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Volume 33 Issue 12
25 December 2017
Analysis of Provincial Variation of TN Loss Intensity of Farmland Based on BRT Method and Its Affecting Factors
WANG Di, WANG Ming-xin, QIAN Zhong-ping, ZHOU Jie, JI Cai-ya
2017, 33(12):  1057-1063.  doi:10.11934/j.issn.1673-4831.2017.12.001
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The boosting regression tree method was used to analyze provincial variation of TN loss intensity of farmland during 2012-2014 and its affecting factors, of which contribution rates were calculated. Furthermore relationships of the intensity with the factors were analyzed. Results show that the mean loss intensity of the period of 2012-2014 was in the range of 9.40-9.50 kg·hm-2 in the country. North China, South China, and East China was relatively high, with mean of the three years being 16.51, 15.16 and 14.01 kg·hm-2, respectively, whereas Northeast China, Southwest China and Northwest China was relatively low with mean being 3.41, 7.02 and 8.18 kg·hm-2, respectively. Factors affecting the intensity were found including structural, technical and regional ones, of which the contribution rate reached 20.9%, 28.5% and 42.6%, respectively. Obviously, regional factor was the major one and the highest in influencing degree. North China, South China, East China and Central China, where soil N in farmland is more liable to get leached, are the focal points for N loss control. Ratio of cereal crops and vegetable in area, nitrogen fertilization intensity and ratio of effective irrigated farmlands in area were also factors positively affecting the intensity, while multiple cropping index, farming output value per capita, and farmland area per capita were negative factors. It is, therefore, recommended to readjust or optimize agricultural structure, water and fertilizer management and land use in the light of the natural and socio-economic conditions of the region, so as to reduce the loss intensity of soil TN from the farmland.

Accumulation, Distribution and Ecological Risk of Zn in Soils in the Xijiang River Valley of Guangxi
YANG Zi-jie, SONG Bo, CHEN Tong-bin, WANG Fo-peng, ZENG Wei-quan, LI Li, LI Hai-xiang, JIANG Jin-ping
2017, 33(12):  1064-1074.  doi:10.11934/j.issn.1673-4831.2017.12.002
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To characterize accumulation and distribution of Zn in the soils of the Xijiang River Valley of Guangxi and to assess its ecological risk, 2 534 samples were collected of the soils in nonferrous metal mining areas, farmlands (paddy and upland fields) and natural land in the region, during a large scale survey carried out in the light of types of sampling sites and physical conditions of the region for analysis. Results show that the soil of the valley was 67.3 mg·kg-1 in background value of Zn significantly higher than the soil of Guangxi Province as a whole. The mean concentration of soil Zn in the mining areas, upland and paddy fields was 2 134, 148.5 and 71.6 mg·kg-1, respectively with the baseline as benchmark, about 77.3%, 7.56% and 3.59% of the soils in the mining areas, upland and paddy fields was above the norm, respectively. The soils in the mining areas displayed an apparent trend of Zn accumulation, and spatial distribution of soil Zn in the valley exhibited a moderate leveled autocorrelation affected jointly by structural factors and stochastic factors. The spatial distribution of soil Zn in the valley shows that the soils high in Zn pollution were concentrated mainly in the southern part of Nandan County of Hechi City, the soils light-moderate in Zn pollution, in Du'an County and Huanjiang County, the soils light in Zn pollution, in Dahua County, Luocheng County, Du'an County, Liucheng County, Wuxuan County, Jinxiu County and Xincheng County and the soils relatively free of Zn pollution in the rest of the valley. Generally speaking the soils in Nandan, Huanjiang and Du'an of Hechi and other areas concentrated with mining, smeltery and tailing dumping were very high in Zn pollution risk, while the soils in the other areas relatively lower in or free of Zn pollution. It is, therefore, recommended to strengthen supervision and to assess environmental and ecological risks and human health risk of soil Zn in those highly Zn contaminated areas, and take actions to control the risks when necessary.

