中文3790字
附录(外文翻译)
BIOMEDICAL AND ENVIRONMENTAL 17,87-100(2004)
Water Quality Assessment of the River Nile System: An Overview
RIFAAT A. WAHAAB AND MOHAMED I. BADAWY
National Research Center, Dokki, Cairo, Egypt
Objectives： The main objective of the present article is to assess and evaluate the characteristis of the Nile water system，and identify the major sources of pollution and its environmental and health consequences. The article is also aimed
to highlight the importance of water management via re-use and recycle of treated effluents for industrial purpose and for cultivation of desert land. Method An intensive effort was made by the authors to collect, assess and compile the available data about the River Nile. Physico-chemical analyses were conducted to check the validity of the collected data. For the determination of micro-pollutants, Gas
Chromatography (GC) and High Performance Liquid Chromatography (HPLC) were used. Heavy metals were also determined to investigate the level of industrial pollution in the river system. Results The available data revealed that the river receives a large quantity of industrial, agriculture and domestic wastewater. It is worth mentioning that the river is still able to recover in virtually all the locations, with very little exception. This is due to the high dilution ratio. The collected data confirmed the presence of high concentrations of chromium and manganese in all sediment samples. The residues of organo-chlorine insecticides were detected in virtually all locations. However, the levels of such residues are usually below the limit set by the WHO for use as drinking water. The most polluted lakes are Lake Maryut and Lake Manzala. Groundwater pollution is closely related to adjacent (polluted) surface waters. High concentrations of nutrients, Ecoli, sulfur, heavy metals, etc. have been observed in the shallow groundwater, largely surpassing WHO standards for drinking water use. Conclusion A regular and continuous monitoring scheme shall be developed for the River Nile system. The environmental law shall be enforced to prohibit the discharge of wastewater (agricultural, domestic or industrial) to River Nile system.
Key words: Water quality; River Nile; Lakes; Pollution sources; Assessment
INTRODUCTION
The availability of water of acceptable quality in Egypt is limited and getting even more restricted, while at the same time, the needs for water increase as a result of population growth, industrial development and cultivation of desert land. The
country depends for more than 90 percent of its water supply on the River Nile. Groundwater resources are limited and the direct contribution of rainfall, except for the Mediterranean coastal area, is neglected. Irrigated agriculture is by far the largest consumer of water (almost 90percent) and,although advances in irrigation and
agricultural technologies stimulate water conservation,further intensification of crop schedules and extension of agricultural areas put an increasing demand on the already scarce water resources. Competing demands between industrial development and human consumption are puttinga severe strain on a balanced allocation ofthe limited resources to the various users.
Water Resources
The River Nile forms the main water resource of Egypt. Through the 1959 Nile Water Agreement with Sudan and the completion of the High Aswan Dam in 1968, a stable 55.5 billion m3/yr. was allocated to Egypt. The actual release from the High Aswan Dam shows very little yearly variation. Annual variation of the release of water from the High Aswan Dam depends mainly on irrigation needs. The release from the high Aswan Dam ranges from approximately 800 m3/s during the (winter) closure period to approximately 2 760 m3/s during the summer months. In the Nile Valley and Nile Delta, groundwater resource use mainly being recharged from the Nile and from account for approximately 4.4 billion m3/yr.,
seepage from irrigated agriculture. Rainfallsplays a minor role in Egypt's water resources, with average rainfall rates declining from 200 million m3/yr. at the Mediterranean Coast to 20 mm .in Cairo and almost zero in Upper Egypt.
