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20 September 2019, Volume 9 Issue 5 Previous Issue   
Ecological protection and restoration system of mountain-river-forest-farmland-lake-grassland: practicing the theory of lucid waters and lush mountains are invaluable assets
JIANG Xia,WANG Kun,ZHENG Shuofang,HU Xiaozhen,CHU Zhaosheng
2019, 9 (5):  475-481.  doi: 10.12153/j.issn.1674-991X.2019.09.020
Abstract ( 169 )   HTML ( 26 )   PDF (1082KB) ( 122 )   Save

China is vast in area, but because the population base is huge, the spatial distribution of available land resources is uneven. With the remarkable improvement of the country's economic power and people's living standard, how to realize the sustainable development of the economy and promote the coordinated development of socio-economy and environmental protection under the limited land and resources has become an urgent problem to be solved. The important concept of “mountains, rivers, forests, farmlands and lakes are a community of life” proposed by President Xi Jinping and the idea of systematic governance have pointed out the direction for solving this development problem. The strategic background of ecological protection and restoration of mountain-river-forest-farmland-lake-grassland (MRFFLG) was analyzed and the guiding ideology, basic principles and systematic design ideas of ecological protection and restoration of MRFFLG explained. The key tasks of ecological protection and restoration of MRFFLG were put forward, including the preparation of restoration plan, the scientific determination of spatial distribution, the optimization and adjustment of the resulting structure and population distribution, carrying out ecological restoration according to local conditions, promoting ecological protection and restoration by multi-departments, and clarifying its technical requirements.

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Ideas and practice of ecological protection and restoration of mountain-river-forest-farmland-lake-grassland system in Lake Fuxian Basin
NIU Yuan,HU Xiaozhen,WANG Linjie,ZHANG Youlin,YU Hui,CAO Xunyu,HE Yongjun,YIN Jiao,JIANG Xia
2019, 9 (5):  482-490.  doi: 10.12153/j.issn.1674-991X.2019.08.010
Abstract ( 105 )   HTML ( 6 )   PDF (2774KB) ( 48 )   Save

Lake Fuxian Basin is an important ecological barrier in southwest China and the Pearl River Basin, and an important part of China's “two screens and three belts” ecological security strategic pattern. Its ecological security is of strategic significance to guarantee the ecological security of the Pearl River Basin and the ecological functional services of the Yunnan-Guizhou plateau and even the national soil and water resources security. Based on the concept of “mountains, rivers, forests, farmlands, lakes and grasslands are a community of life”, and aiming at the eco-environmental problems in Lake Fuxian Basin, such as the need of spatial pattern optimization for the lake basin, the serious land degradation, the overloaded pollutants discharge, and the continuously increasing ecological risk, a set of lake basin ecological protection and restoration schemes were proposed. Putting Class Ⅰof Environmental Quality Standards for Surface Water (GB 3838-2002) for high quality water resources as the goal, and basin space pattern optimization and management and control as the premise, the overall comprehensive protection ideas of “repairing mountains and expanding forests, regulating farmlands and saving water, habitat restoration, pollution control and river management, and lake protection management” were proposed. Five kinds of lake basin ecological protection and restoration schemes covering 47 projects were designed, which included water conservation and mine restoration, farmland regulation and water saving, ecological protection and restoration, pollution source control and clean water restoration, and lake conservation and comprehensive management regulation. After more than one year's implementation, the programme had achieved initial success in expanding the area of forest vegetation, improving the quality and efficiency of farmland, reducing the in-lake pollutant loads, enhancing the ecological stability of the basin and improving eco-environment of lakeside region. The next step is to comprehensively strengthen the spatial control of the river basin and comprehensively promote the pilot projects of ecological protection and restoration, so as to restore the healthy ecological function of the lake basin in an all-round way, guarantee the cleanliness of the water body and the ecological security of the basin, and promote the healthy development of the lake basin.