Multi-Scenario Ecosystem Service Assessment of Wuma River Valley Based on CLUE-S and InVEST Models
LEI Jun-cheng, LIU Ji-xin, YONG Fan, LIU Hui-ming, WU Jun, DING Hui, WANG Jin-mei, WU Song-qin, CHENG Shi, CUI Peng
2017, 33(12):  1084-1093.  doi:10.11934/j.issn.1673-4831.2017.12.004
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Quantitative assessment of ecosystem services is a precondition for scientific management of ecosystems, and hence of great significance to guaranteeing sustainable development and human well-being of a region. So, based on the Integrated Valuation of Ecosystem Services and Trade-offs model (InVEST) and the Conversion of Land Use and its Effects at Small Region Extent model (CLUE-S), quantitative assessment of the three ecosystem services of the Wuma River Valley, i.e. water yield, nutrient translocation and sediment retention, under the present land cover and that in 2030, encompassing two scenarios, that is, scenario of economic development(SED) and scenario of ecological protection(SEP). Results show that at present, the total water yield, the total outputs of nitrogen and phosphorus, and the total sediment retained of the Wuma River Valley is about 2.7×108 m3, 630 t, 142 t and 2×108 t, respectively, and will remain almost unchanged in the SED of 2030, but about 600×104 m3, 34.8% and 35.4%,and 0.7×106 t higher, respectively, in the SEP of 2030. Generally speaking, the three kinds of ecosystem services of the Wuma River Valley are closely related to land cover, and will significantly be improved in the SEP of 2030. This study may serve as reference for further efforts on evaluation of ecosystem services and formulation of development plans for the Wuma River Valley.

Valuation of Ecosystem Services in Wuyishan City
GONG Xi, CAO Ming-chang, SUN Xiao-ping, LE Zhi-fang, LI Shuang, XU Hai-gen
2017, 33(12):  1094-1101.  doi:10.11934/j.issn.1673-4831.2017.12.005
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Ecosystem service is the foundation for human to rely on for survival and development. Wuyishan City, Fujian Province was selected as a case for the study to assess economic values of the following 8 types of ecosystem services:products supply, water supply, water purification, climate regulation, soil conservation, carbon-sequestration and oxygen-release, tourist entertainment and biodiversity conservation. Results show that the total of the ecosystem services in Wuyishan City was valuated at 55.064 billion yuan. Among them, the tourist entertainment service contributed the most, contributing 28.84%, the soil conservation service came the next, contributing 22.15%. Spatial distribution of the ecosystem services in the city in terms of importance was analyzed, showing sharp differences between areas. The southern part of the city, home to the Wuyishan National Scenic Spot, Xingtian Town and the Wuyishan National Nature Reserve were areas of extreme importance and great importance in ecosystem service, while Langu and Wutun Township in the northeastern part and Wufu Town in the southeastern part were areas of importance and general importance. The valuation of the ecosystem services may serve as theoretical basis for scientific management and protection of the ecosystems and ecologically critical areas in Wuyishan City.

Changes in Vegetation Phenology and Its Elevation-Dependent Effects in the Yarlung Zangbo River Valley of Tibet, China
LI Hai-dong, CHEN Bin, YERNAER·Humaerhan, CAO Xue-zhang
2017, 33(12):  1102-1108.  doi:10.11934/j.issn.1673-4831.2017.12.006
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The Yarlung Zangbo River Valley (YZR), stretching across the southern part of the Tibetan Plateau from west to east over a wide range of elevation from 147 m to over 7 000 m above sea level (a.s.l.) with an average elevation of 4 600 m, has been regarded as one of the ideal regions for the study on ecological response to climate change in alpine watershed. Based on the datasets of SPOT-VGT normalized difference vegetation index (NDVI) and SRTM digital elevation model (DEM), phonological features of the valley were extracted and elevation-dependent phenological change of the vegetation of the YZR during 1999-2013 was analyzed. The SPOT-VGT NDVI was first preprocessed with the non-symmetrical Gaussian function (AG) fitting method, and then the start date of growing season (SOG), the end date of the growing season (EOG) and the length of the growing season (LOG) of the vegetation was extracted, separately, through the threshold value method. Results show:(1) The SOG exhibited an advancing trend in 61.3% of the YZR, and a delaying trend in 38.8%, while the EOG did an advancing trend in 45.3% and a delaying trend in 54.7%. As a consequence, the LOG in the YZR was shortening, with the annual changing rate per pixel being -0.47 d·a-1; (2) The SOG was gradually delaying, the EOG gradually advancing and the LOG gradually shortening along the river from the downstream up to the upstream. Besides, LOG and its annual changing rate is generally on a declining trend with rising elevation.

