Effective utilization of water resources is an important strategic issue for economic and social sustainable development of the arid areas of Northwest China. The method of data envelopment analysis with undesirable output was used to analyze water use efficiency (ETE) of the arid areas in Northwest China in the period from 2004 to 2015, and compared it with the water resource utilization efficiency obtained with the method without undesirable output (TE). It was found that ETE was significantly lower than TE in value, indicating that the traditional water use efficiency determination method tends to overestimate the efficiency. From the point of view of time evolution, the water utilization efficiency was increasing rapidly from 2004 to 2015, but distributed unevenly in the arid region of Shaanxi, Qinghai, Xinjiang, Gansu and Ningxia. It was close to the best frontier in Shaanxi, Qinghai and Xinjiang, but rather low in Gansu and Ningxia. The convergence of water use efficiency of the five provinces was analyzed with the a-convergence method. It was found that the water resource utilization efficiency did not have any trend of convergence, but a trend of divergence, instead, which indicates that the discrepancies between the areas will further grow in the future. With the help of the Tobit model factors affecting the water resources utilization efficiency in Northwest China were analyzed, revealing that economic development level, industrial structure, urbanization level and water resource properties all have positive effects, but government intervention does a negative one on water resources utilization efficiency.

The current rapid development of urbanization in China has directly and seriously affected farmlands distribution in its para-urbanized neighboring/adjacent regions, and also posed severe stresses on safety of these land. It is, therefore, essential to build up a comprehensive urbanization and farmland safety assessment indicator system, work out quantitatively urbanization index and farmland safety stress index, and analyze quantitatively neighboring coupling relations between urbanization and arable land safety based on the decoupling theory and method. A case study was conducted of Lianyungang City of Jiangsu Province to explore quantitatively coupling-decoupling relationship between urbanization and farmland safety and response of farmland safety to the progress of urbanization during the period from 2000 to 2014. Results show that during the study period, urbanization index of Lianyungang City increased steadily, while farmland safety stress index fluctuated with a declining trend. Their relationship displayed a wavy trend from 2000 to 2007, i.e. strong decoupling-weak decoupling-expanding negative decoupling-expanding connection and a strong fluctuation curve from 2008 to 2014, including strong decoupling during 2008-2012 and expanding negative decoupling in 2013, which reflects strong impacts of the implementation of the regional development, land use and city overall programs on this typical neighboring/adjacent coupling system. During the study period, Lianyungang City made a huge and steady progress in urbanization, while reducing fluctuation of its stress on farmland safety. Though the two posed a strong decoupling relationship, the problem of uncertainty reflected in the huge fluctuation of the result of the neighboring/adjacent decoupling calls for high attention, and the influence urbanization had on farmland safety needs to be weighed prudently. Compared to the macroscopic single indicator models used in the past, the multi-index decoupling-coupling model built for the neighboring coupling relationship is more comprehensive and capable of analyzing the complex relationship between rapid urbanization and protection of farmland safety in a more holistic and finer way. Furthermore, it may provide theoretical support to landscape safety assessment of para-urbanizd regions and to decision-making on harmonized development of both urbanization and protection of farmland.

Study was carried out of the pollution of PM_2.5 and PM₁₀ occurring during the period from January 18 to 22, 2016 in Shijiazhuang, China. For the study, 3 monitoring posts were set up to collect PM_2.5 and PM₁₀ samples for analysis of mass concentration and chemical compositions (including carbon fractions, water soluble ions and inorganic elements), pollution characteristics and meteorological factors responsible for the pollution and further for air parcel back trajectories using HYSPLIT. Results show that mean mass concentration of PM_2.5 with the three monitoring posts reached 113, 131 and 119 μg·m^-3, separately, during the sampling period, with high mass concentrations observed in the early mornings and at noons, and coal combustion in rural farm households was also a main cause of heavy air pollution in the region of Beijing-Tianjin-Hebei. The highest mass concentration of organic carbon (OC) observed was 218.37 μg·m^-3, and the highest mass concentration of inorganic carbon (IC) 21.22 μg·m^-3. Total concentrations of crustal elements (Na, Ca, Mg, Al, K and Fe) varied in the range from 27.19 to 60.03 μg·m^-3 at the three posts during the period, accounting for 96.5% of the total inorganic elements, which indicate that traffic, road dust and coal combustion are the main sources of the air pollution. Meanwhile, high relative humidity and low wind speed might also accelerate formation of secondary particles and hygroscopic growth. The analysis of potential sources shows that Shijiazhuang was affected mainly by the PM_2.5 coming with the air masses from Beijing-Tianjin, meanwhile the analysis of potential source contribution function (PSCF) shows that Hebei Province was the uppermost potential source-area contributing adversely to the atmospheric quality in Shijiazhuang.

