油气管道的杂散电流腐蚀与防护

阐述了杂散电流对油气管道腐蚀的基本原理、特点,针对杂散电流的特点,提出了防止杂散电流对油气管道腐蚀的措施.     

油气管道的杂散电流腐蚀防护措施

介绍了杂散电流腐蚀的机理、特点以及对油气管道的影响，以及国内外标准关于杂散电流干扰源与油气管线安全间距的规定，并提出了相应防止杂散电流腐蚀的措施。     

地铁杂散电流对埋地钢质燃气管道的腐蚀

分析了地铁杂散电流的形成、对埋地钢质燃气管道的腐蚀机理及腐蚀特点,探讨了宁波市地铁杂散电流的防护措施,对埋地钢质燃气管道的地铁杂散电流腐蚀防护提出了建议。     

供水管道动态杂散电流干扰腐蚀风险研究

为了掌握供水管道杂散电流干扰腐蚀风险,在深圳供水管道上开展了杂散电流测试和现场腐蚀试验,获得了杂散电流对深圳供水管道的整体干扰水平,以及管道自然腐蚀和杂散电流干扰腐蚀速率数据,提出了基于管道电位偏移、流出电流密度以及时间指标的动态直流杂散电流干扰腐蚀风险评判方法,以期为供水企业评估杂散电流对管道造成的腐蚀风险提供参考和依据。     

杂散电流对地铁周边的危害及防治

分析地铁杂散电流的形成原因及其对埋设钢制管道的腐蚀机理及特点,探讨杂散电流的防治措施和监测方式.总结地铁施工对地铁杂散电流腐蚀防治和管道保护的具体做法并提出建议.     

埋地钢制燃气管道受地铁直流杂散电流干扰的影响与分析

<正>1引言杂散电流是指设计或规定回路以外流动的电流~([1])。由杂散电流引起的金属腐蚀以其腐蚀速度快、强度高,腐蚀集中于局部位置的特点,成为金属电化学腐蚀中危害最为严重的一种~([2])。杂散电流根据来源主要分为直流杂散电流和交流杂散电流。其中,直流杂散电流一旦从埋地钢制管道一点进入,再从管道另一点流出,随后进入到土壤或水中,就会在电流流出的那     

埋地钢质燃气管道杂散电流腐蚀的测试与防护

介绍了杂散电流的类型。结合深圳市某测点的埋地钢质燃气管道受杂散电流干扰的调查和测试数据,分析了该管道杂散电流的主要来源。介绍了国家标准及行业标准对杂散电流控制的要求、国外杂散电流防护工作的情况,提出了杂散电流腐蚀防护的措施。     

地铁直流杂散电流对埋地金属管道的腐蚀

分析了地铁直流杂散电流对埋地燃气管道干扰腐蚀的机理与影响，并简述了埋地燃气管道直流杂散电流干扰腐蚀的防护方法。     

杂散电流对埋地燃气管道的腐蚀及其监测

阐述了城市轨道交通产生杂散电流的原凶,并针对杂散电流对轨道周边的埋地的燃气管道的腐蚀进行了分析,最后介绍针对埋地燃气管道的杂散电流监测系统的基本结构,列举了一些城市应用杂散电流监测系统的情况。     

埋地燃气管道杂散电流测试及分析

直流杂散电流会对燃气管道产生严重腐蚀,所以轨道交通杂散电流对燃气管道产生的腐蚀影响不容忽视。以某轨交站附近的埋地燃气管道为研究对象,分别测量了管道的管地通断电电位以及管道附近的地电位梯度来判断管道的实际保护情况以及受干扰的情况,同时测量轨地电压并根据其与管地电位和地电位梯度的时间同步性判断干扰源为轨交系统。最后给出了行之有效的埋地燃气管道杂散电流腐蚀防护措施及对策,为今后的埋地燃气管道杂散电流防护提供了一定的帮助。     

Total arsenic, lead, cadmium, copper, and zinc in some salt rivers in the northern Andes of Antofagasta, Chile

