Stream Phosphorus Transport in the Lake Tahoe Basin, 1989–1996

Lake Tahoe is undergoing the initial stages of culturaleutrophication due to human alteration of the airshed andwatershed. The lake's switch from nitrogen (N) to phosphorus (P)limitation has been attributed primarily to atmospheric Nloading. This places an increased importance on controllingwatershed movement of P to the lake. A stream water qualitymonitoring data set consisting of nine streams in the Lake Tahoebasin has been analyzed to characterize the spatiotemporalvariation of P delivery to the lake. This data is from the LakeTahoe Interagency Monitoring Program (LTIMP), which providesscientific data for planning and regulatory agencies to addressenvironmental problems in the Lake Tahoe basin. Results indicatethat P delivery (concentrations, loads) varies greatly atinterannual, seasonal, and spatial scales. Annual and seasonaltotal P (TP) concentrations can vary up to three orders ofmagnitude in a given stream and are strongly associated withsuspended sediment. Particulate P is the major form of Ptransported by Tahoe streams and was strongly correlated withpercent surficial geologic deposits, which are primarily locatednear streams. Tahoe streams with the highest annualP concentrations often had the lowest annual P loads, and visaversa. P loading is greatest during the spring snowmelt (75% ofannual average). Potential watershed parameters influencing Pdelivery to Lake Tahoe have been identified as precipitation,basin area, basin steepness, and road and human developmentcoverage. Results also suggest that human development impacts onstream P loads are most prevalent during high precipitationyears. Identification and quantification of stream sediment andP sources such as streambanks and impervious surface isnecessary to aid in watershed restoration efforts.     

Assessing the performance of motorcyclists’ impact protectors in simulated ATD knee and shoulder impacts

Objective: Fractures are a common injury among motorcycle riders and can have serious health implications. Impact protection (IP) has been designed to help prevent fractures, yet there are conflicting opinions as to whether this IP does in fact help prevent fractures in real-world crashes. This work aimed to (1) use simulated dummy impacts to examine whether existing types of IP could reduce the force transferred to the underlying bone to below fracture tolerance levels and (2) investigate whether current European Standard (EN 1621-1) test procedures for impact protectors designed for motorcyclists are sufficient to ensure fracture protection.

Method: Twenty-three shoulder and 7 knee IP specimens were tested using a 23-kg impactor contacting axially along the clavicle and femur of an anthropomorphic test device (ATD) at an energy level corresponding to the fracture tolerance of these bones. Sixteen IP specimens were the same as those worn by motorcycle riders involved in crashes where injury outcome was known (knee: n?=?3; shoulder: n?=?13) and the IP had been previously tested to EN 1621-1. Other IP tested represented a wide range of IP available for purchase at a motorcycle accessory store. Double and triple layers of IP were also tested. Energy attenuated during the dummy impacts was compared to energy attenuated when tested to EN 1621-1.

Results: Of the 23 shoulder IP tested, the average percentage reduction of transferred force to the shoulder from the baseline test was 7.6?±?4.8%. The percentage reduction of transferred force to the knee from the baseline was 43.9?±?7.5%. The entire group of knee IP tested reduced the transferred force to the knee to below the 10-kN injury threshold for the femur. There was a positive but nonsignificant correlation between the ATD test and the EN 1621-1 impact test performance, suggesting that the European standard test method likely provides a good indication of IP performance. However, given the low correlation coefficient, the relationship between IP performance in the European standard test method and injury protection remains unclear.

Conclusion: Though the energy attenuation test method in the European standard may be an appropriate approach, distinct differences in injury protection performance observed between knee and shoulder IP indicate that there may be a need for different performance criteria for IP designated to protect different body regions.     

