Water Meters Research Articles

Urban household water usage in adaptation to climate change: Evidence from China

While it has been concluded that climate change poses a significant threat to worldwide supply of freshwater resources, it is unclear if and how demand for water would also be affected. To fill this knowledge gap, we leverage on ‘big data’ collected using smart water meters from over 40,000 Chinese urban households, spanning nine years and ten provinces to examine the relationship between daily household water usage and climate variability. At the baseline, we find that municipal water is not only a coping mechanism for heat, but its usage is accelerated during heatwave events. Heterogeneity analyses reveal that households from lower-valued properties are more likely to substitute water for electricity to counter heat. Importantly, we find evidence of adaptation behaviors where over time, households are using increasingly more water to cope with high-temperature days. In all, after feeding our results into climate projection models, it is estimated that household water usage will increase by around 7–44% in the long-term (2080–2099) under emissions scenarios of SSP245 and SSP370. Our findings are especially relevant for water-scarce countries such as China as well as developing countries where water is a cheaper and more accessible resource to cope with heat.

Special issue: NBS for resilient cities and communities — How understanding the micro components of domestic water consumption can provide multiple water uses to facilitate a transition to a Circular Economy of Water

Resilient cities and communities of the future will require a Circular Economy of Water (CEW), where used water is either reused with minimal treatment and/or separated at source, collected, treated and recycled on or off site to provide a “Fit for Purpose” water. Understanding the micro components of household water use and the different used waters generated is an important first step in this approach. This paper presents results from two separate studies. The first study monitored household water use in four households over a continuous 24-month period in Ireland. Meters were installed to monitor public mains water supply, toilet flushing, hot water, cold water supply to taps and water supply to kitchen. Daily water use profiles were generated. Per capita consumption rates varied from 71 L/hd/day to 132 L/hd/day. This compares to a national average in Ireland of 129 L/hd.d. These variations reflect the diversity between homes in terms of the way occupants utilise water for different practices (personal hygiene, laundry, kitchen, WC use). Averaging the results across all study households, for every 100 L of potable mains water supplied to the household, 28 L was flushed down the toilet, 22 L was used in the hot water system, 17 L was supplied to cold water taps for personal hygiene uses and 33 L was used in the kitchen. This study compares with results from an EU study compiled by the authors where over 75% of household water use across selected EU countries was also used for bathing and showering, WC flushing and laundry. Trends show that household water use has reduced across all selected countries in recent years. The influence of water meters in achieving this reduction is evident in the EU data. This effect is particularly evident from England and Wales, where water use in unmetered households is estimated to be 30% higher than metered households. The data shows that universal metering, increased water charges and a national focus on water efficiency and demand management programs can achieve significant reductions in household water consumption. The authors propose a Circular Economy of Water hierarchy focused on Reduce, Reuse, Recycle and Recover. A twelve step approach is suggested to facilitate this transition to a water smart society.

Leakage control of urban water supply network and mathematical analysis and location of leakage points based on machine learning

Abstract In order to solve the common problems of high leakage rate of urban water supply network and controlling water supply enterprises, a multi index system of leakage evaluation is proposed. The first step in leakage assessment is to recommend non profitable water volume, rather than just based on the percentage of leakage rate (the calculation mode of percentage is easily disturbed by the change of water volume); Advanced indicators also need to consider factors such as pipe network conditions, pressure and the number of user connections; If possible, it is recommended to calculate the leakage index (ILI) of water supply network in line with international standards, and through this index, determine the leakage classification of water supply system according to the target matrix provided by the world bank, so as to formulate corresponding leakage control countermeasures, and finally form a set of leakage performance evaluation system of urban water supply system combined with the actual situation of our country. Experiments have proved that among users with large caliber and large water volume, the promotion of electromagnetic remote transmission water meter should be strengthened to improve the metering capacity of water meter. Since 2014, non household meters above Dn40 in the company's new household installation project have adopted electromagnetic remote transmission water meters. At the same time, strengthen the remote monitoring and management of large-diameter water meters. Through remote transmission, we can grasp the changes of users' water use in real time, and realize the three-level early warning of sudden change of water volume through the mining of remote transmission data.

Effect of bacterial bio fertilization on phosphorous budget, growth, and yield of Faba bean (Vicia faba L.) When intercropping with wheat (Triticum aestivum L.)

