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1.
As the eutrophication of lakes becomes an increasingly widespread phenomenon, cyanobacterial blooms are occurring in many countries. Although some research has been reported, there is currently no good method for bloom removal. We propose here a new two-step integrated approach to resolve this problem. The first step is the inactivation of the cyanobacteria via the addition of H(2)O(2). We found 60 mg/L was the lowest effective dose for a cyanobacterial concentration corresponding to 100 μg/L chlorophyll-a. The second step is the flocculation and sedimentation of the inactivated cyanobacteria. We found the addition of lake sediment clay (2 g/L) plus polymeric ferric sulfate (20 mg/L) effectively deposited them on the lake bottom. Since algaecides and flocculants had been used separately in previous reports, we innovatively combined these two types of reagents to remove blooms from the lake surface and to improve the dissolved oxygen content of lake sediments. 相似文献
2.
Environmental Science and Pollution Research - Dams significantly impact river hydrology by changing the timing, size, and frequency of low and high flows, resulting in a hydrologic regime that... 相似文献
3.
Short-term hydrodynamic fluctuations caused by extreme weather events are expected to increase worldwide because of global climate change, and such fluctuations can strongly influence cyanobacterial blooms. In this study, the cyanobacterial bloom disappearance and reappearance in Lake Taihu, China, in response to short-term hydrodynamic fluctuations, was investigated by field sampling, long-term ecological records, high-frequency sensors and MODIS satellite images. The horizontal drift caused by the dominant easterly wind during the phytoplankton growth season was mainly responsible for cyanobacterial biomass accumulation in the western and northern regions of the lake and subsequent bloom formation over relatively long time scales. The cyanobacterial bloom changed slowly under calm or gentle wind conditions. In contrast, the short-term bloom events within a day were mainly caused by entrainment and disentrainment of cyanobacterial colonies by wind-induced hydrodynamics. Observation of a westerly event in Lake Taihu revealed that when the 30 min mean wind speed (flow speed) exceeded the threshold value of 6 m/s (5.7 cm/s), cyanobacteria in colonies were entrained by the wind-induced hydrodynamics. Subsequently, the vertical migration of cyanobacterial colonies was controlled by hydrodynamics, resulting in thorough mixing of algal biomass throughout the water depth and the eventual disappearance of surface blooms. Moreover, the intense mixing can also increase the chance for forming larger and more cyanobacterial colonies, namely, aggregation. Subsequently, when the hydrodynamics became weak, the cyanobacterial colonies continuously float upward without effective buoyancy regulation, and cause cyanobacterial bloom explosive expansion after the westerly. Furthermore, the results of this study indicate that the strong wind happening frequently during April and October can be an important cause of the formation and expansion of cyanobacterial blooms in Lake Taihu. 相似文献
4.
Effects of ionic strength, pH, organic content, cell concentration, and growth phase on the removal of MA cells using chitosan-modified sepiolite were studied in the laboratory. The MA removal efficiency increased with the increase of salinity for normal clay flocculation. In contrast, for chitosan-modified clays/soils, MA removal efficiency increased with the decrease of salinity. The removal efficiency of chitosan-modified sepiolite was not significantly affected by pH (6-9), but dropped dramatically beyond pH 10. Humic acid had a small negative effect on the removal of MA cells. Cells were removed more effectively by clays around the early senescence growth phase than other growth stages. The removal efficiency increased as the cell concentration increased. In a field enclosure of Taihu Lake, a loading of 0.025 g/L chitosan-modified local soils removed 99% algal cells and no increase of chlorophyll-a was observed during the following one month's monitoring process. 相似文献
5.