Lake Velenje is located in one of the most polluted regions in Slovenia, the Salek Valley. The major source of pollution in the valley is the coal-fired thermal power plant in Sostanj (STPP, capacity 775 MW). It has five separate units. All units have electrostatic precipitators for fly ash removal. Unit 4 also has installed a wet flue gas desulfurisation system (FGD system). Total mercury (THg) concentrations were measured in lignite, slag and ash samples from the STPP. In flue gas, different mercury species (THg, MeHg, Hg2+, Hg0) were determined separately for unit 4 and unit 5 which use different flue gas cleaning technology. Mercury and methyl mercury (MeHg) concentrations were also measured in lake water at different depths, in inflow water, outflow water, rain, snow and lake sediments in order to establish the influence of the power plant on the lake. Most mercury emitted from the power plant is in the elemental form. The ratio between oxidised and elemental Hg depends on the flue gas cleaning technology. Mass balance calculations have been performed for the STPP. The results show that the major sources of mercury in Lake Velenje are wet deposition and lake inflows. Total and MeHg concentrations in the water column are very low and can be compared to other non-contaminated freshwater lakes in the world.     

Mercury levels in lichens from different host trees around a chlor-alkali plant in New Brunswick,Canada

Mercury concentrations were determined in the epiphytic lichen Hypogymnia physodes along five transects starting from a chlor-alkali plant located at Dalhousie, New Brunswick, a landfill site and a nearby electricity generating station. Lichen samples were collected from white birch (Betula papyrifera) and spruce (Picea sp.) or balsam fir (Abies balsamea). Average lichen background mercury values were 0.088+/-0.005 microg/g from white birch and 0.148+/-0.046 microg/g from spruce trees, with a detection limit of 0.05 microg/g. The chlor-alkali plant and a power plant were identified, respectively, as a major source and a minor source of elevated mercury levels in lichens. At 125 m north-west of the New Brunswick Power plant, 0.28 microg/g Hg were found in Hypogymnia physodes from spruce trees, while at 250 m west (downwind) of the chlor-alkali plant, 3.66 microg/g of mercury were determined. High values, 0.98 microg/g in lichens from spruce trees and 0.79 microg/g in lichen samples from white birch were also measured at 125 m south of the chlor-alkali plant and decreased exponentially with distance. The sphere of influence of the chlor-alkali plant with respect to mercury deposition was estimated to extend 2.4-3.4 km from the plant. The mercury concentrations in Hypogymnia physodes collected from white birch were significantly lower than the concentrations in the same lichen from spruce trees in areas with elevated levels of mercury, but not in areas with low mercury levels. The magnitude of this difference dropped with distance from the source.     

Atmospheric mercury near a chlor-alkali plant in Sweden

Atmospheric mercury species/fractions were measured near a chlor-alkali plant in Sweden during August 28 to September 4, 2001. The concentration of total gaseous mercury in the plume from the plant was measured using TEKRAN and GARDIS instruments. Gaseous elemental mercury was measured using a light detection and ranging (LIDAR) technique. From vertical LIDAR sweeps through the plume from the chlor-alkali plant mercury emission rates could be calculated. The concentrations of reactive gaseous mercury (RGM) in the plume and also inside the cell house were measured using annular KCl coated denuders. The RGM emission constitutes 0.5-1.0% of the total mercury emitted from the plant. The mercury concentration adsorbed on particles was measured as well as the mercury flux from soil. The data presented also include an intercomparison showing an excellent agreement between TEKRAN/GARDIS and LIDAR gaseous mercury measurements.     