The study was carried out at the College of Agricultural Engineering Sciences - University of Baghdad on soil with a mixture of loam during the winter season of the year (2020-2021). The study included a field experiment to evaluate the effect of bio fertilizer and mineral fertilization on the phosphorous budget in the soil and in the growth parameters of the faba bean plant and the intercropping faba bean with wheat under the level of 50% of the fertilizer recommendation with the use of a complete fertilizer recommendation treatment of 100% for comparison measured the amount of water added for each Experimental unit After draining 50% of the prepared water using a water meter, a (factorial) experiment was carried out by arranging the split plates (The Split-Plot Design) according to the (RCBD) design.

Water Demand Estimation in Service Areas with Limited Numbers of Customer Meters—Case Study in Water and Sanitation Agency (WASA) Lahore, Pakistan

The Water and Sanitation Agency (WASA) of Lahore, Pakistan, supplies water to 5.29 million people through 598 tube wells but faces difficulties in meeting rapidly increasing water demand, lowering groundwater table, high energy costs, and low water tariffs. However, the actual water consumption and water loss have never been estimated due to water meter outages. This study aimed to estimate the actual water consumption, production, and water losses for the WASA Lahore service area, using the limited number of working water meters and pump operation data. The actual water consumption was estimated by 14,030 working customer meters; the population census was 44.02 m3 per connection per month, or 200 L per capita per day, while the water production was 79.8 m3 per connection. The actual water loss was significantly higher than non-revenue water, with an average of 45.4% (ranging from 35.9–69.4%). Due to high electricity costs, WASA has had to cut their supply hours. Therefore, leakage reduction programs must be implemented in the high-water-loss townships found in this study in order to meet the increasing water demand, reduce electricity consumption, and alleviate groundwater table drawdown.

Energy and environmental performance of a new solar boiler with heat recovery for seawater desalination

This study proposes a new seawater desalination process using concentrated solar energy. Compared with conventional desalination technologies, the proposed process produces tap water with high energy efficiency and a lower environmental impact. The proposed process is based on a new type of solar boiler using solar energy concentrated via a “beam-down” optical system. To improve the productivity, the steam produced is used to feed an adapted multiple-effect distillation (MED) system. A complete process model from seawater and sun to tap water is proposed, coupling an in-house Python program for the solar boiler component and ProSim software for the MED component. Ancillary calculations concerning the pretreatment, post-treatment, and sizing of the components are performed using a spreadsheet program. The environmental impacts of the tap water production by the proposed system are evaluated using the life cycle assessment method. The theoretical feasibility of the proposed process is demonstrated by modeling a reference case, with an estimated annual productivity of 10,000 m3 of tap water. According to the calculation, the energy performance is estimated at 1.57 kWh of electricity and 117.7 kWh of solar energy per cubic meter of tap water produced. An estimated land area of 3845 m2 is required for the solar field. The life cycle assessment indicates that the performance of the proposed process is significantly improved compared with conventional MED, with an 84% reduction in the total impact according to the ReCiPe endpoint method. In addition, the proposed system displays a competitive environmental performance compared with reverse osmosis. The emissions of the new process are estimated at 2.36 kg CO2-eq per cubic meter of tap water produced versus 3.67 kg CO2-eq and 2.97 kg CO2-eq for low- and high-performance reverse osmosis, respectively.

The climate cost of saving water by different plastic mulching patterns

Global water shortage and climate change are two of the most significant challenges for our planet, and how to coordinate their relationship is a problem unsolved. In this study, we proposed the synchronization index of water-saving and CO2 mitigation to evaluate the climate cost of saving water by different plastic mulching patterns and explore way to improve the synchronization. The water-saving performance, carbon footprint, and the synchronization index were analyzed for three typical plastic mulching patterns, namely conventional partial plastic mulching, full plastic mulching, and “one film for two years” mulching. The results indicated that all three types of plastic mulching systems were effective in reducing the water footprint of crop production, with full plastic mulching showing the best performance in terms of improving crop yields and water savings. The application of plastic mulching mainly influences the carbon footprint through increasing indirect greenhouse gas emission, accelerating soil organic carbon decline and increasing N2O emission. Area-scale carbon footprint showed a significant positive relationship with the input amounts of plastic film, and the sort order of yield-scale carbon footprint was partial plastic mulching > full plastic mulching > “one film for two years” mulching. Calculated synchronization index was -0.35 kg CO2-eq m−3, -0.10 kg CO2-eq m−3, and 0.50 kg CO2-eq m−3 for partial plastic mulching, full plastic mulching, and “one film for two years” mulching, respectively. Full plastic mulching and partial plastic mulching resulted in an additional 0.35 and 0.10 kg of CO2-eq for saving one cubic meter of water, and only “one film for two years” mulching resulted in simultaneous water savings and greenhouse gas mitigation. This study suggests that water savings achieved using conventional partial plastic mulching have costs in terms of climate change. Faced with the dual pressure of global water shortages and climate change, controlling input amounts of plastic film and prolonging the lifetime of the film are simple and effective way to coordinate water savings and greenhouse gas mitigation. Moreover, the results of this study suggested that water savings and GHG emission mitigation cannot necessarily be achieved simultaneously and that searching for both water-saving performance and its synchronization with GHG mitigation should become a new paradigm for the development of water-saving technologies in the future.

