#### Table of Content

20 September 2018, Volume 8 Issue 5
 The cause for abnormal water quality deterioration of Waihai of Dianchi Lake in 2017 and the countermeasures ZHENG Binghui,PENG Jiayu,HU Xiaozhen,CHU Zhaosheng,PANG Yan,WANG Lijing,XU Xiaomei,HE Jia 2018, 8 (5):  465-472.  doi: 10.3969/j.issn.1674-991X.2018.05.061 Abstract ( 542 )   HTML ( 11 )   PDF (4592KB) ( 463 )   The water quality of Waihai of Dianchi Lake abnormally deteriorated from Ⅴclass to worse than Ⅴclass (Environmental Quality Standards for Surface Water (GB 3838-2002) ) in 2017. Particularly, the concentration of water quality indicators, TP, TN, CODCr and Chla, abnormally rose during June to August. The roots causing the water quality deterioration are as following: compared with the same period of the last year, the precipitation increased by 81% during June to August in 2017, and it is the highest since 1999. Because of the abnormal precipitation, the pollution loads of TN, TP carried by Baoxiang River, Panlong River and Jinzhi River which are the main inflows of Waihai increased by 50% and 59%, respectively, directly leading to the water deterioration of the north of Waihai. In addition, the combined sewage interception system was overflow during the rainstorm, leading to the low collection rate of waste water treatment plants (WWTPs). Compared with the dry season, the average influent concentration of CODCr, TN, TP of the WWTPs of No.2, No.3, No.4 and No.9 decreased by 15%, 15% and 20% in rainy season, and the average influent concentration of CODCr, TN, TP of the WWTPs of No.10 decreased by 16%,19% and 8%, respectively. Meanwhile, compared with the year of 2016, the water supply by Niulanjiang water transfer project decreased by 50%, the concentration of NH3-N, TP, TN increased by 75.2%, 51.1%, 40.2%, and therefore the effect of water quality improvement was reduced. Four strategies to improve the water quality of Waihai of Dianchi Lake were proposed, including improving the sewage collection system and enhancing the efficiency of wastewater collection by advancing the check of pollution interception system; improving the regulation of the combined sewage by optimizing the operation of the built storage pools; improving the purifying rate of sewage treatment plant by optimizing operation, enhancing supervision and joint operation in rainy season; improving the environment efficiency of water supplement project by enhancing the protection and governance of water source area of Niulanjiang River.
 Buffer type identification and water quality status of inflow rivers under different buffer patterns in Lake Erhai WAN Zhengfen,LU Shaoyong*,JIN Xiangcan,BI Bin,JIN Xiangcan,CHEN Fangxin,QIN Pan,LI Linlin 2018, 8 (5):  475-480.  doi: 10.3969/j.issn.1674-991X.2018.05.062 Abstract ( 452 )   HTML ( 5 )   PDF (1655KB) ( 263 )   Focusing on the buffer zones of Lake Erhai, and using combined methods of on-site investigation, spatial analysis and data survey, the buffer types of Lake Erhai were identified and the water quality of the inflow rivers under different buffer patterns were analyzed. The results indicated that the buffer structure of Lake Erhai is unreasonable, with excessive proportion of farmland-type and village-type buffer zones. In addition, both the area and shoreline of the village buffer patterns close to the inner parts accounted for over 60% of the buffer zones of Lake Erhai, which mainly located in the western part of the lake. The water quality of main inflow rivers was generally poor, being Class Ⅳ and inferior Ⅴ. The buffer zones of the Tao stream and the Luoshi River were typical “outer cycle-village-farmland-village-inner circle” and “outer cycle-farmland-village-farmland-inner circle” respectively, with inferior Ⅴ class of surface water quality, mainly affected by non-point source pollution such as agricultural non-point sources, residential sources, and tourism pollution. In Lake Erhai buffer zones, the village-type buffers have a large number of external pollution load inputs, while the non-point sources from farmland-type buffers with high fertilization rates and highly polluted decentralized livestock and poultry have direct impacts on the river water quality. Therefore, the area of village-type and farmland-type buffer zones nearby Lake Erhai should be strictly controlled and non-point source pollution from village residential sources, farmland sources and tourism sources should be reduced.
