NH3-N在大连湾的水环境行为模拟研究

应用三维水质模型对大连湾中的主要污染物NH3-N的行为进行了模拟,对NH3-N浓度的时空变化规律以及其影响因素进行了研究,选择主要的模型参数进行了灵敏度分析。由空间分布的模拟结果可知,在大连湾,NH3-N浓度主要集中在排污口附近区域,灵敏度分析显示,在排污口区水体的扩散能力对NH3-N浓度的影响较大。由季节变化模拟结果可知,在湾顶部的排污口区NH3-N浓度显示明显的季节变化趋势。在湾中部和朝海边界的湾口区NH3-N浓度较低,变化平缓。模拟结果可以为大连湾的污染控制、水质规划和管理提供科学依据。     

HDTMA改性粘土吸附固定沉积物间隙水中多环芳烃的模拟研究

选用经过十六烷三甲基溴化铵(HDTMA-Br)改性的粘土矿物为吸附剂,探讨其对水中多环芳烃类有机污染物的吸附性能。结果表明,HDTMA改性土吸附固定水中多环芳烃的能力比天然沉积物要高得多且吸附稳定。本文还讨论了环境温度、pH值、盐度、振荡时间、污染物初始浓度以及投土量对吸附性能的影响以确定吸附的适宜条件。根据实验结论,将HDTMA改性土投到实际间隙水样品中,经过充分的吸附,结果显示,经HDTMA改性粘土吸附后的间隙水中多环芳烃的含量均在检出线以下,说明HDTMA改性土可以有效地吸附固定沉积物间隙水中的多环芳烃,降低其迁移性,防止其释放产生二次污染。     

繁茂膜海绵滤食养殖水体中过剩饵料的研究

繁茂膜海绵(Hymeniacidon perleve)可滤食养殖水体中的残饵。对活体饵料新月菱形藻(Natzchia closterum),在无营养盐条件,5 g鲜重海绵处理300 mL,藻数量为1.62×106/mL的藻液240 h后,处理组藻的平均浓度仅为对照组的2.9%,为初始浓度的17.2%;在有营养盐条件,5g鲜重海绵处理300 mL,藻数量为0.87×106mL-1的藻液220 h后,对照组的藻仍处于指数生长期,此时处理组藻的平均浓度仅为对照组的0.05%,为初始浓度的64.4%。对死体海参饵料—藻粉和鱼粉蛋白等,由于海绵的滤食作用,海水中颗粒物的浓度随时间增加而呈指数曲线降低。1.5 g鲜重海绵处理200 mL,含200 mg/L海参饵料的海水,在第4d时,海绵已滤食72.6%的颗粒物,有机颗粒物的最大比截留速率为21.6×10-3/d.L。同时,海绵的生物量明显增加。     

煤矿水害风险量化评价方法

为提高煤矿防治水管理水平,预防和消除矿井水害,在层次分析法的基础上建立中性值作为参照对象对矿井水害风险进行实时评判的方法。根据《煤矿防治水细则》建立以矿井水文地质类型、矿井涌水量标准分数、突水预兆、采掘面位置、探水结果为准则层的层次结构模型,并对各评价指标赋权。依据制定的水害风险评价指标的评分细则和监测监控数据并结合其权重得到水害评价总得分。通过总得分与中性参照分数比较得出预测结果:水害评价总得分大于中性参照分数,证明水害的威胁小,分数越高越安全;反之则水害的威胁较大,分数越低越危险,这时需要加强防治水的力度,令评价分数管控大于中性参照分数。这种方法依赖于井下监测监控数据进行量化评价,能实时、客观、全面且准确地反映煤矿水害的风险情况。     

基于响应曲面法的遗煤自燃分析与研究*

为研究高瓦斯易自燃煤层不同供风量、高抽巷抽采流量、低抽巷抽采流量3因素对采空区自燃“三带”分布影响规律,选取阳煤五矿8406工作面为研究对象,在数值模拟研究基础上,采用Design Expert软件进行Box Behnken试验设计,构建采空区氧化升温带宽度在3因素、3水平条件下的二次回归响应曲面模型,并对不同条件下采空区氧化升温带宽度进行预测与分析。结果表明:二次回归方程P值为0.001 6,预测模型显著,模型的失拟项为0.606 3,不显著,回归方程具有统计学意义;当供风量为1 500~2 000 m3/min,低抽流量为450~650 m3/min,高抽流量为100~200 m3/min时,对氧化升温带宽度一次项重要度排序为C（高抽巷抽采流量）>A（供风量）>B（低抽巷抽采流量）,二次项重要度排序为AC（供风量和高抽巷抽采流量）>AB（供风量和低抽巷抽采流量）>BC（低抽巷抽采流量和高抽巷抽采流量）,且AB,AC,BC之间均无交互作用。     