Identification of pathways that lead to continuous or intermittent water supply by conducting a qualitative comparative analysis of rural water utilities in China

Abstract Ensuring a continuous water supply (CWS) for households is beneficial for the current global drinking water, sanitation, and hygiene agenda. Despite improvements in water supply, intermittent water supply (IWS) remains prevalent in rural areas. To determine the factors that lead to different water supply modes for villages, we select 38 village-level water utilities covered by the Chinese Safe Drinking Water Project for fuzzy set qualitative comparative analysis to identify causal configurations (‘pathways’) that lead to IWS or CWS across systems. Six configurations of water supply mode are identified on the basis of the outcomes of each case. Among these, three configurations for adopting CWS are determined. Configuration 1 features water utility with government subsidy and bills using a water meter. Configuration 2 features water utility with small population coverage, government subsidy, and villager participation in the management. Configuration 3 features a water utility collectively managed and owned by a rich village and water-saving initiatives. Configurations that lack meter-based bills, government subsidies, and water-saving initiatives are the main paths for IWS. Results highlight the uniqueness of the configurational approach in understanding different water supply patterns across various cases and emphasise the importance of government subsidies, villager participation, water-saving programmes, and water meter-based billing to achieve CWS.

Intelligent water flow monitoring system based on internet of things for residential pipeline

Providing sustainable water supply is a huge challenge for Malaysia whereby the residential areas are still equipped with the conventional water meter with lack of monitoring options. In order to detect the locations of internal leakage, the process requires costly plumber service while manual comparison may be inaccurate and time-consuming. Therefore, digitalization transformation aligned with the industrial revolution IR 5.0 is crucial especially with the recent occurrences of high water bills reports during the movement control order (MCO). The objectives of this project is to develop an intelligent water flow monitoring system using Arduino as a microcontroller and to construct a system that can monitor the water usage behaviour at any distant with internet of thing (IoT). It can be installed anywhere in a pipeline whereby the water flow sensor measures the real-time water parameters. The data transferred to the cloud are sent to the homeowner to display the accuracy and availability of their water system via Blynk, a mobile-compatible and user-friendly application that generates clear data visualization. The key goal of this project is to provide a wireless, mobile, economical and systematic solution for residents to self-monitor their water consumption as compared to the conventional manual monitoring.

Lightweight AI Framework for Industry 4.0 Case Study: Water Meter Recognition

The evolution of applications in telecommunication, network, computing, and embedded systems has led to the emergence of the Internet of Things and Artificial Intelligence. The combination of these technologies enabled improving productivity by optimizing consumption and facilitating access to real-time information. In this work, there is a focus on Industry 4.0 and Smart City paradigms and a proposal of a new approach to monitor and track water consumption using an OCR, as well as the artificial intelligence algorithm and, in particular the YoLo 4 machine learning model. The goal of this work is to provide optimized results in real time. The recognition rate obtained with the proposed algorithms is around 98%.

Feedback Linearization Based Flow Rate Control for Centrifugal Pump in Coupled-Tank Water Meter Testing System

A permanent magnet direct current (PMDC) motor centrifugal pump is intended to be used as the water supply unit in a feedback linearization based coupled-tank water meter testing system. Flow rate generated by the pump corresponds to the input variable for implementing the input-output feedback linearization to this single-input-single-output (SISO) system. The pump motor is driven by an Arm Cortex M7 based microcontroller applying the pulse-width modulation (PWM) strategy at various frequencies and pwm methods. It is aimed to determine a suitable PWM frequency and driving method in order to provide a stable flow rate at the desired duty cycle values. An H-Bridge driver integrated circuit (L298N) is used in both fast decay and slow decay modes for driving the pump motor. Flow rate measurements are carried out at 4 range of frequencies between 100 Hz and 20 kHz for each mode. Fast decay mode in low pwm frequency (100Hz) results in higher deviations at the steady-state flow rate. However, slow decay mode provides a faster reduction in motor speed despite the slower current decay, which improves the flow rate stability and minimize deviations at constant pwm duty cycle values. High pwm switching frequencies increase the energy losses resulting in a lower driving voltage range, which reduces the effective range of selection for pwm duty cycle setting of flow rate adjustment. 1 kHz PWM frequency combined with the slow-decay driving mode achieves good performance in terms of linear regression and wider range for pwm duty cycle to flow rate transformation.