Mercury emissions from selected stationary combustion sources in Korea

Mercury emissions from various stationary combustion sources such as coal-fired power plants, oil-fired power plants, industrial utility oil boilers, iron manufacturing plants, and industrial waste incinerators, were measured. The US EPA (Environmental protection agency) method 101A and the Ontario hydro method were used to sample the mercury containing combustion flue gases, at the inlet of the air pollution control devices (APCDs) and at the stack. Collected samples of both gaseous and particulate forms were then analyzed using CVAA (cold vapor atomic absorption) type analyzer. Measurement results from the coal-fired power plant showed percentages of elemental mercury (Hg0) as high as 31.4% and as low as 9.5%. However, the content of Hg0 was in the range of 1.3-3.7% from the industrial waste incinerator. Differences in mercury speciation from various stationary combustion sources are believed to be coming from: (1) difference in the fuel types; (2) difference in the major flue gas compositions (ex. HCl and SOx); and (3) difference in the types of air pollution control devices (APCDs). When the measurement results obtained using different sampling methods were compared, the Ontario Hydro Method gave a slightly higher mercury concentration measurement than that of the US EPA Method 101A.     

Mercury content in vegetation and soils of the Almadén mining area (Spain)

The Almadén area is an exceptional case of mercury concentration in the world, where cinnabar is the predominant mineralised form. Mining activities have been carried out over the past two thousand years and once this activity is concluded, a restoration of the environment is necessary for the affected areas. That implies the selection, optimisation and application of the most appropriate techniques focused on the recovery of contaminated areas. Phytotechnology is one of the proposed techniques, which considers the use of plants due to the low environmental impact and their proved efficiency. In this framework, it is necessary to study the behaviour of mercury in the soil-plant system and to determine the mercury absorption capacity of the different Almadén plant species. Therefore, field and laboratory studies have been carried out to determine the easily available forms of mercury in ten test plots in the Almadén area and the resulting data is related to the mercury accumulation in different plant species of the studied territory. Special attention is given to the easily available forms of mercury in the analysed soils and used as the transfer factor for the Hg-availability index that relates the amount of mercury in a plant with the total amount of mercury in a soil and with the easily available forms. The result of this experimental work is selecting the plant species suitable to be used in a future implementation of phytotechnologies in this area.     

Mercury in the River Nura and its floodplain, Central Kazakhstan: I. River sediments and water

The River Nura in Central Kazakhstan has been heavily polluted by mercury originating from an acetaldehyde plant. Mercury in the riverbed is mainly associated with power station fly ash, forming a new type of technogenic deposit. A systematic survey of the bed was carried out to establish the location, extent and nature of the contaminated sediments, and to evaluate the potential for sediment transport. The bed sediments were found to contain very high concentrations of mercury, particularly in the first 15 km downstream of the source of the pollution. Average total mercury concentrations in this section of the river are typically between 150 and 240 mg/kg, falling rapidly with increasing distance downstream. The estimated total volume of silts in the riverbed between Temirtau, the origin of the pollution, and Intumak Reservoir, located 75 km downstream, has been calculated as 463500 m3, containing an estimated 9.4 tonnes mercury. Forty-six percent of the total volume of contaminated silts containing almost 95% of the mercury are located in the upper 25 km of the river, however. The data clearly support the hypothesis that large quantities of polluted sediment are not transported long distances downstream but are removed from the aquatic environment in times of flood and deposited on the low-lying lands adjacent to the river. This process, however, does not stop mercury moving further downstream in the water column.     