Water Consumption
In the 1993/94 hydrological season, gross water consumption of irrigated agriculture amounted to approximately 54.5 B. (billion) m3/yr. (of which almost 30 B. m3/yr. occurred in the Delta). Other water users, such as municipal and domestic drinking water s industry and others consumed approximately 8.8 B，and an estimated 2.0 B. about 14.0 B. was lost through evaporation anddischarged to the Mediterranean Sea (Table 1). In recent years, theamount discharged to the Mediterranean Sea directly from the River Nile system, declin3ed sharply, in favour of agricultural and drinking water use approximately 2.3.m discharged in 1990 compared with approximately
1.2B.Cu y t3h.e release. of water from the High Aswan Dam (HAD), varies between 52.9 and 57.4 B. m-iyr. with rncreasmg expected uses, Egypt will nave to rely on groundwater aquifers and on expensive desalinization of sea water. Therefore the existing renewable resources must be extremely carefully managed to adequately supply the rapidly increasing
population and industrial activity, through options such as increased efficiency of irrigation and/or changes in crop types, and reducing areas under irrigation.
The current water use from the Nile River and projections to year 2000 shows a rapid increase in demand, which isprojected to be met by using water from the drains and reducing the flow from drainsto the sea. This poses serious issues since the water in the drains is currently of poor quality due to pollution from industrial, municipal and agricultural sources.
Industrial Pollution
Deterioration of its surface and groundwater due to Egypt faces a rapidly
increasing and industrial effluents into its discharges of heavily polluted domestic in agriculture also causes water waterways. Excessiveuse of pesticides and fertilizers pollution problems.
Egyptian industryuses 638 M. m3/yr. of water, of which 549 M. m3/yr. is discharged to activities in the Greater Cairo and Alexandria regions use the drainage system. Industrial 40% of the total. The River Nilesupplies 65% of the industrial water needs and receives more than 57% of its effluents.More detailed information about water consumption, sourcesof pollution and loads from different industrial wastewater discharge and point sectors are provided.
The area has a population of approximately a million and encompasses many industrial and commercial activities. Heavy industry is located around South of Cairo, and, North of Cairo. Many small industries and some heavy industry are randomly located throughout the city. Although wastewater discharges of the small industries are generally low, concentrations of certain industries in specific areas, such as the tanning overview cause local contamination problems. Anof pollution sources is include 23 chemical industries, 27 textile and spinning industries, 7 steel and galvanizing industries, 32 food processing industries (including a brewery), 29
engineering industries, 9 mining and refraction industries, and petrol and car service stations. Bakeries (>350), marble and tile factories (>120) and tanneries are located in South Cairo.
Alexandria is a major industrial center with some 175 industries, about 25
percent of the total in Egypt. These industries include paper, metal, chemical, textile, plastic, pharmaceutical, oil and soap, and food processing. These plants are reported to contribute some 20 percent of the total wastewater of Alexandria. The industries discharge theireffluents mainly to Lake Mariut and pardsewerage network. According to a survey made by Drainage Research Intypes of industrial
lirectly to the lake wastes are disposed to Lake Maryut. At least 17 factories through pipelines; 4 factories collect their wastewater in I lying in the vicinity of the treatment plants; 22 factories discharging to nearby drains and then to the lake.
It is worth mentioning that the totalamount of BOD discharged to the River Nile by industrial plants equals 270 ton/day. Thisamount corresponds to the untreated discharge of wastewater from more than six million people. It can be concluded that these substances are discharged mainly from the industrial activities in the Greater Cairo region and in Delta (0.75 and 0.50 ton/day). The average concentration of heavy metals (HM) in the effluentis less than 5 pg/L, which is slightlymore than a normal background figure (Table 2 C).
Domestic Pollution
The way domestic pollution affects water quality heavily depends on the way of disposal of this pollution. Approximately 65 percent of Egypt's population is connected to drinking water supply and only 24 percent to sewerage services, although the latter percentage is expected to grow rapidly, due to works under
construction. The population not connected to sewerage systems relies on individual means of excreta and wastewater disposal such as latrines and septic tanks.
According to ananalysis of the different references (World Bank, 1993), in Upper 8 wastewater treatment facilities exist with a total capacity of roughly 120 000 with approximately the same amountunder construction now. In Greater Cairo, 5 wastewater treatment plants exist, with a totalcapacity of approximately 1 850
000m3/day. In the delta there are more than 30 wastewater treatment facilities with a total capacity of almost 400 000 , with some 100 000 m3/dayunder construction. In Upper Egypt and in the Delta, some domestic wastewater receives treatment. In the Greater only primary Cairo area,the sewerage systems also serve small industries and commerce.
