Assessment of Point and Nonpoint Sources Pollution in Songhua River Basin,Northeast China by Using Revised Water Quality Model

Individual participation of pollutants in the pollution load should be estimated even if roughly for the appropriate environmental management of a river basin.It is difficult to identify the sources and to quantify the load, especially in modeling nonpoint source.In this study a revised model was established by integrating point and nonpoint sources into one-dimensional Streeter-Phelps(S-P) model on the basis of real-time hydrologic data and surface water quality monitoring data in the Jilin Reach of the Songhua River Basin.Chemical oxygen demand(COD) and ammonia nitrogen(NH 3-N) loads were estimated.Results showed that COD loads of point source and nonpoint source were 134 958 t/yr and 86 209 t/yr, accounting for 61.02% and 38.98% of total loads, respectively.NH 3-N loads of point source and nonpoint source were 16 739 t/yr and 14 272 t/yr, accounting for 53.98% and 46.02%, respectively.Point source pollution was stronger than nonpoint source pollution in the study area at present.The water quality of upstream was better than that of downstream of the rivers and cities.It is indispensable to treat industrial wastewater and municipal sewage out of point sources, to adopt the best management practices to control diffuse pollutants from agricultural land and urban surface runoff in improving water quality of the Songhua River Basin.The revised S-P model can be successfully used to identify pollution source and quantify point source and nonpoint source loads by calibrating and validating.

Numerical simulation of water quality in Yangtze Estuary

In order to monitor water quality in the Yangtze Estuary, water samples were collected and field observation of current and velocity stratification was carried out using a shipboard acoustic Doppler current profiler （ADCP）. Results of two representative variables, the temporal and spatial variation of new point source sewage discharge as manifested by chemical oxygen demand （COD） and the initial water quality distribution as manifested by dissolved oxygen （DO）, were obtained by application of the Environmental Fluid Dynamics Code （EFDC） with solutions for hydrodynamics during tides. The numerical results were compared with field data, and the field data provided verification of numerical application： this numerical model is an effective tool for water quality simulation. For point source discharge, COD concentration was simulated with an initial value in the river of zero. The simulated increments and distribution of COD in the water show acceptable agreement with field data. The concentration of DO is much higher in the North Branch than in the South Branch due to consumption of oxygen in the South Branch resulting from discharge of sewage from Shanghai. The DO concentration is greater in the surface layer than in the bottom layer. The DO concentration is low in areas with a depth of less than 20 m, and high in areas between the 20-m and 30-m isobaths. It is concluded that the numerical model is valuable in simulation of water quality in the case of specific point source pollutant discharge. The EFDC model is also of satisfactory accuracy in water quality simulation of the Yangtze Estuary.

近红外光谱的水体污染指标COD定量预测模型

针对传统化学需氧量(chemical oxygen demand, COD)检测存在检测成本高、耗时、易造成二次污染,以及现有检测模型泛化性较差等不足,难以满足水环境实时监测需求的问题,提出基于近红外光谱技术的COD快速无损定量预测模型.实验结果表明,本模型在污水COD光谱数据集上的预测性能,相较于传统机器学习算法和现有其他深度学习算法更优.测试的决定系数(R^(2))和均方根误差(E_(RMS))分别达到0.992 1和27.47 mg·L^(-1),模型卷积层的输出特征可解释性强,能有效表征关键波长点.该预测模型为实际水体COD含量快速检测提供一种新的方法.

基于注意力机制的跨境断面水质预测模型研究

为了充分掌握水体污染治理效果,为水环境保护和生态治理提供科学依据和技术支持,提出一种基于注意力机制的跨境断面水质预测模型。运用长短期记忆神经网络建立跨境断面水质预测模型,引入注意力机制,建立跨境断面水质预测序列编码矩阵。利用长短期记忆神经网络解码器对序列矩阵数据进行解码操作后,输出跨境断面水质的预测结果。实验结果表明,所提模型可有效提取跨境河流纵向断面水质化学需氧量(COD)时间特征与数据特征,同时可预测跨境纵向断面水质内的余氯、浊度等,且预测跨境断面水质高锰酸盐指数较为准确,应用效果较佳。

