荧光光谱法在水质化学需氧量检测中的应用研究

随着环境污染问题的突显,加强水体检测,提高水体质量刻不容缓。化学需氧量(chemical oxygen demand,COD)是水质检测的重要内容,探寻绿色、便捷、简单的检测方法非常必要。本文采用荧光光谱法对水质化学需氧量标准液进行检测,检测结果显示,荧光强度值与化学需氧量之间有着良好的相关度,该检测方法受pH值、温度等因素的影响,基于此,对模型进行了补偿校正,最终的检测结果显示与实际值之间的相对误差较小,相对误差不超过8%,且与传统的化学检测方法相比更为绿色环保且快速便捷,是一种值得推广的水质化学需氧量检测手段。

水质化学需氧量、高锰酸盐指数和生化需氧量之间的关系探究

本文通过对2019~2020年某市环境监测站监测、分析的地表水水质资料的采集、整理,分析了BOD_(5),COD_(Cr),COD_(Mn)三个指标,并对三个指标的线性、内因以及指标之间的关系进行了研究。研究发现,全年化学需氧量(COD)/高锰酸盐指数(COD_(Mn))平均值为3.91、COD/五日生化需氧量(BOD_(5))平均值为4.41,以及COD_(Mn)/BOD_(5)平均值为1.14。从季节上来看,春季、夏季三个指数具有极强的相关关系,秋季和冬季仅有COD与COD_(Mn)间具有相关性,而这两者与BOD_(5)的相关性不大。

化学需氧量测定方法探究

化学需氧量是水体水质评价的一个重要指标。化学需氧量测定主要有滴定法和光度法2种方法,实验室采用的滴定法对测定人员要求高,测定结果主观因素较大,大批量水样检测时消解时间长,滴定任务繁重,准确度不稳定。为了寻找快速准确检测水中化学需氧量的方法,比较了4种检测方法,并从中选择2种快速消解测定水中化学需氧量的方法,从标准曲线、准确度、精密度等方面进行了验证研究,发现当COD含量较小(50 mg/L以下)时,用商用试剂盒测定法测定,结果较准确;当COD含量高于100 mg/L时,用HJ/T 399-2007方法中低量程自配试剂盒测定和商用试剂盒测定法测定,结果都比较满意,对今后开展快速准确测定水样化学需氧量的工作具有参考价值。

荧光光谱法检测水质COD时温度、浊度、 pH的影响分析

以COD标准液为研究对象,基于特定激发波长下的荧光发射光谱数据,采用化学计量学算法对水质COD进行了检测,分析了水的温度、浊度和pH的变化对发射光谱的影响,并对相关参数的影响进行了补偿校正。在此基础上建立了多参量共同作用时对水质COD预测模型的补偿校正方法。首先采用荧光光谱法对浓度范围为1～55 mg·L^(-1)水质化学需氧量(COD)标准溶液进行三维荧光光谱的采集,去除散射峰以后采用基于蚁群算法优化的偏最小二乘法(ACO-iPLS)对不同激发波长(Ex=255～285 nm,间隔为5 nm)下的荧光发射光谱(Em=275～450nm)数据进行特征提取并采用基于粒子群优化的最小二乘支持向量机算法(PSO-LSSVM)进行预测模型的建立。结果表明,不同激发波长下的荧光发射光谱数据模型的检验集决定系数R■在0.961 8～0.998 1范围内,当采用波长为Ex=270 nm的激发光作用时所激发出的荧光发射光谱数据所建模型的效果最优,其检验集决定系数R■=0.998 1,预测均方根误差RMSEP=0.348 3 mg·L^(-1)。其次,对温度、浊度、 pH对荧光光谱法检测水质COD的影响进行了分析,并给出了相应的补偿模型。结果表明,温度和浊度在检测水质COD时对荧光光谱的影响不可忽略,但通过建立补偿模型可以对其影响进行有效的补偿校正,温度补偿后荧光数据模型的整体平均偏差Bias=0.130 6 mg·L^(-1),经浊度补偿后可以很好的校正浊度变化对荧光光谱法检测水质COD的影响,而pH范围在4～12.3内变化时对荧光光谱的影响相对较小,因此可忽略。最后,结合单一影响因素的分析结果,对荧光光谱法检测水质COD时水体的多种环境因素(温度、浊度、 pH)共同作用的影响进行了分析。实验结果表明,忽略pH影响后,可以采用对温度和浊度同时补偿的方法对二者的影响进行有效的校正。该结果可为水质参数光学传感器在调试过程中抑制环境因素的影响提供参考。

Water quality and eutrophication in the Guangzhou Sea Zone of the Pearl River estuary