Revisiting 2013–2014 Azle seismicity to understand the role of Barnett production on stress propagation and fault stability

Propagation of production- and injection-induced stresses from reservoir layers to basement faults is not well understood, especially in reservoirs with hydraulically segregated production and injection units situated across low-permeability structural or stratigraphic boundaries. This is one of the challenges in understanding the 2013–2014 Azle-Reno earthquake sequence (maximum magnitude M w 3.8) in the Fort Worth Basin of Texas, which occurred after several billion cubic meters of gas and several million cubic meters of brine were produced from the Barnett Shale and several million cubic meters of water was injected into the Ellenburger Formation below the Barnett. The effect of Barnett production on induced stress and reactivation of the synthetic-antithetic fault pair hosting the seismicity is not well understood from prior studies. The interaction among production-induced contraction, injection-induced expansion, and decrease in fault compression due to fluid diffusing from the injection layer strengthens two-way coupling among fluid flow, deformation, and fault failure processes. Using a high-resolution coupled flow-geomechanics-fault reactivation model of the Azle region and a modified corner point meshing algorithm, we integrate structural, seismic, and well data to model novel mechanisms of stress interaction and propagation. The model indicates how Barnett’s production-induced contraction interacts with Ellenburger’s injection-induced expansion in the footwall block of the antithetic fault to cause updip shear on the fault. In the hanging-wall block of the synthetic fault below Ellenburger, the model finds that the downdip shear from Ellenburger expansion colludes with the decrease in fault’s effective compression due to downdip fluid diffusion. The collusion induces normal faulting in the model. Modeling also reveals that the reorientation of the principal stresses is more severe in the Barnett compared with that in the Ellenburger. The model quantifies the impact of stress reorientation on the magnitude and location of fault reactivation events.

A Smart Irrigation System using NodeMCU

In India, agriculture is a prominent feature Agriculture has a considerable impact on the Indian financial system, since agriculture either directly or indirectly supports about half of the nation's population To monitor the water level in the field and to turn on and off the water pump, a farmer must go to the farm, sometimes even in the middle of the night. This issue can be resolved by improving traditional farming methods in many ways. To convert conventional farming into smart farming, a new machine might be created or developed. By using a soil moisture sensor, this work aims to design a clean water pump controller. The Message Queue Telemetry Transport protocol is used to send and receive sensor data. The NodeMCU-12E regulates the movement of a water pump based on the state of the soil moisture content of the fabric and shows data from the soil moisture sensor and water pump performance on a web page or mobile application. This advances a safe, flexible, trust-capable, function and coffee in value machine to address the aforementioned agricultural irrigation problem. By enforcing this responsibility, we can reduce the amount of water utilized in manufacturing, agriculture, and the production of power. Examples of high-tech farming practices include precision farming, smart irrigation, crop water management, and real-time water metering.

Research and Implementation of Civil Residence Right of Internet of Things for Smart Home

With the progress of the times, Internet of things technology is increasingly close to public life, which provides great support for the promotion of an intelligent and convenient lifestyle. The basic research on computer technology can form a contemporary emerging Internet of things technology, which has brought a great breakthrough to the information industry. Internet of things technology has brought a new model to home design. At the same time, through China’s proposal of various schemes, it has more effectively promoted the effective application of smart home. In order to improve the credibility of technical evidence in civil litigation of housing residence right, this research generates a big data portrait algorithm of water and electricity behavior characteristics through a fuzzy neural network (FNN) Fourier function (FFT), remote real-time meter reading data and generates feature code comparison algorithm of civil evidence of civil residence right (CRR) through machine learning decision technology (MLDT). As an important part of the court evidence chain, the in-depth mining of electric energy meters and water meters in the smart home Internet of things technology (IOTT) provides technical evidence for the actual residents of a specific house at a specific time. In this study, FNN and MLDT are used to directly judge the machine learning results of evidence required for ordinary civil court debate. The software that constructs the algorithm in the python big data analysis software environment has higher judgment ability for the house ownership confirmation algorithm and has significant advantages. The technical way to obtain the confirmation result of housing residence right is also significantly better than other results. With the support of other relevant evidence, the conclusion of the software can form an evidence chain to meet the needs of civil defense, and the credibility of its technical evidence is very high. In the simulation analysis, although the algorithm designed in this study can not achieve 100% data expression, it also has comparative advantages.

