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Ecological indicators have widespread appeal to scientists, environmental managers, and the general public. Remote sensing is unique in its capability to record variety of spatio-temporal information on land surface with complete coverage, especially with regard to larger spatial scales, which has been proven to be an effective data source to create indicators to rapidly identify regional eco-environment. In this paper, a new index, remote sensing based ecological index (RSEI) based on the pressure-state-response (PSR) framework, was applied to assess regional ecological changes in Fuzhou City of Fujian Province, southeastern China, using Landsat ETM+/OLI/TIRS images. Taking the advantages of being totally free of artificial interference in the calculation using principal components analysis (PCA) to assign weights of each variable, the RSEI can assess the regional ecological status more objectively and easily. The effectivity of the new index was validated by four approaches, including point-based, classification-based, correlation-based, and urban-rural-gradient-based comparisons. The case study showed that Fuzhou has witnessed ecological improvement during the study period, with the value of RSEI increasing from 0.663 in 2000 to 0.675 in 2016. Spatial variation analysis showed that the poor level of RSEI distributed mostly in the central urban areas, and the ecological degradation was attributed to the fast expansion of the built-up area, characterized by increasing greatly in the value of the normalized differential built up and soil index (NDBSI) in such areas.
相似文献This comparative field study examined the responses of bacterial community structure and diversity to the revegetation of zinc (Zn) smelting waste slag with eight plant species after 5 years. The microbial community structure of waste slag with and without vegetation was evaluated using high-throughput sequencing. The physiochemical properties of Zn smelting slag after revegetation with eight plant rhizospheres for 5 years were improved compared to those of bulk slag. Revegetation significantly increased the microbial community diversity in plant rhizospheres, and at the phylum level, Proteobacteria, Acidobacteria, and Bacteroidetes were notably more abundant in rhizosphere slags than those in bulk waste slag. Additionally, revegetation increased the relative abundance of plant growth-promoting rhizobacteria such as Flavobacterium, Streptomyces, and Arthrobacter as well as symbiotic N2 fixers such as Bradyrhizobium. Three dominant native plant species (Arundo donax, Broussonetia papyrifera, and Robinia pseudoacacia) greatly increased the quality of the rhizosphere slags. Canonical correspondence analysis showed that the differences in bacterial community structure between the bulk and rhizosphere slags were explained by slag properties, i.e., pH, available copper (Cu) and lead (Pb), moisture, available nitrogen (N), phosphorus (P), and potassium (K), and organic matter (OM); however, available Zn and cadmium (Cd) contents were the slag parameters that best explained the differences between the rhizosphere communities of the eight plant species. The results suggested that revegetation plays an important role in enhancing bacterial community abundance and diversity in rhizosphere slags and that revegetation may also regulate microbiological properties and diversity mainly through changes in heavy metal bioavailability and physiochemical slag characteristics.
相似文献Studying the modes of selenium occurrence in high-Se soils and its behaviors can improve understanding and evaluating its cycling, flux, and balance in geo-ecosystems and its influence on health. In this paper, using a modified sequential chemical extraction technique, seven operationally defined selenium fractions and Se valence distribution were determined about five soils in which paddy was planted (W1, W2, W3, W4, W5) and five soils in which maize was planted (H1, H2, H3, H4, H5) around the selenium-rich core, Ziyang County, Shaanxi Province, China. The results show that selenium fractions in the soils mainly include sulfide/selenide and base-soluble Se, and ligand-exchangeable Se is also high for five soils in which paddy was planted. For water-soluble Se, Se (IV) is main Se valence and almost no Se (VI) was determined about five soils in which paddy was planted, while almost 1:1 of Se (IV) and Se (VI) coexist about five soils in which maize was planted. For exchangeable Se, similar results were found. For the first time, two typical high-Se soils (W1 soil and H1 soil) were chosen to measure the pH-dependent solid-solution distribution of selenite in the pH range 3–9, and the results were explained using LCD (ligand and charge distribution) adsorption modeling. The desorbed selenite concentrations from the two soils are in general underestimated by the model due to a comparable binding affinity of phosphate and selenite on goethite and much lower amount of total selenite than total reactively adsorbed phosphate. The pH dependency of adsorption of selenite added to the soil can be successfully described with the LCD model for W1 soil. Whereas considering the influence of Al-oxides, by lowering selenite adsorption affinity constant K of Se adsorption on goethite by 16 times, the LCD model can describe the adsorption much better. The results can help to understand selenium cycling, flux, and balance in typical high-Se soils.
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