Agricultural Pollution
Agricultural is the major non-point sourcepollution, with a number of potential impacts on the environmental and human health. In many agricultural areas, local surfaceand groundwater contamination has resulted from leaching of nitrates from fertilizers and bacteria from livestock and feed wastes. Agricultural pesticides are both a potential diffuse source of water contamination.
Since the construction of the High Aswan Dam, the water quality of the Nile became primarily dependent on the quality and ecosystem characteristics of the Lake Nasser reservoir and less directly dependent on the water quality of the upper reaches of the Nile. Water released from the Lake Nasser generally exhibits the same seasonal variation and the same overall characteristics from one year to another. Downstream changes in river water quality areprimarily due to (i) the hydrodynamic regime of the river, regulatedby the Nile barrages,(ii) agricultural return flows, and (iii) domestic and industrial waste discharges including oil and waste from boats. These changes are more pronounced as the river flows through the densely populated urban and industrial centers of Cairo and the Delta regioni91. Nile Research Institute of the National Water Research Center is intensively involved in the monitoring of water quality of the River Nile and its branches. All the pollution parameters are to be measured according to the updated edition of the American Standard Methods for Examination of Water and Wastewater.
ENVIRONMENTAL IMPACT
As a result of poor wastewater treatment, high concentrations of coliform
bacteria are found in the Nile and its branches downstream of Cairo. Values of 1 to 10 million (Most Probable Number) MPN/100 ml, have been measured in the Rosetta branch. This is far above the standard of five thousand MPN/100 ml, as given in Law 48 of 1982. Since exposure to pathogenic bacteria can cause serious health problems, adequate treatment of sewage should be given high priority.
High concentrations of pesticides are found in the Nile and Rosetta Branch. For example, the reported concentration for linadane (y-HCH) and DDT are 5 to 10 times above European standards. As agricultural activities are the principal source, it is expected that concentrations in agricultural drain are even higher. The risk of pesticides relates to drinking water supply without proper treatment (by means of active carbon) and the accumulation in fish products. The problem asks for a sound baseline study, including a review of pesticide use, import and production and
measured concentrations in variouswater booddiieess,，with special attention given to drinking water resources and fishing areas.or immediate, actions might
be necessary m case unacceptable concentrations are found in drinking water. Although various studies and monitoring efforts have been carried out, information on water quality status, its causes and effects shows many gaps. To enable the formulation of effective measures to prevent further pollution of the vital water resources and to restore polluted areas, more detailed information is required for pollution sources, the transport and behavior of pollutants in the water system, the assimilative (self-purification) capacity of the water system, and the impacts of
pollutants on various water uses. This calls for an adequate routine monitoring system, a data base and information system and an integrated modeling
approach, to analyze the impact of individual pollution sources on ambient water quality, to evaluate the efficiency of proposed actions. The design of the monitoring system could be as follows: (i) early warning system (EWS): an early warning system is recommended. The sensor system will receive and send information to a central processing unit. There can be on-line measurement equipment, the general public observing calamities, the police officially involved in all kind of accidents and the eventual polluters, which then have a legal obligation to report environmental accidents; (ii) monitoring locations: for the river
Nile，the important drinking and irrigation water intake points, together with the sources of pollution along the river are recommended to be monitored according to their km locations. In order to enable some early predication of water quality at the release from the High Aswan Dam, monitoring sites must be planned at a various locations in the Lake Nasser. For Nile branches and the irrigation canals, a similar design procedure are to be followed; (iii) selection of parameters: to obtain a good overview of the water quality status at a particular monitoring location, a minimum package of 35 parameters, including organoleptic parameters, general parameters, major ions, trace metals and non-metals, biodegradable organic materials, nutrients, microbiological and parasitological parameters are to be measured. This package has to be measured, at least seasonally. However, selective parameters are to be measured monthly in some locations.