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Problem identification and scheme study of ecological protection and restoration of mountain-river-forest-farmland-lake-grassland in Xiaoxinganling-Sanjiang Plain
ZHANG Bo,WANG Shuhang,ZHENG Shuofang,JIANG Xia,NI Yanfang
2019, 9 (5):  491-498.  doi: 10.12153//j.issn.1674-991X.2019.07.290
Abstract ( 29 )   HTML ( 5 )   PDF (4069KB) ( 7 )   Save

Xiaoxinganling-Sanjiang Plain is the original ecological security barrier of northeast (north) China. It is a key area of biodiversity and also a key food production base in China. Its eco-environmental protection has attracted much attention. According to the regional characteristics of the Xiaoxinganling-Sanjiang Plain, major eco-environmental problems in the region were identified from forest, mine, grassland, wetland, water and other elements. On the basis of defining the regional functions, the design idea, general layout and specific engineering scheme of ecological protection and restoration programme of mountain-river-forest-farmland-lake-grassland were put forward. It revealed that the main eco-environmental problems in Xiaoxinganling-Sanjiang Plain included the weakening of forest water conservation function, the ecological destruction of abandoned mines, the reduction and degradation of grassland area, the shrinking of wetland area, and the decline of partial water function. According to the optimization of the ecological space control combined with zoning classification precision repair, combined with the area of lakes, mountains, rivers, and other important natural geographical boundaries, it was proposed to build the overall layout of “two barrier, one belt, and one zone” (Xiaoxinganling ecological security barrier, Wandashan ecological security barrier, Songhua river water and soil pollution prevention and control belt, Sanjiang Plain wetland biodiversity conservation zone). On this basis, five major projects, including forest protection and restoration projects, mine environmental control projects, land regulation and restoration projects, biodiversity protection projects and water environmental protection and control projects, were promoted as a whole. The implementation of the programme was expected to bring good ecological, social and economic benefits to the region.

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The theoretical connotation of mountain-river-forest-farmland-lake-grassland thoughts and the practice of ecological protection and restoration: taking Guangxi Zuojiang-Youjiang River Basin pilot project as an example
LI Chunhua,YE Chun,LIU Yan,XIE Hua,ZHANG Zhenhua,YU Cigang,YANG Ruigang,WANG Yakong,LÜ Meiting,DAI Wanqing
2019, 9 (5):  499-506.  doi: 10.12153/j.issn.1674-991X.2019.07.300
Abstract ( 92 )   HTML ( 3 )   PDF (2996KB) ( 41 )   Save

In order to understand and practice the ideology of mountain-river-forest-farmland-lake-grassland (MRFFLG) life community, the general idea of this theory was interpreted and the practice of ecological protection and restoration was explored, taking the pilot project of Zuojiang-Youjiang River Basin in Guangxi as an example. The regional characteristics and eco-environment of the Zuojiang-Youjiang River Basin was analyzed. The basin is a typical karst geomorphology area and at present, its rocky desertification and soil erosion were prominent problems. Many problems had been left over from the history of ecological damage and environmental pollution in mines needed to be solved urgently, and the current situation of biodiversity protection was still under worrying condition. Based on the theory basis of the mechanism of clean water runoff generation in the watershed, the overall idea and performance target of ecological protection and restoration of MRFFLG were clarified. The watershed was divided into four functional areas: mountain water conservation and biodiversity conservation area, hilly soil erosion and stony desertification control area, plain pollution source control and comprehensive environmental improvement area, and wetland and water body ecological protection and restoration area. The restoration schemes of different functional areas were proposed respectively. The pilot programme has been implemented for more than one year and achieved good results, achieving a good combination of economic, social and ecological benefits, which could provide reference for the implementation of similar projects.

