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Coupled nitrogen cycling processes can alleviate the negative effects of eutrophication caused by excessive nitrogen load in estuarine ecosystems. The abundance and diversity of nitrifiers and denitrifiers across different environmental gradients were examined in the sediment of Hangzhou Bay. Quantitative PCR and Pearson's correlation analyses suggested that the bacterial ammonia-oxidizers (AOB) were the dominant phylotypes capable of ammonia oxidation, while the nirS -encoding denitrifiers predominated in the denitrification process. Simultaneously, nitrite and pH were found to be the two major factors influencing amoA and nir gene abundances, and the distribution of bacterial communities. Moreover, the ratio of nirS /AOB amoA gene abundance showed negative correlation with nitrite concentration. Fluorescence in situ hybridization further demonstrated that AOB and acetate-denitrifying cells were closely connected and formed obvious aggregates in the sediment. Together, all these results provided us a preliminary insight for coupled nitrification-denitrification processes in the sediment of Hangzhou Bay. [ABSTRACT FROM AUTHOR]

The potential for a ship-mounted laser fluorometer to provide rapid, non-intrusively measurements in both coastal and lake conditions are investigated. The instrument consists of a high pulse repetition frequency (10-kHz) microchip laser for fluorescence excitation, a broadband hyperspectral micro spectrometer for spectral detection, and a confocal reflective fluorescent probe for signal collection; it weighs only about 1.7 kg. Chlorophyll a (chl- a ) and colored dissolved organic matter (CDOM) measured by the new instrument were observed to agree well with those measured by traditional time-consuming laboratory methods in Hangzhou Bay seawater and Qiandao Lake inland water. Subsequently, laser fluorescence distribution and characteristics of chl- a and CDOM in these regions were analyzed, which will improve our understanding of biogeochemical processes in these optically complex aquatic systems. The portable system is promising for water environment monitoring, especially in coastal and inland water. [ABSTRACT FROM AUTHOR]

Off the Yangtze River Estuary and its adjacent waters (the YRE) are one of the fastest changing regions in the world in terms of the effects of anthropogenic disturbance. Here we address quantitative analysis whether reducing river to sea sediment may cause declining water turbidity then a better light available condition for the algal growth, therefor increasing phytoplankton bloom magnitude in the YRE in the bloom season. An area of high phytoplankton productivity zone is estimated by theoretical and satellite data analysis, which matches well with the spatial distribution of accumulative times of the reported algal bloom events at the decadal time scale. We present 17-year (1998–2014) satellite and hydrological data to reveal an increasing trend in Chlorophyll-a concentration (Chl-a) in the spring bloom season (May to June), which has strong correlation with the decreasing in the sediment discharge from the Yangtze river to the East China Sea. Changes in Chl-a and the sediment load are inversely related in terms of both temporal variation and their corresponding magnitudes (R 2 =0.38, p=0.008, n=17). Furtherly, this relationship is not sensitivity to one-year time lag analysis. On the other hand, euphotic depth in the bloom period shows no significant change, which reflects a balance between the increasing phytoplankton biomass enhancing water turbidity and declining riverine sediment decreasing turbidity. Finally, a stepwise multiple linear regression is used to determine which of the five relatively independent environmental variables most significantly contribute to the interannual variability of the bloom magnitude. The most significant effect (p=0.00007) is also found in the riverine sediment load. Therefor, our results suggest that anthropogenic derived riverine sediment change has been significantly impacted spring phytoplankton production in the YRE. [ABSTRACT FROM AUTHOR]

Using ten years (2003–2012) of satellite Chlorophyll-a data, we report that annual phytoplankton bloom climax in the Northwest Pacific marginal seas (17°–58°N) delays northward at a rate of 22.98 ± 2.86 km day −1 . The spring bloom is a dominant feature of the phytoplankton seasonal cycle in this region, except for the northern South China Sea, which features a winter bloom. The sea surface hourly Photosynthetically Available Radiation (PAR) intensity averaged over the bloom peak duration is nearly uniform (1.04 ± 0.10 W m −2 h −1 ) among the four sub-regions (i.e. the northern South China Sea, the Kuroshio waters, the Sea of Japan and the Sea of Okhotsk), although different algal species in these four distinct ecological provinces could adapt to a much larger change in other environmental parameters (including total daily PAR, day length, sea surface temperature, net surface heat flux, mixed layer depth, wind speed and euphotic depth). The differences of the hourly PAR intensity between the four provinces during their bloom periods are smaller than those during non-bloom seasons. In contrast, an increasing total daily PAR (W m −2 day −1 ), due to the longer day length at higher latitudes, may balance decreasing sea surface temperature and induce algal flowering. Our results point to an optimal hourly light intensity for the annual phytoplankton bloom peak timing in this entire region, which could potentially become an indicator for the requirement of these annual bloom peaks. [ABSTRACT FROM AUTHOR]

