Watershed Ecology and the Environment最新文献

Net ecosystem productivity (NEP) is an important indicator of the capacity of terrestrial ecosystems to absorb carbon. For the purpose of developing adaptation and mitigation strategies, it is essential to investigate the effect of climatic changes and anthropogenic activities on NEP. This study analyzed the spatiotemporal properties of NEP in the Yangtze River and Yellow River Source Region (SRYY) using remote sensing images, climate variable data, and land use data. Then it was examined at how climatic change affected carbon sinks and sources and how changes in land use affected carbon storage. According to the results, the SRYY contributed a carbon sink worth 35.26 Tg C annually from 2001 to 2019 (1 Tg = 10¹² g). Influenced by climate, soil and vegetation, NEP displayed regional differences in space. The spatial distribution of NEP gradually increased from Northwest to Southeast. In recent twenty years, the NEP of SRYY slightly increased with a rate of 3.24 Tg C per decade. The NEP with an increasing trend accounted for 78.9% of the whole study area, which were widely distributed and especially significant in the west, such as Tuotuo River Basin. The correlation analysis between NEP and climate variables suggested that temperature was the dominant control of NEP in the SRYY. About 54.4% of the NEP variance across the entire SRYY was contributed by temperature. However, there was no significant linear relationship between NEP and annual precipitation. In recent two decades, built-up land expansion and ecological degradation reduced carbon sink by 28.61 Gg C (1 Gg = 10⁹ g) and 1.94 Tg C, respectively. Grassland degradation caused by rodent infestation and grazing was the main factor of carbon sink reduction in some areas. The restoration of vegetation and wetland areas resulted in a 0.75 Tg C increase in the carbon sink. It might be benefited from warmer climate condition and ecological protection measures.

The urbanization in Beijing intensified the fragmentation of ecosystems, especially for the forests and wetlands. Wetlands provide multiple ecological services (e.g., a food source, climate regulation). Thus, wetland protection is part of the foundation for sustainable economic and social development for Beijing. This study summarizes the experience of well-developed cities in wetland protection and sustainable development and subsequently analyzes the current issues of Beijing’s wetlands. The results showed that a limited resource space, high human stress, and lack of scientifically based polices are the main obstacles. Therefore, we recommend the following: (1) support the utilization of rainwater and reclaimed water and optimize the coordinated utilization of water resources, (2) strengthen the ecological protection and restoration efforts to realize the ecological protection system of water–city integration, (3) build a forest water complex ecosystem in metropolises to create a livable environment with forest and water, and (4) conduct scientific and technological research on the optimal total amount of wetlands and develop wetland technologies.

The changing dynamics of river ecosystems from aquatic to terrestrial in the Southwestern areas of Bangladesh have been widely observed in recent years. Nevertheless, there has been no consensus on whether the changes are caused by human activities or by natural processes. For a better understanding of the cause, this study was conducted based on a field survey through a pre-tested structured questionnaire measuring the river water quality. The water quality of the river was assessed to know how much the existing river water was affecting its aquatic ecosystem or not. People’s perception was also investigated to assess the factors mostly responsible for changing the river ecosystem. It was found that the most responsible factors are human activities. Among them, the construction of cross embankments over and along the Bhairab River was the most (22%) responsible factor for changing the river ecosystem. The 2nd and 3rd most responsible factors were bridge construction (18%) and illegal encroachment (18%). Other reasons for changing the ecosystem of the river were the diversion (16%), cultivation of the riverside land (12%), the introduction of exotic species (8%), and disposal of wastes and industrial effluents into the river (6%), respectively. Besides, it is also believed that the construction of Farakka Barrage on the River Ganges (the mother of the Bhairab River) is also responsible for changing the aquatic ecosystem into a terrestrial ecosystem.