Pollution control in large scale-The Egyptian Environment:Affairs Agency (EEAA) has identified 41 industrial enterprises in the public sector, whichurgently need to reduce their discharge of untreated wastewater. Feasibility studies were
carried out (financed by USAID five years ago), and implementation of recommended solutions could begin immediately after review of the studies. The action also aims to introduce (a) a datahase system to identify all effluents from large-scale
industries ;and (b) an effluent monitoring program for regular sampling. This action will initiate a vital clean-up of current majo industrial discharges in the chemical, textile and food processing sectors, resulting in an increased availability of surface water resources without high treatment costs. It will also provide a considerable source of important information to EEAA and other water managing authorities to support planning of futuremeasures
生物医学与环境科学 17，87－100（2004）
尼罗河体系的水质评价：综述
拉夫特A·瓦哈博 穆罕默德I·巴达维
埃及·开罗·Dokki研究中心
题目：目前许多课题的主要目标是对尼罗河水系进行评估，并且鉴定其主要污染物质以及其对环境和人类健康造成的危害，这些课题还注重之处水处理和水的再生回用的重要性，可以将其回用给工业用水或者沙漠地带的灌溉用水。
方法：作者做出很大的努力收集和编纂有关尼罗河的有用的数据，物理化学分析被用来检验收集数据的有效性，其中气相色谱和高性能液体色谱法均被采用，重金属也也被调查看是尼罗河受到工业废水的污染。
成果：这些有用的数据证实河体接纳了大量的工业、农业和居民生活污水，值得一提的是，除了一小部分以外，大部分区域水体还能够自然的恢复到原来的状态，这主要是由于很高的稀释率，这些收集到的数据证实了高浓度的铬和锰，水中监测到有杀虫剂中的氧氯化合物，尽管如此，这些沉淀物的含量还是比WHO规定的饮用水最大的含量要低，污染最严重的湖泊是Maryut湖和Manzala湖，地下水污染经常是和地表水的污染有密切关系的，高浓度的氮、硫＝重金属等等，已经在地下水中被监测到，其含量大大超过了WHO所要求的饮用水最高要求。
结论：尼罗河水系急需一个有秩序的、连续的管理机制，环境法律将严格禁止工业、农业和生活废水排入尼罗河。
关键词：水质，尼罗河，湖泊，污染源，评估
简 介
在埃及水质可以被接受的水的利用是有限的，甚至是受限的，而与此同时，伴随着人口增长，工业发展和土地沙漠化，水的需求量有增无减，埃及90％的水供应来源于尼罗河，除了地中海沿线区域，地下水是很有限的并且是降雨的主要来源，这一点被忽略，灌溉用水占总用水量的90％，尽管灌溉和农业技术节