A field, light-weight laser fluorometer based on the method of laser induced fluorescence was developed for water quality monitoring. The basic instrument configuration uses a high pulse repetition frequency microchip laser, a confocal reflective fluorescent probe and a broadband hyperspectral micro spectrometer; it weights only about 1.7 kg. Simultaneous estimates of three important water quality parameters, namely, chlorophyll a (chl-a), colored dissolved organic matter (CDOM), and total suspended matter (TSM) measured by the laser fluorometer were observed to agree well with those measured by traditional methods (0.27–0.84 μg L −3 chl-a, R 2 = 0.88; 0.104–0.295 m − 1 CDOM absorption, R 2 = 0.90; and 59.8–994.9 mg L − 3 TSM, R 2 = 0.86) in Hangzhou Bay water. Subsequently, distribution and characteristics of CDOM and chl-a laser fluorescence in Hangzhou Bay were analyzed, which will enhance our understanding of biogeochemical processes in this complex estuarine system at high-resolution, high-frequency and long-term scale. [ABSTRACT FROM AUTHOR]

The dinoflagellate Prorocentrum donghaiense ( P. donghaiense ) is one of the most common species making up harmful algal blooms in the Yangtze River Estuary and the adjacent area of the East China Sea. Based on the differences between the absorption characteristics of P. donghaiense and diatoms from the East China Sea and an extensive in-situ remote sensing reflectance ( R rs ) dataset, a multispectral approach for discriminating P. donghaiense blooms from other water types was developed based on MODIS R rs spectral shape discrimination. The procedure is separated into two steps. First, the bloom waters are identified by the low R rs (555) and high R AB owing to their relatively low reflectance and high spectral slope in the green bands. Second, two new indices of P. donghaiense index (PDI) and diatom index (DI) are developed for discriminating P. donghaiense from diatom blooms, based on the distinct spectral differences found in the green and red spectral ranges of phytoplankton absorption between the two algal groups. The validation using observations collected during near-con-current field surveys showed that the application of our practical method to MODIS imagery can provide reliable information on the inferred pattern and spatial distribution of the algal bloom, and that the classification technique for P. donghaiense bloom is considered successful, which may allow coastal mangers to better mitigate the harmful effects of P. donghaiense blooms in the East China Sea. [ABSTRACT FROM AUTHOR]

Abstract: Accuracy of aerosol scattering reflectance in atmospheric correction is crucial for satellite ocean color remote sensing. A new approach is developed to estimate aerosol scattering reflectance from satellite data based on a look-up table of in situ water-leaving reflectance. A decision rule is set to determine the water-leaving component of the total satellite-measured radiance from the table under an assumption that aerosol scattering reflectance follows the Angstrom law. The epsilon spectrum, obtained from the ratio of aerosol scattering reflectance, is used to select the two closest aerosol models for determining the corrected epsilon values, which is adjusted to new values according to the reference wavelength. The actual aerosol scattering reflectance is obtained from the mean value of the reflectance and the new epsilon spectrum. The performance of the model is evaluated using the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) imagery, showing that the component of aerosol scattering reflectance can be completely separated from the total satellite-measured radiance, and effects of non-zero water-leaving reflectance can be eliminated over highly turbid waters. The accuracy is validated by in situ measured aerosol optical thickness (AOT) using a handheld multi-band sun photometer and the Aerosol Robotic Network (AERONET) measured AOT data during the 2006 winter cruise and 2007 autumn cruise over the East China Sea (ECS). The analysis gives the mean relative errors of 23.73% and 32.04%, respectively. Our analysis shows that aerosol scattering reflectance can be significantly overestimated over turbid waters when using the atmospheric correction method based on the black ocean assumption (BOA). It may also have some errors over oceanic waters because a small 1% bias of satellite-measured reflectance in the near-infrared (NIR) bands will lead to a relatively large error of ~10% in aerosol scattering reflectance in Band 1. This error will spread to water-leaving reflectance, possibly leading to negative values of water-leaving reflectance. This amplifying effect of aerosol scattering reflectance can be limited by matching aerosol models using epsilon spectrum in our model. Because the assumption of aerosol scattering reflectance following the Angstrom law can eliminate effects of different types of waters including open ocean, coastal regions, lakes and rivers, our model offers a potentially universal algorithm for estimating aerosol scattering reflectance from satellite remote sensing data. [Copyright &y& Elsevier]