 Effects of inflow modes on sewage nitrogen removal by ecological gravel beds WU Xin,HE Shuzhuang,LU Yifeng,LU Shaoyong,ZHANG Junpeng,HU Tao,ZHANG Senlin,CHEN Fangxin 2018, 8 (5):  481-487.  doi: 10.3969/j.issn.1674-991X.2018.05.063 Abstract ( 366 )   HTML ( 4 )   PDF (1176KB) ( 265 )   In order to improve the nitrogen removal rate of residential sewage by ecological gravel beds, four kinds of constructed ecological gravel bed were designed, including Schoenoplectus tabernaemontani bed, Phragmites australis bed, Typha orientalis bed and blank bed without vegetation. The effects of two inflow modes, i.e. continuous inflow and intermittent inflow, on the removal of TN, N$H4+$-N, and N$O3-$-N were studied. The hydraulic load (HL) was 7.5 cm∕d and the hydraulic retention time (HRT) was 1.8 d under the continuous inflow, while the HL was 7.5 cm∕d and the HRT was 5.4 d under the intermittent inflow. The results show that there exists great difference of the nitrogen removal efficiency between two inflow modes for different ecological gravel beds. The removal rates of TN and ammonia nitrogen under continuous inflow were in the order of Typha orientalis bed> Schoenoplectus tabernaemontani bed > blank bed > Phragmites australis bed, with the highest removal rates by Typha orientalis bed, which removal rate of TN and ammonia nitrogen were 77.68% and 81.33%, respectively; the removal rates of nitrate nitrogen were in the order of blank bed>Phragmites australis bed>Tyha orientalis bed>Schoenoplectus tabernaemontani bed, with thee highest removal rates by blank bed, which removal rate of nitrate nitrogen was 65.29%. The removal rates of TN and ammonia nitrogen under intermittent inflow were in the order of Schoenoplectus tabernaemontani bed > Phragmites australis bed > Typha orientalis bed> blank bed, and the effect of Schoenoplectus tabernaemontani bed was the best, which removal rate of TN and ammonia nitrogen were 89.54% and 91.79%, respectively; the removal rates of nitrate nitrogen were in the order of Schoenoplectus tabernaemontani bed>Typha orientalis bed>blank bed>Phragmites australis bed, the Schoenoplectus tabernaemontanid bed was the best with a removal rate of 46.43%. The removal efficiency of ammonia nitrogen and TN were better improved by intermittent inflow in plant systems. The removal rate of TN and ammonia nitrogen increased by 19.63% and 14.76% in Phragmites australis bed, and the removal rate of TN and ammonia nitrogen increased by 19.14% and 18.60% in Schoenoplectus tabernaemontani bed, respectively.
 Nitrogen removal of simulated low-polluted water of Lake Erhai buffer zone by surface-flow wetland ZHANG Junpeng,LU Yifeng,GUO Xiaochun,LU Shaoyong,WU Xin 2018, 8 (5):  488-494.  doi: 10.3969/j.issn.1674-991X.2018.05.064 Abstract ( 391 )   HTML ( 1 )   PDF (1882KB) ( 357 )   Aiming at the pollution problem of typical low-polluted water (produced by agricultural non-point sources) in Lake Erhai buffer zone, the typical buffer zone mostly occupied by farmland between Baihe Stream and Mei Stream in the western Lake Erhai basin were selected to monitor the surface runoff quality of the buffer zone, and to set up the surface flow pilot wetland for field study. The nitrogen removal effect for simulated low-polluted water of Lake Erhai buffer zone from September 2016 to August 2017 was studied. The results indicate that the pilot system has a high nitrogen removal effect, with annual average removal rate of total nitrogen as Nymphoides peltatum wetland (83.1%) >reed wetland (73.9%) >Hydrilla verticillata wetland (73.3%) >blank wetland (65.5%). The average annual removal rate of ammonia nitrogen was higher than 77%. Among different plant systems, Nymphoides peltatum system has the best removal effect of total nitrogen and the most stable removal rate. The removal rate and width of each system were simulated, and it reveals that the optimum width of the Nymphoides peltatum, Hydrilla verticillata and Phragmites communis wetland systems was respectively 7.04 m, 8.64 m and 6.92 m while the effluent water quality is of class Ⅲ water. The contribution rate of nitrogen removal in Nymphoides peltatum, Hydrilla verticillata and Phragmites communis wetland systems during the test is 5.88%, 3.23% and 21.12%, respectively. The total nitrogen content of reeds in wetlands is significantly higher than that of Nymphoides peltatum and Hydrilla verticillata. The contribution rate of Phragmites communis and Hydrilla verticillata to nitrogen removal in wetland shows a large seasonal difference, while the contribution rate of Nymphoides peltatum in wetland to nitrogen removal in different seasons varies little.
