The current status of ecotourism in rural China was analyzed in this paper.Empirical surveys covering the whole country indicate that ecotourism in rural China has attracted a large number of tourists who,however,didn’t generate revenues that can match the number.Although the environmental quality of those rural ecotourism destinations is high with little negative impacts,several problems have already appeared,suggesting a need to monitor those areas.The current practice of interpretation in most rural ecotourism destinations did not provide environmental education opportunities to the tourists.And local communities need more effective ways to decide on the prospects of local ecotourism development by themselves.Finally,a few recommendations for improving the sustainability of ecotourism destinations were provided. 相似文献
• Upgrade process was investigated in a full-scale landfill leachate treatment plant.• The optimization of DO can technically achieve the shift from CND to PND process.• Nitrosomonas was mainly responsible for ammonium oxidation in PND system.• An obviously enrichment of Thauera was found in the PND process.• Enhanced metabolic potentials on organics was found during the process update. Because of the low access to biodegradable organic substances used for denitrification, the partial nitrification-denitrification process has been considered as a low-cost, sustainable alternative for landfill leachate treatment. In this study, the process upgrade from conventional to partial nitrification-denitrification was comprehensively investigated in a full-scale landfill leachate treatment plant (LLTP). The partial nitrification-denitrification system was successfully achieved through the optimizing dissolved oxygen and the external carbon source, with effluent nitrogen concentrations lower than 150 mg/L. Moreover, the upgrading process facilitated the enrichment of Nitrosomonas (abundance increased from 0.4% to 3.3%), which was also evidenced by increased abundance of amoA/B/C genes carried by Nitrosomonas. Although Nitrospira (accounting for 0.1%–0.6%) was found to stably exist in the reactor tank, considerable nitrite accumulation occurred in the reactor (reaching 98.8 mg/L), indicating high-efficiency of the partial nitrification process. Moreover, the abundance of Thauera, the dominant denitrifying bacteria responsible for nitrite reduction, gradually increased from 0.60% to 5.52% during the upgrade process. This process caused great changes in the microbial community, inducing continuous succession of heterotrophic bacteria accompanied by enhanced metabolic potentials toward organic substances. The results obtained in this study advanced our understanding of the operation of a partial nitrification-denitrification system and provided a technical case for the upgrade of currently existing full-scale LLTPs. 相似文献
• Selective molecularly imprinted polymer (MIP) binding gel was prepared.• MIP-DGT showed excellent uptake performance for antibiotics.• In situ measurement of antibiotics in wastewaters via MIP-DGT was developed.• The MIP-DGT method was robust, reliable, and highly sensitive. Urban wastewater is one of main sources for the introduction of antibiotics into the environment. Monitoring the concentrations of antibiotics in wastewater is necessary for estimating the amount of antibiotics discharged into the environment through urban wastewater treatment systems. In this study, we report a novel diffusive gradient in thin films (DGT) method based on molecularly imprinted polymers (MIPs) for in situ measurement of two typical antibiotics, fluoroquinolones (FQs) and sulfonamides (SAs) in urban wastewater. MIPs show specific adsorption toward their templates and their structural analogs, resulting in the selective uptake of the two target antibiotics during MIP-DGT deployment. The uptake performance of the MIP-DGTs was evaluated in the laboratory and was relatively independent of solution pH (4.0–9.0), ionic strength (1–750 mmol/L), and dissolved organic matter (DOM, 0–20 mg/L). MIP-DGT samplers were tested in the effluent of an urban wastewater treatment plant for field trials, where three SA (sulfamethoxazole, sulfapyridine, and trimethoprim) and one FQ (ofloxacin) antibiotics were detected, with concentrations ranging from 25.50 to 117.58 ng/L, which are consistent with the results measured by grab sampling. The total removal efficiency of the antibiotics was 80.1% by the treatment plant. This study demonstrates that MIP-DGT is an effective tool for in situ monitoring of trace antibiotics in complex urban wastewaters. 相似文献
Environmental Science and Pollution Research - While nitrogen (N2) fixation is an important process in nitrogen (N) biogeochemical cycling, supplying a significant portion of the N in natural... 相似文献
The adverse impacts of lead and cadmium exposure on health outcomes have been reported in the past. Few studies have been conducted on the relationship between lead and cadmium exposures and disability. We evaluated whether lead and cadmium exposures were associated with functional dependence including the total number of disabilities, activities of daily living (ADL), instrumental activities of daily living (IADL), leisure and social activities (LSA), lower extremity mobility (LEM), and general physical activities (GPA) in an elderly population. A total of 5513 eligible subjects were enrolled in the study from the National Health and Nutrition Examination Survey 2001–2006. Serum lead and cadmium exposure assessments were performed using atomic absorption spectrometry. Functional dependence was assessed by 19 structured questions. The relationships between lead and cadmium exposures and functional dependence were investigated using by multivariable linear regression models. Q2, Q3, and Q4 of lead exposure were significantly associated with the total number of disabilities, with β coefficients of ??0.62 (95% CI ??0.99, ??0.24), ??0.64 (95% CI ??1.02, ??0.26), and ??0.81 (95% CI ??1.19, ??0.42), respectively. This relationship remained significant in males. Furthermore, we analyzed the relationships between lead and cadmium exposure quartiles and various functional dependence metrics, and we determined that lead content was significantly associated with decreased ADL, LEM, and GPA (p?<?0.05) and cadmium content was inversely associated with ADL (p?<?0.05). Our study demonstrated a strong relationship between exposure to lead and cadmium and functional dependence in an elderly population.
Environmental Science and Pollution Research - The combustion of fossil fuels has resulted in rapidly increasing emissions of nitrogen oxide (NOx), which has caused serious human health and... 相似文献