Abstract: On the basis of field measurements, the quantitatively different relationships of peak position in the red band of the remote sensing reflectance vs. Chl concentration are found in the bloom waters of the diatom Skeletonema costatum and the dinoflagellate Prorocentrum donghaiense in coastal areas of the East China Sea. Model simulations of remote sensing reflectance, Rrs , accounting for the influence of variations in the bio-optical parameters such as chlorophyll fluorescence quantum efficiency, Φ, and specific absorption coefficient, aph ⁎ , are carried out to analyze the characteristics of this spectral peak. The strong effect of fluorescence on the magnitude of Rrs results in the inhibition of the shift of the peak to longer wavelengths, increasing Φ enhances this effect. Increasing aph ⁎ , specifically in the red-wavelength band, causes a sharper shift in the red peak position by decreasing the effect of the fluorescence. The dominant parameter governing the slope of the shift is aph ⁎ . The analysis indicates that the higher aph ⁎ of S. costatum in the red region is primarily responsible for the much higher slope of the peak shift than for that of P. donghaiense. We show that the relationship between the peak position and Chl concentration may be useful for discriminating S. costatum blooms from those due to P. donghaiense, although information about chlorophyll fluorescence quantum efficiency should be included. Finally, we show that using the band ratio Rrs (708nm)/Rrs (665nm) instead of Chl in the relationship with peak position can be useful for the practical identification of S. costatum blooms from hyperspectral measurements of remote sensing reflectance. [Copyright &y& Elsevier]

Abstract: Aerosol scattering reflectance is the most uncertain term to be determined in the atmospheric correction of satellite remote sensing data. The values in the visible bands depend on the aerosol scattering ratios (the epsilon spectrum). The epsilon value in the Near-infrared (NIR) band is estimated on the dark pixel assumption of the water-leaving reflectance in the two NIR bands and then the epsilon spectrum is determined from the aerosol models. This assumption usually becomes invalid for turbid coastal waters, leading to lost regions in the satellite imagery masked by the failure of the atmospheric correction. A new approach was developed to accurately estimate epsilon from turbid coastal waters. This method is based on the idea that the aerosol scattering reflectance and the epsilon values can be obtained from the known water-leaving reflectance of in situ measurements. The water-leaving reflectance is determined from the choice of a look-up table of the water-leaving reflectance based on the Angstrom law of the candidate aerosol scattering reflectance using the best non-linear least squares fit function. In this approach, the entire epsilon spectra can be obtained and used to determine the two closest aerosol models which are used to interpolate the actual epsilon values. It is demonstrated that the results from matching the entire spectra are more robust than that obtained from using only one epsilon value. The performance of the approach was evaluated using the simulated reflectance at the top of the atmosphere, the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) imagery, and in situ measured aerosol optical thickness. This approach is based on the assumption of the aerosol scattering reflectance following the Angstrom law instead of the standard dark pixel assumption, named as the ENLF model. This new assumption is valid for both Case 1 and Case 2 waters, even over terrestrial regions. Therefore, the ENLF model provides a potential approach for a universal algorithm of the atmospheric correction of satellite remote sensing data. [Copyright &y& Elsevier]