Urinary mercury in people living near point sources of mercury emissions

As part of the European Mercury Emissions from Chlor Alkali Plants (EMECAP) project, we tested the hypothesis that contamination of ambient air with mercury around chlor alkali plants using mercury cells would increase the internal dose of mercury in people living close to the plants. Mercury in urine (U-Hg) was determined in 225 individuals living near a Swedish or an Italian chlor alkali plant, and in 256 age- and sex-matched individuals from two reference areas. Other factors possibly affecting mercury exposure were examined. Emissions and concentrations of total gaseous mercury (TGM) around the plants were measured and modeled. No increase in U-Hg could be demonstrated in the populations living close to the plants. This was the case also when the comparison was restricted to subjects with no dental amalgam and low fish consumption. The emissions of mercury to air doubled the background level, but contributed only about 2 ng/m(3) to long-term averages in the residential areas. The median U-Hg levels in subjects with dental amalgam were 1.2 microg/g creatinine (micro/gC) in Italy and 0.6 microg/gC in Sweden. In individuals without dental amalgam, the medians were 0.9 microg/gC and 0.2 microg/gC, respectively. The number of amalgam fillings, as well as chewing, fish consumption, and female sex were associated with higher U-Hg. The difference between the countries is probably due to higher fish consumption in Italy, demethylated methyl mercury (MeHg) being partly excreted in urine. Post hoc power calculations showed that if the background mercury exposure is low it may be possible to demonstrate an increase in U-Hg of as little as about 10 ng/m(3) as a contribution to ambient mercury from a point source.     

Detection of localized methylmercury contamination by use of the mussel adductor muscle in Minamata Bay and Kagoshima Bay, Japan

Based on our previous finding that the concentrations of total mercury in mussel adductor muscle approximated those of methylmercury, we compared concentrations of total mercury in the adductor muscle of the mussel Mytilus galloprovincialis, collected from four sites around Minamata City from 1993 to 1995 and four sites in Kagoshima Bay from 1997 to 1998, to assess the level of localized methylmercury contamination. Though the input of mercury from the chemical plant had stopped by around 1970, concentrations of total mercury in the mussel adductor muscle were higher at two sites (26-121 ng/g, n = 135) near the main fallout of wastewater from the chemical plant in Minamata Bay than at the other sites, i.e. two sites 1-5 km from the former sites in Minamata City (6-28 ng/g, n = 52), and all sites in Kagoshima Bay (2-30 ng/g, n = 287). The localized methylmercury contamination around the chemical plant in Minamata Bay was documented also by our sensitive analysis of mercury concentrations in seawater and sediment samples. The survey of concentrations of total mercury in the mussel adductor muscle seems to be useful for monitoring the methylmercury contamination in coastal areas.     

Binding, distribution, and plant uptake of mercury in a soil from Oak Ridge, Tennessee, USA

A large amount of mercury has been discharged on the U.S. Department of Energy's Oak Ridge Site (Tennessee) as a part of the U.S. nuclear weapon program during the 1950s through the early 1960s. Increases in mercury concentration in fish and in lower East Fork Poplar Creek of Oak Ridge have been recently reported. This is an experimental study mimicking the initial stage of transformation and redistribution of mercury in soils, which are comparable to those of the Oak Ridge site. The objectives of this study were to investigate potential transformation, distribution, and plant uptake of mercury compounds in soils. Results show that the H(2)O(2)-oxidizable mercury fraction (organically bound mercury) was the major solid-phase fraction in soils freshly contaminated with soluble mercury compounds, while cinnabar fraction was the major solid phase fraction in soils contaminated with HgS. Langmuir relationships were found between mercury concentrations in plant shoots and in soil solid-phase components. Mercury in HgS-contaminated soils was to some extent phytoavailable to plants. Mercury transformation occurred from more labile fractions into more stable fractions, resulting in strong binding of mercury and decreasing its phytoavailability in soils. In addition, high mercury losses from soils contaminated with soluble mercury compounds were observed during a growing season through volatilization, accounting for 20-62% of the total initial mercury in soils.     

Mercury distribution in a polluted marine area, ratio of total mercury, methyl mercury and selenium in sediments, mussels and fish

Total mercury, methyl mercury and selenium concentrations were determined in sediments and organisms from the Kaštela bay in the Central Adriatic, polluted with inorganic mercury by a chlor-alkali plant. Sediments and mussels (Mytilus galloprovincialis) contained high total mercury concentrations, especially in the vicinity of the source of pollution. The percentage of mercury in the methyl form increased from surface sediments (up to 1.37%) to the edible parts of mussels (0.1–27%, negatively correlated with total mercury concentrations) and to the fish, in which methyl mercury accounted for most of the mercury in the muscle tissue.