LAKE SUPERIOR REGULATION EFFECTS

ABSTRACT: The outflows of Lake Superior through the St. Marys River have been modified from natural conditions, initially by the construction of engineering works, such as bridges, and later by the construction of control works and the regulation of the lake. For all practical purposes, the period from 1860 to 1887 represents the natural river conditions. During the period 1888-1900 the regimen was modified by the construction of the International Railroad Bridge and the Chandler-Dunbar Power Canal. In 1901 construction began on the compensating works. Following the completion of the compensating works in August 1921, the Lake Superior outflows were regulated in accordance with the Orders of Approval, 26 and 27 May 1914. A hydrologic response model was developed to simulate the natural Lake Superior regime. The model was run for the 1860–1975 period to simulate natural Lake Superior levels and outflows. The simulated levels were compared with the recorded levels to determine the effect of regulation. It was found that regulation has resulted in a rise in Lake Superior water levels. The simulated natural outflows for the period from 1937 to 1975 were run through the Great Lakes hydrologic response model to analyze the regulation effects on Lakes Michigan-Huron, St. Clair, and Erie. The results show no long-term bias due to regulation.     

湖泊水动力模型外部输入条件不确定性和敏感性分析

以我国典型的大型浅水湖泊太湖为研究区域,采用国内外常用的环境流体动力学模型(EFDC),结合拉丁超立方取样(LHS)方法,研究湖泊水动力模型中4个重要的外部输入条件,即3个边界输入条件(出入湖流量、风速、风向)和1个初始输入条件(初始水位),对模型水动力模拟结果(水位、水龄以及流场)的影响与贡献.结果表明,初始水位的设定对模拟全湖水位和水龄产生决定性影响,不确定性的贡献率分别达到85.73%和66.125%,对垂向平均流速影响的贡献率只有3%;风速对表面流速模拟结果影响较大,贡献率达到58.70%,而对水位和水龄的贡献率分别为5.25%和3.00%.在垂向上,各层流速受外部输入条件不确定性的影响规律相似,贡献率排序为风速(55%~60%)>风向(10%~15%)>初始水位≈出入湖流量(1%~5%).因此在模拟大型浅水湖泊水动力过程时,可以根据不同的输出目标能够有针对性地提高外部输入条件的准确度,为提高模型精确度提供有效信息.     

洱海湖区非点源污染与洱海水质恶化

洱海湖区由于农用化肥、畜禽养殖和农业水土流失引起的非点源污染对洱海水质由贫营养化过渡到中营养化,向富营养化发展起到了重要作用.应大力发展生态农业,使用化肥农药减量提效,实现有机肥料资源化利用,控制污染转移过程,综合防治非点源污染.     

城市不同类型水体有色可溶性有机物来源组成特征

过去几十年里,我国飞速的工业活动和城市化进程对城市地表水体生态系统产生巨大影响,地表水体水质变化直接影响城市居民用水安全、城市景观维护及城市热点区域碳循环过程.通过2020年6月采集长春市各类水体（城市河流、公园湖泊及水库）共50个样品,结合光谱吸收及三维荧光光谱-平行因子分析法（EEMs-PARAFAC）分析了各类水体的有色可溶性有机物（CDOM）光学特性、组成特征及潜在来源.结果表明,长春市城市河流DOC浓度显著高于水库水体（t-test,P<0.05）.城市河流水体的CDOM吸收系数a₂₅₄均值显著大于公园湖泊和水库（t-test,P<0.05）,表明城市河流水体中CDOM浓度最高.CDOM光谱吸收斜率S_275-295与光谱吸收斜率比S_R均值均表现为公园湖泊>水库>城市河流（t-test,P<0.001）.平行因子分析法解析三维荧光光谱得到3个荧光组分,陆源类腐殖酸C1（E_x=260 nm,E_m=452 nm）、微生物作用类腐殖酸C2（E_x=245/290 nm,E_m=388 nm）和类色氨酸C3（E_x=275 nm,E_m=340 nm）.城市河流水体各组分荧光强度均值均显著高于公园湖泊与水库（t-test,P<0.005）,水库水体陆源类腐殖酸C1荧光强度均值显著高于微生物作用类腐殖酸C2和类色氨酸C3（t-test,P<0.005）,城市居民生活污水排放对长春市城市水体,尤其是城市河道中有机碳贡献较大,且该部分有机质中微生物降解潜力强的类蛋白组分贡献率高.因此,应加强城市污水排放管控以有效保障长春市城市水体经济、环境与生态功能的发挥.     