Abstract: The East China Sea (ECS) is well known for its high concentration of total suspended matter (TSM). Some regions of the ECS have concentrations higher than 5000gm−3, exceeding the valid ranges of many TSM remote sensing algorithms. To overcome the limitation of the existing algorithms, a new TSM model, the “complex proxy TSM model” (CPTSM), is developed in this study. The model is established on the basis of a complex proxy of remote sensing reflectance. The proxy is designed to convert the non-linear relationship between reflectance and TSM to a quasi-linear function over the entire range of TSM concentrations. This proxy is deduced from four indices defined by combinations of the reflectance at different bands. The four indices take advantage of the different relationships between the band combinations of the reflectance and total TSM concentrations. The band selections and model parameters are based on correlation coefficients and regression analysis between the indices and TSM. The results show that the correlation coefficient of 0.912 between the proxy and TSM is higher than that between any individual index and TSM. To validate the CPTSM model, TSM, turbidity, and reflectance data were collected in the ECS during 4 cruises in 2006 and 2007. The actual TSM concentration was measured by weighing the samples collected on filter papers. Turbidity was measured by a Seapoint Turbidity Meter. The turbidity data with values higher than 750FTU were re-calibrated using an empirical equation. All turbidity values were converted to TSM concentrations using a linear equation. The in situ reflectance was measured using the above-water method at 459 stations and the in-water method at 146 stations. A total of 87 pairs of reflectance measured by both methods were used for inter-comparison with a relative difference of 4.5%. The reflectance values were used to retrieve TSM concentrations using the CPTSM model. A comparison with in situ measurements gave a mean relative error of 23%. Applying the CPTSM model to the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) data and analyzing the errors from a match-up dataset of SeaWiFS and in situ data, we found that the average relative error was 24.5%. We propose to use the CPTSM model to map TSM concentrations from satellite data in the ECS. [Copyright &y& Elsevier]

Abstract: Understanding the spectral characteristics of remotely-sensed reflectance by different phytoplankton species can assist in the development of algorithms to identify various algal groups using satellite ocean color remote sensing. One of the main challenges is to separate the effect of species composition on the reflectance spectrum from other factors such as pigment concentration and particle size structure. Measuring the absorption spectra of nine different cultured algae, and estimating the reflectance of the different species, provides a useful approach to study the effects of species composition on the bio-optical properties. The results show that the absorption spectra of different species exhibit different spectral characteristics and that species composition can significantly change the absorption characteristics at four main peaks (438, 536, 600 and 650nm). A ‘distance angle index’ was used to compare different phytoplankton species. Results indicate that this index can be used to identify species from the absorption spectra, using a database of standard absorption spectra of known species as reference. By taking into account the role of species composition in the phytoplankton absorption model, the performance of the model can be improved by up to 5%. A reflectance-species model is developed to estimate the remotely-sensed reflectance from the absorption spectra, and the reflectance of different phytoplankton species at the same chlorophyll-a concentration is compared, to understand effects of species composition on the reflectance spectra. Different phytoplankton species can cause up to 33% difference in the modeled reflectance at short wavelengths under the condition of the same chlorophyll-a concentration, and variations in the reflectance spectrum correspond to the colors of the algae. The standard deviation of the reflectance among different species shows that the variations from 400 to 450nm are sensitive to species composition at low chlorophyll-a concentrations, whereas variations in the 510 to 550nm range are more sensitive under high chlorophyll-a concentrations. For this reason, the green bands may be more suitable for estimating species composition from hyperspectral satellite data during bloom conditions, whereas the blue bands may be more helpful in detection of species under low chlorophyll-a concentrations. In this theoretical approach, variations in reflectance at the same chlorophyll-a concentration can be used to identify phytoplankton species. Another approach to identify phytoplankton species from remotely-sensed hyperspectral reflectance measurements would be to derive the absorption spectra of phytoplankton from the reflectance measurements, and compare these with a standard database of absorption spectra. [Copyright &y& Elsevier]

Mono-Schiff bases containing crown ether ring (HL1, HL2, HL3 and HL4) and their transition-metal complexes were synthesized and characterized by 1H NMR, IR, MS spectra and elemental analysis. The crystal structures of HL1, HL3 and CoL21 were determined from X-ray diffraction data. The oxygenation constants (Ko2) of Schiff-base Co (II) complexes were measured over a range of −5 °C to 25 °C, and the values of ΔH0 and ΔS0 were also calculated based on Ko2. In the presence of Mn (III) Schiff base complexes, the biomimetic catalytic oxidation for styrene to benzalhyde was carried out at 100% selectivity. Compared with the uncrowned analogue, the influence of crown ring and its bonding pattern, the distance between the coordination center and crown ring on the dioxygen affinities and biomimetic catalytic oxidation performance of the crowned Schiff base complexes were observed. [Copyright &y& Elsevier]

