Wang, Y. and Du, Y., 2024. Eutrophication evaluation assessment based on the multidimension cloud model and projection pursuit method.Lake eutrophication evaluation is challenging because the ...evaluation process is uncertain and random and monitored data are usually inaccurate within a wide range. To deal with the uncertainty and randomness in evaluation eutrophication, the integration of multidimension cloud model (MDCM) and projection pursuit (PP) method were proposed, called the MDCM-PP method. The MDCM considers each evaluation factor as a one-dimension attribute, and the weights of evaluation factors were determined by PP method. In addition, the uncertainty and fuzziness of data was processed by triangular fuzzy numbers (TFNs). The combination of the MDCM-PP model and TFNs was applied to Dongting Lake in China to evaluated eutrophication statuses. The results indicated that the eutrophication levels in the East Dongting Lake were more serious than the South Dongting Lake and West Dongting Lake, which is in accordance with other research. The proposed method can consider fuzziness and randomness with the MDCM-PP model and TFNs in the eutrophication evaluation, which can also be applied to other evaluation processes with character of fuzziness and randomness.
Groundwater age is an important indicator of groundwater susceptibility to anthropogenic contamination and a key input to statistical models for forecasting water quality. Numerical models can ...provide estimates of groundwater age, enabling interpretation of measured age tracers. However, to extend to national‐scale groundwater systems where numerical models are not routinely available, a more efficient metamodeling approach can provide a less precise but widely applicable estimate of groundwater age, trained to make forecasts based on predictor variables that can be measured independent of numerical models. We trained gradient‐boosted regression tree statistical metamodels to MODFLOW/MODPATH‐derived groundwater age estimates in five inset models in the Lake Michigan Basin, USA. Using high‐throughput computing, we explored an exhaustive range of tuning parameters and tested metamodels through cross validation, a 20% holdout, and a round robin approach among the five inset models withholding each inset model from training and testing on the held‐out inset model. Forecast skill—measured by Nash Sutcliffe efficiency—was high for age‐related responses in the 20% hold‐out case (ranging from 0.73 to 0.84). The round robin analysis provided the opportunity to explore extending to unmodeled areas and a greater range of skill indicated the need to evaluate when it is appropriate to apply a metamodel from one region to another. We further explored the ramifications of metamodel simplification achieved through removing predictor variables based on their estimated importance. We found that similar metamodel performance was achievable with a fraction of the candidate set of predictor variables with well construction variables being most important.
Plain Language Summary
Constructing computer models of groundwater and making forecasts to help water resource managers can both be time consuming. Metamodeling takes advantage of recent advances in artificial intelligence to make simple, fast‐running statistical models learned from paired inputs and outputs generated by a more complicated computer model. These metamodels are easier to construct, based on salient environmental characteristics, which can be obtained using maps spanning large scale. When metamodels adequately duplicate the underlying model behavior, they can be extended into previously unmodeled areas. In this work, we created metamodels to forecast groundwater age in pumping wells in the Lake Michigan Basin. Groundwater extracted from wells represents a mixture of water ranging in age from recent to thousands of years old. Water younger than 65 years old is more likely to contain nitrate as this time period saw high use of inorganic nitrogen for agricultural fertilizer resulting in nitrate entering the groundwater. The ability to rapidly create a metamodel of a previously unmodeled area allows forecasting and mapping groundwater age over large regions. Our metamodels reproduce 73% to 84% of the underlying training model information. This prototype screening approach, with age indicating nitrate vulnerability, can be extended for planning new well locations throughout the glaciated northern United States.
Key Points
Metamodels can emulate groundwater age forecasts from MODFLOW/MODPATH models
Metamodels have the potential to be applied in areas where a numerical model is not available
Metamodels make forecasts rapidly with benefit for decision support
Globally, lakes are drying up and shrinking and inland lakes, in particular, face severe water shortage problems. Thus, the degradation mechanisms and protection measures for inland lakes urgently ...need to be explored. Hongjiannao Lake (HL), an inland lake on the border of Shaanxi Province and Inner Mongolia Autonomous Region of China, was selected for the present case study. The evolution of HL was analyzed and the current lake water storage was measured on site. The driving factors of water resource changes in HL were discussed based on meteorological and landcover data. The results showed that (1) from 1929 to 2021, the lake area of HL experienced four stages: formation, stability, shrinkage and recovery. The smallest water area was 31.08 km2 in 2015, half the size of lake in the 1960s. (2) Spatially, the morphological changes of HL mainly occurred where the rivers entered the lake. (3) In 2021, the average depth of HL was 3.77 m, and the water storage capacity was 140.56 million m3. (4) The annual average evaporation was 3.36 times the amount of the annual average precipitation in Hongjiannao Basin (HB), but climate change was not the main driver of changes in the HL area. (5) In the past 20 years, cultivated land and artificial surface increased by 3.11% and 1.04%, respectively, whereas grassland and water body decreased by 3.51% and 0.45%, respectively. The expansion of cultivated land and artificial surface, as well as the construction of reservoirs upstream of the lake, hindered the replenishment of water resources to HL. This study recommends a range of strategies for water resource protection in inland lakes, including implementing ecological restoration projects, carrying out inter-basin water transfer measures, improving the efficiency of regional water resource use, and improving industrial structure and distribution.