Community Characteristics of a Subtropical Evergreen Broad-Leaved Forest Plot Typical of Xianju of Zhejiang Province, Eastern China
CHEN Shui-fei, LI Yao, GE Xiao-min, ZHOU Xu, WANG Le, CHEN Ting-ting, DING Hui
2017, 33(12):  1109-1116.  doi:10.11934/j.issn.1673-4831.2017.12.007
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The Xianju Kuocangshan Provincial Nature Reserve is regarded by experts as a natural plant "gene pool" and "plant museum" in rarely existing in Zhejiang Province. In 2016, a large-scaled forest dynamics monitoring plot was established in the Kuocangshan Mountain with an area of 1 hm2, and based on the international protocols, a field survey of plant communities was conducted for the first time and community characteristics of the sampling plot analyzed from the aspects of species composition, flora feature, diameter class structure, and spatial distribution pattern. Results show that a total of 194 species of vascular plants were found and identified belonging to 126 genera and 68 families, in the plot. Among them there were 121 species of 67 genera and 36 families of arbor plants with DBH ≥ 1 cm. Plant families and genera of tropical nature accounted for 66.67% and 59.70% of their respective totals, while plants families and genera of temperate nature accounted for 33.33% and 38.81% of their respective totals. The plot was home to one and two species of wild plant under the national Grade Ⅰ and Ⅱ priority protection, 10 species listed as nearly endangered or higher in endangered level in the Biodiversity Red List of China, one species listed in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) (Appendix Ⅱ), 53 species unique to China, indicating that merit sound protection and in-depth research, and 23 species, rare and precious (less than 1 ind·hm-2) accounting for 19.01% of the total number of tree species. Castanopsis eyrei was the highest in importance value (Ⅳ), reaching 8.69%, and followed by Rhododendron latoucheae (6.80%) and Schima superba(5.92%), with mean DBH being 6.95 cm, indicating that most of the trees were low in DBH in this plot. The analysis of spatial distribution pattern shows that different species of plants varied in spatial distribution, but followed certain rules, separately.

Effects of Elevated Temperature and Simulated Acid Rain on Enzyme Activity and Temperature Sensitivity of Paddy Soil
HAN Wei, SUN Chen-xi, SU Jing
2017, 33(12):  1117-1124.  doi:10.11934/j.issn.1673-4831.2017.12.008
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Enzymes are considered a key category of components of soil. Global warming and intensifying acid rain may occur simultaneously. It is of great significance to study soil enzyme activity as affected by elevated temperature and intensified acid rain. Effects of warming and acid rain on soil enzyme in activity and sensitivity to temperature (Q10) of various enzymes in paddy soil were investigated. A laboratory incubation experiment was conducted and designed to have two levels of temperature, 25 and 30℃ and two levels of acid rain in pH, pH 5.0 and pH 6.7. Results show that:(1) Under the simulated normal rain of pH 6.7, warming (30℃) increased the mean activity of soil invertase, cellulase, amylase, and protease by 13.37%, 13.57%, 6.14%, and 17.60%, respectively, but decreased the mean activity of urease and catalase by 3.25% and 12.89%, respectively as compared with 25℃. When temperature was kept at 25℃, acid rain (pH 5.0) increased the mean activity of soil invertase, protease, urease, and catalase by 22.91%, 7.65%, 38.24% and 69.98%, respectively, but decreased that of cellulase and amylase activities by 35.73% and 19.63%, respectively. (2) The effect of the interaction between warming and acid rain was significant on invertase, cellulase, and catalase activities, but not so on amylase, protease, and urease. (3) Soil enzymes varied in Q10. Invertase was sensitive to changes in temperature, while amylase was not. Under acid rain, invertase, cellulase, protease, and urease declined in Q10, while catalase rose in Q10 and amylase was almost unaffected. (4) In a short period of time both elevated temperature and acid rain increased the integrated activity of the soil enzymes. In the soil under both elevated temperature and acid rain, the rise was the biggest, which suggests that both global warming and a short-term of acid rain low in concentration may enhance soil enzyme activity and hence accelerate recycling of soil matter.