Adaptation of Climate Model Projections of Streamflow to Account for Upstream Anthropogenic Impairments

A statistical procedure is developed to adjust natural streamflows simulated by dynamical models in downstream reaches, to account for anthropogenic impairments to flow that are not considered in the model. The resulting normalized downstream flows are appropriate for use in assessments of future anthropogenically impaired flows in downstream reaches. The normalization is applied to assess the potential effects of climate change on future water availability on the Rio Grande at a gage just above the major storage reservoir on the river. Model‐simulated streamflow values were normalized using a statistical parameterization based on two constants that relate observed and simulated flows over a 50‐year historical baseline period (1964–2013). The first normalization constant is a ratio of the means, and the second constant is the ratio of interannual standard deviations between annual gaged and simulated flows. This procedure forces the gaged and simulated flows to have the same mean and variance over the baseline period. The normalization constants can be kept fixed for future flows, which effectively assumes that upstream water management does not change in the future, or projected management changes can be parameterized by adjusting the constants. At the gage considered in this study, the effect of the normalization is to reduce simulated historical flow values by an average of 72% over an ensemble of simulations, indicative of the large fraction of natural flow diverted from the river upstream from the gage. A weak tendency for declining flow emerges upon averaging over a large ensemble, with tremendous variability among the simulations. By the end of the 21st Century the higher‐emission scenarios show more pronounced declines in streamflow.     

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.     

Spatial and Seasonal Response of Municipal Water Use to Weather across the Contiguous U.S.

Weather variability has the potential to influence municipal water use, particularly in dry regions such as the western United States (U.S.). Outdoor water use can account for more than half of annual household water use and may be particularly responsive to weather, but little is known about how the expected magnitude of these responses varies across the U.S. This nationwide study identified the response of municipal water use to monthly weather (i.e., temperature, precipitation, evapotranspiration [ET]) using monthly water deliveries for 229 cities in the contiguous U.S. Using city‐specific multiple regression and region‐specific models with city fixed effects, we investigated what portion of the variability in municipal water use was explained by weather across cities, and also estimated responses to weather across seasons and climate regions. Our findings indicated municipal water use was generally well‐explained by weather, with median adjusted R² ranging from 63% to 95% across climate regions. Weather was more predictive of water use in dry climates compared to wet, and temperature had more explanatory power than precipitation or ET. In response to a 1°C increase in monthly maximum temperature, municipal water use was shown to increase by 3.2% and 3.9% in dry cities in winter and summer, respectively, with smaller changes in wet cities. Quantifying these responses allows urban water managers to plan for weather‐driven variability in water use.     

Estimating Potential Climate Change Effects on the Upper Neuse Watershed Water Balance Using the SWAT Model

Climate change poses water resource challenges for many already water stressed watersheds throughout the world. One such watershed is the Upper Neuse Watershed in North Carolina, which serves as a water source for the large and growing Research Triangle Park region. The aim of this study was to quantify possible changes in the watershed’s water balance due to climate change. To do this, we used the Soil and Water Assessment Tool (SWAT) model forced with different climate scenarios for baseline, mid‐century, and end‐century time periods using five different downscaled General Circulation Models. Before running these scenarios, the SWAT model was calibrated and validated using daily streamflow records within the watershed. The study results suggest that, even under a mitigation scenario, precipitation will increase by 7.7% from the baseline to mid‐century time period and by 9.8% between the baseline and end‐century time period. Over the same periods, evapotranspiration (ET) would decrease by 5.5 and 7.6%, water yield would increase by 25.1% and 33.2%, and soil water would increase by 1.4% and 1.9%. Perhaps most importantly, the model results show, under a high emission scenario, large seasonal differences with ET estimated to decrease by up to 42% and water yield to increase by up to 157% in late summer and fall. Planning for the wetter predicted future and corresponding seasonal changes will be critical for mitigating the impacts of climate change on water resources.     

张家港河凤凰段水质达标整治方案研究

张家港河凤凰段位于张家港市凤凰镇,受上游、支流水质以及区域生活污染源等影响,河道出入境断面水质达标率较低,主要超标因子为氨氮和总磷。本文通过水质现状分析和现场调研,总结了水质难达标的主要原因,提出了针对性较强的水质提升整治方案,对改善张家港河水环境具有非常重要的意义。