Drought is a harmful natural disaster with various negative effects on many aspects of life. In this research, short-term meteorological droughts were predicted with hybrid machine learning models using monthly precipitation data (1960–2020 period) of Sakarya Meteorological Station, located in the northwest of Turkey. Standardized precipitation index (SPI), depending only on precipitation data, was used as the drought index, and 1-, 3-, and 6-month time scales for short-term droughts were considered. In the prediction models, drought index was predicted at t?+?1 output variable by using t, t???1, t???2, and t???3 input variables. Artificial neural networks (ANNs), adaptive neuro-fuzzy inference system (ANFIS), Gaussian process regression (GPR), support vector machine regression (SVMR), k-nearest neighbors (KNN) algorithms were employed as stand-alone machine learning methods. Variation mode decomposition (VMD), discrete wavelet transform (DWT), and empirical mode decomposition (EMD) were utilized as pre-processing techniques to create hybrid models. Six different performance criteria were used to assess model performance. The hybrid models used together with the pre-processing techniques were found to be more successful than the stand-alone models. Hybrid VMD-GPR model yielded the best results (NSE?=?0.9345, OI?=?0.9438, R2?=?0.9367) for 1-month time scale, hybrid VMD-GPR model (NSE?=?0.9528, OI?=?0.9559, R2?=?0.9565) for 3-month time scale, and hybrid DWT-ANN model (NSE?=?0.9398, OI?=?0.9483, R2?=?0.9450) for 6-month time scale. Considering the entire performance criteria, it was determined that the decomposition success of VMD was higher than DWT and EMD. 相似文献
6.
Environmental Science and Pollution Research - Land use and land cover (LULC) change has become a critical issue for decision planners and conservationists due to inappropriate growth and its... 相似文献
7.
Environmental Science and Pollution Research - Internet of Things (IoT) in the field of agriculture promises to continuously provide global access to the farming information. The smart agriculture... 相似文献
8.
Environmental Science and Pollution Research - The study proposes a novel and sustainable method to appropriately utilize wastes from granite as well as glass industries in brick manufacturing. An... 相似文献
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Environmental Science and Pollution Research - Natural hazards and severe weather events are a matter of serious threat to humans, economic activities, and the environment. Flash floods are one of... 相似文献
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Environmental Science and Pollution Research - Harmful cyanobacterial blooms are exemplified as a major environmental concern due to producing toxin, and have generated a serious threat to public... 相似文献
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Environmental Science and Pollution Research - In Turkey, facilities for the use of biomass resources in energy production are increasing, and new conversion facilities are commissioned every year... 相似文献
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Environmental Science and Pollution Research - Coronavirus disease 2019 (COVID-19) has delayed global economic growth, which has affected the economic life globally. On the one hand, numerous... 相似文献
13.
Algal removal abilities of 26 clays/minerals were classified into three categories according to the 8-h equilibrium removal efficiency (Q8h) and removal rate at a clay loading of 0.7 g/L. Type I clays (sepiolite, talc, ferric oxide, and kaolinite) had a Q8h > 90%, a t50 (time needed to remove 50% of the algae) < 15 min, and a t80 < 2.5 h. Type II clays (6 clays) had a Q8h 50-90%, a t50 < 2.5 h, and a t80 > 2.5 h. Type III clays (14 clays) with Q8h < 50%, t50 > 8 h and t80 > 14 h had no practical value in removal of algal blooms. When the clay loading was reduced to 0.2 g/L, Q8h for all the 25 materials decreased to below 60%, except for sepiolite whose Q8h remained about 97%. The high efficiency for sepiolite to flocculate M. aeruginosa cells in freshwaters was due to the mechanism of netting and bridging effect. 相似文献
14.
Environmental Science and Pollution Research - Land oil spills in Nigeria have a long history of contaminating the soil, groundwater, vegetation, and streams with spill extension being the primary... 相似文献
15.
The impounding of the Three Gorges Reservoir (TGR) at the Yangtze River caused large flooding of urban, industrial, and agricultural areas, and profound land use changes took place. Consequently, substantial amounts of organic and inorganic pollutants were released into the reservoir. Additionally, contaminants and nutrients are entering the reservoir by drift, drainage, and runoff from adjacent agricultural areas as well as from sewage of industry, aquacultures, and households. The main aim of the presented research project is a deeper understanding of the processes that determines the bioaccumulation and biomagnification of organic pollutants, i.e., mainly pesticides, in aquatic food webs under the newly developing conditions of the TGR. The project is part of the Yangtze-Hydro environmental program, financed by the German Ministry of Education and Science. In order to test combinations of environmental factors like nutrients and pollution, we use an integrated modeling approach to study the potential accumulation and biomagnification. We describe the integrative modeling approach and the consecutive adaption of the AQUATOX model, used as modeling framework for ecological risk assessment. As a starting point, pre-calibrated simulations were adapted to Yangtze-specific conditions (regionalization). Two exemplary food webs were developed by a thorough review of the pertinent literature. The first typical for the flowing conditions of the original Yangtze River and the Daning River near the city of Wushan, and the second for the stagnant reservoir characteristics of the aforementioned region that is marked by an intermediate between lake and large river communities of aquatic organisms. In close cooperation with German and Chinese partners of the Yangtze-Hydro Research Association, other site-specific parameters were estimated. The MINIBAT project contributed to the calibration of physicochemical and bathymetric parameters, and the TRANSMIC project delivered hydrodynamic models for water volume and flow velocity conditions. The research questions were firstly focused on the definition of scenarios that could depict representative situations regarding food webs, pollution, and flow conditions in the TGR. The food webs and the abiotic site conditions in the main study area near the city of Wushan that determine the environmental preconditions for the organisms were defined. In our conceptual approach, we used the pesticide propanil as a model substance. 相似文献
16.