Highlights • A semi-analytic Monte Carlo radiative transfer model for inhomogeneous water is developed. • The input optical vertical profile can vary with a resolution as high as 0.11 m. • The influences of water optical properties, boundary and lidar systems were studied. • The simulation curve was quite similar to that of the lidar measurements. Abstract Current Monte Carlo simulation methods of laser propagation in sea water are mostly based on the assumption of homogeneous water. In this study, a semi-analytic Monte Carlo radiative transfer model is developed to study laser propagation in inhomogeneous sea water within subsurface plankton layer. It is based on analytical estimate of the probability of collection by a remote receiver of scattered or emitted photons; in particular, the water optical input parameter of vertical profile is no longer simply set as a constant. In the new transfer model, the input optical vertical profile can vary with a resolution as high as 0.11 m. Using this model, we study the influences of water optical properties, multiple scattering, wind-driven sea surface condition, and lidar incident angle. The effective lidar attenuation coefficient is found to depend on the field of view of the lidar system: it approaches attenuation coefficient with a narrow field of view, and approaches absorption coefficient with a wide-enough field of view. We also find the lidar transmittance through the air-sea interface decreases significantly as the wind speed increases to greater than 7 m/s, and the transmittance can even be reduced by half when the wind speed reaches 18 m/s. Finally, we compare the simulations by our new model with airborne lidar measurements. We find that the simulation curve is quite similar to that of the lidar measurements. The absolute error of normalized simulation signals compared with the measurements is within 0.05, suggesting the effectiveness and applicability of our approach for inhomogeneous water. [ABSTRACT FROM AUTHOR]

In this study, we successfully address the formation tracking challenge for underactuated autonomous surface vehicles (ASVs) in uncertain environments, despite the lack of direct target information. Leveraging only relative angle measurements, we develop a control scheme that ensures the closed-loop error trajectory remains globally uniformly ultimately bounded. The bound achieved is influenced by the precision of the dynamic controllers and the effectiveness of the adaptive mechanism, highlighting the robustness and adaptability of our approach. This work provides a practical solution for ASV formation tracking in real-world scenarios. • Introduces relative angle-based ASV guidance, mitigating uncertainty. • Achieves convergence with smaller, rational virtual signal. • Error trajectory GUUB, bound depends on controller precision. [ABSTRACT FROM AUTHOR]

This paper studies the trajectory tracking control of an underwater glider in the vertical plane under prescribed performance. A sliding mode control method is designed for the error transformation system with a novel finite-time performance function to guarantee that the glider tracking errors meet the specified performance. Radial basis function neural networks are employed to estimate the effects of model uncertainty and external time-varying disturbances on underwater glider. Besides, the input saturation problem of the glider system is solved by designing an auxiliary system. The proposed scheme can reduce tracking errors in transients and steady states more than the previous scheme via numerical simulation. • Proposed a sliding mode control to trajectory tracking method for an underwater glider under prescribed performance. • The novel finite-time performance function for switching systems is introduced. • Solved the input constraints of the underwater glider and the model uncertainty and external disturbances. [ABSTRACT FROM AUTHOR]

Evaluates the quality and availability of typical ocean color images. Difficulty to measure atmospheric correction for gaseous absorption; Factors influencing the transfer of solar radiation; Importance of atmospheric correction to extract water color information.

The actuator failure in a Marine Vehicle (MV) possibly happens because of the complicated marine environment. This paper proposes an Adaptive Generalized Actuator Fault Reconstruction (AGAFR) algorithm based on an observer for a class of Euler–Lagrange systems, of which the actuator fault and environmental disturbance are combined into a generalized actuator fault for reconstruction uniformly. The adaptive method that handles the nonlinear term reduces the range of fault errors by about 62% and the convergence time by over 46% compared to the algorithm already in the literature. The stabilization term is introduced into the algorithm to effectively reduce the chatter of a high-gain algorithm. The reconstructed error is uniformly convergent to an adjustable boundary using a Lyapunov analysis. Both the adaptive method's advantage and the stabilizing effect are demonstrated through comparative simulation. • An adaptive generalized actuator fault reconstruction algorithm is proposed for marine vehicles. • The environmental disturbance is treated as the actuator's abnormal value. • The algorithm can reconstruct fault signals accurately and reduce the chatter obviously. [ABSTRACT FROM AUTHOR]

