As an important part of the ecological environment, degraded coastal soils urgently require efficient and eco-friendly soil amendment. Biochar and wood vinegar have been proved to be effective soil amendments, and acid-modified biochar has great potential in ameliorating the degraded coastal saline–alkali soil. However, the effects of individual or combined application of biochar (BC), acid-modified biochar (ABC), and wood vinegar (WV) on coastal saline–alkali soil are unknown. Hence, biochar, wood vinegar, and acid-modified biochar were prepared by pyrolysis of poplar wood. The properties of biochar were characterized, and soil incubation experiments were conducted. The results showed that ABC decreased the soil alkalinity by acid-base neutralization and improved the soil fertility by increasing the nutrients (C, N, P). ABC provided a more suitable environment and changed the abundance and diversity of soil microorganisms. ABC increased the relative contents of specific families (e.g., Pseudomonadaceae and Sphingomonadaceae), which had strong ecological linkages in the C, N, and P cycles and organic matter degradation. The results indicated that WV had little effect on coastal saline–alkali soil, whereas individual and combined application of biochar (especially ABC) showed an efficient remediation effect. Our preliminary study demonstrated that the ABC could be a suitable solution for ameliorating degraded coastal saline–alkali soils.

The continued increase in greenhouse gas emissions as a result of unprecedented eutrophication has resulted in a rising trend of red tides in the sea, which may be responsible for ecological degradation in the surrounding environment. Studies rarely investigate the accurate concentration of seawater eutrophication substances in offshore aquaculture areas, which may lead to the exacerbated pollution of inshore aquaculture. We examined whether offshore seawater quality monitoring can be effectively performed through unmanned aerial vehicles’ (UAVs) airborne hyperspectral remote sensing technique at Jiaozhou Bay, a water body associated with eutrophication. We used the UAV airborne hyperspectral imager to detect and measure typical marine aquaculture areas in Jiaozhou Bay and selected the key parameters of seawater quality, chlorophyll-a (Chl-a) concentrations, and total suspended matter (TSM) concentrations as indicators of seawater eutrophication. The hyperspectral inversion model of the Jiaozhou Bay seawater (JZBZ) was established with the optimal sensitive band of parameters. Results showed that in comparison with the traditional inversion model, the inversion R² of the Chl-a was 0.712, the RPD was 3.72, and the inversion R² of the TSM concentration was 0.756 while the RPD was 5.83. We found that this model is more suitable for the retrieval of water color parameters in Jiaozhou Bay. Additionally, by actual measurement, it can be seen that the concentration ranges of Chl-a in the observation area are 0.380–1.74 mg/m³, and the concentration range of TSM is 12.6–131 mg/L. The results of this study indicate that the Jiaozhou Bay Water Quality Translation Model (JZBM), based on the UAV airborne hyperspectral imager, performs well in the inversion of the concentration of chlorophyll and suspended particulate matter in offshore water, which advances our understanding with a new method to assess the degree of eutrophication in coastal waters.

With the wide application of lidar in the future, the problem of crosstalk between lidars will become more serious. True random coding photon counting lidar with high anti-crosstalk ability will play an important role in solving this problem. In this paper, based on the working principle of Gm-APD, the detection probability theoretical model of true random coding photon counting lidar is built, and the impact of jitter on detection probability is considered for the first time. The influence of mean echo photon number, mean pulse count density, sequence length and pulse width on detection probability is analyzed. Monte Carlo simulation and experimental results are highly consistent with the theoretical model, which proves the correctness of the detection probability theoretical model. This theoretical model provides an effective means to evaluate the system performance.

Focusing on the three critical factors influencing laser communication systems operating in marine environments: atmospheric turbulence disturbances, atmospheric attenuation, and optical aberration effects, in this paper, we employ numerical simulation methods to systematically investigate the influence of four typical Zernike aberrations (defocus, y-coma, spherical aberration, and y-secondary quadrupole) on laser atmospheric transmission characteristics and system bit error rates. A comparison of their atmospheric transmission performance with that of the aberration-free state is also presented. The results show that reducing turbulence strength or increasing receiver aperture radius can effectively mitigate the scintillation effect of intensity fluctuations. Among the four typical aberrations, the fluctuation range of the relative change rate of the scintillation index for y-coma aberration relative to the aberration-free state is the largest. In weak turbulence and short-distance laser transmission over the sea, the beam drift caused by these four aberrations is not significant, and stronger turbulence strength or higher weight coefficients lead to more severe beam expansion. The on-axis logarithmic intensity probability density distribution of laser beams with different aberrations approximately follows a log-normal distribution. The skewness (S) and kurtosis (K) of the logarithmic intensity distribution are negatively correlated and always satisfy S < 0 and K > 0. Additionally, we found that as turbulence strength increases, turbulence effects significantly raise the required signal-to-noise ratio (SNR) values to achieve a bit error rate of 10⁻⁹. When turbulence strength reaches a certain level, the impact weights of different aberrations on system performance may undergo changes. These results can provide theoretical references for the design and optimization of laser system parameters in marine laser communication.

A compact all-fiber pulsed coherent Doppler lidar (PCDL) for boundary layer wind measurement was developed by the Institute of Oceanographic Instrumentation, Qilu University of Technology (Shandong Academy of Sciences). It has been deployed at Zhongshan Station (69.4° S, 76.4° E) during the 2020 austral summer season by the 36th Chinese National Antarctic Research Expedition (CHINARE) and started routine observation in January 2020. This system, based on the 1550 nm all-fiber components, employs a 100 mm telescope with a long focal length of 632.6 mm to emit and collect laser pulses. It provides the ability to measure vertically resolved wind fields with a spatial resolution of 30 m and a temporal resolution of 1 min; the maximum detection range is up to 1.5 km in Antarctica. Wind speed and direction inversion methods were introduced subsequently. Preliminary measurement results of wind profiles indicate that this Doppler lidar can be operated successfully in Antarctica. The synchronous observations between the lidar, anemometer, and radiosondes at Zhongshan station are presented and have good consistency with each other. The comparison results between the lidar and anemometer indicate a root mean square deviation (RMSD) of 0.98 m s⁻¹ and 10.55° for wind speed and direction, respectively. The lidar continuous observations of wind profiles provide an opportunity to study the spatiotemporal variation of Antarctic wind with high resolutions, which is useful for further understanding of the atmosphere in Antarctic regions.

The atmospheric boundary layer is the lowest part of the troposphere, directly influenced by the Earth’s surface. The boundary layer’s height is a critical parameter for weather forecasting, air quality monitoring, and climate modeling. Lidar has become a premier tool for continuous boundary layer height detection with its high spatial–temporal resolution. A multi-wavelength aerosol lidar with 355 nm, 532 nm, and 1064 nm has been developed and deployed for operational observations at the Haidian District Meteorological Service of Beijing. The structure design, specifications, observation campaign, and detection principle of the multi-wavelength aerosol lidar are presented and the retrieval method of the boundary layer’s height is introduced. By comparing it with the data of the digital radiosonde, it is verified that the first normalized gradient of the range-corrected signal can more accurately retrieve the boundary layer’s height. The typical daily variation characteristics and influencing factors of urban boundary layer height are analyzed through observational examples and the monthly mean value of the boundary layer’s height in 2019 is acquired and analyzed.