约了大量的水，但是植物生长和农业区的扩张都需要大量的水，工业发展和人类消耗对有限的水资源的平均分布造成了严重的威胁。
水源 ：
尼罗河是埃及主要的水源，通过19xx年和苏丹大城的关于尼罗河的协定，还有19xx年阿斯旺大坝的建成，每年都要55.5亿立方米的水被分配给埃及，每年的阿斯旺大坝的放水，取决于农业灌溉的需要，阿斯旺大坝冬季的放水量大约是800立方米每秒，夏季的放水量为2760立方米每秒，在尼罗河流域和尼罗河三角洲，地下水资源的利用可达每年44亿立方米，主要用于农业灌溉，降雨调节着埃及的水资源分配，地中海沿岸的降雨量平均是每年2亿立方米，而开罗和埃及其他地区降水量几乎为零。
耗水量：
在1993/94年度的丰水季节，农业灌溉用水的总耗水量大约为545亿立方米，而像市政和居民生活用水，工业和其他消耗用水大约占88亿立方米，每年都有20亿立方米的水蒸发流失，还有大约140亿立方米的水流进地中海，近年来，流进地中海的水量急剧下降。
当前，阿斯旺大坝的放水量保持在529～574亿立方米，伴随着需求量的增加，埃及将不得不依靠地下水和昂贵的海水淡化，因此，现有的水资源必须被严格的管理以保证人口和工业需求，这些可以通过提高灌溉用水的利用率以及缩减灌溉区域。
目前关于尼罗河的水资源的利用预示着需求量的快速增长，这就要求必须使用地下水和尽量减少流入大海额水量，既然当前水质受到工业、农业和市政用水的严重污染，这就形成了严重的问题。
工业污染：
由于污染严重的生活和工业污水流入水体，埃及面临着地表水和地下水的恶化，杀虫剂和化肥的大量使用都将造成严重的水体污染，
埃及的工业生产每年使用6.38亿立方米的水，其中5.49亿用于排泄系统，在开罗和亚力山大地区的工业活动用水量占总的40％，尼罗河供应工业用水的65％，接纳多于57％的水量。
开罗地区大约有1500万人，从事着许多工业和商业活动，重工业坐落在开罗南部，或者北部，许多小工业和一些重工业零散地分布在城市中，尽管小工业产生的废水量很低，但是都集中在一些特殊工业领域，这些污染源包括23个化工工业，27个纺织和针纺工业，7个钢铁工业，32个食品加工工业，29个机械生产工业，和9个矿产业。
亚力山大地区是主要的工业中心，它有175种工业，大约占埃及总量的25％，这些工业包括造纸，钢铁，化工，纺织，塑料，制药，适于，食品加工，这些工厂制造了亚力山大地区20％的污水量，这些工业将污水排入Mariut湖，一部分排入市政污水管道，通过Drainage研究所的一项调查，不同的工业废水被排入Maryut湖，至少17个工厂通过排水管道直接排入河体，4个工厂收集她们的污水，19个工厂设有污水处理设施，22个工厂把水处理后排入湖泊。
值得一提的是工业企业排入尼罗河的BOD的量相当于每天270吨，这个量相当于600万人口的废水未经处理直接排放，于是我们得出结论，这些污染物质主要来源于开罗和亚力山大地区的工业活动，重金属的含量为5毫克每升。
生活污水污染：
生活污水的污染作用于水质主要决定于这些污染物的排放途径，大约65％的埃及人口与饮用水的供应有直接关系，但是只有24％的水经过处理，尽管后者增长迅速，那些不参与水处理的人口依靠自身的方法将污水进行处理。
经过世界银行的分析，在埃及北部，8个污水处理厂承担着大约120000吨每天的污水处理量，在开罗地区，共有5座污水处理厂，处理能力在每天1850000吨，在delte，总共有30个污水处理厂处理能力为400000吨每天，并且有一些每天处理量为100000吨的处理厂正在建设。
农业污染：
农业是主要的不定点污染源，对环境和人类健康都有潜在的威胁，在许多农业地区，当地的地表水和地下水污染主要是由于化肥中氮的过量排放，农药也是一个潜在的水污染源。据估计，在埃及北部，大约4十亿的污水返流回尼罗河，这些污水含有大量的污染物，幸运的是，尼罗河大的稀释率将污染物保持在可以接受的浓度范围内。