This paper deals with the formalization, design, theorization, and implementation of a robust adaptive nonlinear control scheme to solve the bottom sitting-oriented soft landing control problem for an underwater glider under model uncertainties, actuator dynamics, and external disturbances. First, uniformized motion equations are derived based on Lie derivatives for describing pitch angle and vertical velocity tracking control. Then, the robust adaptive control framework is enhanced by containing an anti-windup auxiliary system and a disturbance observer. The stability of the closed-loop control system based on Lyapunov theory is proven to guarantee the boundedness of the entire internal signals. Finally, multifarious experimental results are also conducted by a self-developed underwater glider to demonstrate the effectiveness of the proposed controller. • Formularize the bottom sitting-oriented soft landing problem for UG. • Propose uniformized motion equations for pitch/vertical velocity tracking control. • Operate without detailed a priori knowledge of parametric uncertainties and perturbations. • Provide economical thoughts for easy-to-operate experiments to verify control performance. [ABSTRACT FROM AUTHOR]

Marine phytoplankton accounts for roughly half the planetary primary production, and plays significant roles in marine ecosystem functioning, physical and biogeochemical processes, and climate changes. Documenting phytoplankton assemblages' dynamics, particularly their community structure properties, is thus a crucial and also challenging task. A large number of in situ and space-borne observation datasets are collected that cover the marginal seas in the west Pacific, including Bohai Sea, Yellow Sea, and East China Sea. Here, a customized region-specific semi-analytical model is developed in order to detect phytoplankton community structure properties (using phytoplankton size classes, PSCs, as its first-order delegate), and repeatedly tested to assure its reliable performance. Independent in situ validation datasets generate relatively low and acceptable predictive errors (e.g., mean absolute percentage errors, MAPE , are 38.4%, 22.7%, and 34.4% for micro-, nano-, and picophytoplankton estimations, respectively). Satellite synchronization verification also produces comparative predictive errors. By applying this model to long time-series of satellite data, we document the past two-decadal (namely from 1997 to 2017) variation on the PSCs. Satellite-derived records reveal a general spatial distribution rule, namely microphytoplankton accounts for most variation in nearshore regions, when nanophytoplankton dominates offshore water areas, together with a certain high contribution from picophytoplankton. Long time-series of data records indicate a roughly stable tendency during the period of the past twenty years, while there exist periodical changes in a short-term one-year scale. High covariation between marine environment factors and PSCs are further found, with results that underwater light field and sea surface temperature are the two dominant climate variables which exhibit a good ability to multivariate statistically model the PSCs changes in these marginal seas. Specifically, three types of influence induced by underwater light field and sea surface temperature can be generalized to cover different water conditions and regions, and meanwhile a swift response time (approximately < 1 month) of phytoplankton to the changing external environment conditions is found by the wavelet analysis. This study concludes that phytoplankton community structures in the marginal seas remain stable and are year-independent over the past two decades, together with a short-term in-year cycle; this change rule need to be considered in future oceanographic studies. Image 10578 • A novel remote sensing approach is developed to detect PSCs in BS, YS, and ECS. • The past two-decadal spatiotemporal variations are documented for the first time. • Underwater light field and sea surface temperature mainly affect the PSCs changes. [ABSTRACT FROM AUTHOR]

This study introduces a novel adaptive sliding mode controller that incorporates a pseudo-inverse-based allocation method for underwater vehicles with variable coefficients, such as mass and center of gravity. In scenarios like deep-sea mining or dredging, the mass and center of gravity of the vehicle may fluctuate. Taking into account these variations and the changing rate limitations of the thrusters, the primary focus of this research is to address the challenges associated with attitude control and input force allocation. • A new ASMC is designed to solve the attitude control problem for ROV with variable coefficients. • A new control allocator is designed based on the pseudo-inverse. • Combining the controller and allocator, the comparative simulation experiments under different conditions are performed. [ABSTRACT FROM AUTHOR]

