日本湖泊富营养化对策措施

1、日本湖泊富营养化对策措施-霞浦湖保护计划之富营养化对策措施水落元之 (Motoyuki MIZUOCHI)日本国立环境研究所 亚洲水环境研究室1 概 述尽管水污染控制法规定了工厂和商业公司的污水排放标准，但这还是不能使湖泊的保护让人满意。 因此1984年通过了湖泊水质保护特别措施法，并纳入了水污染控制法 。这么做旨在对以下十个富营养化非常严重的湖泊实施综合性的、有计划的水环境保护：琵琶湖 (滋贺县), 霞浦湖 (茨城县), 中海 (岛根县和鸟取县), 宍道湖（岛根县），諏访湖（长野县）,印旛沼（千叶县）,儿岛湖（冈山县）,手贺沼（千叶县）,野尻湖（长野县）和釜房水库（宫城县）。根据新的法律，要

2、求包括霞浦湖在内的这十个湖泊所在各区制定并执行一个水保护计划来改进湖泊水质。计划中每个执行期为5年。霞浦湖，印旛沼，手贺沼，琵琶湖和儿岛湖的4期计划已经在2005年结束，新计划正在实施当中。在这项研究中，我们将介绍霞浦湖水质保护计划中提到的富营养化对策措施。2 霞浦湖总体情况霞浦湖的特点之一就是它很浅，其平均深度为4米,尽管它有着220 平方公里的面积，这使其成为日本第二大湖。虽然它起初是带咸味的，在下游水闸被关闭，将其作为一个淡水水源和防止盐水损害后，它就成为一个淡水湖。蓄水量大约8亿立方米，平均保持时间大约200天。该湖泊积水面积2157平方公里，大约有100万人口居住在其周围地区。这些地

3、区多为农业，主要种植水稻和畜牧业，没有大型化工业。因此，水主要用来灌溉和用作清洁水，尽管捕鱼业有所下降，但渔业仍然存在。由于鲤鱼疱疹病毒的爆发，曾经繁荣的鲤鱼养殖业也停止运作。3 霞浦湖水质现状霞浦湖周围水质标准（水污染环境质量标准）包括COD（化学氧需求），T-N（总氮）T-P（总磷）；其量值设定分别低于3，0.4和0.03 mg/L以便可以用来饮用。但是，在2003年，平均值远远超过了标准值：COD为7.5 mg/L，T-N为0.91 mg/L，T-P为0.10 mg/L。在过去的十年，水的质量几乎保持在一个没有多大变化的水平上。来自非点源和生活系统的负荷在COD，T-N和T-P中占了很大

4、的比例。从1972年到2003年，霞浦湖每年的COD，T-N和T-P浓度变化如下：CODT-NT-P图1 霞浦湖COD，T-N和T-P浓度年平均变化 (19722003)4 霞浦湖水质保护计划霞浦湖水质保护计划第一期开始于1986年并持续了4期直到去年2005年止。第五期计划已于今年2006年开始；但细节部分还未公开。尽管伴随水质保护计划在过去的20年中实施了多种措施，但尚未观测到其对水质的效果，因此，要求进行审查，包括对规划方法的审查。5 水质保护计划富营养化措施和政策第4期计划中的措施和政策总方针概括如下：（1）生活污水措施 安装下水道系统：将普及率从46% (438,400人)提高到53

5、% (541,900人)。 在农业社区安装下水道系统：在18个社区安装下水道系统（增加系统的人口覆盖率，从49,500人增加到69,200人）。 安装蓄水池综合处理系统：作为一项赠款项目安装6000个蓄水池（影响人口：23,600人），总共安装16,719个蓄水池（2）湖内净化措施 湖底挖泥（在西浦挖泥265万m3），总挖泥量800万m3 创建前滩及随后发展水生植被区，包括芦苇和印度水稻（约20处） 湿地维护（包括大円寺川和园部川） 沼泽恢复工程（(土浦市田村地区) 减少家养鲤鱼生产（从当前的5000吨减少到4700吨） 维护和扩大渔业资源措施（放养鱼苗，包括鲤鱼，鳝鱼和淡水胡瓜鱼，创建植被区

6、） 捕抓有害外来鱼种（太阳鱼和鲶鱼）和无用的小鱼（鲢鱼，胭脂鱼等）（每年捕获总量：有害鱼为113吨；鲢鱼80吨；小鱼160吨） 推进霞浦湖输水工程（3）河道直接净化措施，包括河流 通过汇入河流直接净化（清明川, 樱川和恋瀬川） 并行河道直接净化（在霞浦湖周围修建河道来接受堤防周围降水和农业排水） (樱川村，美浦村和霞浦镇) 农业水道的直接净化（新利根镇和岩瀬镇）生活污水污染的水道的直接净化(潮来市和另一场点) （4）其他措施 工厂和商业点污水排放管理：终止污水排放标准的新的和已有的分类，考虑将排放水质量标准适用于小规模商业点（每天污水排放量小于20立方米） 推进调查和研究：有效利用合作研究网（

7、霞浦湖水环境创新工程）和促进研究成果的现实应用。 建立霞浦湖环境科学中心作为一个水质改善研究综合基地6 结 论在过去的20年中，尽管根据水质保护计划采取了各种各样的措施，然而，霞浦湖的水质没有显现大的改善。直到去年截止的第4期的计划正在总结之中，并将与第四期计划的成果一并在研讨会上提出来。Measures against Eutrophication of Lakes in Japan-Measures against Eutrophication in Plan forConservation of Kasumigaura Lake-Motoyuki MIZUOCHIsian Water E

8、nvironment Section, Asian Environmental Research GroupNational Institute for Environmental Studies (NIES), Japan (Email: mizuochinies.go.jp)1 IntroductionAlthough the Water Pollution Control Law regulates the discharge of effluents from factories and business establishments, it has been unable to sa