The Punta de la Mona Rhodolith Bed: Shallow-Water Mediterranean Rhodoliths (Almuñecar, Granada, Southern Spain)

Shallow-water rhodolith beds are rare in the Mediterranean Sea and generally poorly known. The Punta de la Mona rhodolith bed extends for 16,000 square meters in shallow and oligotrophic waters at the southern coast of Spain, off Almuñecar in the Alborán Sea. We present a detailed analysis of the structure (rhodolith cover and density, rhodolith size and shape, sediment granulometry) and morphospecies composition of the bed along a depth gradient. A stratified sampling was carried out at six depths (9, 12, 15, 18, 21, and 24 m), estimating rhodolith cover and abundance; rhodoliths were collected from one 30 by 30 cm quadrat for each transect, resulting in 18 samples and a total of 656 rhodoliths. The collected rhodoliths were measured and the coralline algal components identified morphoanatomically through a stereomicroscope and SEM. Sediment on the seafloor mainly consisted of pebbles and cobbles; the highest rhodolith cover occurred between 15 and 18 m, and the lowest at the shallowest and deepest transects (9 and 24 m). Mean Rhodolith size was similar throughout the depth range (23–35 mm) with a slight increase at 24 m, although the largest rhodoliths occurred at 21 m. In monospecific rhodoliths, size depended more on the forming species than on depth. We found 25 non-geniculate coralline morphospecies, nearly all rhodolith-forming morphospecies reported in the Mediterranean Sea in recent accounts. The highest morphospecies richness (18–19) and proportional abundance were found at intermediate depths (15–18 m), where rhodolith cover is also highest. Lithophyllum incrustans and Lithophyllum dentatum dominated at shallow depths (9–12 m), whereas Lithothamnion valens was the dominant species at intermediate and greater depths. Overall, the latter species was the most common in the rhodolith bed. The shallow-water rhodolith bed in Punta de la Mona is probably the most diverse in the Mediterranean Sea. This highlights the importance of the conservation of this habitat and, in general, emphasizes the role of the Alborán Sea as a diversity center of coralline algae. The Punta de la Mona example contradicts the common assumption in the geological literature that rhodolith beds are indicative of oligophotic environments with high nutrients levels.

Reducing carbon emissions through water conservation: An analysis of 10 major U.S. cities

Drinking water supply requires energy, which in turn emits greenhouse gases with undesirable climate impacts. Water conservation, therefore, offers environmental benefits by reducing such emissions. This research estimates carbon-dioxide-equivalent (CO2eq) emissions associated with water supply in 10 major U.S. cities by combining existing observations on the energy intensity of water supply and the carbon emissions of energy systems. Results range from 21 to 560 gCO2eq per cubic meter of water delivered. As a pathway for future carbon budgeting, the approach demonstrates how existing water, energy, and emissions data may be combined in studies of multiple sites which are not practical with typical life-cycle analyses. Considering a hypothetical 10% water conservation scenario in each city shows that the potential to reduce emissions (1,200–65,000 tCO2eq/yr in each city) is especially effective where energy-for-water intensities, electricity emission factors, and/or water conservation volumes are high. The results of this and similar analyses may guide future sustainability decisions by considering the co-benefits of reducing energy use and emissions associated with water conservation.

Research on intelligent management of campus water supply system based on mathematical model

The campus water supply system is an important part of the campus utilities. This paper studies the campus water supply management from the water supply data obtained from the smart water meter of a university campus in China. It used the mathematical modeling method to analyze the water consumption characteristics of each functional area of the campus, drew a mind map of the hierarchical relationship, and made a line graph of water consumption in each area with the change of month, established a model between each water meter data, and obtained the hierarchical relationship and model error of the campus water meter. For the leakage of the water transmission network, a leakage rate model was derived to help the school address the leakage problems that exist.

