Uncertainty Analysis of Hydrologic and Water Quality Predictions for a Small Watershed Using SWAT2000

Hydrologic and water quality (H/WQ) models are being used with increasing frequency to devise alternative pollution control strategies. It has been recognized that such models may have a large degree of uncertainty associated with their predictions, and that this uncertainty can significantly impact the utility of the model. In this study, ARRAMIS (Advanced Risk & Reliability Assessment Model) software package was used to analyze the uncertainty of the SWAT2000 (Soil and Water Assessment Tool) outputs concerning nutrients and sediment losses from agricultural lands. ARRAMIS applies Monte Carlo simulation technique connected with Latin hypercube sampling (LHS) scheme. This technique is applied to the Warner Creek watershed located in the Piedmont physiographic region of Maryland, and it provides an interval estimate of a range of values with an associated probability instead of a point estimate of a particular pollutant constituent. Uncertainty of model outputs was investigated using LHS scheme with restricted pairing for the model input sampling. Probability distribution functions (pdfs) for each of the 50 model simulations were constructed from these results. Model output distributions of interest in this analysis were stream flow, sediment, organic nitrogen (organic-N), organic phosphorus (organic-P), nitrate, ammonium, and mineral phosphorus (mineral-P) transported with water. Developed probability distribution functions for the model provided information with desirable probability. Results indicate that consideration of input parameter uncertainty produces 64% less mean stream flow along with approximately 8.2% larger sediment loading than obtained using mean input parameters. On the contrary, mean of outputs regarding nutrients such as nitrate, ammonia, organic-N, and organic-P (but not mineral-P) were almost the same as the one using mean input parameters. The uncertainty in predicted stream flow and sediment loading is large, but that for nutrient loadings is the same as that of the corresponding input parameters. This study concluded that using a best possible distribution for the input parameters to reflect the impact of soils and land use diversity in a small watershed on SWAT2000 model outputs may be more accurate than using average values for each input parameter.     

烧结烟气中SO3的测定

建立了烧结烟气中SO3的检测技术,包括SO3的采集装置和测定方法。实验结果表明:质量分数为80%的异丙醇适宜作为吸收液,方法的回收率为95.79%~102.80%,相对标准偏差为0.46%~1.38%。该技术能有效消除烟气中粉尘及SO2对测定的干扰,具有准确、可靠、方便等特点,可应用于烧结烟气脱硫等装置日常运行中SO3含量的测定。     

Pairing Modern and Paleolimnological Approaches to Evaluate the Nutrient Status of Lakes in Upper Midwest National Parks

Understanding what constitutes a reference (background) nutrient condition for lakes is important for National Park Service managers responsible for preserving and protecting aquatic resources. For this study we characterize water quality conditions in 29 lakes across four national parks, and compare their nutrient status to U.S. Environmental Protection Agency (USEPA) nutrient reference criteria and alternative criteria recently proposed by others. Where appropriate we also compare the nutrient status of these 29 lakes to state or tribal nutrient reference criteria or standards. For lakes that exceed reference criteria we investigate physical and chemical patterns, and for a subset of lakes compare modern nutrient conditions to paleolimnological (i.e., diatom‐inferred [DI]) nutrient reconstructions. Many lakes exceeded USEPA nutrient reference criteria, but met alternative less restrictive criteria. Modern nutrient conditions were also largely consistent with DI historic (pre‐1900) nutrient conditions. Lakes exceeding alternative nutrient criteria and with elevated nutrient levels relative to DI historic conditions were mostly small, shallow, and dystrophic; continued attention to their nutrient dynamics and biological response is warranted. Coupling modern and paleolimnological data offer an innovative and scientifically defensible approach to understand long‐term nutrient trends and provide greater context for comparison with reference conditions.     

