我国不同类型地下工程中的氡水平

为了解我国地下工程内氡的浓度水平及其可能对人体产生的危害,采用核固体径迹法,在不同季节对全国23个城市的234个地下工程测点的氡浓度进行了测量。根据工程的建筑类型及用途的不同,将所有被测工程分为坑道、干道(包括掘进式地道工程)、地下室(高层建筑地下室和掘开式工程)和停车场四类,各类工程的氡浓度平均值分别为327、619、96.9、59.1 Bq.m-3。对于不同山体岩性的坑道,氡浓度值由高到低的顺序是花岗岩>凝灰岩>石英砂岩>石灰岩>安山玢岩。比较各类工程不同季节的氡浓度,得出,停车场氡浓度季节变化不大,其它三类工程都有氡浓度夏季明显高于冬季的特点,而且通风差的未使用的坑道和干道比使用中的同类工程具有相对高的氡浓度夏/冬比值。     

应用XAD系列树脂分离和富集天然水体中溶解有机质的研究进展

溶解有机质(dissolvedorganicmatter,DOM)是一类由腐殖质和非腐殖质构成的非均质混合物,广泛存在于土壤、煤炭和水体中,产生重要的生态环境效应。溶解有机质中相似组分的分离一直是有机质研究的难点。近年来,随着XAD树脂分离技术在DOM分离中的广泛应用,腐殖质和非腐殖质的分离取得了很大进展,文章对这些方法进行了详细的综述,并做了进一步的展望。     

综合管廊内火灾自动报警探测器实验研究

为了能够有效提升综合管廊内火灾自动报警系统的准确性和可靠性,本文采用火灾实体试验的方法,通过对各类型火灾自动报警探测器响应时间的情况进行分析和比较,研究综合管廊电力舱内常用探测器的性能。研究结果表明:接触式缆式线型感温火灾探测器可以较早的探测到电缆温度异常变化的现象,可用于早期预警。点型感烟探测器对烟粒子浓度较为敏感,可用于综合管廊电力舱室的空间探测。分布式光纤型感温火灾探测器对明火温度的变化较为敏感,作为空间型的火灾探测器比较可靠。     

呼吸效应对矿井封闭火区氧浓度的影响分析

为避免因火区封闭导致重大安全事故发生,通过采集某矿井1 d内3个不同监测点的大气压力变化情况,建立大气压力波动模型并分析计算,同时建立火区内外压差100,750 Pa情形下的氧浓度模型进而获得火区内侧氧气浓度因呼吸效应,在不同压差、体积大小火区、风阻、瓦斯涌出量、封闭时刻等多因素耦合影响下随时间的变化规律,以评估火区危险性。研究结果表明:井下大气随地面大气周期波动,封闭火区内、外侧之间的气压差因外界大气波动呈现16 h的余弦波动和8 h的线性波动周期变化;密闭质量好的火区具有更好地抗干扰性,内侧氧浓度的降低主要依靠瓦斯稀释;密闭质量差的火区,内侧氧浓度易受到火区涌出瓦斯、外界涌入大气双重影响;火区氧浓度在2%~12%之间波动,以至火区存在发生瓦斯爆炸的可能性;火区内外压差较大时,氧浓度波动变化幅度更大,危险作用持续时间更长。结合火区氧浓度波动模型,可有效地对矿井火区采取安全的防范措施,避免瓦斯爆炸事故发生。     

深部煤层钻屑粒度随钻进深度分布规律

为了研究煤层钻屑粒度随钻进深度分布规律,选取具有冲击危险性的平煤八矿己15煤作为研究对象,采取钻屑量测试和孔口瓦斯浓度监测,通过筛分实验煤样并应用Rosin Rammler分布模型,探究了钻屑粒度和钻屑量大小随孔深变化关系,分析不同点钻屑粒度分布特征。结果表明:小于0.075 mm钻屑粒度分布随孔深变化与钻屑量变化规律相吻合;不同钻孔随深度变化分别对应不同Rosin Rammler分布函数,随着应力过渡越平缓,粒径分布宽度系数n值越小,煤体应力越大粒径相关系数D越大;不同范围钻屑粒度占比大小也会影响钻屑量大小;在钻屑量较大时,孔口瓦斯体积分数会出现增高现象。通过对钻屑粒度分布规律分析,更好地了解深部煤体应力分布,有助于冲击危险的预警。     

抛光铝粉爆炸及ABC粉体抑爆特性的实验研究

为研究抛光铝粉的爆炸危险和ABC粉体的抑爆特性,在对实验粉体粒径分布进行分析的基础上,采用20 L粉尘爆炸特性实验装置,分别对不同铝粉尘浓度、不同抑爆剂浓度条件下的爆炸特性参数进行测试。研究结果表明:在实验条件下,铝粉的爆炸下限为45 g/m3＜C＜60 g/m3;随铝粉浓度增加,爆炸烈度呈现出先增强后减弱的变化趋势,在浓度为400 g/m3时爆炸烈度最大。ABC抑爆剂能够有效抑制铝粉爆炸超压和爆炸反应进程,随着惰性粉体浓度的增加,抑制效果愈加明显,爆炸逐渐减弱。当ABC惰性粉体的质量占比增加到50%时,相较单一铝粉爆炸,反应过程时间由72 ms增加至785 ms,爆炸最大压力、最大压力上升速率分别下降了61.7%,89.5%;当ABC粉体质量占比为53%时,铝粉被完全惰化,未发生爆炸。     