Downed logs are important carbon and nutrient pools in forest ecosystems. Monitoring of dynamics of microbial biomass and dissolved organic carbon/nitrogen are of great significance to in-depth understanding of the mechanism of downed log decomposition. Microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and ratio of carbon to nitrogen in bark, sapwood and heartwood of downed T. longibracteata logs various in decaying degree from Grade I to Grade V in the Tianbaoyan National Nature Reserve, Fujian Province of China was analyzed. Results show:(1) The downed logs varied from 7.41% to 63.27% in water content, and were 311.66-564.87, 2.34-5.82 and 0.09-0.35 g·kg^-1, respectively, in organic carbon, TN and TP; (2) In terms of MBC and MBN, the three components of the highly decayed downed logs (Grades Ⅳ and Ⅴ in decaying degree) displayed an decreasing order of heartwood > sapwood > bark; (3) Sapwood and heartwood was higher in DOC than bark of the logs the same in decaying degree, while sapwood was higher in DON than bark and heartwood, except for logs of Grade Ⅱ in decaying degree; (4) Microbial biomass C/N ratio in heartwood varied sharply between logs different in decaying degree, whereas DOC/DON ratio in sapwood did; (5) Position in the log, decaying degree and their interactions all had remarkable impacts on MBC, MBN, DOC, DON, MBC/MBN and DOC/DON (P<0.01); and (6) MBC, DOC and DON were extremely and positively related to water content in the log (P<0.01), whereas NBC/MBN and DOC/DON negatively to TP in the log (P<0.05). To sum up, during the downed log decaying or decomposing process, water content is the major factor affecting MBC, MBN, DOC and DON in decaying downed logs.

In order to explore changes in community structure and diversity of the planktonic and sediment bacteria in the Zhushan Bay of Lake Taihu, and to investigate relationships between bacteria and environmental factors, researches were carried out on community structure and diversity of planktonic and sediment bacteria in the Zhushan Bay of Lake Taihu in winter using the technique of 16S rRNA gene high-throughput sequencing, and relationships of the top ten genera of planktonic bacteria leading in dominancy with environmental factors (pH, dissolved oxygen concentration, chlorophyll a concentration, algal density, total nitrogen concentration, total phosphorus concentration, etc) through redundancy analysis. Results show that at the phylum level, Cyanobacteria is relatively higher in relative abundance in the water and sediment, reaching 46.95% and 22.19%, respectively, while at the class level, unidentified Actinobacteria and unidentified Cyanobacteria in the water, accounting for 31.87% and 30.46%, respectively, of the total, and Chloroplast, Gammaproteobacteria and Nitrospira in the sediment, making up 14.34%, 10.97% and 9.89% of the total, respectively, and at the genus level, Microcystis is the most dominant one in the water and followed by hgcI clade, and Microcystis and unidentified Nitrospiraceae are the dominant ones in the sediment. Through the study it is found that in the surface water, the genus of Microcystis is the highest in relative abundance, which is positively related to algal density, dissolved oxygen concentration and pH.