CaCO_3对生活垃圾热解气体组成的影响

利用固定床反应器,选用CaCO_3和SiO_2为添加剂,进行了生活垃圾催化热解实验研究,结果表明,CaCO_3在生活垃圾热解中的催化作用比SiO_2更加明显。为此,研究了不同CaCO_3添加量对热解可燃气产量的影响,探讨了CaCO_3在生活垃圾热解过程中的催化作用机理,重点分析了CaCO_3对生活垃圾热解气中CH_4和CO的影响机理。通过对比分析生活垃圾中添加不同量CaO的热解实验结果,得出CaCO3的催化作用主要在于其分解产物CaO促进了垃圾的二次热解,以及CO_2与C的还原反应。     

云南分散畜禽养殖密集型农村污水特征及污染风险评价

农村污水是造成水环境污染的主要原因之一,它不仅是农村水源地的安全隐患,还会危害农民自身的生存发展,因此对农村污水特征分析及风险评价具有重大意义。通过对云南省文山州八道哨村(畜禽养殖型)的农村污水进行采样和处理,分析了总磷、正磷、总氮、氨氮、COD、p H等污染指标,明确了畜禽养殖型农村污水的污染特征状况。结果表明:每个样点排放污水的氮和COD浓度均超过了GB 18918—2002《城镇污水处理厂污染物排放标准》,磷的浓度整体超过污染标准,仅有个别样点位于正常范围内;主干道污水的氮、磷和COD浓度均明显超过GB 18918—2002二级标准。通过运用内梅罗指数法对各污染指标进行统一处理,评价不同区域污水的污染程度。3个分区的内梅罗指数大小依次为东部(4.55)>中部(3.34)>西部(3.14),污染等级均为重污染。     

三峡水库沉积物不同赋存形态磷的时空分布

为了认识三峡水库沉积物磷的赋存状况,利用磷形态标准测试程序SMT法对干流和三条代表性支流(香溪河、大宁河、小江)的柱状沉积物进行了总磷(TP)、无机磷(IP)、有机磷(OP)、铁/铝磷(Fe/Al-P)、钙磷(Ca-P)的测定,结果表明干流沉积物TP含量为781~1026 mg·kg-1,支流沉积物TP含量为382~1085 mg·kg-1.TP主要由IP组成,OP所占比例较低;IP主要由Ca-P组成,Fe/Al-P所占比例较低.干流TP含量空间差异不显著,但各赋存形态磷的含量普遍高于支流,支流中香溪河磷含量高于大宁河和小江.垂直方向上各赋存形态磷含量在不同沉积深度没有明显规律;TP、IP、Ca-P三者变化趋势较一致,主要受Ca-P含量的影响.鉴于支流的独特水文条件,相比于干流,更应警惕支流沉积物磷的释放风险及其对水体的环境化学效应.     

燃气发动机瞬态工况下NOx排放特征

NO_x排放控制是发展燃气汽车的核心问题.为获得增压中冷燃气发动机瞬态工况NO_x的排放特征,实验选取了6MK375N-50增压中冷燃气发动机,研究了不同转速、转矩、进气流量、进气温度及湿度对NO_x排放的影响.试验结果表明NO_x的排放随着转速的增加先升高后减缓,转速为1400 r·min-1时NO_x排放最高,转矩的增加也会使NO_x排放增加,随着进气流量的增加,NO_x排放量先增加后稳定,进气流量为180 kg·h~(-1)时NO_x排放最高,进气温度对NO_x排放也有直接影响,进气温度为31℃时NO_x排放最高,随着进气湿度的增加,NO_x排放水平降低,对试验结果的双因素方差分析得到,各影响因素对NO_x的排放影响均非常显著.对1400 r·min-1下各个工况对应NO_x进行拟合,变化规律符合公式y=a-b×ln(x+c).     

高效重金属捕集剂EDTC的结构表征及对酸性络合铜的去除特性研究

以乙二胺和二硫化碳为反应物,无水乙醇和去离子水的混合溶液为溶剂,制备了一种巯基类重金属捕集剂N,N-双(二硫代羧基)乙二胺(EDTC),采用紫外光谱、红外光谱和元素分析对其结构进行表征,重点研究了其对EDTA络合铜、柠檬酸络合铜和酒石酸铜3种酸性模拟络合铜的去除性能及螯合沉淀物的溶出特性,并探讨了EDTC脱除络合铜的机理.研究结果表明,处理50 mg·L-1的含铜废水,p H值范围为3~9,EDTC投加量为mEDTC/mCu=8(质量比),反应时间3 min,PAM投加量为1 mg·L-1,此时出水Cu2+浓度均低于0.25 mg·L-1,去除率达到99.5%以上.螯合沉淀物在弱酸性和弱碱性条件下很稳定,不易产生二次污染.红外光谱图分析结果表明,EDTC与Cu会发生螯合反应,即EDTC直接脱出络合铜中Cu2+,并与Cu2+生成难溶的螯合产物EDTC-Cu,进而有效地去除废水中Cu.     

