Shengjin Lake wetland is located in the middle and lower reaches of the Yangtze River in China. It is a typical lake-type wetland and is also an ideal place for rare cranes to overwintering. The changes of wetland landscape are closely related to the habitat quality of wintering cranes. It is of great significance to study the habitat change of wintering cranes in wetland for wetland ecological restoration and restoration. In this paper, we analyze four kinds of winter cranes and wetland landscape pattern types from the years 1986 to 2015. Also, we adopted the Pearson correlation analysis method to analyze the relationship between wetland landscape types and crane population, and the main landscape types of cranes habitat were obtained. We selected disturbance degree, food richness, vegetation cover, and hydrological condition as the main factors affecting wintering habitat of cranes. We established a habitat suitability index model for wintering cranes and generated habitat suitability assessment maps by ArcGIS. The results show that the change of landscape pattern in Shengjin Lake protected area was obvious, the number of wetland patches increased, the fragmentation degree of landscape increased, the landscape patch difference became smaller, and the diversity index and evenness index increased gradually. From 1986 to 2015, the number of wintering cranes decreased and the habitat suitability index of wintering cranes decreased from 0.845 to 0.465, and the habitat suitability of wintering cranes fell from 13,577.11 to 7424.42 ha, which showed the overall habitat deteriorated significantly and had a positive correlation between the crane population and habitat suitability.
Environmental Science and Pollution Research - The biotoxicity of heavy metals in sediments toward benthic organisms has evoked great concern for the health of freshwater ecosystems. This study... 相似文献
Environmental Geochemistry and Health - The purpose of this study was to investigate the associations between levels of lead (Pb), cadmium (Cd), chromium (Cr), and manganese (Mn) in the PM2.5 and... 相似文献
The study aimed to estimate resource use efficiency and economic losses by using stochastic frontier analysis. The data set were collected in An Giang Province of Vietnam through personal interviews with 199 rice farmers. The results revealed that returns to scale are decreasing. Rice farmers had high levels of output-oriented and input-oriented technical efficiency with the means of 91.92 and 85.39 %, respectively. The mean environmental efficiency was 82.03 %. The mean efficiency of normal inputs was 61.20 %. Among the bad inputs, pesticide and energy were the least efficient ones with the mean values of 51.39 and 45.53 %, respectively, indicating serious overuses of these inputs. As regards normal inputs, capital had the lowest efficiency score at 21.08 %, followed by seed quantity at 26.4 %. Further, the total economic losses were estimated at 8261 thousand VND (380 USD) per hectare, which is equal to the sales of about 1600 kg of rice per hectare or the efforts to increase by 20 % of output level. This study suggests that rice farmers need to contract inputs, particularly environmentally detrimental inputs to improve profits. To improve the productive efficiency, the use of ecological engineering, collective pump and cultivation of three rice crops per year are possible options. 相似文献
The Environmental Protection Agency has encouraged voluntary efforts at pollution prevention by facilities through participation in voluntary environmental programs (VEPs) such as the 33/50 program to reduce toxic releases. This paper examines the effectiveness of the 33/50 program in the adoption of pollution prevention practices and disentangles the effect of adoption from that of program participation on releases of 33/50 chemicals. Using facility-specific panel data and controlling for the endogeneity of program participation and pollution prevention adoption, we find that program participants were 38% more likely to adopt pollution prevention practices than non-participants. Program participants who adopted pollution prevention practices reduced their 33/50 releases by 52% compared to facilities that neither participated nor adopted pollution prevention. This indicates that VEPs that emphasize pollution prevention can play a complementary role in reducing toxic releases. 相似文献
Abstract Two pyrethroid insecticides were compared with two fungicides for their effects on the rhizobial and seedling components of the N2‐fixing symbiosis in soybeans (Glycine max Merr. variety Olinda). In vitro growth of Rhizobium japonicum RI16, was inhibited in the order of HgCl2 > thiram > cypermethrin > permethrin. The emergence of the seedlings was stimulated by all chemicals tested. Also, none of the pesticides studied had any significant effect on N2 fixation (acetylene reduction), at the dosages used. Consequently, yields of the various organs were also not significantly influenced by the chemicals. 相似文献
Plastics from waste electrical and electronic equipment (WEEE) have been an important environmental problem because these plastics commonly contain toxic halogenated flame retardants which may cause serious environmental pollution, especially the formation of carcinogenic substances polybrominated dibenzo dioxins/furans (PBDD/Fs), during treat process of these plastics. Pyrolysis has been proposed as a viable processing route for recycling the organic compounds in WEEE plastics into fuels and chemical feedstock. However, dehalogenation procedures are also necessary during treat process, because the oils collected in single pyrolysis process may contain numerous halogenated organic compounds, which would detrimentally impact the reuse of these pyrolysis oils. Currently, dehalogenation has become a significant topic in recycling of WEEE plastics by pyrolysis. In order to fulfill the better resource utilization of the WEEE plastics, the compositions, characteristics and dehalogenation methods during the pyrolysis recycling process of WEEE plastics were reviewed in this paper. Dehalogenation and the decomposition or pyrolysis of WEEE plastics can be carried out simultaneously or successively. It could be ‘dehalogenating prior to pyrolysing plastics’, ‘performing dehalogenation and pyrolysis at the same time’ or ‘pyrolysing plastics first then upgrading pyrolysis oils’. The first strategy essentially is the two-stage pyrolysis with the release of halogen hydrides at low pyrolysis temperature region which is separate from the decomposition of polymer matrixes, thus obtaining halogenated free oil products. The second strategy is the most common method. Zeolite or other type of catalyst can be used in the pyrolysis process for removing organohalogens. The third strategy separate pyrolysis and dehalogenation of WEEE plastics, which can, to some degree, avoid the problem of oil value decline due to the use of catalyst, but obviously, this strategy may increase the cost of whole recycling process. 相似文献
Titanium dioxide (TiO2) is a promising sorbent for As removal. There are two main and physico-chemically distinct polymorphs of TiO2 in nature, namely anatase and rutile. Since the difference of arsenic removal by the two polymorphs of TiO2 is now well known, study on the arsenic removal efficiency and the underlying mechanism is of great significance in developing new remediation strategies for As-polluted waters. Here batch experiments were carried out in combination with instrumental analysis of X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) to investigate the effects, influential factors and mechanisms of As removal from aqueous solution by two types of nano TiO2 crystals. The adsorption behavior of anatase and rutile for As(V) and As(III) are well described by Freundlich equations. Anatase had higher As removal efficiency and adsorption capacity than rutile. Solution pH had no influence on the As adsorption of anatase TiO2, whereas the As removal by rutile TiO2 was increased by 7?C18% with pH from 4 to 10. Presence of accompanying anions such as phosphate, silicate, nitrate and sulfate, decreased the As(V) and As(III) removal by both crystals, with phosphate being the most effective. However, removal of As by rutile TiO2 was greatly enhanced in the presence of divalent cations i.e. Ca2+ and Mg2+. Shading of light decreased the removal of As(V) and As(III) of anatase by 15.5% and 17.5%, respectively, while a slight increase of As removal was observed in the case of Rutile TiO2. FT-IR characterization of As(V) or As(III)-treated nano TiO2 crystals indicated that both Ti-O and As-O groups participated in As adsorption. Both FT-IR and XPS analysis demonstrated that As(III) was photooxidated into As(V) when adsorbed by anatase under the light condition. Thus, the effect of crystal types and light condition on As removal should be taken into consideration when nano TiO2 is applied for As removal from water. 相似文献