EVALUATING THE INFLUENCE OF SOURCE BASINS ON DOWNSTREAM WATER QUALITY IN THE MISSISSIPPI RIVER1

ABSTRACT: Chemical variability in the Mississippi River during water years 1989 to 1998 was evaluated using stream discharge and water‐quality data in conjunction with the DAFLOW/BLTM hydraulic model. Model simulations were used to identify subbasin contributions of water and chemical constituents to the Mississippi River upstream from its confluence with the Ohio and the Mississippi River and at the Atchafalaya Diversion in Louisiana. Concentrations of dissolved solids, sodium, and sulfate at the Thebes site showed a general decreasing trend, and concentrations of silica and nitrate showed a general increasing trend as the percentage of discharge from the Mississippi River upstream from Grafton increased. Concentrations of most chemical constituents in the Mississippi River at the Atchafalaya Diversion exhibited a decreasing trend as the percentage of water from the Ohio River increased. Regression models were used to evaluate the importance of the source of water to the water chemistry in the Mississippi River at Thebes and the Atchafalaya Diversion. The addition of terms in regression equations to account for the percent of water from sub‐basins improved coefficients of determination for predicting chemical concentrations by as much as nine percent at the Thebes site and by as much as 48 percent at the Atchafalaya Diversion site. The addition of source‐water terms to regression equations increased the estimated annual loads of nitrate and silica delivered from the Mississippi River Basin to the Gulf of Mexico by as much as 14 and 13 percent, respectively.     

A Critical Appraisal of Field Evidence From A Regional Survey for Acid Deposition Effects On Scottish Moorland Podzols

Samples have been collected from major horizons of 34 podzol profiles distributed throughout Scotland, all developed from granite or granitic tills and under Calluna moorland. the pH in water and calcium chloride pastes, exchangeable cations and cation exchange capacity, and extractable aluminium of the soils collected have been measured, and the results studied in relation to reported atmospheric deposition of H⁺, non-marine sulphur and nitrate. for all horizons, significant positive correlations were found between soil pH and rainfall mean pH, as might be expected when the critical load of H⁺ deposition is exceeded. Acidifying pollutant deposition also apparently increased soil extractable aluminium concentrations in the B and C horizons. However, exchangeable base cation concentrations tended to increase, rather than decrease, with increasing precipitation acidity. This effect was attributed to increases in biogeochemical cycling of base cations, increases in leaching inputs of base cations from overlying A/E horizon soils, and increases in the inputs of base cations leached from upslope. the results suggest that the simple steady state mass approach to the quantification of critical loads, as often applied, may be an oversimplification.     

Needs of communications with general public about the potential risk of electromagnetic fields and methods for achieving this goal

In the recent years concerns whether exposure to electromagnetic fields (EMF) from base station antennae can cause adverse health effects are grown. Great attention is paid on risk of EMF exposure to people living in a close proximity of base stations. In this issue, a point of interest is the personnel mounting, adjusting and maintaining base stations. Their working tasks require stay in high EMF levels’ conditions. There are only few studies concerning this specific occupational group. The results from our previous investigation (Zaryabova and Israel 2006) show that in␣many cases on performing some specific tasks operators are overexposed according to our national legislation, and ICNIRP guidelines. Here, we present an extended study covering more base stations and more precise scenario for performed tasks and working positions. Results of exposure assessment are presented. They include energetic load calculations on the basis of Bulgarian national legislation, and the corresponding SAR values. Data are used to determine permissible time duration for each particular work operation and served as a base for limiting the exposure and proposal for protective measures for the personnel.     

建筑物地震损失估计方法对比分析

合理而准确地确定建筑物的地震损失是当今防震减灾研究的一个主要课题,也是地震保险费率厘定的前提.目前,我国已经在地震发生概率、场地类型、结构性能、财产分布等方面积累了许多震害统计资料.同时,不断应用地震学、抗震工程学和计算方法方面新的研究成果于地震损失的计算,形成了几种常见的损失估计思路和方法.这其中主要包括传统的地震灾害损失风险评估方法、基于动力可靠度的损失分析方法和基于结构性能的损失确定方法.从合理性和适用性的角度,对这3种方法进行了评述和比较,以此看出各种方法的优点和局限性以及分析思路的发展演变过程,并希望从中能够看出今后研究工作的一些方向.     