•After entering the 21st century, the area of HL shrank sharply.•In 2021, the water storage capacity was approximately 141 million m3.•Climate change was not the main driver of changes in the HL area.•In the past 20 years, cultivated land and artificial surface increased in the HB.•The strategies for water resource protection in inland lakes were recommended.
Understanding the natural variability of the East Asian monsoon (EAM) system, mainly consisting of summer and winter monsoons, is essential to predict future climate changes that will influence ...agricultural and industrial activities in the highly populated region. To date, the variability of the East Asian winter monsoon (EAWM) and its controlling factors is still unclear in downwind areas that experience the Siberian High, mostly due to the lack of a high-resolution winter monsoon index. Based on the correlation between diatom variations in a volcanic cone of Jeju Island, South Korea, with past regional climate changes (e.g., temperature, dust, and sea ice) and solar activity, in this study, we evaluated the changes in the climate from the sum of acidophilous species (SAS), known to be mainly controlled by the pH of the prevalent water pool, and inferred that the SAS increased during the cold and dry periods (e.g., Little Ice Age and Dark Age Cold Period). Furthermore, millennial-timescale fluctuation in the detrended SAS during the past 8000 years, with peaks at ~500, 1500, 3000, 5600, 6600, and 7600 cal yr B·P., corresponded to the ice-rafted events reported from studies conducted on subpolar ocean sediments and solar activity. In this study, we suggest that, historically, high-latitude climate change driven by solar activity has controlled the EAWM; additionally, we support the application of the SAS in Jeju Island as a high-resolution EAWM index.
•The diatom variation is correlated to climate change during the Holocene•The present pH changes depend on the season and indicate the EAWM variability•Acidophilous species correlate with the Little Ice Age and Dark Ages Cold Period•During Holocene, the relative abundance of acidophilous species is related to Bond events.•The EAWM was mainly controlled by the solar irradiance during the Holocene
Summary
Located on the shore of Kandalaksha Bay (the White Sea, Russia) and previously separated from it, Trekhtzvetnoe Lake (average depth 3.5 m) is one of the shallowest meromictic lakes known. ...Despite its shallowness, it features completely developed water column stratification with high‐density microbial chemocline community (bacterial plate) and high rates of major biogeochemical processes. A sharp halocline stabilizes the stratification. Chlorobium phaeovibrioides dominated the bacterial plate, which reached a density of 2 × 108 cell ml−1 and almost completely intercepts H2S diffusion from the anoxic monimolimnion. The resulting anoxygenic photosynthesis rate reached 240 μmol C l−1 day−1, exceeding the oxygenic photosynthesis rate in the mixolimnion. The rates of other processes are also high, reaching 4.5 μmol CH4 l−1 day−1 for methane oxidation and 35 μmol S l−1 day−1 for sulfate reduction. Metagenomic analysis demonstrated that the Chl. phaeovibrioides population in the bacterial plate layer had nearly clonal homogeneity, although some fraction of these cells harbour a plasmid. The Chlorobium population was associated with bacteriophages that share homology with CRISPR spacers in the host. These features make the ecosystem of the Trekhtzvetnoe Lake a valuable model for studying regulation and evolution processes in natural high‐density microbial systems.
The capacity of a lake to remove reactive nitrogen (N) through denitrification has important implications both for the lake and for downstream ecosystems. In large oligotropic lakes such as Lake ...Superior, where nitrate (NO₃ ⁻) concentrations have increased steadily over the past century, deep oxygen penetration into sediments may limit the denitrification rates. We tested the hypothesis that the position of the redox gradient in lake sediments affects denitrification by measuring net N-fluxes across the sediment–water interface for intact sediment cores collected across a range of sediment oxycline values from nearshore and offshore sites in Lake Superior, as well as sites in Lake Huron and Lake Erie. Across this redox gradient, as the thickness of the oxygenated sediment layer increased from Lake Erie to Lake Superior, fluxes of NH₄ ⁺ and N₂ out of the sediment decreased, and sediments shifted from a net sink to a net source of NO₃ ⁻. Denitrification of NO₃ ⁻ from overlying water decreased with thickness of the oxygenated sediment layer. Our results indicate that, unlike sediments from Lake Erie and Lake Huron, Lake Superior sediments do not remove significant amounts of water column NO₃ ⁻ through denitrification, likely as a result of the thick oxygenated sediment layer.
1000. NICOTIANA SALINA Chase, Mark W.; Fay, Michael F.; Christenhusz, Maarten J. M.
Curtis's botanical magazine (1995),
09/2021, Letnik:
38, Številka:
3
Journal Article
Recenzirano
Summary
Nicotiana salina
is described here and illustrated from plants collected at Weelhamby Lake, a salt lake in Western Australia, and cultivated at the Royal Botanic Gardens, Kew. We discuss its ...ecology and cultivation.