Land use and temperature are two main factors affecting soil N₂O emission. However, so far little information is available in the literature about interactive effects of land use and temperature on soil N₂O emission. A long-term (400 days) incubation experiment was conducted to determine interactive effect of land use and temperature on soil N₂O emission relative to type of land use. Soil samples were collected in Shouguang of Shandong, one of the largest vegetable production regions of China, from lands under different types of land use including farmland (FL), 6 year-old greenhouse cultivation (6GH) and 12 year-old greenhouse cultivation (12GH) and abandoned 12 year-old greenhouse cultivation (AG). Results of the incubation experiment show that both elevated temperature and change of land use in type from FL to 6GH and 12GH significantly promoted soil N₂O emission (P<0.05). 6GH was significantly higher than 12GH (P<0.05) in N₂O emission, and AG was significantly lower than FL (P<0.05). Q₁₀ of N₂O emission was higher in 6GH than in FL, but lower in AG than in FL (P<0.05). Moreover, Q₁₀ in 12GH was similar to that in FL. Furthermore, the interactive effect of elevated temperature and change of land use from FL to 6GH on N₂O emission was synergistic effect on N₂O emission, which turned into an additive one when 6GH became 12GH and into antagonistic one when 12GH was turned into AG, which was attributed to the variation of Q₁₀ with the alteration of land use from FL to 6GH, 12GH and AG. All the findings in this study demonstrate that the study on effect of a single factor on N₂O emission may underestimate soil N₂O emissions, while the study on comprehensive effect of multifactors on N₂O emission may over the emission.

With the aid of the eddy covariance technique, monitoring was carried out of net ecosystem CO₂ exchange (NEE) of the Nanji Wetland National Nature Reserve, sitting in the south of Poyang Lake, for analysis of diurnal variation of NEE and its affecting factors, during non-flooding and flooding periods of April, 2015-October, 2016. Results show that during the non-flooding period, diurnal variation of NEE exhibited a typical "U" shaped curve. In the day, CO₂ uptake peaked up to 18.24 μmol·m^-2·s^-1, while at the night CO₂ release did up to 24.92 μmol·m^-2·s^-1. During the flooding period, the vegetation in the area was submerged by water, except for the parts in shoals and high lands around the lake. Diurnal variation of NEE in this period didn't have any distinct characteristics, and was much narrower in amplitude than that in the non-flooding period. In daytime, CO₂ uptake peaked up to 2.29 μmol·m^-2·s^-1 while at night CO₂ release did up to 12.66 μmol·m^-2·s^-1. Correlation analysis and principal component analysis show that during the non-flooding period, monthly mean daily NEE variation in daytime was the most closely related to photosynthetic photon quanta flux density, and then to air temperature, precipitation, soil moisture content and soil temperature, whereas at night, it was closely related to air temperature, soil temperature and soil moisture content. During the flooding period, monthly mean daily NEE variation in daytime was related to photosynthetic photon quanta flux density and soil moisture content, whereas at night, it was related to soil temperature, soil moisture content and air temperature.

Being an important factor affecting deposition of sediments in a cave, CO₂ concentration in the air of the cave influences significantly stability of the secondary sediment landscape and amenity of the tourist environment. Monitoring of CO₂ concentration, temperature and relative humidity of the environments inside and outside the Zhijin Cave of Guizhou Province hydrogeochemical indices, CO₂ concentration in the overlying soil, precipitation and flow of tourists was carried out consecutively for 18 months from January, 2015 to June, 2016, in addition to the 5 consecutive days of round-the-clock monitoring of the air environment in the cave during the national holiday period, 2015, to investigate spatio-temporal variation of CO₂ concentration in the air inside the cave and its controlling factors. Results show that spatial variation of CO₂ concentration from the entrance to the deep corner of the cave did exist in the Zhijin Cave at all temporal scales and CO₂ concentration rose nonlinearly and tended to level off with the cave going deeper, which might be the result of the joint effect of the airflow exchange in and out of the cave, tunnel structure, as well as variation of elevation inside the cave. Seasonally, CO₂ concentration in the air of the cave on the whole was significantly higher in rainy seasons than in dry seasons, which is attributed mainly to tourist activities, karstification that absorbs a large volume of CO₂ containing water drips from the overlaying soil layer, and degassing of the water inside the cave, while daily, CO₂ concentration varied sharply around the clock, especially during the National Holidays when the flow of tourists visiting the cave in day time increased drastically in volume, making CO₂ concentration much higher by day than by night and on the whole on a rising trend, with temperature and humidity being two factors affecting variation of air CO₂ concentration inside the cave, but relatively weak in effect. Generally speaking, variation of the CO₂ concentration in the air of the cave is regulated mainly by the joint effect of air exchange (ventilation effect), between in and out of the cave, tunnel structure, tourist activities changes in the natural environment and karstification. It is, therefore, essential to take into consideration all the aspects or factors listed above in protecting the cave environment, and adopt scientific management to promote sustainable development of cave tourism.