蚁群算法在马斯京根模型参数估计中的应用

蚁群算法是一种模拟进化算法,该算法具有许多优越的性质.研究了一种可用于求解连续空间优化问题的蚁群算法策略,针对洪水演算的马斯京根模型参数估计问题,应用连续性空间优化问题的蚁群算法模型进行了求解.应用实例表明,蚁群算法在求解连续空间优化问题中是很有效的,可以广泛应用于各种自然灾害模型的优化问题.     

Ecological modeling for water quality management of Kwangyang Bay, Korea

This study estimated the appropriate pollutant load reduction from point sources in Kwangyang Bay, Korea, using an eco-hydrodynamic model. The total chemical oxygen demand (COD), nitrogen (TN), and phosphorus (TP) loads from rivers and ditches that provide input to the bay were approximately 2.8x10(4), 2.5x10(4), and 5.9x10(2) kg day-1, respectively. Wastewater discharge from industrial complexes was the greatest contributor to pollutant loads in the inner part of the bay. COD values in the inner part of the bay were greater than 3.0 mg l-1, and exceeded Korean seawater quality grade III limits. A residual current was simulated, using a hydrodynamic model, to have a slightly complicated pattern in the inner part of the bay, ranging from 0.001 to 8 cm s-1. In the outer part of the bay, the simulated current flowed out to the South Sea with a southward flow at a maximum of 15 cm s-1. The results of the ecological model simulation of COD levels showed high concentrations, exceeding 4 mg l-1, in the southwest of the Myodo, an area of wastewater discharge, and lower levels, approaching less than 1 mg l-1, closer to the outer part of the bay. Engineering countermeasures to reduce the organic and inorganic material loads from point sources by more than 45% were required to keep the COD levels below 2 mg l-1.     

POINT‐NONPOINT SOURCE WATER QUALITY TRADING: A CASE STUDY IN THE MINNESOTA RIVER BASIN1

ABSTRACT: Contrary to the general trend of only a few actual trades occurring within point‐nonpoint source water quality trading programs in the United States, two trading projects in the Minnesota River Basin, created under the provisions of National Pollutant Discharge Elimination System (NPDES) permits, have generated five major trades and numerous smaller ones. In this paper, these two projects are described to illustrate their origins, implementation, and results. It was found that several factors contributed to the relatively high number of trades in these projects, including the offsetting nature of the projects (hence a fixed number of credits that the point sources were required to obtain), readily available information on potential nonpoint source trading partners, and an effectively internal trading scheme used by one of the two projects. It was also found that long term structural pollution control measures, such as streambank stabilization, offered substantial cost savings over point source controls. Estimates of transaction costs showed that the total costs of the trading projects were increased by at least 35 percent after transaction costs were taken into account. Evidence also showed that in addition to pollution reduction, these two trading projects brought other benefits to the watershed, such as helping balance environmental protection and regional economic growth.     

区域大气污染总量控制的渐进方法

对污染物实施总量控制是我国当前和今后污染控制和管理的方向。本文对区域大气污染总量控制的一般方法进行了讨论。考虑到污染控制成本和公平性要求 ,采用浓度控制与总量相结合的循序渐进方法 ,并提出了促进环境与经济协调发展的总量控制负荷优化分配模型 ,以期对各地总量控制的实施提供参考和借鉴     

大气污染预测软件的测试

针对大气预测工作中可能出现的各种偏差,结合影响大气扩散的主要因素,对大气污染预测软件的测试方法进行了归纳,提出了测试大气预测软件的基本方案。     

固体废弃物填埋场产气率的估算

填埋气体的产生过程可分为需氧分解、需氧/酸性分解、向厌氧分解过渡、厌氧分解和稳定阶段5个.填埋场产气率的估算是填埋场气体收集和控制系统设计的重要环节.本文对填埋场气体和集气井产气量的估算方法进行研究.给出了2种较简单的填埋场气体量的估算方法.并用该方法对一个三角形布置的集气井的产气量进行了估算.结果表明,这2组公式可用于填埋场的产气率的估算.