavement deicer exhibited toxicity to the microorganisms, so BOD testing did not work properly for this formulation. BOD testing of alternative freezing point depressants worked well for some, there was little response for some, and for others there was a lag in response while microorganisms acclimated to the freezing point depressant as a food source. Where the traditional BOD₅ test performed adequately, values ranged from 251 to 1,580?g/kg. Where the modified test performed adequately, values of BOD₂₈ ranged from 242 to 1,540?g/kg.     

生化需氧量检测标准现状与发展

水环境监测是切实推进生态文明建设的重要方面.生化需氧量(Biochemical Oxygen Demand,BOD)是在微生物存在下水体有机物生化降解所需的氧量.作为反映水中有机污染物含量的重要指标,在城镇、工业和农业农村环境等领域的监测工作中均不可忽视.该研究剖析了国内外关于BOD检测的标准和方法,总结了稀释接种法和...     

Oxygen Isotopic and Chemical Characterization of Soils with Surface Gleyzation from Central and Northeastern Japan

Four soils with surface gleyzation (Humi-stagnic Gleysols; provisional) from central and northeastern Japan are characterized by a combination of oxygen isotopic, chemical dissolution (pyrophosphate and acid oxalate) and X-ray diffraction analyses. Oxygen isotopic composition of quartz indicates residuum of volcanic materials and eolian dust from interior China as major parent materials of the clayey surficial horizons.     

Tryptophan-mediated denaturation of beta-lactoglobulin A by UV irradiation

beta-Lactoglobulin A, a genetic variant of one of the main whey proteins, was irradiated at 295 nm for 24 h. After irradiation, 18% of the protein was denatured (determined by reverse-phase chromatography). The fluorescence spectrum of the irradiated protein was red-shifted compared to that of the native protein, indicating a change in protein folding. Sulfhydryl groups, which are buried in native beta-lactoglobulin, were exposed following irradiation and became available for quantification using the Ellman assay. The quantity of exposed sulfhydryls increased, but the number of total sulfhydryl groups decreased. Gel permeation chromatography showed that some protein aggregation occurred during irradiation. Fourier transform infrared (FTIR) spectroscopy of irradiated beta-lactoglobulin revealed changes in the secondary structure, comparable to that of early events during heat-induced denaturation. There was evidence for some photo-oxidation of tryptophan.     

Quantification of Oxidant Demand and Consumption for In Situ Chemical Oxidation Design: in the Case of Potassium Permanganate

Accurate estimation of oxidant consumption during in situ chemical oxidation (ISCO) is the key to determining the treatment effectiveness in contaminated sites. We established the estimation model of soil oxidant demand (SOD) and simulation equations of potassium permanganate (KMnO₄) dynamic consumption based on the reaction equation of KMnO₄ with reductive minerals and the estimation model of SOD. Model validation, model application, and simulation assessment had been accomplished. Results indicated that the simulations are in good agreement with measured data. The confidence level of the SOD estimation model of KMnO₄ was over 80%, with sensitivity in decreasing order as follows: organic matter content > initial KMnO₄ concentration > reductive minerals (RMs). Particularly, the organic matter played a dominate role in the SOD model estimation. The coefficient of determination (R²) of the SOD dynamic consumption simulation equation was above 0.9. Among the various types of soils, the overall trend of SOD value and reaction period decreased as follows: clay > loam > sand. However, the consumption rate of KMnO₄ decreased in the order of clay > sand > loam. In addition, SOD value, reaction period, and reaction rate all increased as the initial concentration of KMnO₄ went up. This work can provide a methodology and reference for selecting and estimating of the optimal oxidant doses and reaction period during field application.     

鳞盖红菇与正红菇成分分析及毒性实验

对鳞盖红菇（RussulalepidaFr）与正红菇（RussulavinosaLindbl）子实体的粗蛋白、水溶性粗多糖、微量元素、氨基酸等成分进行了分析、比较;并以正红苗为对照,对鳞盖红菇进行了急性毒性实验。结果表明：两种菇所测成分相近,且均属于安全食用菌。     