Lung cancer is the leading cause of cancer-related deaths worldwide, and approximately 85% are diagnosed as non-small-cell lung cancer (NSCLC). However, efficient detection and diagnosis of NSCLC at early stage is still challenging. In this work, we developed a simple, ultrasensitive and high selective strategy for A549 human NSCLC cells detection based on combining the reorganization property of a novel cyanine dye 3,3′-di(3-sulfopropyl)-4,5,4′,5′-dibenzo-9-methyl-thiacarbocyanine triethylammonium salt ( cy-M ) to aptamer S6 G-quadruplex structure having specific affinity to NSCLC cells, which induced a dramatic fluorescence enhancement (~ 10 4 times). Moreover, this strategy was successfully used for detecting of A549 cancer cells in complex media such as human serum and clinical pleural effusion, which strong indicated that the proposed method could be applied for the early diagnosis of lung cancer. [ABSTRACT FROM AUTHOR]

The aerosol optical depth (AOD) is a key factor to assess atmospheric environment, and accurate monitoring of it is conducive to the research and environmental protection. The Land Surface Reflectance Code (LaSRC) algorithm has been used to retrieve AOD from fine resolution satellite instruments, including the Landsat-8 and Sentinel-2. This study evaluated the AODs against the in situ data (i.e., Aerosol Robotic Network and Sun-Sky Radiometer Observation NETwork measurements). The temporal window and wind speed were jointly applied to determine the spatial window size (i.e., 6 km) centered on the in situ site. And a three-step strategy for calculating the average of satellite retrieved AODs within the spatial window was proposed in this study. As a result, both STEPs 2 and 3 had improvements compared to STEP 1 and the three-step strategy achieved the best performance in terms of the highest coefficient of determination (R2: 0.754) and within expected error (EE: 60.81%), the lowest root mean square error (RMSE: 0.150) and mean absolute error (MAE: 0.113). Then the contemporaneous AOD matchups were used for validation and evaluation of the LaSRC retrieved AODs. The Sentinel-2 AOD retrievals outperformed the Landsat-8 AOD retrievals with lower RMSE (0.138 and 0.173, respectively), lower MAE (0.102 and 0.136, respectively), higher R2 (0.818 and 0.707, respectively) and higher within EE (64.36% and 53.19%, respectively). However, there are 31.91% of Landsat-8 matchups falling below EE and 32.67% of Sentinel-2 collocations falling above EE, which were mainly detected at HKP and HKS sites. And the site-scale validation results revealed that the LaSRC algorithm performed well over inland urban areas, but should be developed further over coastal and water areas in the next generation. • A three-step strategy, which considered weighted averages, was fit to validate the mid/high resolution satellite retrievals. • Temporal window and wind speed are jointly to determine the spatial window size. • LaSRC AODs from Sentinel-2 outperformed that from Landsat-8. • LaSRC algorithm needs further improvement over coastal urban areas. [ABSTRACT FROM AUTHOR]

The vertical distribution of subsurface phytoplankton in the ocean contains key information about not only ocean ecology but also water column optical properties relevant to remote sensing. The existing methods for measuring this vertical distribution are mainly field bio-optical and biogeochemical observations, which are time- and labor-intensive and do not provide sufficient spatial coverage. Passive satellite remote sensing provides global observations of phytoplankton but offers no information on subsurface vertical structure. In this study, we made the first quantitative measurements of vertical distribution of the subsurface phytoplankton layer (SPL) in the South China Sea (SCS) using airborne lidar. A total of five lidar flight experiments were conducted between 2017 and 2019 in the SCS, and approximately 2.5 terabytes of data were obtained. A hybrid retrieval method combining the Klett method for k lidar and the perturbation method for β π was developed. The lidar-retrieved chlorophyll- a concentrations and in situ data show good agreement (R2 greater than 0.8). The mean absolute percentage error for the lidar-retrieved chlorophyll- a concentrations is less than 15%. SPLs were observed both in Sanya Bay and in the open sea near Lingshui city, Hainan Province, China. The SPLs were observed at depths between 50 and 70 m in the open sea near Lingshui city, and between 5 and 30 m in Sanya Bay. The SPL depths have spatiotemporal variability, and we analyzed the possible factors (monsoon, seafloor depth, and sea surface temperature) that influence this spatiotemporal variability. The results show that lidar technology has a great potential for wide-range and long-term monitoring of SPLs, and is a good complement for discrete in situ observations and passive satellite remote sensing. • Subsurface phytoplankton layer below 50 m was observed by lidar for the first time. • First quantification of SPL vertical structure in SCS using lidar • A hybrid retrieving method for lidar was developed. [ABSTRACT FROM AUTHOR]