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Characteristics, problems and ecological protection and restoration measures of mountain-river-forest-farmland-lake-grassland elements in Lake Erhai Basin
CHU Zhaosheng,GAO Sijia,PANG Yan,WANG Shengrui,XIONG Zhonghua,DUAN Biao,YANG Xuesong,ZHAO Jidong
2019, 9 (5):  507-514.  doi: 10.12153/j.issn.1674-991X.2019.07.291
Abstract ( 87 )   HTML ( 4 )   PDF (1766KB) ( 30 )   Save

Lake Erhai, as a representative of lakes with good water quality in China, is one of the key protection lakes of the “new three lakes”. Ecological protection and restoration of mountain-river-forest-farmland-lake-grassland (MRFFLG) is an important content of ecological civilization construction in the basin, and also an inevitable requirement to solve the current problems in protection and management of Lake Erhai. The ecological environmental characteristics of MRFFLG elements of Lake Erhai were expounded systematically, and the main problems diagnosed. Following a general idea of “mountains restoration and afforestation, farmlands and rivers pollution control, ecological restoration and livable environment, and environment capacity increasing and water retention”, with Lake Erhai water quality improvement as the core target, and insisting on comprehensive measures and systematic management of MRFFLG, the overall goal and performance indexes of protection and restoration were defined. A series of tasks and measures, including ecology spatial pattern optimization, mine treatment and forest ecosystem repair, green and ecological agriculture development, inlake small watershed systematic governance, aquatic ecosystem regulation and restoration, and environment supervision management enhancement, were put forward. The integrated protection and restoration programme of Lake Erhai Basin was thus formed, so as to provide a general outline and guidance for the protection and management of MRFFLG in Lake Erhai Basin and also provided a scientific basis for the protection and management and sustainable development of Lake Erhai Basin.

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Research on the ecological protection and restoration of mountain-river-forest-farmland-lake-grassland system in typical farming-pastoral ecotone: taking Daihai Lake Basin in Inner Mongolia as an example
WANG Shuhang,BAI Miaoxin,CHEN Junyi,ZHAO Li,ZHANG Bo,GUO Yunyan,JIANG Xia
2019, 9 (5):  515-519.  doi: 10.12153/j.issn.1674-991X.2019.08.050
Abstract ( 39 )   HTML ( 3 )   PDF (1918KB) ( 9 )   Save

Daihai Lake Basin, a typical farming-pastoral ecotone, is an important part of the northern sand control belt in China's “two screens and three belts” ecological security strategic pattern, as well as an important part of the ecological barrier in the Beijing-Tianjin-Hebei Region, and its eco-environmental protection is of great significance. In view of the unique geographical characteristics and habitat conditions of Dahai Lake Basin, and centering on the two core issues of water quantity reduction and ecological degradation, the priority list of water quantity, water quality and water ecology was sorted out. With the guarantee of the ecological security of Dahai Lake Basin as the core goal, and in accordance with the idea of combining the optimization of ecological space management and control with the accurate restoration of zoning and classification, the land space management and control system of “one lake and three districts” and the ecological protection and restoration project system of mountain-river-forest-farmland-lake-grassland of “two increases, two decreases and three balances” were constructed. It was expected to strengthen the ecological service function of Daihai Lake Basin and promote the socio-economic development of ecologically fragile areas in the ecologically fragile farming-pastoral ecotone.

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Application of a best multi-model ensemble method in PM2.5 forecast in heavily polluted regions of China
ZHANG Tianhang,WANG Jikang,ZHANG Hengde,ZHANG Bihui,LÜ Mengyao,JIANG Qi,CHI Qianyuan,LUAN Tian
2019, 9 (5):  520-530.  doi: 10.12153/j.issn.1674-991X.2019.04.250
Abstract ( 32 )   HTML ( 3 )   PDF (14348KB) ( 13 )   Save