施用生物质炭对土壤腐殖质组成和胡敏酸结构特征影响

为研究玉米秸秆生物质炭施用后土壤腐殖质组成和土壤胡敏酸结构的变化,选择腐殖质组成修改法和国际腐殖质协会推荐的方法进行土壤腐殖质组分提取和HA样品纯化,采用重铬酸钾外加热法和TOC分析仪测定土壤、水溶性物质(WSS)、富里酸(FA)、胡敏酸(HA)和胡敏素(Hu)有机碳含量,采用元素组成和红外光谱分析HA的结构变化.研究结果表明:施入玉米秸秆生物质炭后,表层和亚表层土壤及其腐殖质组分有机碳含量均有不同程度的提高,表层土壤、WSS、FA、HA和Hu有机碳含量增加幅度较大,分别增加了83.61%、112.50%、89.63%、91.78%和89.82%,说明玉米秸秆生物质炭的施用更有助于表层土壤有机碳的积累;PQ值(HA在腐殖酸中的比例)略有增加;土壤HA的缩合程度和芳香性增强,氧化度降低.此外,施用玉米秸秆生物质炭后,土壤及其腐殖质组分有机碳含量随土层深度的增加而降低,与表层相比,亚表层土壤、WSS、FA、HA和Hu有机碳含量分别下降了62.84%、52.94%、62.38%、66.62%和61.61%;土壤PQ值略有降低;土壤HA的缩合程度和芳香性降低,氧化度增加.     

西固炼化基地区域大气质量变化特征与减排建议

西固炼化基地是西北地区最大的石油化工生产基地,在带动区域经济腾飞的同时,也随之产生了显著的大气环境问题。收集该区域2005年、2008年、2012年和2014年的大气现状监测资料,对近10年区域大气质量变化特征进行分析,确定针对西固炼化基地的管控污染物主要是特征污染物,结合基地排污情况提出相应的减排措施。研究表明,近10年SO_2、NO_2大气污染治理取得了显著效果,从2005年近半监测点超标到2014年无超标现象,污染物浓度逐年下降。2005—2014年的数次监测中几乎所有监测点颗粒物浓度全部超标。NMHC浓度呈先下降后上升的态势,2005年和2014年超标现象明显,其中2014年全部监测点超标。     

济宁南部区域耕作层土壤地球化学特征及其成因分析

济宁市南部区域是著名的国家商品粮、优质大蒜、优质稻米和有机蔬菜生产基地,由于土壤地球化学特征与农业生产、人类健康关系密切,所以对济宁南部区域耕作层土壤地球化学特征及其成因的研究具有十分重要的意义。本文以济宁南部煤田地区作为典型区域,以耕作层土壤为研究对象,采集了77件耕作层土壤样品,定量分析了As、B、Cd、Co、Cr、Cu、F、Hg、Li、Mn、Mo、Ni、Pb、Sr、Se、Zn、S、Corg、p H、Si O2、TFe2O3、Mg O、Ca O、Na2O、K2O、CEC等共计26项指标。经统计分析发现,济宁南部区域耕作层土壤中地球化学指标含量变异系数的大小顺序为HgCECSCdNa2OMoCa OCorgAsMnCuMg OCoLiNiTFe2O3SeZnFCrPbBSi O2SrK2Op H,其中Hg、CEC和S的变异系数较大,均超过了50%,这一特点与地球化学指标含量频率直方图及平均值与背景值的比对柱状图所显示的特征完全吻合。在摸清耕作层土壤地球化学特征的基础上,采用R型因子分析法对济宁南部区域耕作层土壤地球化学特征的成因进行了详细分析,提取了风化作用和淋溶作用复合因素、蒸发淀积作用和粘土物理化学吸附作用复合因素、植物根际富集因素作用、煤矿生产因素作用等四个因子,其方差贡献率分别为55.022%、12.753%、9.803%、8.009%,四个因子可以用于说明济宁南部区域表层土壤地球化学特征85.587%的形成原因。研究结果可以为研究区今后开展耕作层土壤环境质量评价,以及生态平衡研究奠定基础。