• The global distribution of ocean penetration depth and the corresponding optimum wavelength bands are calculated for spaceborne photon-counting oceanic lidar. • Wavelength bands of 488 nm and 443 nm have good penetration ability and by taking advantage of the characteristic of solar Fe Fraunhoferline (438.355 nm) and H-β Fraunhoferline (486.134 nm), the background light can be suppressed and the penetration depth can be further increased. • Wavelength of 486.134 nm is the optimum wavelength of single-wavelength lidar and the combination of 486.134 nm and 438.355 nm is a good choice for dual-wavelength lidar for purpose of global ocean detection. The evaluation of the wavelength parameters of spaceborne oceanic lidar is of great importance to ensure that the lidar system can provide more information of ocean and can be realized in engineering. In this paper, the optimum wavelengths of spaceborne oceanic lidar for purposes of ocean detection at coastal and global scales are analyzed mainly in terms of the penetration depth. The global distribution of ocean penetration depth and the corresponding optimum wavelength bands are calculated by using the oceanic optical properties data from Moderate Resolution Imaging Spectroradiometer (MODIS). Ocean with optimum penetration wavelength of 488 nm covers 61.82% of the global ocean and the optimum wavelength of 443 nm with ocean area share of 14.81% is a good complement for 488 nm. The penetration depths of 96.26% of the global ocean are deeper than 0.8 times the euphotic zone depths by using wavelengths of 488 nm and 443 nm, simultaneously. More importantly, taking advantage of the characteristic of solar Fe Fraunhoferline (438.355 nm) and H- β Fraunhoferline (486.134 nm), 70% of the background light can be suppressed by a filter with bandwidth of 0.1 nm and the penetration depth can be increased by approximately 5.0%. In conclusion, we propose that 486.134 nm is the optimum wavelength of single-wavelength spaceborne oceanic lidar and the combination of 486.134 nm and 438.355 nm is a good choice for dual-wavelength lidar for purpose of global ocean detection. [ABSTRACT FROM AUTHOR]

Optical identification and quantification of various marine-spilled oils play an important role in oil spill monitoring, assessment, and response. Through weathering processes, oil may become emulsified in two forms of oil-water mixture: water in oil (WO) and oil in water (OW). These two forms of oil emulsion are significantly different in their volume concentration (oil/water ratio), physical properties (viscosity, density, thickness), and optical properties (spectral reflectance (R u (λ), sr−1), and spectral absorption (a (λ), m−1)). In this study, the optical properties of both types of oil emulsion, with different volumetric concentrations, are determined from carefully prepared oil emulsion samples, with the aim of helping to interpret optical remote sensing imagery. The concentrations of stable WO and OW emulsions range from 45% to 95% and from 0.025% to 3%, respectively. They exhibit different R u spectral shapes in the near-infrared and shortwave-infrared wavelengths, with five "-CH" molecular bonds evident in the WO emulsion spectra. R u (600–1400 nm) of OW emulsions increases with volume concentrations from 0% to 3.0%, but R u (600–2400 nm) of the WO emulsions decreases with volume concentrations from 45% to 100%. On the other hand, for a fixed concentration (80%), R u (600–2400 nm) of WO emulsions increases monotonically with thicknesses of up to ~0.4 mm, beyond which R u (600–2400 nm) no longer increases with oil thickness. The difference between the R u spectral shapes of OW and WO emulsions, as well as the statistical relationships between volume concentrations and R u (NIR-SWIR) and between oil thickness and R u (NIR-SWIR), provide the basis for developing optical models to classify oil emulsion types and for quantifying oil volume from remote sensing imagery. The potential of such an application is demonstrated using hyperspectral AVIRIS imagery collected over the Deepwater Horizon (DWH) oil spill in the Gulf of Mexico (GoM). • Oil emulsions are found to form two types: oil in water (OW) and water in oil (WO). • Spectral reflectance and absorption of oil emulsions are determined from experiments. • OW and WO emulsions with various concentrations have different spectral features. • For fixed oil type, oil thickness of up to 0.4 mm can be estimated from reflectance. • The proof-of-concept is demonstrated with AVIRIS data over the DWH oil spill. [ABSTRACT FROM AUTHOR]