To improve the forecast accuracy of PM2.5 concentration in heavily polluted regions of China, ensemble forecasts were built by mean ensemble, weighted ensemble, multiple linear regression ensemble and back propagation artificial neural networks ensemble, respectively, based on four numerical air quality models developed and maintained by national or regional environmental metrological service centers. A best multi-model ensemble forecast was established based on real-time evaluations of performances of single numerical models and ensemble methods. Through evaluation of the forecast results during 2015-2016, compared with single numerical air quality forecast models, improvements on forecast biases due to mean and weighted ensembles were limited, but multiple linear regression, back propagation artificial neural networks and best ensembles could largely reduce the forecast biases. The NMB and RMSE values between best ensemble forecast and observation were from -10% to 10% and from 10 to 70 μg/m 3, respectively. Best ensemble showed strong correlation with observations at more sites compared with other ensemble methods, but also underestimated PM2.5 concentrations in high pollution level. During the pollution process occurred in Jing-Jin-Ji region from February 25 to March 4, 2018, best ensemble had the ability to forecast the trend and magnitude of PM2.5 concentrations. In three representative cities of Beijing, Shijiazhuang and Zhengzhou, the NMB and R values between best ensemble and observations varied from 26% to 4% and from 0.49 to 0.77, respectively. The TS scores of best ensemble for mild and moderate pollution ranged from 0.39 to 0.73, and that of severe and above pollution ranged from 0.13 to 0.30. These indicate that best ensemble can provide a strong objective reference to forecaster, but its forecast ability of peak values needs to be further improved.

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The influence of air characteristics on wet plume control technology
GUO Xiaohu,ZHANG Xiaolong,LI Junmin,DU Yuan,LI Yuan
2019, 9 (5):  531-537.  doi: 10.12153/j.issn.1674-991X.2019.02.250
Abstract ( 31 )   HTML ( 4 )   PDF (2150KB) ( 5 )   Save

The influences of air characteristics such as pressure, temperature and relative humidity on the thermal state of flue gas, the formation of wet plume, and on the effectiveness of wet plume control technologies were analyzed. Results showed that air characteristics would affect the selection of temperature and humidity of the saturated flue gas. The temperature of air had a greater effect on wet plume than its relative humidity. In addition, the influence of air pressure on gas emission temperature increased with the decrease of the temperature of the saturated wet flue gas. The lower the temperature of the air was, the smaller the reference change rate of gas emission temperature would be. Air temperature and relative humidity would affect white smoke elimination effect and the desired effect would then determine the condensation and reheating temperature of flue gas.

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Characteristics of the water-soluble inorganic ions of indoor PM2.5 in Xuanwei City in winter
WU Fan,SHAO Longyi,LU Jing,XI Chunxiu,CHANG Lingli,GAO Qiusheng
2019, 9 (5):  538-543.  doi: 10.12153/j.issn.1674-991X.2019.03.220
Abstract ( 35 )   HTML ( 3 )   PDF (1785KB) ( 9 )   Save

A total of 48 sets of PM2.5 samples of atmospheric fine particles were collected indoors during the winter of 2016 in two villages of Xuanwei City, Yunnan Province. The mass concentrations of PM2.5 were obtained by weighing. Eight kinds of water-soluble inorganic ions, including Na +, $NH^{+}_{4}$, K +, Mg 2+, Ca 2+, Cl -, $NO^{-}_{3}$ and $SO^{2-}_{4}$, were analyzed by ion chromatography. The results showed that the daily average concentrations of PM2.5 in old coal-fired households in Xuanwei ranged from 52.5 to 417.0 μg/m 3 and those in new electrical households ranged from 43.6 to 77.9 μg/m 3. The daily average concentrations of water-soluble inorganic ions in old coal-fired households ranged from 21.90 to 68.90 μg/m 3, and the mass concentration levels of eight water-soluble inorganic ions were in the order of Cl ->Na +>$NO^{-}_{3}$ >$SO^{2-}_{4}$ >$NH^{+}_{4}$ >K ++Ca 2++Mg 2+. The daily average mass concentrations of water-soluble inorganic ions in new households ranged from 12.53 to 48.04 μg/m 3 and the mass concentration levels of eight water-soluble inorganic ions were in the order of $NO^{-}_{3}$>$SO^{2-}_{4}$ >Cl ->Na +>$NH^{+}_{4}$ >K +>Ca 2+>Mg 2+. The indoor PM2.5 concentration and water-soluble inorganic ion concentration in the old coal-fired households were higher than that of new electrical households in Xuanwei City. Coal burning was the main source of indoor air pollution.

