A New Spectrophotometric Method for Measuring COD of Seawater

This research studied a new spectrophotometric method for measuring the chemical oxygen demand （COD） of seawater. In this method, the COD was measured using a spectrophotometer instead of titrating with sodium thiosuiphate. The measuring wavelength was selected to be 470 nm, and the COD of three standard glucose solutions （COD = 0.5, 1.5 and 2.5 mgL^-1, respectively） and two seawater samples （from the South Yellow Sea and Jiaozhou Bay） were measured using the spectrophotometric method and titrimetric method respectively. The results showed that the spectrophotometric method was somewhat better than the titrimetric method. The relative standard deviation （RSD） of the spectrophotometric method was less than 2.7%, and the recovery of seawater samples ranged from 96.3% to 103.8%. In addition, the spectrophotometric method has other advantages such as expeditiousness, operation simplicity, analysis automatization, etc. Therefore the spectrophotometric method can be used to measure the COD of seawater with satisfactory results.

Uncertainty and Sensitivity Analyses of the Simulated Seawater—Freshwater Mixing Zones in Steady-State Coastal Aquifers

The uncertainty and sensitivity of predicted positions and thicknesses of seawater-freshwater mixing zones with respect to uncertainties of saturated hydraulic conductivity, porosity, molecular diffusivity, longitudinal and transverse dispersivities were investigated in both head-control and flux-control inland boundary systems. It shows that uncertainties and sensitivities of predicted results vary in different boundary systems. With the same designed matrix of uncertain factors in simulation experiments, the variance of predicted positions and thickness in the flux-control system is much larger than that predicted in the head-control system. In a head-control system, the most sensitive factors for the predicted position of the mixing zone are inland freshwater head and transverse dispersivity. However, the predicted position of the mixing zone is more sensitive to saturated hydraulic conductivity in a flux-control system. In a head-control system, the most sensitive factors for the predicted thickness of the mixing zone include transverse dispersivity, molecular diffusivity, porosity, and longitudinal dispersivity, but the predicted thickness is more sensitive to the saturated hydraulic conductivity in a flux-control system. These findings improve our understandings for the development of seawater-freshwater mixing zone during seawater intrusion processes, and give technical support for groundwater resource management in coastal aquifers.

Henry's Law constant for phosphine in seawater:determination and assessment of influencing factors

The Henry＇s Law constant （k） for phosphine in seawater was determined by multiple phase equilibration combined with headspace gas chromatography. The effects of pH, temperature, and salinity on k were studied. The k value for phosphine in natural seawater was 6.415 at room temperature （approximately 23℃）. This value increases with increases in temperature and salinity, but no obvious change was observed at different pH levels. At the same temperature, there was no significant difference between the k for phosphine in natural seawater and that in artificial seawater. This implies that temperature and salinity are major determining factors for k in marine environment. Double linear regression with Henry＇s Law constants for phosphine as a function of temperature and salinity confirmed our observations. These results provide a basis for the measurement of trace phosphine concentrations in seawater, and will be helpful for future research on the status of phosphine in the oceanic biogeochemical cycle of phosphorus.

Chemical Oxygen Demand of Seawater Determined with a Microwave Heating Method

This paper investigates a microwave heating method for the determination of chemical oxygen demand (COD) in seawater. The influences of microwave-power, heating time and standard substances on the results are studied. Using the proposed method, we analyzed the glucose standard solution, the coefficient of variation being less than 2%. Compared with the traditional electric stove heating method, the results of F-test and T-test showed that there was no significant difference between the two methods, but the microwave method had slightly higher precision and reproducibility than the electric stove method. With the microwave heating method, several seawater samples from Jiaozhou Bay and the South Yellow Sea were also analyzed. The recovery was between 97.5% and 104.3%. This new method has the advantages of shortening the heating time, improving the working efficiency and having simple operation and therefore can be used to analyze the COD in seawater.

China's Seawater Desalination Plants Produce Megatons Freshwater For Low Cost

China, as many other parts of the world, has a serious shortage of water resources. In China, there is a total amount of 2.8×10^12 m3 of freshwater, but that is only 2000 m3 per capita, which is about one quarter of the world average. Thereforc, seawater desalination engineering is of great significance to the nation.