To gain a better understanding of water quality and eutrophication, we investigated the seasonal and spatial distribution of water quality at 17 stations in the Guangzhou Sea Zone （GZSZ）. Nutrients, chlorophyll-a （Chl-a）, salinity, chemical parameters were determined in February, May, oxygen demand, and other physical and chemical August and October from 2005 to 2007. The concentrations showed ranges of 93.2-530.4 μmol/L for dissolved inorganic nitrogen （DIN）, 0.62-3.16 μmol/L for phosphate （PO4-P） and 50-127 μmol/L for silicate （SiO3-Si）, The results indicated that DIN was strongly influenced by domestic sewage coming from Guangzhou City and NO3-N was the main form of DIN in most areas, while concentrations of phosphate and silicate were generally controlled by Pearl River runoff, land-based sources along the land or islands, and algae assimilation. N/P ratios were very high in both dry season and wet season, and varied from 57 to 667, suggesting that P was potentially the most limiting nutrient in the GZSZ. The concentrations of Chl-a were 3-96 μg/L, and were highly correlated with the distribution characteristics of COD, The concentrations of nutrients have increased over the past two decades （1982-2007）. This means it is necessary to control the input of nutrients to the GZSZ, especially that of phosphate.

Water Quality Index of Pravara River for Drinking Purpose at Sangamner in Ahmednagar District, MS, India

River water is still a major source of drinking water for major part of population. Sangamner city is using the River water for drinking, domestic and industrial purpose. At the same time the waste generated is discharged into the River without or with partial treatment. So in present investigation the River water quality was analyzed for the parameters like pH, Electrical Conductivity, Total Dissolved Solids, Total Hardness, Calcium, Magnesium, Alkalinity, Chloride, Dissolved Oxygen, Chemical Oxygen Demand, Biological Oxygen Demand. Sodium, Potassium, Sulphate, Phosphate and Nitrate. The water quality index for drinking purpose was calculated using same data. The grading system was used to assess the water quality index. The result indicates that the poor water quality at four sites ranging from 250 to 745. Only site 1 shows good water quality which is 36.08 which lies in grade B.

Effects of Self-purification of River Water on Laundry Wastewater

[Objective] This study was conducted to investigate the effect of laundry wastewater on the quality of river water and the dilution purification effect of river water on laundry wastewater. [Method] The effects of laundry wastewater on the contents of total nitrogen(TN), total phosphorus(TP), suspended solids(SS), chemical oxygen demand(COD) and linear alkylbenzene sulfonic acid(LAS) were studied in 7 rivers of Shaoxing City. [Result](1) The contents of TN, TP, SS, COD and LAS increased by 92%, 99%, 340%, 351% and 923%, respectively, at the discharging moment of laundry wastewater; and(2) the five pollutional indexes significantly decreased over time, and especially 2 h after the discharge of laundry wastewater, compared with former the discharge of laundry wastewater, the contents of TN, TP, COD and LAS increased by 6%, 11%, 9% and13%, respectively,while the contents of SS still increased by 76%, i.e., SS required a longer time to achieve self-purification. [Conclusion] Laundry wastewater has some influence on thequality of river water, and the self-purification function of river water could effectively remove pollutants.

Pond Water Quality and Cyclops Population in Dracunculiasis Endemic Areas of Ogun State, Nigeria

This study investigated the association between Cyclops population and physico-chemical properties of pond water in villages selected from Odeda and Obafemi-Owode areas of Ogun State, Nigeria. Epidemiological data on guinea worm were collected from Global 2000 South-West Zonal Office. Two villages were selected from each of Odeda and Obafemi-Owode LGAs while one village was sampled from Abeokuta North LGA as control. Physico-chemical analysis and microscopic examination of pond water utilized for domestic purpose in the selected villages were conducted. Mean values of 6.78±0.10, 33.00±0.14℃, 1.09＋0.80 mg/L and 1.30±0.25 mg/L were recorded for pH, temperature, DO and nitrate respectively while control had 7.30±0.14, 36.30±14℃2, 2.72±0.14 mg/L and 5.80±0.57 mg/L. These values with the exception of DO and nitrate were within WHO standard but vary significantly （P〈0.05） between the villages. The results further showed that BOD, COD and acidity were positively correlated with Cyclops population during the rainy and dry seasons while temperature, nitrate, pH, and alkalinity have negative correlation coefficients （r=-0.81, -0.91） with Cyclops population during the two seasons. Regression analysis showed that nitrate, BOD and acidity levels explained 67.7 percent, 50.4 percent and 44.5 percent of Cyclops population in the ponds. Guinea worm eradication in endemic rural areas should incorporate ecological strategy.