Nexus analysis and life cycle assessment of regional water supply systems: A case study from Italy

Ensuring reliable access to water sources is an emerging issue being currently addressed by governments and international communities. However, local conditions play a primary role in determining requirements for urban water supply systems and cascade implications due to simultaneous interlinkages with complementary resources such as energy. As such, addressing sustainability in water management comes through quantitative evaluation modelling and assessment.To this aim, nexus analysis and life cycle assessment methodologies are applied to the drinking water supply system in the Romagna region (Italy). Our research provides detailed characterization of the involved material and energy flows, which is used as a basis for determining water-for-energy and energy-for-water results, and to conduct environmental assessment for complementary impact categories by withdrawal, treatment, and distribution processes.The results show that the energy needed to produce drinking water ranges from 0.27 MJ to 2.53 MJ per cubic meter of water delivered. Water deriving from the artificial basin and treated following a conventional technology turned out to be both the less energy intensive and the less impacting process. Overall, the study provides an exhaustive comparison of the environmental impacts of different water production alternatives, which may ultimately support decision-makers and local communities to the planning of strategies for optimized and long-term reliable access to water resources.

Tanggung Jawab Perusahaan Daerah Air Minum (Pdam) Terhadap Kerugian Konsumen Dan Melonjaknya Rekening Air Akibat Kebocoran Instalasi Dalam (Studi Pada Pdam Tirtanadi Provinsi Sumatera Utara)

The management of clean water (drinking water) is managed by the Regional Drinking Water Company (PDAM). PDAM Tirtanadi often gets complaints from consumers regarding its services. Most of the consumer complaints to PDAM Tirtanadi are in the form of objections to paying bills that are not in accordance with the frequency of use so that it can cause consumers to suffer losses. Therefore, it is necessary to compensate for damages and rain-check effort to provide clean water. The research method used is a normative juridical approach. Research materials consist of primary, secondary and tertiary legal materials. This research is descriptive-analytical and to complete the research data it is supported by conducting interviews. The results of the study are the form of implementing compensation for negligence by the Regional Drinking Water Company (PDAM) in the form of restitution or refunds that will be included in the next month's account, the efforts of the Regional Drinking Water Company (PDAM) in providing clean water to consumers refers to clean water standards. drinking water based on the Minister of Health Regulation (PERMENKES) Number 907 of 2002 concerning Drinking Water Quality, namely passing standard tests including bacteriological, chemical, radioactive and physical requirements, PDAM's efforts to overcome soaring accounts due to leaks in internal installations by repairing pipes before the water meter (persil pipe) ), both repair costs and water usage are the responsibility of the PDAM, but if the pipe is damaged or leaks after the water meter, all costs are borne by the drinking water customer.

Determination of four trihalomethanes in ship ballast water by gas chromatography-negative chemical ionization-mass spectrometry

我国每年的船舶压载水排放量巨大,压载水中含有浮游生物、病原体及其幼虫或孢子等,若处理不当,会对排放水域的生态环境造成严重影响。排放压载水前常使用电解法对其进行处理,电解产生的次氯酸钠溶液,能有效杀灭残余的微生物。但电解后会产生副产物三卤甲烷(THMs),其对人体有一定的健康风险,建立船舶压载水中三卤甲烷的测定方法具有重要意义。该研究建立了采用气相色谱-负化学源质谱(GC-NCI-MS)测定船舶压载水中4种三卤甲烷(包括三氯甲烷、二氯一溴甲烷、一氯二溴甲烷、三溴甲烷)的分析方法。船舶压载水样品经过顶空进样技术处理后,通过DB-5MS UI毛细管色谱柱(30 m×0.25 mm×1.0 μm)分离,气相色谱-负化学源质谱仪测定,在选择离子扫描(SIM)模式下分析,采用外标法进行定量。4种三卤甲烷在0.2~50 μg/L范围内线性关系良好,相关系数(r)≥0.995,定量限(S/N=10)为0.1~0.2 μg/L,在0.2、0.5、2.0 μg/L 3个加标水平下,4种THMs的平均回收率为90.3%~106.8%,相对标准偏差(RSD)为1.4%~6.2%。该方法准确、稳定、可靠,可用于测定船舶压载水中4种THMs的含量。使用建立的测定方法对36个船舶压载水进行测定,三溴甲烷、二溴一氯甲烷、一溴二氯甲烷与三氯甲烷的检出率分别为83.3%、69.4%、22.2%和19.4%,检出值分别为34.25~221.5 μg/L、3.52~41.87 μg/L、1.52~8.56 μg/L和0.02~5.46 μg/L。