Accurate estimation of spatially distributed air temperature (Ta) is useful for a wide range of disciplines such as hydrology, meteorology and ecology. Moderate Resolution Imaging Spectroradiometer ...(MODIS) land surface temperature (Ts) products hold the potential to get spatial estimates of land surface temperature at high temporal (daily) and spatial resolution (1km) across the world. In this paper, the possibility of retrieving high-resolution Ta data from MODIS Ts data on both Terra and Aqua satellites was investigated over Xiangride River basin in the north Tibetan Plateau. The results of statistical analysis show that during the night MODIS Ts data on Terra satellite provides a good estimation of daily minimum air temperature with RMSE=2.97°C, MAE=2.37°C, and r=0.94, while during the day the difference between Terra MODIS Ts data and daily maximum air temperature is large with RMSE=7.45°C, MAE=6.21°C, and r=0.83. In order to improve the accuracy of the estimation of daily maximum air temperature, the temperature-vegetation index (TVX) method was used in this paper. By lowering the threshold for the negative correlation coefficient between NDVI (Normalized Difference Vegetation Index) and Ts to −0.1, the TVX method was applied to MODIS land products to estimate daily maximum air temperature successfully for the first time. The validation results show that the TVX method has improved the accuracy of daily maximum air temperature significantly with RMSE=3.79°C, MAE=3.03°C, and r=0.83. Finally, the diurnal air temperature variation was simulated using a simple sine curve model for the period 21:00–9:00UCT. The simulation results were in good agreement with observed values with RMSE=3.43°C, MAE=2.54°C, and r=0.86. The results of this study show that daily maximum and minimum air temperature can be retrieved effectively from MODIS land surface products through the use of TVX method.
► MODIS Ts product provides a good estimation of daily minimum air temperature. ► TVX method is not very sensitive to the correlation between NDVI and Ts. ► Daily maximum air temperature can be retrieved from MODIS Ts by the use of TVX method.
While the presence of microplastics (MPs) in marine environments has been detected worldwide, the importance of MPs pollution in freshwater environments has also been emphasized in recent years. ...However, the body of knowledge regarding the biological effects of MPs on freshwater organisms is still much more limited than on marine organisms. The aim of the present study was to evaluate the accumulation and tissue distribution of MPs in the freshwater fish red tilapia (Oreochromis niloticus), as well as the biochemical effects of MPs on O. niloticus. During 14 days of exposure to 0.1 μm polystyrene-MPs at concentrations of 1, 10, and 100 μg L−1, the MPs concentrations in various tissues of O. niloticus generally increased over time following the order gut > gills > liver ≈ brain. Moreover, the acetylcholinesterase (AChE) activity in the fish brain was inhibited by MPs exposure, with a maximum inhibition rate of 37.7%, suggesting the potential neurotoxicity of MPs to freshwater fish. The activities of cytochrome P450 (CYP) enzymes 7-ethoxyresorufin O-deethylase (EROD) and 7-benzyloxy-4-trifluoromethyl-coumarin O-dibenzyloxylase (BFCOD) in the fish liver exhibited clear temporal variabilities, with significant decreases followed by elevations compared to the control. The alterations of the EROD and BFCOD activities indicate the potential involvement of CYP enzymes for the metabolism of MPs. The activity of antioxidative enzyme superoxide dismutase (SOD) in the liver was significantly induced throughout the exposure period, while the malondialdehyde (MDA) content did not vary with MPs exposure, suggesting that the antioxidative enzymatic system in O. niloticus could prevent oxidative damage. These results highlight the ingestion and accumulation of MPs in different tissues of freshwater fish, which lead to perturbations in fish biological systems and should be considered in environmental risk assessment.
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•The accumulation level of PS-MPs followed the order gut > gills > liver ≈ brain.•Exposure to PS-MPs inhibited AChE activity in the brain of red tilapia.•Exposure to PS-MPs disturbed metabolism in the liver of red tilapia.•Antioxidant systems in red tilapia can cope with oxidative stress from PS-MPs.
Exposure to polystyrene-microplastics can result in obvious accumulation in red tilapia and provoke alterations in various biochemical endpoints.