To search for a practical economical phytoremediation strategy for remediation of hyper-eutrophied sea water discharged from marinelands in the areas of costal tidal flats in China, an in-lab simulated aqucultural experiment was conducted on biomass production and nutrient removal efficiency of Suaeda glauca in eutrophied sea water. Results show that the plant growing in the hyper-eutrophied water with TN and TP reaching 2.4 and 0.05 mmol·L^-1, respectively, turned out the highest biomass, either dry or fresh, or significantly higher than those growing in moderately eutrophied water with TN and TP reaching 1.6 and 0.03 mmol·L^-1, respectively or low-eutrophied water with TN and TP reaching 0.8 and 0.01 mmol·L^-1, respectively during the experiment. TN and TP removal efficiency of the plant reached 73.2% and 74.4%, separately, and declined with rising TN and TP concentrations in the eutrophied water. In addition, biomass, N and P contents and accumulation of all organs of Suaeda glauca were analyzed, with results suggesting that Suaeda glauca as a pioneer annual species in coastal tidal flats could be used to remedy hyper-eutrophied sea water as tail water from marinelands.

An in-laboratory experiment was carried out to simulate Vallisneria natans growing in wastewaters different in eutrophication degree (moderate, high and super-high) and in tetracycline hydrochloride (TH) contamination degree (0, 0.1, 0.2 and 0.5 mg·L^-1). Leaves of the plants were sampled 30 days after the initiation of the experiment for analysis of activities of peroxidase (POD) and superoxide dismutase (SOD) and contents of malondialdehyde (MDA), soluble proteins and chlorophyll for responses of the plants to changes in the environment. Results show that TH, N and P worked together affecting soluble protein, SOD, Chl-a and Chl-b in the plant significantly. In the super-eutrophication group, addition of 0.5 mg·L^-1 TH affected soluble protein the most significantly, which dropped by 47.4% in content vs that in CK of the group (0 mg·L^-1 TH). In the super-eutrophication group, addition of 0.2 mg·L^-1 TH enhanced SOD activity significantly or by 1.45 times vs that CK. In the group of moderate eutrophication, addition of 0.5 mg·L^-1 TH affected the concentrations of Chl-a and Chl-b the most significantly, which was increased by 75.7% and 64.6%, respectively, vs that in CK of the group.

This paper was designed to explore effects of two soil amendments, biochar (with some pig manure) and ground oyster shell (as biological lime), on arsenic (As) pollution in paddy soil in an attempt to provide some technical reference to the region for controlling As pollution in paddy fields under the double rice cropping system. The two soil amendments are both porous and high in specific surface area and adsorption capacity. To that end, a pot experiment was conducted to compare application of biochar plus mineral lime and ground oyster shell with application of pig manure plus mineral lime and ground oyster shell in effect on As pollution. Soil available As in the pot soils and As contents in rice straw, grain and rice in different treatments were analyzed, and the relationship between soil available As with As absorption of rice quantified. Results show that compared with the soil in CK, the soil in the treatment of pig manure plus mineral lime and ground oyster shell were 29.1%-57.0% lower, and the soils in the treatment of biochar plus mineral lime and ground oyster shell were 35.1%-65.9% lower in content of soil available As. The decrease in soil available As in turn lowered the As accumulation in the crop. The straw, grain and rice in the two treatments was 67.6%-68.5%, 66.6%-67.8% and 76.0%-76.9% lower than their respective one in CK in As content. Meanwhile, it was found that the relationship between soil available As and As absorption of rice could well be fitted with an exponential equation, with R² > 0.75, and P< 0.01. Therefore, in acid paddy fields, it is feasible to reduce soil available As and then As absorption of rice through adding biochar and ground oyster shell, but the effect is not so obvious when soil available As content is lower than 30 mg·kg^-1.

