RELATING TRENDS OF PRINCIPAL COMPONENTS TO TRENDS OF WATER-QUALITY CONSTITUENTS1

ABSTRACT: The seasonal Kendall test is used for detecting water-quality trend or lack of trend for monthly data of 15 water-quality constituents at 15 sampling stations in the Arkansas River, the Neosho River, and the Verdigris River basins. Trends of individual constituents and the trends of the first four principal components for the correlation matrix of water-quality data at each station are determined, and the relationships between the trends of constituents and the trends of principal components are established. Using the principal components not only reduces the high dimensionality of the original data to a few principal components, but also presents an overall picture of water-quality trend of these river basins.     

TRENDS IN FRESHWATER INFLOW TO SAN FRANCISCO BAY FROM TUE SACRAMENTO-SAN JOAQUIN DELTA1

ABSTRACT: Outflow from the Sacramento-San Joaquin river system (Delta outflow) provides about 90 percent of the freshwater flow to San Francisco Bay. Because this river system also supplies most of the water used in California, some believed that annual freshwater flow to the Bay had declined by as much as 50 to 60 percent as water use increased. Consequently, we studied trends in actual Delta outflow and precipitation for the period 1921 to 1986, which is when Delta outflow data are available. We found that there has been no decrease in the annual Delta outflow over this period. In fact, a statistically significant increase in annual Delta outflow of 87 cfa/yr has occurred during the period 1921 to 1986. One reason that Delta outflow has increased is because precipitation has increased faster than water use. Other contributing factors include increased runoff from land use changes, water imports from other areas, and the redistribution of ground water. In addition, statistically significant seasonal trends in Delta outflow were found. Over the period 1921–1986 Delta outflow decreased in April and May and increased from July through November. Changes in other months were not statistically significant. These seasonal changes result primarily from the operation of upstream flood control and water development projects, which store water in the spring and release it in the summer and fall. These seasonal changes are also influenced by a climatic shift that has decreased spring snowmelt runoff and increased late summer through winter precipitation.     

NEW ZEALAND'S NATIONAL WATER QUALITY MONITORING NETWORK - DESIGN AND FIRST YEAR'S OPERATION1

ABSTRACT: The design and implementation of a national surface water quality monitoring network for New Zealand are described. Some of the lessons learned from the first year of operation are also addressed. Underpinning the design, and specified in advance, are the goal and objectives, the data quality assurance system, and the mechanism for data interpretation and reporting. Because of the difficulties associated with the use of a multitude of different agencies, only one agency is involved in field work and one laboratory undertakes the analysis. Staff training has been given a high priority. The network has been designed to give good trend detectability for regular sampling over a 5–10 year period.     

农村商品流通网络模型及其发展趋势

农村商品流通是影响农业发展和农民消费的直接因素，完善农村商品流通网络对开拓农村市场，增加农民收入，发展农村经济具有推动作用。首先论述了农村商品流通网络的内涵；其次提出了基于主导要素的3种农村商品流通网络模型，即交易市场主导型、企业组织主导型和流通技术主导型，并对网络主体及其关系等方面进行了分析；最后提出了农村商品流通网络的发展趋势及其相应对策。     

矿山机械安全技术的现状与对策

从机械故障诊断、机械安全设计、机械安全法规及标准、煤矿安全认证和人员培训等方面,简述机械安全技术的现状及发展趋势;指出目前我国矿山机械安全技术领域存在的主要问题。提出加强高级技术人才培养,强化操作人员培训;建立矿山机械安全设计体系,加强矿山机械高防爆性能的本质安全设计;制定和完善矿山机械安全法规及标准,落实煤矿安全认证和监察;加大技改资金的投入力度等重要对策和措施。逐步提高矿山机械安全技术水平,从而保障煤炭生产设备的安全高效运行。     