基于Scholte波频散特性的深海海底横波速度反演

深海环境下海水的声波速度是非匀速的,变速的海水会影响海底Scholte波的频散特性,为了提高利用Scholte波频散特性反演海底横波速度的精度,需建立速度连续变化的水平分层海水-分层海底(HLSLS)模型。本文基于波动理论推导HLSLS模型Scholte波频散方程和振幅深度方程。然后,基于南海海水声速剖面和实际海底弹性介质参数,分析深海环境海水速度变化对Scholte波频散特性的影响。最后,将方法用于南海深水OBS地震数据反演得到一条二维海底横波速度剖面,反演结果很好的指示了海底天然气水合物储层的分布。结果表明:深海环境下,利用海底OBS数据中的Scholte波反演海底浅层横波速度结构是可行的,南海实际深水OBS数据应用进一步验证了方法的准确性和实用性。

市售鱼类中双酚A、双酚S污染水平及风险评估

目的:建立固相萃取和超高效液相色谱-串联质谱法测定鱼类中双酚A(Bisphenol A,BPA)及双酚S(Bisphenol S,BPS)的方法。方法:使用固相萃取和超高效液相色谱-串联质谱方法分析240份鱼类样品中BPA和BPS含量,并计算膳食暴露量和风险指数。结果:240份鱼类中均未检出BPA。BPS检出率为81.67%,含量检测最大值为65.31μg·kg^(-1),中位数为5.28μg·kg^(-1),平均值为12.99μg·kg^(-1)。结论:鱼类食品中检出BPS,未检出BPA。日常食用海水鱼或是淡水鱼都不会引起暴露风险。

亚硝酸盐对海水COD测定的影响及消除方法的研究

研究了ＮＯ－２对海水ＣＯＤ测定的影响。结果表明：海洋监测规范中ＣＯＤ的测定方法不适合于ＮＯ－２较高的污染海水，比较了氨基磺酸与叠氮化钠对ＮＯ－２的掩蔽效果及测定方法。认为在依次加热氧化，冷却后加入固体ＫＩ，然后加入０．２ｍＬ浓度为５ｇ／Ｌ的ＮａＮ３再酸化，可以消除２ｍｇ／Ｌ以下的ＮＯ－２－Ｎ的干扰作用。

流动注射法分析海水中的COD

采用流动注射碱性高锰酸钾法测定海水中的COD,对实验条件进行优化,改变氧化液浓度、氢氧化钠浓度、进样环体积等条件,可以更好地提高灵敏度和准确度,本方法适于现场实时监测,具备了快速、连续、自动、精密度好、抗干扰能力强等特点。线性范围为0～10mg.L-1,回收率在102.9%～113.6%之间。

军港海水冲厕污水化学耗氧量(COD)指标的分析方法

提出一种军港海水冲厕排放污水COD的分析方法。先微波消解30 min,利用硫酸-重铬酸钾体系将氯离子完全氧化,冷却后再加入0.1 g硫酸银作催化剂,继续微波消解30 min,使绝大部分有机物被氧化,从测得的总表观COD值中减去氯离子表观COD值(从校准曲线中查得),即为所测水样的COD值。试验表明该方法对于[Cl-]≤20 000 mg/L、CODCr=100 mg/L标准溶液的相对误差≤10%,对于军港海水冲厕排放污水的RSD%≤5%。

海水COD流动注射测量技术研究

利用流动注射分析技术 (FIA)快速、连续测定海水化学耗氧量 (COD)。高锰酸钾作为氧化剂 ,Na OH溶液和硫酸溶液作为载流分别进入流路 ,“葡萄糖 +谷氨酸”作为标准物质。采用人工海水与标准物质配制系列COD浓度的测量水样以及海水加标测量 ,得到的分析结果具有很好的重现性和分辨率。

丁腈橡胶NBR240S乳化体系的改进

阐述了丁腈橡胶NBR2 40S聚合过程中 ,通过改进其原有的乳化体系 ,改善了胶乳的稳定性 ,减轻了设备堵挂 ,胶乳凝聚过程中胶粒流失减少 ,污水COD值明显降低 ,达到了长周期稳定运行及提高产品质量的目的。

流动注射光度法快速测定海水中的COD_(Mn)

采用流动注射光度法对海水化学需氧量（ CODMn ,高锰酸盐指数）进行快速测定。实验以KMnO4作氧化剂,淀粉-KI作显色剂,葡萄糖作标准物质；对流动注射分析流路进行了设计,优化了反应圈长度、反应温度、反应物浓度、进样量、泵速等实验条件；并通过自动加热装置对反应器进行在线加热；在最优条件下,测定方法的线性范围为0~6mg·L^-1（实际需氧量）,最低检出限为0．13mg·L^-1,实际海水测定时加标回收率在96%~104%范围内,对1mg·L^-1的COD标准溶液进行了11次连续测定,相对标准偏差（ RSD）为1．88%。该方法操作简单、方便、灵敏度高,用于海水实际样品分析时,其测定值与国标法测定值一致。