 Treatment ideas and technical measures of black and stinky water bodies ZHU Yunjie,LI Guowen,ZHANG Lieyu,XU Qiujin,SONG Yonghui 2018, 8 (5):  495-501.  doi: 10.3969/j.issn.1674-991X.2018.05.065 Abstract ( 1277 )   HTML ( 25 )   PDF (893KB) ( 325 )   In China the blackening and stinking of urban waters is a common phenomenon. At present, large-scale governance of black and stinky (BS) water bodies is underway. The seriousness of the problem of BS water bodies in China was briefly introduced, and the current national policy and governance objectives for the treatment of BS water bodies elaborated. The concept of BS water bodies was analyzed, and the idea for their treatment was put forward. The treatment technical route was clarified, including the investigation and diagnosis of problems, the verification of pollutant loads, and the determination of treatment targets of BS water bodies. Formulation of applicable technologies and governance programs, and forecasting of governance effects were also involved. On these bases, the main technical measures for the treatment of BS water bodies were proposed, including pollution source control, hydraulic regulation and ecological restoration, and meanwhile, it was noted that comprehensive management must be strengthened. The progress and of governance cases of BS water bodies at home and abroad were reviewed, and the governance process and existing problems were analyzed. Finally, the suggestions for the treatment of BS water bodies were proposed from four aspects, i.e. the evaluation indicators, the technical systems, the management mechanisms, and the publicity and education.
 Nutritional characteristics and aquatic ecosystem health assessment in cascade reservoirs of Wuxijiang ZHANG Xiaolin,ZHANG Jingtian,CHI Chunjuan,MA Chunzi,LI Xiaochuang,XIAO Zhe,AN Zhenzhen 2018, 8 (5):  502-509.  doi: 10.3969/j.issn.1674-991X.2018.05.066 Abstract ( 463 )   HTML ( 0 )   PDF (1042KB) ( 329 )   Extensive cascading hydropower dam exploitation may profoundly affect the river ecosystem health. The nutritional characteristics and community structure of phytoplankton in upstream Hunanzhen reservoir and downstream Huangtankou reservoir in Wuxijiang cascade reservoirs from June 2017 to November 2017 were investigated, and the assessment of the reservoir aquatic ecosystem health was performed by Index of Biological Integrity (IBI) method. The results indicated that nitrogen, phosphorus and organic matter contents of Wuxijiang cascade reservoirs were low, the nutritional level was poor. The 152 taxa of phytoplankton belonging to 8 phyla were identified, the densities of cyanobacteria and chlorophyte were high, and the phytoplankton density in downstream Huangtankou reservoir was lower than that in upstream Hunanzhen reservoir. The IBI assessment result showed that Wuxijiang cascade reservoirs were in relatively high biological integrity, and at normal to sub-health level. The IBI index was significantly affected by the water temperature, suggesting that the good health level was found in Huangtankou reservoir with low water temperature, but in Hunanzhen reservoir with high water temperature.
 Study on variation characteristics and estimation model of PM2.5 concentration in Beijing in winter XIONG Junli,LI Caiyan 2018, 8 (5):  533-538.  doi: 10.3969/j.issn.1674-991X.2018.05.070 Abstract ( 347 )   HTML ( 5 )   PDF (806KB) ( 370 )   Based on the hourly air quality monitoring data in Beijing in January 2017, the hourly and regional changes of the concentration of PM2.5 in Beijing were discussed, and the estimation models of PM2.5, PM10 and major gaseous pollutants of 12 sites were constructed by multiple stepwise regression. The results showed that the hourly concentration change trend of PM2.5 concentration in Beijing was high at night (18:00-07:00) and low in the daytime (08:00-17:00), the monthly averaged PM2.5 concentrations of 3 sites in Huairou Town, Changping Town and Dingling were relatively low (78-94 μg∕m 3), while that of other sites were between 106-128 μg∕m 3. The correlation between PM10, 4 kinds of gaseous pollutants and PM2.5 was in the order of PM10>CO>NO2>O3>SO2. The adjustment coefficient $R adj 2$ of the PM2.5 concentration estimation model of the 12 sites was all more than 0.96, and the standard error SE was between 13.6-24.5. It is more effective to estimate the PM2.5 concentration of the site by using the estimation model of the site itself, and the effect of estimating the PM2.5 concentration was poorer by using the data of other sites.