Geochemical stability of phosphorus solids below septic system infiltration beds

Review of 10 mature septic system plumes in Ontario, revealed that phosphorus (P) attenuation commonly occurred close to the infiltration pipes, resulting in discrete narrow intervals enriched in P by a factor of 2-4 (. MSc thesis, Dept. Earth Sci., University of Waterloo, Waterloo, Ont.; Ground Water 36 (1995) 1000; J. Contam. Hydrol. 33 (1998) 405). Although these attenuation reactions appeared to be sustainable under present conditions, the potential for remobilization of this P mass, should geochemical conditions change, is unknown. To test the stability of these P solids, dynamic flow column tests were carried out using sediments from three of the previously studied sites (Cambridge, Langton and Muskoka) focusing on sediments from the 'High-P' and underlying (Below) zones. Tests were continued for 166-266 pore volumes (PVs), during which time varying degrees of water saturation were maintained. During saturated flow conditions, relatively high concentrations of PO4 were eluted from the Cambridge and Langton High-P zones (up to 4 and 9 mg/l P, respectively), accompanied by elevated concentrations of Fe (up to 1.4 mg/l) and Mn (up to 4 mg/l) and lower values of Eh (<150 mV). The Below zones from Cambridge and Langton, however, maintained lower concentrations of P (generally<2 mg/l), Fe (<0.2 mg/l) and Mn (<1 mg/l) and maintained higher Eh (>250 mV) during saturated flow conditions. During unsaturated flow, P and Fe declined dramatically in the High-P zones (P<1 mg/l, Fe<0.2 mg/l), whereas concentrations remained about the same during saturated and unsaturated flow in the Below zones. This behavior is at least partly attributed to the development of reducing conditions during saturated flow in the High-P zones, leading to reductive dissolution of Fe (III)-P solids present in the sediments. Reducing conditions did not develop in the Below zones apparently because of lower sediment organic carbon (OC) contents (0.03-0.04 wt.%) compared to the High-P zones (0.2-0.65 wt.%). At the Muskoka site, where the sediments were noncalcareous, low values of P (<0.2 mg/l) were maintained in both the High-P and Below columns and reducing conditions did not develop. Results indicate the possibility of remobilizing P accumulated below septic system infiltration beds should conditions become more reducing. This could occur if sewage loading patterns change, for example when a seasonal use, lakeshore cottage is converted to a permanent dwelling.     

盐城市区饮用水源富营养化趋势研究

运用综合营养指数法对盐城市区饮用水源地水质的富营养化趋势进行了评价,针对饮用水污染状况提出了防治意见和建议。     

近年来广州市氮氧化物变化趋势分析

氮氧化物是生成臭氧光化学反应的主要前体物,氮氧化物可以经过一系列的光化学反应生成硝酸盐气溶胶,导致城市能见度下降,出现灰霾现象。氮氧化物也是造成酸雨污染的主要物质。广州作为珠江三角洲的中心城市,近年来氮氧化物的污染不容忽视。本文以2003年-2008年监测数据为基础,对广州市氮氧化物浓度的日变化、月际变化、年际变化作了详尽的分析。结果表明,广州市氮氧化物浓度近年来呈现下降趋势;氮氧化物的月际变化呈明显的季节特征,冬季污染较严重,夏季污染较轻。     

20年来昆明市环境空气质量变化趋势及影响因素分析

通过昆明市环境空气监测资料,研究昆明市20a来环境空气质量的变化趋势及其影响因素。结果表明,从年际变化看二氧化硫有明显上升趋势;二氧化氮有上升趋势,但不明显;综合污染指数、可吸入颗粒物有明显下降趋势。20a来环境空气质量变化的主要影响因素有：产业结构的变化、重点污染源的整治、节能减排和能源结构调整、清洁能源的使用、机动车尾气的控制等。     

除夕夜烟花爆竹燃放对呼和浩特市空气质量的影响

分析2005～2009年除夕夜空气质量浓度资料,结果表明,烟花爆竹燃放集中燃放时段PM10、SO2、NO2浓度出现高峰值,各监测站点浓度变化趋势基本一致。