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Bacterial community characteristics and key driving factors of surface sediments in Huailai section of Yongding River in winter
ZHAO Jianguo,ZHAI Xuezheng,GUO Xiang,WANG Yejiao,WANG Jianghua,ZHOU Zimeng,JIANG Tiantian
2019, 9 (5):  544-551.  doi: 10.12153/j.issn.1674-991X.2019.03.250
Abstract ( 45 )   HTML ( 4 )   PDF (3335KB) ( 16 )   Save

The water quality indexes of surface sediments and overlying water in Huailai section of the Yongding River in winter were analyzed, the characteristics and diversity of bacterial community in sediments were studied by high-throughput sequencing technology, and the correlation between bacterial species in main sediments and relevant environmental factors was analyzed. The results showed that the average amount of OTUs of surface sediments in Huailai section of the Yongding River in winter was 7 357, the dominant bacterial species in surface sediment phylum level were Proteobacteria, Bacteroidetes, Chloroflexi and Firmicutes etc., and the dominant species in bacterial genus level were not obvious. The Shannon index of sediment bacteria ranged from 8.135 to 10.647, ACE index ranged from 6 060.643 to 7 182.679, Chao1 index ranged from 5 553.562 to 6 967.912, the bacterial species were the most abundant in cattail wetland sediments, while the bacterial species were less in the tributary surface sediments under ice-sealed water body. Organic phosphorus (OP) and $NH^{+}_{4}$-N concentration of surface sediment, TP and $NO^{-}_{2}$-N concentration of overlying water were the main driving factors of bacteria relatively abundance of surface sediments in winter in Huailai section of the Yongding River. Among them, sediment bacteria abundance were negatively correlated with sediment OP and $NH^{+}_{4}$-N concentration, and positively correlated with overlying water TP and $NO^{-}_{2}$-N concentration.

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Characteristics of aluminum sludge composite filler and its application in constructed wetlands
XI Daoguo,ZHANG Ruibin,ZHOU Nai,CHEN Fan,ZU Baiyu,WANG Leyang
2019, 9 (5):  552-558.  doi: 10.12153/j.issn.1674-991X.2019.05.070
Abstract ( 80 )   HTML ( 13 )   PDF (2113KB) ( 32 )   Save

Three kinds of aluminum sludge composite fillers, including aluminum sludge-zeolite, aluminum sludge-steel slag, aluminum sludge-zeolite-steel slag, were prepared by using aluminum sludge, steel slag and zeolite. The physical properties and isothermal adsorption properties of phosphorus were studied. The composite fillers were used in a pilot-scale constructed wetland system, and their purification effects on wetland water quality were discussed. The results showed that the three kinds of composite fillers had higher volume density, porosity and specific surface area compared with aluminum sludge and conventional wetland fillers. The adsorption effect on phosphorus was quite different, with the order as follows: aluminum sludge-steel slag>aluminum sludge-zeolite> aluminum sludge-zeolite-steel slag. The removal rate of CODCr was about 70% in constructed wetland which revealed no significant differences. The removal rate of TP, TN and NH3-N were significantly different; the removal rate of aluminum sludge-steel slag and aluminum sludge-zeolite on TP was higher (above 93%), while that of aluminum sludge-zeolite, aluminum sludge-zeolite-steel slag on TN and NH3-N was higher (TN above 65% and NH3-N 77%). The aluminum sludge-zeolite composite filler had the best comprehensive removal effect on pollutants in constructed wetlands, and the effluent quality of constructed wetlands could reach level A of Pollutant Discharge Standard for Urban Sewage Treatment Plants (GB 18918-2002).