Effects of Timing and Duration of Waterlogging on Cd Absorption and Accumulation by Rice Under Cadmium Stress
LIU Zhao-bing, JI Xiong-hui, GUAN Di, XIE Yun-he, ZHU Jian, PENG Jian-wei
2017, 33(12):  1125-1131.  doi:10.11934/j.issn.1673-4831.2017.12.009
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A pot experiment was conducted using extraneous cadmium as soil Cd contaminant for exploration of effect of timing and duration of waterlogging on rice yield and Cd accumulation in rice. Results show that rice yield lowered to a varying extent in all the flooding treatments vs CK (CI), especially Treatment WI (wetting irrigation throughout the rice growing season) and Treatments T1, T2, T3 and T4 (flooding beginning at the prime tillering stage and lasting for 1, 2, 3 and 4 weeks, respectively), which was 23.7%, 16.0%, 15.5%, 20.2% and 18.6%, lower, respectively, than CK. Cd content in brown rice decreased with duration of waterlogging, and Treatment WF (flooded throughout the rice growing season) was the lowest or only 3.4% of Treatment WI in Cd content in brown rice. Under the same waterlogging conditions, Treatment T1, T2, T3 and T4 was 27.1% (P<0.05), 46.6% (P<0.05), 56.0% (P<0.05) and 35.2% lower than Treatment F1, F2, F3 and F4 (flooding beginning at the filling stage and lasting for 1, 2, 3 and 4 weeks, respectively), respectively or 41.2% lower by mean in Cd in brown rice. Cd contents in shoots and brown rice varied along basically similar trends. Cd transport efficiency of the shoots decreased with duration of waterlogging. Cd enrichment factor of shoot and brown rice differed significantly between treatments and even by 17.8 and 28.0 times between Treatments WI and Treatments WF. All the findings demonstrate that flooding could effectively inhibit uptake and accumulation of Cd in rice, and the effect is positively related to duration of and timing of flooding, and better with the beginning of flooding at the tillering stage than at the filling stage.