With the increasing impact of human activities and the rapid loss of biodiversity, how to prevent the continued decline in biodiversity has become a serious challenge we are facing in sustainable development. Thus, there is an urgent need for accurate and efficient assessment of regional biodiversity in practical work. Based on the forest inventory data, we designed a set of indicating system which had been used to evaluate the regional biodiversity of Beijing City. We manually identified eight biodiversity hotspots consisted of forest sublots by utilizing the established biodiversity evaluation results and high-resolution remote sensing images. The evaluation complied with the principle of consecutiveness and comprehensiveness. All hot spots were located in the northern and western mountain areas of Beijing, with a total area of about 3 791 km², taking account for 23% of Beijing's land area approximately. The results well reflected the biodiversity status of Beijing city. These hotspots areas identified which covered the existing nature reserves are consistent with the findings of field surveys. Meanwhile, we also identified the potential distribution of the protection gap areas and ecological corridors by using existing protected areas and remote sensing images. The system is simple and stable and requires very little professional backgrounds and data. It could be used as a reference for assessments of biodiversity at the regional level, especially useful for those lacking biodiversity expertise and field survey data. Therefore, the system is significantly practical in biodiversity conservation work. At the same time, the demarcation method solved the problem of operation planning difficulties by using boundaries of forest sublots. It also provided the theory evidences which could help and support government decisions.

In order to implement scientific assessment of heavy metal pollution of farmland soils in regions well developed in industry, a modified empowered fuzzy comprehensive evaluation model was established based on the concept and fuzzy nature of risk, and moreover, analysis was done of factors affecting the risk. The model consists of a target layer, a criterion layer and an index layer. The target layer is the target object for evaluation, that is, risk of a soil getting polluted by heavy metals. The target layer is composed of 3 criterion layer indexes (tendency, vulnerability and hazardness). The index layer of tendency covers accumulation rates of heavy metals (Hg, Cd, Cr, Pb, As, Cu, Zn and Ni); the index layer of vulnerability consists of pH, organic matter, soil texture; and the index layer of hazardness refers to potential ecological risk index. Weights of the criterion layer are obtained with the analytic hierarchy process, while comprehensive weights of the indices in the index layer are determined with the group decision making analytic hierarchy process (the subjective weight) and the entropy weight method (the objective weight). Risk level is determined with the fuzzy comprehensive evaluation results vector. Validity of the maximum membership degree law is tested in the process of determining risk level. The weighted average method is used to determine risk level when the validity is low. Priority order of the risk management of various indices can be determined according to the importance degree and risk degree of each index. A case study was carried out of the Pearl River Delta Region. Results show that the principle of maximum membership degree is inefficient in Guangzhou, Dongguan, Zhongshan and Jiangmen, with risk grade value being 2.8, 2.5, 2.4 and 2.4, respectively; and the principle of maximum membership degree is valid in Shenzhen, Zhuhai, Foshan and Huizhou, with maximum membership degree being 0.50 (third-level), 0.47 (second-level), 0.46 (third-level) and 0.63 (second-level), respectively, both suggesting that Guangzhou, Shenzhen, Foshan and Dongguan, as a result of high human disturbance, are high in risk, reaching up to Grade Ⅲ or "moderate risk", while Zhuhai, Huizhou, Zhongshan and Jiangmen, relatively low in human disturbance are in Grade Ⅱ or "slight risk". Analysis of affecting factor indicates that major risk affecting factors vary with the administrative region. All the findings are expected to serve as scientific basis for designing risk management strategies and defining a priority order of management.