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Application of wheat bran flocculation technology on mixed culture fish pond of silver carp and carps
LIU Chao,ZHAI Guowei,LÜ Yajun,FENG Peng,WANG Bin
2019, 9 (5):  559-565.  doi: 10.12153/j.issn.1674-991X.2019.03.270
Abstract ( 26 )   HTML ( 2 )   PDF (936KB) ( 4 )   Save

An experiment on the carbon source from supplementary wheat bran was carried out in the mixed ponds of silver carp and carps, in order to study the effect of wheat bran on the bioflocculation generation in the ponds under conventional culture and its influence on the fish growth and the aquaculture water quality. The results showed that supplementary wheat bran could significantly promote biological flocculation, with the fresh fish yield increased by 16.32% compared with the control fish ponds. The weight gain rate, specific growth rate and growth potential of the experimental fish ponds were significantly higher than those of the control ponds. The growth performance of silver carp was higher than that of carp, and the feed coefficient of carp was lower than that of the control fish ponds. The effect of bioflocculation on the growth of silver carp was higher than that of carp. Compared with the control fish ponds, the water transparency of the fish ponds with supplementary wheat bran decreased, the total suspended solid concentration increased, the concentration of nitrite nitrogen, amino nitrogen and total nitrogen significantly decreased, and the water quality of the aquatic water was improved.

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Adsorption properties of ammonia-modified wheat straw on aquatic cadmium
LI Zhilin,XIE Yufeng,CHENG Deyi,WANG Lei,SHI Jiaqi,ZHU Xin
2019, 9 (5):  566-572.  doi: 10.12153/j.issn.1674-991X.2019.04.010
Abstract ( 24 )   HTML ( 4 )   PDF (1835KB) ( 5 )   Save

In order to solve the problem of chromium-contaminated wastewater, urea ammoniated modified wheat straw was prepared as a kind of Cd 2+ sorbent. The characterization before and after modification was observed by scanning electron and Fourier transform infrared spectroscopy, and the effects of different initial pH and dosage concentration on adsorption capacity of Cd 2+ by wheat straw before and after modification were studied. The adsorption kinetics and isothermal characteristics of wheat straw were fitted by kinetic and thermodynamic models. The results showed that the structure of the ammoniated wheat straw (N1) was loose, the pores were enlarged, the surface was grafted with primary amide group, and the activity of each functional group was enhanced, which was conducive to improving the adsorption capacity of Cd 2+. The optimum conditions for Cd 2+ adsorption on wheat straw after ammoniation modification were pH of 6, temperature of 25 ℃ and sorbent dosage of 1/300 g/mL. Under these conditions, the removal rate and the biggest saturated adsorption capacity were 74.32% and 11.29 mg/g, respectively. At different temperatures, the adsorption kinetics of Cd 2+ on wheat straw modified by ammonia could be described by the quasi-second order kinetic equation, which was shown as the endothermic reaction. The thermodynamic process could be described by Langmuir model, indicating that the adsorption on Cd 2+ was dominated by chemical adsorption.

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The simulation and prediction of TN in wastewater treatment effluent using BP neural network and ARIMA model
LIN Jiamin,CHEN Jinliang,LIN Jingjing,LI Xuanji,MA Cong,ZHANG Zhiqiang,SHEN Liang
2019, 9 (5):  573-578.  doi: 10.12153/j.issn.1674-991X.2019.03.261
Abstract ( 37 )   HTML ( 7 )   PDF (2632KB) ( 15 )   Save

Total nitrogen in effluent is one of the critical indicators for evaluating the performance of wastewater treatment plants. A BP neural network model was developed to simulate the present nitrogen removal system for wastewater treatment, and an autoregressive integrated moving average (ARIMA) model was creatively applied to realize the short-term prediction of future effluent. The results showed that the simulation average relative error of BP model on training set was 15.9%, and that on test set was 16.5%,which revealed that the stability of model prediction was poor. The average error of the ARIMA model for predicting the total nitrogen value in the coming week was around 4.41%, which showed high prediction accuracy. The combination of the two models could help fast and efficient on-line detection of wastewater treatment plants.