污水处理厂水质检测中化学需氧量(COD)测定的手工分析法和仪器法对比

化学需氧量是污水处理厂进、出水水质检测中重要的常规参数之一,主要反映水体受有机物污染程度以及污水处理厂处理效果。随着有机物对水体的污染日益严重,污水中化学需氧量的测定也越来越受到重视,对测定结果的要求也越来越高。本文依据标准《HJ 828—2017水质化学需氧量的测定重铬酸盐法》要求,通过采用两种浓度范围4个有证标准物质对比了手工法和仪器法在化学需氧量测定中的准确度和精密度,并通过测定污水处理厂进、出水水样的化学需氧量而比较了两种测定方法的相对偏差。

重铬酸钾法测定水中化学需氧量的影响因素探讨

化学需氧量是水质监测的重要指标之一,其数值可以直接反映水体的污染程度。目前实验室常采用重铬酸钾法测定化学需氧量,但是实验操作过程中会受到多方面因素的影响,导致实验数据出现偏差,从而影响水质分析。因此,本文从消解时间、氯离子含量、冷却时长、冷却方式、保存条件等方面进行探讨,详细分析影响测定的原因,以期获得更加准确的分析数据结果。

测定水中五日生化需氧量的影响因素研究

五日生化需氧量是水质监测中的重要指标。对试样中溶解氧的测定方法进行比对分析,并对五日生化需氧量随温度的影响进行了详细研究。结果显示,在其他条件一定的情况下,电化学探头法在实验室测定五日生化需氧量中具有相对优势,且最佳测定温度为20℃。在最优实验条件下,对实际样品的检出限、精密度和准确度进行了分析测定,结果均满足质控要求。

水体化学需氧量监测技术创新与发展趋势分析

本文探讨了水体化学需氧量监测技术的创新和发展趋势,强调了化学需氧量(COD)监测的重要性,深入探讨了先进的传感器技术、人工智能驱动的预测模型、纳米技术应用及遥感和物联网设备的集成,讨论了新兴COD监控技术的潜在应用,以及解决数据隐私和安全问题的重要性,以期能够加强环境保护和可持续水资源的管理。

Performance of a water hyacinth(Eichhornia crassipes)system in the treatment of wastewater from a duck farm and the effects of using water hyacinth as duck feed

Nowadays, intensive breeding of poultry and livestock of large scale has made the treatment of its waste and wastewater an urgent environmental issue, which motivated this study. A wetland of 688 mz was constructed on an egg duck farm, and water hyacinth （Eichhornia crassipes） was chosen as an aquatic plant for the wetland and used as food for duck production. The objectives of this study were to test the role of water hyacinth in purifying nutrient-rich wastewater and its effects on the ducks＇ feed intake, egg laying performance and egg quality. This paper shows that the constructed wetland removed as much as 64.44% of chemical oxygen demand （COD）, 21.78% of total nitrogen （TN） and 23.02% of total phosphorus （TP）. Both dissolved oxygen （DO） and the transparency of the wastewater were remarkably improved, with its transparency 2.5 times higher than that of the untreated wastewater. After the ducks were fed with water hyacinth, the average daily feed intake and the egg-laying ratio in the test group were 5.86% and 9.79% higher, respectively, than in the control group; the differences were both significant at the 0.01 probability level. The egg weight in the test group was 2.36% higher than in the control group （P 〈 0.05）, but the feed conversion ratios were almost the same. The eggshell thickness and strength were among the egg qualities significantly increased in ducks fed with water hyacinth. We concluded that a water hyacinth system was effective for purifying wastewater from an intensive duck farm during the water hyacinth growing season, as harvested water hyacinth had an excellent performance as duck feed. We also discussed the limitations of the experiment.