Microplastic (MP) contamination represents an issue of global concern for both aquatic and terrestrial ecosystems, but only in recent years, the study of MPs has been focused on freshwaters. Several ...monitoring surveys have detected the presence of a wide array of MPs differing in size, shape, and polymer composition in rivers and lakes worldwide. Because of their role of sink for plastic particles, the abundance of MPs was investigated in waters, and deep and shoreline sediments from diverse lakes, confirming the ubiquity of this contamination. Although diverse factors, including those concerning anthropogenic activities and physical characteristics of lakes, have been supposed to affect MP abundances, very few studies have directly addressed these links. Thus, the aim of the present study was to explore the levels of MP contamination in mountain and subalpine lakes from Northern Italy. Fourteen lakes dislocated at different altitudes and characterized by dissimilar anthropic pressures were visited. Lakeshore sediments were collected close to the drift line to assess MPs contamination. Our results showed the presence of MPs in lakeshore sediments from all the lakes, with a mean (± standard deviation) expressed as MPs/Kg dry sediment accounting to 14.42 ± 13.31 (range 1.57–61.53), while expressed as MPs/m
2
, it was 176.07 ± 172.83 (range 25.00–666.67). The MP abundance measured for Garda Lake was significantly higher compared to all the other ones (
F
1,13
= 7.344;
P
< 0.001). The pattern of contamination was dominated by fibers in all the lakes, but they were the main contributors in mountain lakes. These findings showed that the MP abundance varied according to the altitude of the lakes, with higher levels measured in subalpine lakes located at low altitudes and surrounded by populated areas.
Characterization of Cyanobacteria in lakes with different physicochemical properties provides insights into the diversity of this phylum and knowledge of their features that are relevant to ...biotechnology applications. Six Cyanobacterial isolates were recovered from freshwater Lake Nasser and saline Lake Qarun, Egypt. The isolates were identified based on both morphology and molecular markers, 16S rRNA, and RuBisCO
cbbL
genes. The isolates SN1, SN2, SN3, SN4, Q1, and Q2 showed homologies with
Merismopedia
,
Oscillatoria
,
Limnothrix
,
Persinema
, and
Jacksonvillea
, respectively. The
cbbL
sequences for isolates SN1, Q1, and Q2 represented the first records for candidates relating to the genera
Merismopedia
and
Persinema
, and
Jacksonvillea
, respectively. Biochemical contents, carbohydrates, proteins, lipids, pigments, and ash-free dry weight were measured for each isolate. Isolate SN2 had the highest content of allophycocyanin, 71 ± 4.8 mg/g DW, and phycoerythrin, 98 ± 6.7 mg/g DW, while the isolate SN4 had the highest composition of total protein, lipid, carotenoid, and chlorophyll a, recording 364.7 ± 6.4 mg/g DW, 67.6 ± 0.2 mg/g DW, 0.261 ± 0.01 mg/g DW, and 10 ± 0.6 mg/g DW, respectively. Isolate Q1 recorded the maximum amount of phycocyanin, 114 ± 20.7 mg/g DW among isolates. The isolate Q2 was observed to have the highest carbohydrate content, 274 ± 14.5 (mg/g DW), and ash-free dry weight, 891.8 ± 2.8 mg/g DW. Thus, the study indicated that the current isolates may represent promising resources for biotechnological applications.
•The quality of remotely sensed reflectance products was assessed.•A robust power function model was constructed for inland lakes.•The consistency of the SDD values from Landsat series data was ...evaluated.
Water clarity (expressed as Secchi disk depth (SDD)) reflects light transmission capacity of a water body and influences growth of aquatic plants, aquatic organisms, and primary productivity. Here, we calibrated and validated a general model based on Landsat series data for deriving SDD of various inland waters across China. The quality of remotely sensed reflectance products from different Landsat series images was assessed using in situ reflectance measurements. The results indicated that the products in the visible bands are the most robust and stable to estimate SDD for inland waters. Subsequently, a simple power function model based on red band was built using 887 pairs of in situ SDD measurements and concurrent Landsat images. The model was validated with an independent dataset of 246 SDD measurements, and the results showed that the mean relative error and normalized root mean square error were 34.2% and 55.4%, respectively. Finally, the model was applied to Landsat images acquired between 2016 and 2018 to investigate the SDD spatial distribution of all lakes with water area ≥ 10 km2 (total 641 lakes) in China. The estimation results demonstrated that the Eastern Plain Lake Zone and Northeast Plain Lake zone have relatively low SDD, with multiyear average SDD of 0.56±0.17 m and 0.47±0.29 m, respectively. The Yunnan‐Guizhou Plateau Lake Zone and Tibetan Plateau Lake Zone have relatively high SDD, with multiyear average SDD of 1.48 ± 0.86 m and 1.30 ± 0.83 m, respectively. The results indicated that the proposed model exhibits strong ability to accurately construct SDD coverage for various lakes.
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