The Pearl River basin (PRB) is an important producing area and the gene pool of wild resources of Four Major Chinese carps (FMCC). However human activities and climate changes causes the area shrink of the river network in PRB, the pollution aggregation, the serious habitat destroy of aquatic organisms, and the threat of biological resources and their living environment. Based on the accurate location and distribution data of FMCC from the literature and the field survey report of 2015–2016, this study used the MaxEnt model to predict the hot spot distribution area of FMCC in PRB. The simulation results show that the distribution of FMCC in the PRB gradually increases from the upper reaches to the middle and lower reaches. According to the MaxEnt model, the hot spots of FMCC in the PRB are mainly distributed in the south reaches and the lower reaches of the southeast. The model simulation also demonstrates that the hottest spots for the distribution of FMCC species in the PRB are the Yujiang basin, the Qianjiang basin and the lower reaches of the Xijiang basin. This study can provide the scientific guidance for the protection and the restoration of FMCC species in the PRB.

Environmental factors such as climate change and human activities are the basic driving forces that affect the growth and distribution of vegetation. Based on the MODIS-EVI data from 2000 to 2019, this paper analyzed the interannual changes of vegetation activity in the upper reaches of the Yangtze River (UYR), and examined their responses to climatic factors (effective precipitation, accumulative temperature and solar radiation) and anthropogenic factors (urbanization, afforestation). The results showed an increasing trend in EVI over the 20-year period, with an increasing rate of 0.021/10a. Contribution amount of effective precipitation, accumulative temperature, solar radiation and anthropogenic factors to EVI inter-annual variations in the UYR were 0.004/10a, 0.009/10a, 0.001/10a and 0.007/10a, respectively. Contribution rate of climate change and anthropogenic factors accounted for 67.8% and 32.2% of the total EVI changes respectively. In areas with significant changes in EVI, influence of anthropogenic factors is generally greater than that of climatic factors, especially in Chengdu-Chongqing urban agglomeration, Wujiang River Basin and the middle and lower reaches of the Jinsha River. In alpine regions such as the source region of the Yangtze River, significant changes in EVI were dominated by climatic factors.

The livestock resources of Bangladesh are under tremendous strain due to several natural and anthropogenic causes. Especially in the Northwestern region of Bangladesh, these resources are more vulnerable to deterioration resulting from human actions, a lack of environmental and rangeland legislation, climate change, drought, poor management, and inadequate disaster mitigation plans. GIS based multicriteria decision analysis (MCDA) and remote sensing techniques have been used in this research to locate ideal land for sheep, goats, buffalo and cow production. In this study, the suitability analysis for livestock production has been considered in eight thematic layers: slope, land use & land cover (LULC), soil types, rainfall, water accessibility, road distance, relative humidity, and average temperature. Besides, this research had been used geospatial tools for combining these eight geographical layers, when analytical hierarchy process, a MCDA approach helped to measure the weight of each criterion. The final map that is perfect for raising cattle has been divided into four categories, such as low, medium, high and excellent. Each of these rangeland suitability groups has portions in the Northwestern region of Bangladesh that fall into the following percentages: 11.14%, 26.07%, 35.27%, and 27.53%. This research also depicts that the western part of the study region, which includes Thakurgaon, Panchagar, Dinajpur, Naogaon, Joypurhat and Bogra has a low suitability index for livestock production while the eastern region, which includes Kurigram, Nilphamari, Pabna, Lalmonirhat, Gaibandha, Rangpur and Sirajganj contributes to an excellent zone. The outcome of this study will be useful to identify the best places for livestock production in the Northwestern part of Bangladesh. Finally, this research may additionally assist government officials in creating environmental and rangeland strategies for the livestock population in the study area.