Spatiotemporal Variation of Riverine Nutrients in a Typical Hilly Watershed in Southeast China Using Multivariate Statistics Tools

The water quality of lakes can be degraded by excessive riverine nutrients.Riverine water quality generally varies depending on region and season because of the spatiotemporal variations in natural factors and anthropogenic activities.Monthly water quality measurements of eight water quality variables were analyzed for two years at 16 sites of the Tianmuhu watershed.The variables were examined using hierarchical cluster analysis(HCA) and factor analysis/principal component analysis(FA/PCA) to reveal the spatiotemporal variations in riverine nutrients and to identify their potential sources.HCA revealed three geographical groups and three periods.Two drainages comprising towns and large villages were the most polluted, six drainages comprising widely distributed tea plantations and orchards were moderately polluted, and eight drainages without the factors were the least polluted.The river was most polluted in June when the first heavy rain(daily rainfall > 50 mm) occurs after fertilization and the number of rainy days is most(monthly number of rainy days > 20 days).Moderate pollution was observed from October to May, during which morethan 60% of the total nitrogen fertilizer and all of the phosphorus fertilizer are applied to the cropland, the total manure is applied to tea plantations and orchards, and a monthly rainfall ranging from 0 mm to 164 mm occurs.The remaining months were characterized by frequent raining(i.e., number of rainy days per month ranged from 5 to 24) and little use of fertilizers, and were thus least polluted.FA/PCA identified that the greatest pollution sources were the runoff from tea plantations and orchards,domestic pollution and the surface runoff from towns and villages, and rural sewage, which had extremely high contributions of riverine nitrogen, phosphorus,and chemical oxygen demand, respectively.The tea plantations and orchards promoted by the agricultural comprehensive development(ACD) were not environmentally friendly.Riverine nitrogen is a major water pollution parameter in hilly watersheds affected by ACD, and this parameter would not be reduced unless its loss load through the runoff from tea plantations and orchards is effectively controlled.

2017—2022年深圳市罗湖区中小学校及托幼机构直饮水中耗氧量监测结果分析

本文收集汇总了2017—2022年深圳市罗湖区中小学校及托幼机构直饮水样本耗氧量检测结果,并进行了统计分析。结果显示,直饮水处理系统可有效降低耗氧量检测结果,需要各部门加以长期严格管理,及时监测直饮水水质情况。

水环境中有机污染综合指标监测方法及其进展

化学需氧量是判断水体受到有机化合物污染的主要指标之一,也是我国水环境污染物排放总量的主要控制指标。经典的化学需氧量测定方法采用化学氧化剂氧化,将测定结果折成消耗氧的量,常用的化学氧化剂有重铬酸钾和高锰酸钾,也有采用紫外UV254的吸收来判断水体的有机污染程度。这些方法简单易行,但费时、费力,目前通过现代科学技术和化学计量学发展在线监测和遥感反演法测定化学需氧量,可以综合海量监测数据,更有效、客观地评价水体受有机污染的程度和范围。

基于快速消解分光光度法的化学需氧量在线分析仪

介绍了一款自主研制的基于快速消解分光光度法的操作简便、分析速度快、自动化程度高、所需试剂少的化学需氧量在线分析仪,其可实现10~2000 mg·L^(-1)质量浓度范围内的化学需氧量的自动在线监测。对分析仪的测量原理、检测试剂、反应消解检测模块和控制模块进行了阐述,并根据环境标准对分析仪进行了示值误差、定量下限、重复性等性能测试。结果表明:该分析仪稳定好、定量下限低、重复性好、精度高,能够满足现场应用需求,具有良好的应用推广价值。

重铬酸盐法应用于高氯废水低化学需氧量检测中的价值及其改进

在实际水质检测过程中,氯离子浓度对于化学需氧量(COD)这一重要指标的测定有较强的干扰,严重影响了水质检测的质量与效果,如何合理屏蔽这一干扰已经成为值得检测人员深入研究的重点课题。本文通过对相关文献进行查阅,在国标重铬酸盐方法的基础上,建立了一种与被测水样等氯离子浓度的蒸馏水为空白的方式。通过进一步讨论可知,该方法能够达到6 mg/L的检出限,标差能够控制在5%以内,准确性满足了实际水质检测的基本要求,并为相关检测提供了较为标准的COD值。希望本文的研究内容能够为相关单位的水质检测提供一定的理论指导。