Environmental Science and Pollution Research - Mosquitoes are the underlying cause of various public health and economic problems. In this study, patterns of mosquito occurrence were analyzed based... 相似文献
17.
Elevated concentrations of ground-level ozone (O 3) are frequently measured over farmland regions in many parts of the world. While numerous experimental studies show that O 3 can significantly decrease crop productivity, independent verifications of yield losses at current ambient O 3 concentrations in rural locations are sparse. In this study, soybean crop yield data during a 5-year period over the Midwest of the United States were combined with ground and satellite O 3 measurements to provide evidence that yield losses on the order of 10% could be estimated through the use of a multiple linear regression model. Yield loss trends based on both conventional ground-based instrumentation and satellite-derived tropospheric O 3 measurements were statistically significant and were consistent with results obtained from open-top chamber experiments and an open-air experimental facility (SoyFACE, Soybean Free Air Concentration Enrichment) in central Illinois. Our analysis suggests that such losses are a relatively new phenomenon due to the increase in background tropospheric O 3 levels over recent decades. Extrapolation of these findings supports previous studies that estimate the global economic loss to the farming community of more than $10 billion annually. 相似文献
18.
Total airborne mercury (TAM) and carbon monoxide (CO) were measured in 22 pollution transport “events” at Mt. Bachelor Observatory (MBO), USA (2.8 km asl) between March 2004 and September 2005. Submicron particulate scattering ( , ozone ( , and nitrogen oxides ( were also measured and enhancement ratios for each chemical and aerosol species with CO were calculated. Events were categorized based on their source regions, which were determined by a combination of back trajectories, satellite fire detections, chemical and aerosol enhancement ratios, and meteorology. The mean values for each source region are: East Asian industrial ( , events, 236 h), Pacific Northwest U.S. (PNW) biomass burning ( , events, 173 h), and Alaska biomass burning ( , events, 96 h). The means from Asian long-range transport (ALRT) and biomass burning events are combined with previous estimates of CO emissions from Chinese anthropogenic, global biomass burning, and global boreal biomass sources in order to estimate the emissions of gaseous elemental mercury (GEM) from these sources. The GEM emissions that we calculate here are: Chinese anthropogenic ( ), global biomass burning , and global boreal biomass burning , with errors estimated from propagating the uncertainty in the mean enhancement ratios and CO emissions. A comparison of our results with published mercury (Hg) emissions inventories reveals that the Chinese GEM emissions from this study are higher by about a factor of two, while our estimate for global biomass burning is consistent with previous studies. 相似文献
19.
The cytotoxic drug, cisplatin ( cis-PtCl 2(NH 3) 2), has been added to cultures of the marine macroalga, Ulva lactuca, under various experimental conditions. Both accumulation and internalisation over a 48 h period was greater when cisplatin was added to coastal sea water (salinity = 33) from a distilled water solution than when added to either sea water or estuarine water (salinity = 16.5) from a saline solution. This effect is attributed to the greater abundance of the more reactive monoaqua complex ( cis-PtCl(OH 2)(NH 3) 2+) in the distilled water solution and kinetic constraints on its conversion back to cis-PtCl 2(NH 3) 2 in sea water. Despite its mode of action at the cellular level, cisplatin added up to concentrations of 150 nM did not incur a measurable reduction in the efficiency of photochemical energy conversion under any of experimental conditions tested. 相似文献
20.
Environmental Science and Pollution Research - The study on land use and land cover (LULC) changes assists in analyzing the change and regulates environment sustainability. Hence, this research... 相似文献
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