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Effects of different degradation degrees on soil characteristics in Bayanbulak Grassland, Xinjiang
HU Yanbin,XU Qiujin,HU Xiaozhen,BA Yaer,ZHANG Hui,YANG Tianxue
2019, 9 (5):  579-586.  doi: 10.12153/j.issn.1674-991X.2019.04.180
Abstract ( 24 )   HTML ( 3 )   PDF (1913KB) ( 2 )   Save

Taking alpine steppe Bayanbulak Grassland as a research object, and based on the differentiation of grassland utilization ways, soil degradation degrees and vegetation types of different grasslands, the effects of the grassland degradation degree of different grasslands on soil physical and chemical properties were analyzed, and the effects of vegetation and surface characteristics as well as grassland use patterns on soil fertility revealed. The results showed that alpine marsh grasslands and alpine grasslands were utilized in a reasonable way, the grasslands had not been degraded, the soil nutrient content was high, and the vegetation was in a good state. As to the alpine meadow, the higher the grazing pressure, the worse the habitat degradation and the worse the soil degradation, which was reflected in the increase of soil bulk density, the decrease of soil moisture content, and the decrease of soil total phosphorus and organic matter concentration, resulting in the decrease of vegetation coverage. The degree of grassland degradation of different types was positively correlated with soil bulk density, pH and water-soluble salt concentration, and the correlation was up to a significant level. It had highly significant negative correlation with water content, total phosphorus concentration, organic matter concentration and vegetation coverage, with the correlation coefficient up to -0.907. There was a significant positive correlation between soil fertility factor and vegetation state in the process of grassland degradation.

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Research on adsorption efficiency and mechanism of clay and coal fly ash for rural domestic waste leachate
WU Haixia,WU Xiaohui,MENG Bangbang,YUE Bo,HE Hailing,GAO Hong
2019, 9 (5):  587-596.  doi: 10.12153/j.issn.1674-991X.2019.05.140
Abstract ( 29 )   HTML ( 4 )   PDF (3440KB) ( 9 )   Save

The effects of contact time, adsorbent dosage and initial pH on adsorption efficiency and its adsorption mechanism of clay and coal fly ash were investigated in batch experiments. Considering the removal effect, operation cost and maneuverability, the contact time of 180 min, adsorbent dosage of 50 g/L, initial leachate pH of natural value(7.5-8.0)were chosen as the actual operation condition. The results showed that under this condition, the removal rates of clay and coal fly ash for normal pollutants of rural domestic waste leachate (CODCr, NH3-N, TN, TP) were 25.58% and 33.01%, 14.87% and 18.18%, 41.63% and 22.07%, 62.25% and 60.46%, respectively. The removal rates of clay and coal fly ash for heavy metals (Cr, As, Cd, Ni, Pb) were 13.04% and 10.53%, 43.34% and 31.52%, 60.24% and 84.30%, 47.52% and 65.73%, 61.77% and 68.65%, respectively. The isothermal dates of clay and coal fly ash for various pollutants in landfill leachate could be well described by the Freundlich adsorption model, and the chemisorption was the dominant mechanism.

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Study on properties of acrylic resin paint slag modified PVC foam composites
ZHANG Qingjie,MA Pengyang,XIANG Lan
2019, 9 (5):  597-602.  doi: 10.12153/j.issn.1674-991X.2019.01.242
Abstract ( 29 )   HTML ( 4 )   PDF (2233KB) ( 5 )   Save

Polyvinyl chloride (PVC) foam system was modified with the blending of recycled thermoplastic acrylic resin and paint slag, and the foam composite was prepared by using hot-pressing method. The effects of the paint slag dosage on the shear viscosity of blending systems and microstructure, apparent density, mechanical properties and heat resistance of the resulting PVC foam composites were investigated. The results indicated that the addition of acrylic resin paint slag could increase the interaction between PVC molecular chains, improve the shear viscosity and regulate the melt strength of PVC foaming systems, thus leading to PVC foams with small and homogeneous cellular structures. With adding of 10% paint slag, the shear viscosity of blending system increased from 2 726.1 Pa·s to 9 029.4 Pa·s, and the resulted PVC foam composite exhibited optimal comprehensive performances, in which the apparent density decreased from 0.63 g/cm 3 to 0.49 g/cm 3, the flexural and impact strength increased from 13.6 MPa and 4.7 kJ/m 2 to 18.2 MPa and 8.9 kJ/m 2, respectively, and Tg increased from 72 ℃ to 75 ℃.