洪泽湖硝基苯类化合物的污染特征

对洪泽湖水质、底泥及水生生物样品10种硝基苯类化合物的浓度进行了测定,水样中总硝基苯类化合物的含量在0.179~5.17μg/L,北部湖区和南部湖区的总硝基苯类化合物的浓度较高,其中成河北(S7)的浓度最高。底泥中的含量在0.137~4.50μg/kg,北部湖区及出湖口附近形成一个硝基苯类化合物的污染带,其中成河东(S6)的浓度最高。水生生物体内的总硝基苯含量按鲫鱼、白鱼、泥鳅、龙虾、河蚌、螺蛳依次升高。     

湖泊底泥土地利用对土壤中重金属铅、铜形态影响

采用田区试验研究了田间种植冬小麦条件下,底泥土地利用前后土壤中重金属铅、铜的形态演变及小麦各器官中铅、铜的富集。结果表明,随着底泥施用量的增加,土壤中重金属铅、铜的可交换态、碳酸盐结合态、铁锰氧化物结合态、有机结合态、残渣态均有不同程度的增加,本试验所有处理中,可交换态铅的质量分数范围为0.02~0.10 mg·kg-1,碳酸盐结合态铅的质量分数范围为0.04~0.24 mg·kg-1,铁锰氧化物结合态铅质量分数为0.41~1.88 mg·kg-1,有机物结合态铅质量分数范围为1.23~4.92 mg·kg-1,残渣态铅质量分数范围为4.82~23.66 mg·kg-1;各处理与对照相比,可交换态铜质量分数增加了40.00%~200.00%,碳酸盐结合态铜质量分数增加了36.84%~363.16%,铁锰氧化物结合态铜质量分数增加了7.17~45.15%,有机结合态铜质量分数增加了7.98%~62.61%,残渣态铜质量分数增加了0.12%~9.69%,各处理的残渣态铅、铜质量分数均较高。随着底泥用量增加,小麦根系、茎叶、籽粒中铅、铜质量分数均呈增加趋势,植株对重金属铅、铜的富集顺序为根系>茎叶>籽粒,铜的富集系数均大于铅。小麦籽粒产量、茎叶生物量及地上部生物量随着底泥施用量的增加,均出现了先增加后减少的现象,当小麦籽粒产量达到最大值时,籽粒中铅、铜质量分数未超出我国相应标准,依此确定底泥环境安全施用量为3051.29 t·hm-2。     

滇池水葫芦生物防治的研究

安全性测定结果发现:在供试的具有代表性的24个科,46种植物中,水葫芦象甲只危害水葫芦,不危害其他任何的当地植物。控制效益实验表明:象甲成虫可大量取食水葫芦叶片和叶柄及茎杆,明显降低植株光合作用;象甲幼虫钻蛀茎杆,致使茎杆变黄植株枯萎,甚至茎杆根部腐烂死亡;象甲可十分有效地降低水葫芦植株的繁殖速率(t>0.01,差异十分显著);象甲还可明显抑制植株个体生长量(t>0.01,差异十分显著);象甲对水葫芦株高和根长也能起到明显的抑制作用。象甲在昆明地区一年发生2~3代,卵,幼虫,蛹和成虫均可正常生长发育,高海拔并不影响象甲的自然生长。     

“十一五”期间滇池水质变化及原因

根据2006～2010年滇池水质监测数据,分析了“十一五”期间滇池水体富营养化主要指标的变化情况,结果表明滇池水体的富营养化程度虽有所下降,但水质整体仍属于重度富营养化状态,认为昆明市在“十一五”期间为治理滇池所作的大量工作其成效还未完全显现。     

高原湖泊流域水环境特征与污染防治综合整治研究

在深入分析玉溪市抚仙湖、星云湖、杞麓湖水质现状、污染源贡献、污染成因以及存在问题的基础上,探索基于流域系统的源头削减、过程控制、末端治理相结合的良好型湖泊保护与污染防治型湖泊综合整治的全过程治理思路,提出高原湖泊资源“优先保护、协调发展、限量开发、强化管理”的保护与开发管理全新理念.以经济社会发展与资源环境承载能力相适应为基础,提出适应“大玉溪”新形势发展需求下的高原湖泊流域水环境保护与综合整治措施.     

Effects of land use on water quality of two high-altitude lakes and catchments in Yunnan Province,China

SUMMARY

Reclaiming farmland from lakes in China in the 1950s damaged the water quality of many lakes. Tremendous efforts have been made since the late 1990s to restore vegetation around the damaged lakes. This paper examines water quality of Fuxian and Qilu Lakes and land-use characteristics within the two catchments in the high-altitude area of Yunnan Province, China. Landsat TM data acquired in 1989, 1994, 1999 and 2005 were used to extract land use and land cover (LULC) information. Measurements of five water quality indices (WQIs), BOD, COD, pH, TN and TP, for the same period of time were examined. The results showed that the area of residential and forest/shrub increased, whereas that of cropland and barren land decreased from 1989 to 2005 in both catchments. Qilu Lake was much more polluted than Fuxian Lake, and pollution worsened over time for both lakes. The differences in water quality between the two lakes were caused by differences in LULC composition and continued degradation in water quality was caused by intensive farming and urban sprawl. Unless the landscape is converted back to its pre-1950 composition and structure, water quality in both lakes cannot be significantly improved and will continue to threaten sustainable development in the region.