There are hundreds of thousands metric tons of microplastics (MPs) present in aquatic environments. The MPs coexist with other pollutants in water bodies, such as pharmaceuticals, and may carry and ...transfer them into aquatic organisms, consequently causing unpredictable ecological risks. The purpose of the present study was to evaluate the effect of the presence of polystyrene microplastics (PS-MPs) on the distribution and bioaccumulation of roxithromycin (ROX) in freshwater fish red tilapia (Oreochromis niloticus) as well as their interactive biochemical effects in red tilapia. PS-MPs were found to enhance the bioaccumulation of ROX in fish tissues compared to ROX-alone exposure. In the treatment of PS-MPs (100 μg L−1) combined with ROX (50 μg L−1), the highest concentrations of ROX reached 39,672.9 ± 6311.4, 1767.9 ± 277.8, 2907.5 ± 225.0, and 4307.1 ± 186.5 μg kg−1 in gut, gills, brain, and liver, respectively. Furthermore, compared to the ROX alone, the neurotoxicity caused by ROX was alleviated due to the presence of MPs after 14 d of exposure. The activities of cytochrome P450 (CYP) enzymes 7-ethoxyresorufin O-deethylase (EROD) and 7-benzyloxy-4-trifluoromethyl-coumarin O-dibenzyloxylase (BFCOD) in fish livers exposed to all co-exposure treatments exhibited great variability compared to ROX alone after 14 d of exposure, suggesting that the presence of MPs may affect the metabolism of ROX in tilapia. Compared with ROX alone, the superoxide dismutase (SOD) activity increased significantly, and malondialdehyde (MDA) contents decreased in the co-exposure treatments, showing that oxidative damage in situations of co-exposure to MPs and ROX was mitigated in fish livers after 14 d of exposure. Collectively, the presence of MPs could affect the fate and toxicity of other organic pollutants in fish. The results emphasize the importance to study the interactions between MPs and other organic pollutants in aquatic environments.
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•Interactive effects of microplastics and roxithromycin on fish were studied.•PS-MPs could enhance ROX bioaccumulation in red tilapia.•PS-MPs could mitigate the neurotoxicity and oxidative damage caused by ROX.•The presence of PS-MPs could affect the metabolism of ROX.
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•Effects of nano- and micro-plastics (N/MPs) with three sizes on tilapia were studied.•MPs with the size of 70 − 90 μm could be accumulated and were hazardous in tilapia.•5 μm MPs ...caused stronger toxicity than 70 − 90 MPs or 0.3 μm NPs in tilapia.•Toxicity of N/MPs may not be simply negatively correlated with their sizes.
Nanoplastics (NPs) and microplastics (MPs) are a heterogeneous class of pollutants with diverse sizes in aquatic environments. To evaluate the hazardous effects of N/MPs with different sizes, the accumulation, oxidative stress, cytochrome P450 (CYP) enzymes, neurotoxicity, and metabolomics changes were investigated in the red tilapia exposed to three sizes of polystyrene (PS) N/MPs (0.3, 5, and 70 − 90 μm). After 14-d exposures, the largest particles (70 − 90 μm) showed the highest accumulation levels in most cases. Exposures to PS-MPs (5 and 70 − 90 μm) caused a more severe oxidative stress in red tilapia than PS-NPs. The activity of CYP3A-related enzyme was obviously inhibited by PS-NPs, whereas the CYP enzymes in the liver may not be sensitive to MP exposures. In the brain, only 5 μm PS-MPs significantly inhibited the acetylcholinesterase activity. After exposures, the treatments with 0.3, 5, and 70 − 90 μm N/MPs resulted in 31, 40, and 23 significantly differentially expressed metabolites, respectively, in which the pathway of tyrosine metabolism was significantly affected by all the three PS-N/MP exposures. Overall, the PS particles within the μm size posed more severe stress to red tilapia. Our results suggest that the toxicity of N/MPs may not show a simply monotonic negative correlation with their sizes.
Whether the northern Tarim Craton was an active or passive continental margin during the Paleozoic is vital to our understanding of the subduction polarity of paleo-oceanic plates in the Tianshan ...Orogen and the accretion history of the southwestern Central Asian Orogenic Belt. We identified undeformed granitoids intruding into the Paleoproterozoic metamorphic rocks in the Korla area at the northern Tarim Craton. Zircon LA–ICP-MS U–Pb dating of three samples from a porphyritic granodiorite pluton yields three indistinguishable crystallization ages: 420.6±2.3Ma (MSWD=1.02, n=27), 421.7±2.8Ma (MSWD=0.75, n=17) and 419.8±3.3Ma (MSWD=1.10, n=13), highlighting a late Early Paleozoic magmatic event. In-situ zircon Hf isotope data of the youngest zircon population (ca. 420Ma) vary in large ranges (up to 11 epsilon Hf units for single sample), with the lowest εHf (t) value (−14.2) approaching the evolution line of the Early Paleoproterozoic crust in the northern Tarim Craton, suggesting magma mixing between the old crust-derived magma and the relatively juvenile materials probably derived from depleted mantle. Geochemical data suggest that these granitoids are metaluminous, high K calc-alkaline granodiorite. They show a moderately differentiated REE pattern with insignificant Eu anomalies and are relatively depleted in Nb, Ta, Ti, P, but enriched in K and Ba, resembling Andean arc granite. In various discrimination diagrams, all samples consistently plot into the subduction-related areas. These geochemical and isotopic features suggest that this magmatic event probably occurred in an Andean-type continental arc. Therefore, if the northern Tarim Craton was a passive continental margin in the Early Paleozoic, it must have changed into an active margin at least since ca. 420Ma, probably as early as the Ordovician–Silurian boundary, necessitating a southward subduction of the South-Tianshan Ocean. Considering the coeval arc magmatism on the Central Tianshan Block, a divergent double subduction model for the South-Tianshan Ocean is tentatively proposed.