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Comparison of enhancements of NaOH and liquid digestate soaking pretreatments for the anaerobic digestion of wheat husk
SUN Jiachen,LI Zifu,ZHU Lixin
2019, 9 (5):  603-608.  doi: 10.12153/j.issn.1674-991X.2019.01.150
Abstract ( 44 )   HTML ( 4 )   PDF (1463KB) ( 7 )   Save

The enhancements of NaOH and liquid digestate soaking pretreatments for the anaerobic digestion of wheat husk were compared. Different concentrations of NaOH (2%, 4%, 6%, 8%) at 80 ℃ for 2 h were investigated, and the results showed that 6% NaOH treated wheat husk obtained maximum methane yield of 199.5 mL/g, which was 191.2% higher than untreated raw substance (68.5 mL/g),and the digestion time was only 6 days. The results showed that after 5 days of pretreatment of wheat bran with liquid digestate, the effect of liquid digestate from chicken manure was apparently superior to that from cattle manure, and the maximum methane yield reached 130.8 mL/g, being equivalent to that from 2% NaOH pretreatment, but without additional chemical or biological pretreatment drugs. Thus, the two pretreatment methods could be selected and applied flexibly according to the practical demand.

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Thoughts on technical specification for application and issuance of rare earth industry's pollutant permits
ZHAO Ruonan,MA Zhong,QIAO Qi,LI Yanping,CHANG Dunhu
2019, 9 (5):  609-615.  doi: 10.12153/j.issn.1674-991X.2019.04.290
Abstract ( 42 )   HTML ( 5 )   PDF (1024KB) ( 10 )   Save

China's rare earth industry has the characteristics of numerous products, complicated production process and obvious industrial pollution particularity. Therefore, it is urgent to scientifically formulate technical specification for application and issue of pollutant permits according to their pollution characteristics. The main production technologies of rare earth industry, the types of pollutants and the main pollution links were analyzed. Based on the experience of permit application and issue of technical specifications from nonferrous metal industry and renewable metal industry, key technical specifications such as determination of pollution factors, classification of discharge outlets and calculation of permitted discharges were analyzed in formulation of technical specifications for pollutant discharge permits of the rare earth industry. Suggestions on the formulation of technical specifications for the rare earth industry were put forward from the aspects of increasing the characteristic pollution factors of the industry, dividing the discharge outlets into the main ones and the general ones, determining the permitted discharge limits and calculating the permitted discharges, and increasing the pollution control requirements for the southern ion-type rare earth mines.

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Biological monitoring method of water environment and its application
JI Ye,WU Yumeng,XU Qiujin
2019, 9 (5):  616-622.  doi: 10.12153/j.issn.1674-991X.2019.04.150
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In recent years, hazardous events caused by water environmental pollution have occurred frequently. Monitoring water environment is the basis of scientific water pollution prevention and control. Compared with traditional physio-chemical monitoring technology, biological monitoring has incomparable advantages in terms of sensitivity, stability, diversity and long term, and can directly and effectively reflect the ecological risk of water environment. The importance and advantages of biological monitoring methods and the main biological monitoring types were summarized. Based on a large number of literatures at home and abroad, the research progress of monitoring methods for main biological types of water environment, such as microorganism, phytoplankton, zooplankton, periphyton, zoobenthos, higher aquatic plants and fish, was reviewed. The practice and application of biological monitoring methods at home and abroad were discussed, and the future development of biological monitoring prospected.

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