污水排放影响下平潭近岸海水COD和DIN浓度场的数值模拟

利用Delft3D数学模型建立了平潭综合实验区近岸海域物质输运数学模型,模拟了澳前、海坛海峡北、海坛海峡南、流水、竹屿5个排污口在不同污水排放量下COD、无机氮浓度的分布.结果表明:在污水排放规模为3.0×104t/d时,竹屿排污口邻近海域海水COD、无机氮质量浓度分别为3.80、0.51mg/dm3,流水排污口邻近海域海水COD、无机氮质量浓度分别为3.60、0.42 mg/dm3,都超过二类海水水质标准值,表明这2个海域水动力条件较弱、污染物扩散缓慢,不是理想的排污口.在污水排放量为1.5×105t/d时,海坛海峡北排污口邻近海域海水COD、无机氮质量浓度分别为1.87、0.28 mg/dm3,海坛海峡南排污口邻近海域海水COD、无机氮质量浓度分别为1.84、0.27 mg/dm3;澳前排污口在污水排放量为5.0×105t/d时,其邻近海域海水COD、无机氮质量浓度分别为2.48、0.28 mg/dm3,均符合二类海水水质要求,表明上述海域水动力条件良好、纳污能力强、环境容量大,是较好的污水排放口.该研究可为平潭综合实验区海域污水排放口选址优化提供科学依据,为该海域入海污染物总量控制和海洋环境管理提供参考.

基于T-S模糊神经网络的东滩湿地水域海水水质评价

长江口东滩湿地是重要的自然保护区,该水域水质评价对保护该地区的生态环境非常重要。海水水质的评价涉及到化学需氧量、有害元素含量等多因素,本文基于T-S模糊神经网络,根据海水水质标准对2010年5月东滩湿地保护区水域的海水水质进行评价,为长江口的水生物和环境保护建立了可行的评判机制。

人工湿地对海水淡化厂污泥中重金属和COD去除效果的初步研究

选用芦苇作为人工湿地的植物，构建了4个规格为5m×10m×1.5m的人工湿地，并进行了实验。结果表明：人工湿地对污泥中重金属Pb、Cd、Hg、As及渗滤液中COD均有一定的去除作用。系统经过6个月的试运行后，测得上述4种重金属的去除率在49%～65%之间；2013年8～11月期间测得的渗滤液中COD去除率不太稳定，最高为63.5%。本研究为合理利用人工湿地技术对海水淡化厂污泥进行稳定和无害化处理提供参考。

密封法测定焦化厂废水COD_(Cr)值的研究

通过用密封法与回流法对焦化厂废水 CODCr的测定实验比较表明 ,密封法与回流法有很好的相关性。密封法应用于焦化废水的 CODCr测定中 ,具有可进行批量分析。

Na_2S沉淀与混凝沉淀组合工艺处理电镀废水的研究

采用Na_2S 沉淀与混凝沉淀组合工艺处理电镀废水中的Cu^(2+)与COD,并研究了各工艺条件对电镀废水处理效果的影响。Na_2S 沉淀工艺的最佳条件为:Na_2S 的投加量100mg/L,初始pH值7.5,反应时间15min。混凝沉淀工艺的最佳条件为:混凝pH值7.5,混凝剂PAC的投加量8.0mg/L,助凝剂PAM的投加量8.0mg/L,混凝时间6min,沉降时间60min。在最佳处理工艺条件下,出水中Cu^(2+)的质量浓度为0.43mg/L,COD的质量浓度为41.27mg/L,能够达到电镀废水排放标准。

碱性高锰酸钾法测量海水化学耗氧量(COD)不确定度的研究

以葡萄糖+谷氨酸为海水COD的标准物质。用人工海水和标准物质配制成系列标准溶液。根据对系列标准溶液的测量结果,获得了碱性高锰酸钾法海水COD测量不确定度的分布规律。

聚酯化纤废水中特征污染物含量与COD的相关性研究

研究了聚酯化纤废水中主要有机污染物乙醛、乙酸、乙二醇含量与ＣＯＤ之间的相关性，确定了ＣＯＤ与上述特征污染物含量的比值，并测定了它们的氧化率，为企业的生产工艺管理和环保管理提供了基础数据。