水质化学需氧量测定全程质量控制

在开展环境监测工作中,质量控制是必要手段,通过质量控制可提升环境监测数据的可靠性与准确性。目前,水质化学需氧量测定采用的方法有很多种,如重铬酸盐法、高锰酸钾法以及分光光度法等。首先对各种测定方法进行简要介绍,然后结合四川省某县域内河流的水质情况,选择适当的测定方法对该河流的水质化学需氧量进行测定,并制定测定全程质量控制方法,从而为水质化学需氧量测定的质量和效果提供保障。

阳极表面积对生物电化学传感器的性能影响研究

以生物电化学系统(BES)为基础提出了一种BOD水质监测传感器,探究了生物电化学传感器产生的电信号与底物BOD值之间的相关关系,并评估了阳极表面积对其性能的影响。采取循环伏安法(CV)和线性扫描伏安法(LSV)对其生物活性和电子传递能力进行了讨论,并利用微生物多样性分析其阳极界面上的微生物均匀度和丰富度。研究结果表明,完整碳刷和1/2碳刷传感器的最大电流都达到了1.18 mA,而1/4碳刷的只有0.5 mA。完整碳刷和1/2碳刷传感器在不同时间下的BOD-电流拟合曲线的R2值在3 min时高达0.9,1/4碳刷在2 min时,R2值达到了0.9以上。完整碳刷、1/2碳刷和1/4碳刷的负峰电位接近,峰值电流密度逐渐提高。1/2碳刷的微生物菌群分布较为均匀。3种表面积的碳刷阳极都具有较高的传感器性能,其中,1/2碳刷阳极整体利用效率最高。容积为236 mL的BOD监测传感器,利用碳刷作为阳极时,阳极的表面积为1193.13 cm^(2)比较合适。

消解温度对化学需氧量测试结果的影响

不同的试验条件对化学需氧量检测结果会产生一定影响,《水质化学需氧量的测定重铬酸盐法》(HJ 828—2017)的化学需氧量测试步骤中并没有规定具体的消解温度。结合水质检测工作实际,研究了消解温度在化学需氧量测试过程中的影响。结果表明,消解温度对化学需氧量检测结果的精密度和准确度存在很大影响,不同消解仪采用的消解温度稍有差别,温度的设定应根据仪器本身性能调节,获得最佳的消解温度。当消解温度为220~230℃时,化学需氧量测试结果准确。

河北某河段水质环境现状及污染来源分析

为了落实“十四五规划”对地表水环境质量的要求,为该河段今后的水环境管理提供理论依据和数据支撑,基于自动监测和手工采样监测数据,探讨河北某一河段水质现状,并结合河段周边污染源资料,进一步对该河段可能存在污染汇入的工业点源、农业面源进行排查,并对进入河道的主要污染源的污染负荷进行定量评估,通过核算河段污染物排放总量,进一步溯源解析了河段的污染物来源。结果表明:该河段COD和总氮均存在超标情况,该河段有污染物汇入的风险;主要污染来源为上游的污水处理厂排水。

快速消解法测定水中化学需氧量的影响探究

随着经济的快速发展,污染问题日益突出,而化学需氧量是反映水体污染程度的一个重要指标。目前,实验室采用的重铬酸钾法测定化学需氧量,虽然具有精密度和准确度高等优点,但是该方法耗时长,而且操作繁琐。而快速消解法在保证化学需氧量测定结果准确性的前提下,还可以省时省力。本文从快速消解法的检出限、精密度、准确度等方面探讨了化学需氧量的测定。

化学需氧量标样的保存时间对水质分析的影响研究

化学需氧量(COD)是水质检测项目之一,其标样保存时间对分析结果会有重大影响。本文通过对不同保存时间的标样进行水质化学需氧量测定,评估保存时间与测定结果的关系。结果表明:标样保存时间对测定结果会有一定影响。经统计分析发现,保存时间与COD浓度呈负相关趋势,即保存时间越长COD浓度越低,长时间保存会导致标样中的物质失效,降低COD浓度。因此,测定水质化学需氧量时,要注意标样的保存时间对测定结果的影响,以提高水质监测的精确性和可比性。