9、tisfactorily protect lakes. Therefore the Law Concerning Special Measures for Conservation of Lake Water Quality was enacted into the Water Pollution Control Law in 1984. This was done to implement comprehensive and planned measures for water conservation by designating 10 lakes with extremely progr

10、essive eutrophication: Biwa lake (Shiga prefecture), Kasumigaura lake (Ibaraki prefecture), Nakanoumi lake (Shimane and Tottori prefectures), Shinji lake (Shimane prefecture), Suwa lake (Nagano prefecture), Inba lake (Chiba prefecture), Kojima lake (Okayama prefecture), Tega lake (Chiba prefecture),

11、 Nojiri lake (Nagano prefecture) and Kamafusa dam reservoir (Miyagi prefecture). Based on the new law, the prefectures of each of the 10 designated lakes, including Kasumigaura lake, are required to formulate and enforce a water conservation plan to improve the water quality of the lakes. The durati

12、on of one term of a plan is considered to be five years. The 4th term plan for Kasumigaura, Inba, Tega, Biwa and Kojima lakes ended last year (2005), and the new plan is under way. In this study, we will introduce the measures against eutrophication mentioned in the Plan for Conservation of Kasumiga

13、ura Lake Water Quality.2 Overall Condition of Kasumigaura LakeOne of the characteristics of Kasumigaura lake is its average shallow depth of 4 m despite its large area of 220 km2; this makes it the second largest lake in Japan. Although originally brackish, it became a freshwater lake after the down

14、stream sluice was closed to use the lake as a freshwater source (in 1973) and to prevent salt damage. The storage volume is approximately 800 million m3 and its average retention time is approximately 200 days. The lake covers an area of 2157 km2, and approximately one million people reside in its s

15、urrounding areas. These areas are mostly used for agriculture, mainly rice field and livestock industry, and no development of heavy chemical industries has been observed. Therefore, the water is mainly used for irrigation and as clean water; although the fish catch is declining, fishing is still pr

16、acticed. Due to the outbreak of the carp herpes virus, the farm-raising carp business, which was popular until recently, has ceased operation. 3 Current State of Water Quality of Kasumigaura LakeThe ambient water quality criteria (Environmental Quality Standard for Water Pollution) for Kasumigaura l

17、ake includes COD (chemical oxygen demand), T-N (total nitrogen) and T-P (total phosphorus); their values are set to lower than 3, 0.4 and 0.03 mg/L, respectively, so that the water can be used for drinking purpose. However, in 2003, the average values were far beyond the set standards: COD was 7.5 m

18、g/L; T-N, 0.91 mg/L; and T-P, 0.10 mg/L. In the last 10 years, the water quality has remained almost the same without any considerable change. The loads from both the non-point sources and the life systems occupy a large share of the loading dose in COD, T-N and T-P. The annual changes in the averag

19、e COD, T-N and T-P concentrations in Kasumigaura lake from 1972 to 2003 are shown below:CODT-NT-PFig. 1 Annual changes in the average COD, T-N and T-P concentrations in Kasumigaura lake (19722003).4 The Plan for Conservation of Water Quality in asumigaura LakeThe 1st term of the Plan for Conservatio

20、n of Water Quality in Kasumigaura lake commenced in 1986 and continued into its 4th term until last year (2005). The 5th term plan has started this year (2006); however, the details are not yet available to the public. Although various measures have been implemented for the last 20 years along with

21、the Plan for Conservation of Water Quality, the effects on the water quality have not been observed, therefore, a review, including one for the planning methods, is required.5 Measures and Policies Against Eutrophication in the Plan for Conservation of Water QualityIn the 4th term plan, the general

22、guidelines for the measures and policies are outlined as follows:（1）Measures against domestic wastewater Installation of sewerage systems: improve the prevalence rate from 46% (438,400 people) to 53% (541,900 people) Installation of the sewerage systems in agricultural communities: sewerage systems

23、to be installed in 18 communities (increase the population coverage of sewerage systems from 49,500 to 69,200) Installation of the integrated tank treatment systems: install 6,000 tanks as a grant-aided project (affected population: 23,600)a total of 16,719 tanks（2）In-lake purification measures Dred

24、ging of the bottom mud (dredged 2.65 million m3 in Nishiura)a total of 8 million m3 Creation of foreshores and subsequent development of the water vegetation zone, including reed and Indian rice (ca. 20 sites) Maintenance of the wetland (including Daienji and Sonobe rivers) Swamp Recovery Project (T

25、suchiura City, Tamura District) Reduction in the production of farm-raised carp (from the current 5,000 tons to 4,700 tons) Measures to maintain and expand fishery resources (release of fingerling fishes, including crucian carp, eel and freshwater smelt, and the creation of vegetation zones) Capture

26、 and collection of harmful fish species of foreign origin (bluegill and hornpout) and unused small fish (silver carp, mullet, barbell steed, etc.) (Annually captured amount: harmful fish, 113 tons; silver carp, 80 tons; and small fish, 160 tons) Promotion of the water transmission project of Kasumig

27、aura lake （3）Direct purification measures in channels including rivers Direct purification by influx rivers (Seimei, Sakura and Koise rivers) Direct purification of the collateral channel (channels built around Kasumigaura lake to receive rainfall around the levee and agricultural drainage) (Sakurag

28、awa village, Miura village and Kasumigaura town) Direct purification of the agricultural waterway (Shin-Tone and Iwase towns) Direct purification of waterways contaminated by domestic wastewater (Itako city and another site) （4）Other measures Regulation of effluents from factories and business establishments: dissolution of newly-built and existing classifications of