► We identify granitoids with zircon U–Pb ages of ca. 420Ma in the northern Tarim Craton. ► Our data indicate these granitoids are emplaced in a continental arc setting. ► A continental arc was created by the southward subduction of the South-Tianshan Ocean. ► A divergent double subduction model of the South-Tianshan Ocean is tentatively proposed.
A comprehensive and reliable assessment of the water resources in China's transboundary river basins is vital for water resources management and peaceful development. In this study, we built machine ...learning (random forest, gradient boosting, and stacking) and traditional linear models to identify the relation between the runoff coefficient and its influencing factors, including topography, climate, land cover, and soil. The cross‐validation results show that the machine learning models greatly outperform the traditional linear model in predicting runoff coefficient. High‐resolution (0.1°) runoff coefficient and runoff maps for the China's transboundary river basins riparian countries were produced and compared with other estimates at the country level. The best water resources estimates achieved from the machine learning model are consistent with the Food and Agriculture Organization of the United Nations AQUASTAT database (root‐mean‐square error = 76.97 km3/year, normalized root‐mean‐square error = 12%) at the country level. This outperformed two currently available runoff products: the UNH/GRDC Global Composite Runoff Fields and the Global Streamflow Characteristics Dataset. The study also demonstrated that accurate precipitation data can improve runoff and water resources estimation accuracy and that climate and topographic factors have a controlling role in prediction, whereas the influences of land cover and soils are weak. Finally, China's transboundary water resources were calculated and thoroughly assessed at basin and country levels.
Key Points
High‐resolution (0.1 degrees) runoff coefficient and runoff maps of all the CTRB riparian countries were produced
Machine learning models were more accurate than a traditional linear model and two popular runoff data products
The water resources of China's transboundary river basins were comprehensively assessed at basin and country level for the first time
The Tarim Craton, located in the center of Asia, was involved in the assembly and breakup of the Rodinia supercontinent during the Neoproterozoic and the subduction‐accretion of the Central Asian ...Orogenic Belt (CAOB) during the Paleozoic. However, its tectonic evolution during these events is controversial, and a link between the Neoproterozoic and Paleozoic tectonic processes is missing. Here we present zircon U‐Pb ages, Hf isotopes, and whole‐rock geochemical data for the extensive granitoids in the western Kuruktag area, northeastern Tarim Craton. Three distinct periods of granitoid magmatism are evident: circa 830–820 Ma, 660–630 Ma, and 420–400 Ma. The magma sources, melting conditions (pressure, temperature, and water availability), and tectonic settings of various granitoids from each period are determined. Based on our results and the geological, geochronological, geochemical, and isotopic data from adjacent areas, a long‐lived accretionary orogenic model is proposed. This model involves an early phase (circa 950–780 Ma) of southward advancing accretion from the Tianshan to northern Tarim and a late phase (circa 780–600 Ma) of northward retreating accretion, followed by back‐arc opening and subsequent bidirectional subduction (circa 460–400 Ma) of a composite back‐arc basin (i.e., the South Tianshan Ocean). Our model highlights a long‐lived accretionary history of the southwestern CAOB, which may have initiated as part of the circum‐Rodinia subduction zone and was comparable with events occurring at the southern margin of the Siberian Craton, thus challenging the traditional southward migrating accretionary models for the CAOB.
Key Points
Three periods of granitoids intrusion and tectonic settings are determined
A long‐lived accretionary orogenic model is proposed for southwest CAOB
The model links the early history of the CAOB with Rodinia evolution
Mafic dykes are observed in the Korla region along the northern Tarim Block, NW China. Our sensitive high-resolution ion microprobe U-Pb zircon ages, the first determined for these dykes, indicate ...that the mafic dykes were mainly formed at 650-630 Ma, and thus document the youngest known igneous activity associated with rifting in the Tarim Block during the Neoproterozoic. Combined with previous geochronological data, at least three pulses of magmatic activity, from c. 830 to 800 Ma, from c. 790 to 740 Ma and from c. 650 to 630 Ma, are recognized, which reveal that multiple episodes of rifting occurred within the Tarim Block, implying that the breakup of the Rodinia supercontinent in the Tarim Block may have been a long-lasting process.
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