自从阿斯旺大坝建成之后，尼罗河的水质主要取决于Nasser湖储水机制，不太直接依赖于尼罗河上游的水质，从Nasser流出的水呈现出相同的季节变化，具有年复一年的相同的特性。埃及国家水质研究中心尼罗河研究所正致力于尼罗河以及分支的水质监管工作，所有的污染参数将根据美国水质监测标准进行测量，据报道，由于有机物和非有机物的排入，尼罗河将其大大稀释和降解，尼罗河中的微生物状况良好，除了阿斯旺大坝下游40公里内的水域，其他水域的水中溶解氧含量均接近饱和，均在每升3.1至9.5毫克之间，大量的污染物，比如总氮、总磷、BOD均保持在最大容量以内。
在埃及北部地区共有4个主要湖泊，他们直接属地中海流域，这些湖泊被分裂成狭长地带，并且都不组2米深，它们盛产鱼类，并且Maryut湖曾经被用于水上飞机的一个着陆点，不幸的是，这些湖泊已经严重变质，原因是在过去的20年，大量的污水排入其中，三种废水导致这些污染，生活污水、未经处理的工业废水和农业水，生活污水直接排入大海，工业废水由于新工业的增加，其量大大增加，而农业废水伴随着阿斯旺大坝的建成也急剧增加，原因是农业用地被用于更多的农作物生产。
污染最严重的湖泊是Maryut湖和Manzala湖，Maryut湖接纳农业废水和生活工业废水，许多工厂将其污水直接排入湖泊，导致BOD等污染物的浓度很高，鱼类生产也几经由60年代的每年7000吨下降到现在的每年不足100吨，这是一个警告，渔民不得不离开原来的居住地，或者转向其他的工作，比如便宜的农业劳动力或者捡垃圾。
环境影响
由于不良的废水处理，在尼罗河和它的分支中发现高浓度的细菌，每100毫升100万到1000万MPN已经被检测出来，这远远大于每100毫升5000MPN的标准，这个标准是19xx年法规的第48条规定的，既然大量的细菌会导致严重的健康问题，充分的处理就应该得到高度的重视。
高浓度的农药被排入尼罗河和Rodetta分支，例如，据报道的DDT含量是欧洲标准的5～倍，由于农业活动是农药的主要来源，所以估计农业废水中的浓度会更高，农业废水未经处理排河，在鱼类体内富集，这与饮用水安全有很大的关系。
这个问题要求进行最基本的研究，包括农药使用、进口、生产和在不同水体进行测量，短期之内，这些研究是有必要的。
据报道在Rosetta分支中发现高浓度的金属含量，亚力山大地区和Manzala湖泊也有，Rosetta分支中的测量表明，镉铜锌是高于标准的，埃及关于铜和锌的标准是每升中1000毫克，而欧洲的标准中铜为50毫克每升，锌为150毫克每升，在亚力山大地区还发现有高浓度的汞含量，在Manzala湖的底部沉淀物中含有大量的富集金属，这对湖泊中鱼类的影响尚未证实，由于重金属沉积在湖泊中，这对环境构成一个长远的威胁，现在有必要采取措施制止这一趋势。
尽管大量的被水生生物导致的疾病已经被报道，但是肯定会有更多的人在承受着由水污染导致的疾病的折磨，饮用水中的和食品中的农药成分和重金属可以作用于人体健康，对饮用水水质和鱼类产品的有序控制必须在短时期内实现，并采取充分的措施以防止人类受有害污染物的更深的危害。
尽管各种研究和监管措施已经得以实施，但是有关水质变化的产生和带来的影响方面的信息还不足，为了能够形成有效的测量机制以防止更严重的水资源污染，需要对污染源、污染物在水体中的传递、个污染物的影响个方面有更详细的信息，这就要求有一个充分的管理体系，数据库和信息系统，用来分析污染物对水质的影响，检测系统的设计应按照以下程序：1.早期预警系统：一个早期预警系统是必需的，监测系统接受和发送信息给中心控制系统，这些可以是在线监测设备，通常的公共预警机制，警察可以很快参与到各种事故和污染时间中去，2.监测点：对于尼罗河来说，重要的饮用和灌溉水源需要通过定点进行监测，为了能够使对于从阿斯旺大坝放的水进行早期的水质预测，监测点必需布置在Nasser湖的附近，对于尼罗河及其分支还有灌溉渠道都有设置相似的监测。
埃及环境事务所已经确定了41家工业企业，这些企业需要降低它们未经处理就排放的水量，适当的研究工作已经实施，紧接着就要采取措施，这些措施可以为埃及环境事务所提供重要的信息和其他污水管理措施，以便进行更甚的研究。