Mitigating Impact of Devils Lake Flooding on the Sheyenne River Sulfate Concentration

Devils Lake is a terminal lake located in northeast North Dakota. Because of its glacial origin and accumulated salts from evaporation, the lake has a high concentration of sulfate compared to the surrounding water bodies. From 1993 to 2011, Devils Lake water levels rose by ~10 m, which flooded surrounding communities and increased the chance of an overspill to the Sheyenne River. To control the flooding, the State of North Dakota constructed two outlets to pump the lake water to the river. However, the pumped water has raised concerns about of water quality degradation and potential flooding risk of the Sheyenne River. To investigate these perceived impacts, a Soil and Water Assessment Tool (SWAT) model was developed for the Sheyenne River and it was linked to a coupled SWAT and CE‐QUAL‐W2 model that was developed for Devils Lake in a previous study. While the current outlet schedule has attempted to maintain the total river discharge within the confines of a two‐year flood (36 m³/s), our simulation from 2012 to 2018 revealed that the diversion increased the Sheyenne River sulfate concentration from an average of 125 to >750 mg/L. Furthermore, a conceptual optimization model was developed with a goal of better preserving the water quality of the Sheyenne River while effectively mitigating the flooding of Devils Lake. The optimal solution provides a “win–win” outlet management that maintains the efficiency of the outlets while reducing the Sheyenne River sulfate concentration to ≤600 mg/L.     

Experimental research of LNG accidental underwater release and combustion behavior

Evaluating potential hazards caused by accidental LNG release from underwater pipelines or vessels is a significant consideration in marine transportation safety. The aim of this study was to capture the dynamic behavior of LNG jet released under water and to analyze its vapor dispersion characteristics and combustion characteristics on the water surface during different release scenarios. Controlled experiments were conducted where LNG was jet released from a cryogenic storage tank. The dynamic process of LNG being jet released from orifices of different sizes and shapes, as well as the rising plume structure, were captured by a high-speed camera. The leakage flow rate and pipeline pressure were recorded by a flow meter and pressure gauge, respectively. The concentration distribution that emanated from the water surface was measured utilizing methane sensors in different positions with various wind speeds. The flame combustion characteristics of LNG vapor clouds, which immediately ignited upon the enclosed water tank, were also recorded. Additionally, the mass burning rate of the flame on the water surface was evaluated, and a new correlation between the ratio of flame length and width was established. The results indicated a large dimensionless heat release rate (Q*) and a continuous release flow rate in a limited burning area. This study could provide greater understanding of the mechanisms of LNG release and combustion behavior under water.     

大型碳化硅生产园区面源源强及减排指标核算

以某年产25万吨大型碳化硅园区无组织排放面源为例,提出基于多个地面站气象数据的CALPUFF模型地面浓度反推方法,优化流场模拟,使得无组织面源源强核算结果更加准确,并以环境保护目标空气质量达标为原则,核算其大气污染物减排指标,得出具体结论:园区大气污染物SO2、NOX、CO、PM10年排放量分别为449.06t、86.98t、5158.58t、115.06t;无组织排放SO2、CO及PM10的减排比例分别为63.5%、19.2%、42.44%,对应减排量分别为285.16 t/a、990.45 t/a、48.83 t/a。     

Environmental forensic investigation of the air pollution from a cement manufacturing unit

Abstract

Cement manufacturing is a process that results in the emission of significant quantities of suspended particulate matter (SPM) to the ambient air. An environmental forensic investigation was carried out in the surroundings of a major cement manufacturing unit at a place called Coimbatore in the southern Indian state of Tamil Nadu. The investigation was carried out to identify the contribution of the cement manufacturing unit to the SPM concentration of the surrounding air environment. The sampling points’ selection and sample collection were done following the principles outlined in the INTERPOL Manual for Pollution Crime Forensic Investigation. On-site monitoring of the air samples was carried out using Mini Laser Aerosol Spectrometer (GRIMM, Mini-LAS Model 11R). The instrument was capable of measuring particles ranging from 0.25 to 32 µm and classifying them into 31 size channels. The test results at majority of the monitoring locations were well above the limits specified in the National Ambient Air Quality Standards of India. Microscopic studies of the dust samples were carried out for surface texture and particle shape. The spatial distribution of particles was analysed using geographic information system (GIS) for the visual identification of the extent of the pollution by keeping the cement factory as the focal point. The results from the GIS and microscopic analysis established the role of the cement factory in the particulate matter pollution of its surroundings, specifically in the areas North-West of the factory. The successfully adopted procedure can serve as a guideline for the environmental forensic investigation of similar pollution incidences.