城市移动通信基站电磁辐射环境调查与评价——以连云港为例

对连云港移动通信基站电磁辐射环境进行现状调查与评价,将3个时段内移动基站电磁辐射监测数据进行统计分析和分区评价。结果表明,监测数据均能符合相应的环境标准,县域电磁环境辐射水平整体略低于城市区域,基站周边整体受电磁辐射影响程度随高度上升呈增加趋势,10 m～15 m高度处的综合场强平均峰值最高。     

负载咪唑型离子液体硅胶吸附材料制备及应用研究

制备了3种取代咪唑键合的硅胶负载型离子液体(甲基咪唑-SIL、氨丙基咪唑-SIL及十二烷基咪唑-SIL),比较了其对水中双酚A(BPA)的吸附能力。在该研究的实验条件下,BPA在十二烷基咪唑-SIL与水溶液之间的分配系数K_d值高达(2.58±0.02)×10³ L/kg,氨丙基咪唑-SIL、甲基咪唑-SIL的K_d值也分别达到(2.26±0.28)×10、(2.71±0.16)×10 L/kg。采用甲醇为洗脱液,可以对十二烷基咪唑-SIL相中的BPA进行有效回收,2次洗脱的合并回收率为106.7%±4.8%。以十二烷基咪唑-SIL作为被动采样装置的接收相,对污水处理厂出水中BPA进行了被动采样监测应用的微宇宙实验研究。结果表明,在实验周期内,十二烷基咪唑-SIL被动采样器对水体中BPA的被动采集呈线性,其采集速率为0.33 L/d,与以HLB为接收相的商品化被动采样器接近,并且同HLB固相萃取填料相比,离子液体接收相对BPA的采集更具选择性,基质效应较小,可作为被动采样监测装置的理想接收相材料。     

固定源低浓度颗粒物监测技术现状与思考

简述了固定源颗粒物监测技术的国内外现状,建议从规范现有方法和研发新方法入手,对低浓度颗粒物监测方法加以研究和改进。     

固定污染源烟气在烟道中流速分布的研究

针对固定污染源烟气在烟道中流速分布对净化方法的效率和排放总量计算的影响,采用自主研制的组合式流场的流速采样枪和国标方法对某电厂矩形烟道进行了烟气在烟道中流速分布的研究。实验结果表明,组合式流场的流速采样枪在烟道同一断面上各测点进行同时、同步、多点测量,其测量数据既能反映同一断面各测点上的流速特征,又能反映断面上各点的均值。组合采样枪各测点的伸入深度与流速之间呈对数关系,相关系数为0.960 6,数据具有真实性和准确性。烟气流速在烟道分布相当不均匀,呈现高流速、中流速、低流速3个区域。烟气流速由烟道内侧向外侧逐步增大,由内侧3 m/s,增加到外侧16 m/s。烟道顶部流速要高于烟道底部流速。     

电磁辐射环境信访分析与应对措施探讨

以南通市辐射环境信访调处为例,对该市近年来电磁辐射信访投诉量及其变化,投诉对象、方式、诉求等进行分析,并结合调处经验,提出上门实测、合法性核查、组织协调等应对措施,以及完善执行机制,优化评价技术;加强辐射环境监管;保障公众参与权、知情权和监督权;正确引导公众舆论等解决辐射环境信访问题的建议。     

北京市PM2.5质量浓度特征及组分化学质量闭合研究

2013年7—9月分2次在北京市朝阳区的4个采样点(来广营、垡头、奥体和建外)进行PM_2.5手工采样,共获得164个有效滤膜样品。以石英滤膜为例,这4个采样点的均值分别为85、94、81、86 μg/m³。数据显示PM_2.5质量浓度呈"南高北低"的特点。化学质量闭合研究表明:碳质组分(OM+EC)和二次无机离子是PM_2.5的主要组成;碳质组分对夏季PM_2.5的质量浓度贡献比较稳定,2次采样对PM_2.5的贡献均在1/3左右,与采样时间和地点无关;二次无机离子的贡献则与采样时间有关,对PM_2.5的贡献在第一和第二次采样时间分别约为30%和20%。4个采样点中,最南端的垡头PM_2.5质量浓度最高,有机颗粒物、SO₄^2-、NO₃^-和NH₄⁺的质量浓度平均值最高,分别为26、18.2、10.5、5.9 μg/m³。     

固定源硫酸雾国内外采样方法优劣分析

固定污染源硫酸雾的国标采样方法为滤筒法,但对其采样效率研究较少。在调研国内外标准方法及相关文献的基础上,通过大量实样测定,对国标采样法进行改进：在内装滤筒的烟尘采样管后串联一个冲击式吸收瓶,此改进方法弥补了国标漏测气态硫酸雾的缺陷,采样效率达到99％以上,国标法仅为改进法的47％～68％。将国标改进法与USEPA采样法进行比对,结果表明,由于中国环境本底颗粒物浓度较高,硫酸雾易吸附于颗粒物上,致使USEPA采样效率仅为国标改进法的2?4％～12％。