Characterization of Cr6+ and Phosphorus Adsorptions of Biochars Derived From Submerged Plants
ZHENG Meng-jie, LI Ji-zhou, JIN Hong-mei, ZHANG Song-he
2017, 33(12):  1132-1139.  doi:10.11934/j.issn.1673-4831.2017.12.010
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Biochar has been widely used as adsorbent to treat wastewater polluted with heavy metals and phosphorus polluted water, which has become a front-line hot spot in the field of environmental science. Submerged plants, abundant in quantity and vast in availability can be utilized as raw materials of biochar. However, little has been reported about researches on characteristics of Cr6+ and phosphorus removal by the biochar. Three common submerged plants (Potamogeton crispus, Vallisneria natans and Ceratophyllum demersum) were taken and pyrolyzed at 350, 450 and 600℃ into biochars, which were tested for exploration of effects of initial pH and equilibrium time on Cr6+ and phosphorus adsorption by the biochars. Results show that acid conditions facilitated Cr6+ and phosphorus adsorptions by the biochars, J350 (biochar prepared out of Ceratophyllum demersum at 350℃) and Y350 (biochar prepared out of Potamogeton crispus at 350℃) was the highest in Cr6+ and phosphorus adsorption capacity, being 0.094 2 mmol·g-1 at pH 4 and 0.338 1 mmol·g-1 at pH 6, respectively. The adsorption of two substances followed the pseudo-second-order model, which indicates that the adsorption process was dominated with chemical adsorption. The biochars derived from submerged plants were rich in carboxyl, hydroxyl and other oxygen containing functional groups. All of the biochars were 8 in pHpzc, except for K450 (biochar prepareed out of Vallisneria natans at 450℃), which was only 6. Having adsorbed Cr6+ and phosphorus, the biochars had rougher surface with apparent folds and bright spot, and their contents of Cr6+ and phosphate increased significantly. Because of their unique physical and chemical structure, the biochars derived from submerged plants can be prepared into porous carbon for use in pollutant adsorption and other fields.

Preparation of Biochar From Cyanobacteria and Function of the Biochar for Persulfate Activation
SHI Chen-fei, LI Yu-meng, FENG Rui-jie, JIA Shu-min, XUE Rui-jie, WANG Guo-xiang
2017, 33(12):  1140-1145.  doi:10.11934/j.issn.1673-4831.2017.12.011
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Biochar was prepared out of cyanobacteria and used as activator of persulfate in degrading Orange G. Effects of biochar preparation conditions on element composition, pore structure and persulfate activation performance of biochar were investigated. Orange G degradation process of the biochar-persulfate system and its influencing factors were studied. Results show that the biochar prepared out of H3PO4 treated cyanobacteria was higher in carbon content, less developed in pore structure and better in persulfate activation performance than that out of NaOH treated cyanobacteria. Higher pyrolysis temperature could improve activation performance of the biochar. The biochar obtained at 500℃ out of H3PO4 treated cyanobacteria (CHB500) exhibited excellent activation performance. CHB500/persulfate system could efficiently degrade or remove Orange G in solutions with pH varying in the range from 2.7 to 10.7 with radical and non-radical mechanisms playing a joint role.

Effect of pH on Characterization of COD With Three-Dimensional Fluorescence in the Process of AOA-SBR Treating Wastewater
HUANG Jian, WU Zhao-liang, ZHANG Hua, ZHANG Yong, ZHANG Xiong, YU Xiao-kun, LING Ling
2017, 33(12):  1146-1152.  doi:10.11934/j.issn.1673-4831.2017.12.012
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To explore effect of pH on rapid characterization of COD in the treatment of urban sewage using AOA-SBR technology, the three-dimensional fluorescent spectrum method was used to investigate relations between COD and fluorescence intensity of DOM, and further effect of pH on this relationship. Analyses of the three-dimensional fluorescence spectra obtained and their relationships with COD show that the DOM in the sewage under treatment contained the following three substances:tryptophan low in excitation wavelength, tryptophan high in excitation wavelength and humic acid. The two types of tryptophan and their sum in fluorescent intensity was highly and positively related to COD with R2 being 0.982 3, 0.977 4 and 0.980 9, respectively, turning to be 0.871 1, 0.856 7 and 0.873 3 respectively, when pH was at 4, varying in the range of 0.926 2-0.983 4, 0.969 3-0.982 7 and 0.952 1-0.988 8 respectively, when pH varied between 6 and 8, and fluctuating in the range of 0.845 7-0.749 0, 0.900 8-0.869 9 and 0.889 5-0.837 6, respectively, along a declining trend with pH rising on above 8. Then it could be concluded that when pH was 6-8, DOM and COD concentrations are closely related in fluorescence intensity.

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2017, 33(12):  0-0. 
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