基于溶解无机碳中碳氧同位素及化学组分的瓶装饮用水产地真实性鉴别

为了鉴别我国市场上销售的瓶装饮用水的产地和产品类型,本试验分析了瓶装饮用水溶解无机碳(DIC)中的δ¹⁸O_DIC和δ¹³C_DIC、水中的δ¹⁸O和δ²H值、矿物元素(K、Ca、Na、Mg、Sr)含量、阴离子(Cl^-、SO₄^2-、HCO₃^-)含量、pH值与电导率等水化学指标,结合费希尔判别分析(Fisher-DA)建立模型,对瓶装饮用水的类别和产地进行鉴别。结果表明,不同产地瓶装饮用水的δ¹⁸O_DIC、δ¹³C_DIC、δ¹⁸O、δ²H值均具有显著差异,而且矿物元素与阴离子的含量变化范围广,具有不同的地域性特征。产地溯源判别模型对不同产地瓶装饮用水的判别准确率高达100%,且采用水化学指标还能区分瓶装饮用水的类型。正态化重要性分析显示,对产地具有指示效应的前五项重要指标分别为K、Cl^-和δ¹³C_DIC、δ²H和pH值。综上所述,通过稳定同位素指纹信息和水化学指标的差异进行融合分析,结合多元统计模型可有效鉴别市场上瓶装饮用水的真实性,保护消费者的合法权益,维护市场公平。     

Photodegradation of metolachlor applying UV and UV/H2O2

Metolachlor is one of the most widely used herbicides in the world for controlling weeds. It has been detected in both ground and surface waters in the United States, and there are rising concerns in regard to its health risks and in developing effective treatment processes for its removal from water. Degradation of metolachlor via ultraviolet (UV) photolysis and an UV/hydrogen peroxide advanced oxidation process (AOP) was studied. The quantum yield of metolachlor at 254 nm was found to be 0.302 +/- 0.001 mol E-1 through direct UV photolysis in the range of pH 6-8. The second-order rate constant of the reaction between metolachlor and hydroxyl radical was determined to be 9.07 (+/-0.21) x 10(9) M-1 s-1 by using a competition kinetics model that utilized nitrobenzene as a reference compound. In addition, these parameters were successfully applied in modeling the kinetics of elimination of metolachlor using an UV/H2O2 process in both laboratory and natural waters. The formation of several photolysis byproducts was identified using gas chromatography/mass spectrometry, and a scheme for the metolachlor photodegradation pathway is proposed.     

池塘溶解氧动态模型的研究

池塘是一个复杂的生态系统,溶解氧是描述该系统的重要参数之一。池塘溶解氧呈24小时周期连续变化,因而可用时间序列分析的方法来建立池塘溶解氧的ARMA(p,q)模型。通过一个实例,阐明了建模的原理、步骤、模式识别方法和模型参数的估计过程,建立的模型与实测数据拟合良好,并可用于池塘溶解氧的实时预报。表明该方法与其它方法相比,具有简捷、实时性好、精度较高、适合于用计算机实现对多个池塘的溶解氧的动态监测和管理等特点。     

鲤鱼摄食生长与呼吸耗氧动态模型的研究

建立了鲤鱼摄食生长与呼吸耗氧动态模型,并结合网箱养鲤鱼高产试验数据进行了参数估计与模型检验,结果表明模拟值与试验值吻合很好。为高产养鲤鱼的生产管理与经济评估提供了量化依据,为鱼类的摄食生长与呼吸耗氧的研究提供了新的方法。     

A Simple Wheat Flour Swelling Test

Flour swelling tests have been widely used to assess the intercultivar differences in starch properties. This note describes a modified flour swelling test which uses ≈30 mg of flour. It avoids the use of a high-temperature water bath, and does not require a set of uniform and leak-proof tubes. The modified procedure offers a simpler and more rapid alternative to those previously reported, and provides a similar level of discrimination and precision. It is particularly suitable as a micro-scale early generation test for wheat flour swelling properties.     

鲤鱼摄食生长与呼吸耗氧动态模型的研究

建立了鲤鱼摄食生长与呼吸耗氧动态模型,并结合网箱养鲤鱼高产试验数据进行了参数估计与模型检验,结果表明模拟值与试验值吻合很好。为高产养鲤鱼的生产管理与经济评估提供了量化依据,为鱼类的摄食生长与呼吸耗氧的研究提供了新的方法。     

一种新的池塘溶解氧预测模型

池塘溶解氧的精确预测一直是池塘人工养殖生产中的瓶颈问题。该文建立了基于神经网络的池塘溶解氧智能预测模型，并对预测模型进行了验证，其预测结果与实测数据拟合良好。     

生物降解聚氨酯包膜尿素化肥的研究

以天然吸水剂魔芋为掺杂料,参与合成生物降解型聚氨酯泡沫材料,用作为尿素化肥缓释包膜材料,研究结果表明通过调整魔芋粉的数量、水的份量及控制包膜的厚度,可控制尿素氮的缓释速度及包膜材料的降解速度。用水溶解方法测定试样缓释速率,用埋入法测定包膜材料的降解情况,结果表明该材料能够自然降解。