Urbanization has expanded rapidly worldwide in recent decades, and has led to a series of environmental changes. With the improvement of the urban habitat, the density of wildlife is on the rise, especially for the birds. However, birds are host to a variety of viruses, pathogenic microorganisms and parasites, and the increase of their density may amplify the risk of disease transmission in cities. Thus, understanding the characteristics of regional bird community aids the integration of knowledge about the risk of disease transmission by birds. Here, we conducted a field survey in summer, 2021, to compare the differences in vegetation, species richness and individual numbers of bird in Shanghai urban and surrounding areas covering 28 zones along an urbanization gradient and to assess the possibility of bird transmission risk in Shanghai. We recorded 122 plant species and 3416 bird individuals of 23 species. Our results found that urbanization has led to a decline in bird species and densities than relatively pristine habitats (rural, agroforestry habitat, urban park), and based on our literature collection, most species carrying avian influenza virus were migratory waterbirds (anatidae and shorebird) that relatively away from urban area. Our study suggests that urbanization reduces bird diversity, but urban birds may have a low probability of transmitting the avian influenza virus to humans.

Emerging chemical substances have dramatically increased in aquatic ecosystems throughout the last few decades and are creating harmful effects on sustainable environments. Herbicides and antibiotics are usually consumed simultaneously and liquidated into the aquatic system as effluents. Due to the dearth of rigorous control of emerging substances, it poses a threat to ecotoxicologists and limnologists because of their hidden roles against non-target aquatic organisms like zooplankton. These substances have a negative impact on grazer inducers and disrupt community-level zooplankton-phytoplankton relationships. But the hidden role of these phenomena due to these substances is still clearly unknown. So, the present mesocosm study summarises and updates the current status of antibiotics and herbicides on the survival of zooplankton species. We also discuss the role of various herbicides and antibiotics on these non-targeted organisms and create baseline information to overcome the above-mentioned risks and expand the scope of future research in this field.

In the present study, hydrophilic silica aerogel (HPSA) was synthesized by ambient pressure drying method and was successfully used as an adsorbent for the removal of Cationic dyes (Crystal violet- CV) from the aqueous solution. The synthesized sample was characterized and examined by Fourier transform infrared spectroscopy (FTIR), Bruner – Emmett – Teller (BET), x-ray diffraction (XRD), Zeta potential pH _zp, Nuclear Magnetic Resonance Spectrometer (NMR), and Scanning Electron microscope (SEM). The effect of different parameters such as pH, initial concentration of dyes, contact time, temperature, and their effect on the removal of CV dyes was studied. Silica aerogel synthesized was excellent and 96 % removal of CV dyes on the optimum value of the parameters of 30 min contact time, 303 K temp, 7 pH, 50 mg/l Conc., 0.3 g/l dose of HPSA was obtained. Langmuir, Freundlich, Temkin,and D-R models were applied in the equilibrium studies and obtained the maximum adsorption capacity 137.17 mg/g. pseudo-first, second-order, and intraparticle diffusion models were employed to indicate the chemisorption behavior in the kinetic study on the adsorption. Thermodynamic parameters showed the adsorption process as Exothermic and spontaneous. Sticking Probability (S*≪1) indicated HPSA as a good adsorbent for the removal of dyes. HPSA has demonstrated the potential for regeneration while affirming its remarkable removal efficiency, Cost effectiveness and Environmental compatibility.

Taipu River is one of the important river channels of Taihu Lake, and also an important water body in the demonstration zone of green and integrated ecological development of the Yangtze River Delta. In this study, we collect the water quality monitoring data of Taipu River and related research results of Taipu River water quality, and analyze the water environment characteristics of Taipu River by analyzing the water quality status of Taipu River main stream and East Taihu Lake. The results indicate that from 2016 to 2018, the annual mean values of conventional indexes in main sections of the Taipu River main stream were maintained in Class II to III. The incoming water from the Taipu River mainly includes the East Taihu Lake and its tributaries. The water quality of the East Taihu Lake is superior to that of the Taipu River. The water quality of the Jinze section is mainly affected by the inflow from the East Taihu Lake. Increase the discharge under Taipu sluice to supply high-quality water, which can effectively guarantee the water quality of the section. Then we identify the main water environmental problems in Taipu River basin. The results of our analysis can provide support for the water ecological environment protection of Taipu River.