Huge amount of trace metals emitted through manmade activities are carried by the Changjiang River into the East China Sea. Most of them deposit in the Changjiang River Estuary and threaten the regional aquatic environment. In this study, major and trace elements of 34 archive surface sediments and two cores are examined. Sequential extraction procedures were also performed on surface sediments from 12 sites. We found that Tl, Tm, Er show distinct accumulation in surface sediments in the order of Tm > Tl > Er. Particularly, abnormally elevated HREE are observed mainly in those sites near the mouth of the estuary. Most elements exhibit an obvious reduction in the upper 30 cm of core B8, reflecting a decrease of sediment discharge from Changjiang River runoff. The increase of some trace elements recorded in the upper 20 cm of core C3 demonstrates a distinct local anthropogenic input in recent years.
Sea salt aerosols are mostly distributed over the oceans and they can significantly affect the atmospheric radiative transfer. This article investigated sea salt aerosol impact on the polarization state of radiance at the top of the atmosphere (TOA) through the use of sea salt particle models. Specifically, six models of sea salt aerosols, including a homogeneous sphere, two super-spheroids, and three inhomogeneous spheres with both spherical and nonspherical cores, were considered and their optical properties were computed using the Lorenz–Mie theory and the invariant imbedding T-matrix method. The polarized radiance at the TOA was simulated by using a vector adding–doubling radiative transfer model. It was demonstrated that the inhomogeneous sphere-modeled TOA polarized radiance had a minimum at the backscattering angles ranging from 170° to 175°, whereas such features disappear when a homogeneous sphere or nonspherical model is used. To prove this effect, the satellite marine aerosol vertical feature mask data from the Cloud Aerosol Light Detection and Ranging (Lidar) and Infrared Pathfinder Satellite Observations (CALIPSO) over global ocean areas were collocated with the measurements from Polarization and Anisotropy of Reflectance for Atmospheric Science Coupled with Observations from a Lidar (PARASOL). It was found that the PARASOL polarized radiance also had negative values at the backscattering angles ranging from 170° to 175°. Thus, the obvious negative polarized radiances at these backscattering angles could be indicative of inhomogeneous sea salt aerosols. Both homogeneous and inhomogeneous sea salt models related to ambient relative humidity (RH) should be considered for accurate radiative transfer simulations.
Polymetallic nodules are enriched in critical metals and possess high economic values. The authors observed, for the first time, high abundance of spherical polymetallic nodules on the abyssal basin around the Caiwei Guyot in the northwestern Pacific Ocean. In order to reveal their metal resource potential and long-term metallogenic process, the authors carried out high-resolution scanning electron microscopy (SEM), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), X-ray diffraction (XRD), transmission electron microscopy (TEM) of laminas, and marine chemical analysis. The polymetallic nodules are composed of columnar or lamina growth patterns with low reflectance, which can be subdivided into four types of laminas based on microtexture. The Mn/Fe ratios of the laminas increased in the order type 1.2 < type 1.3 < type 2 < type 1.1. The nodule laminas yielded low Mn/Fe ratios (<4.01), Ni (<12000 ppm) and MgO (<3.74%) contents but high contents of Co (average 8516 ppm), Pt (average 416 ppb), and rare earth elements and Y (REY, average 2887 ppm), relative to other polymetallic nodules in the global ocean. XRD and TEM analyses indicated that the polymetallic nodules are composed of Fe-vernadite. Evidences from micro-texture, geochemistry and mineralogy imply that the polymetallic nodules around the Caiwei Guyot have been forming from oxic bottom water since initial growth, due to oxygen-rich bottom water flowing-through and low surface productivity. The dissolved Mn and Fe elements in the bottom water are continuously precipitated into ferromanganese oxides under oxic conditions. The ferromanganese oxides absorb high contents of multivalent metals such as Co, Pt, and Ce, owing to surface oxidation of the manganate octahedral layer during precipitation. The northwest Pacific Ocean shows deep depth, slow sedimentary rates, moderate-to-high contents of dissolved oxygen, and low summer surface productivity. Based on this, the authors propose that the northwest Pacific Ocean is an ideal metallogenic belt for polymetallic nodules with abundant Co, Pt, and REY resources.
In recent years, with the rapid development of regional economy in the Pearl River Estuary, drastic change in the content and transport patterns of suspended sediment in water bodies, which mainly caused by variations in land use patterns and bank erosion, imposed a profound impact on the development and evolution of the estuary Delta as well as the coastal ecological environment. In this study, we used the measured spectral data to establish inversion algorithm and to inverse suspended sediment based on CASI hyperspectral data, the accuracy of the inversed CASI and MODIS suspended sediment were verified with in-situ measured data. The results show that: 1) Single-band exponential model (SSC=4.5e21.922*Rs(622.486)) can well retrieve the suspended sediment concentration in the experimental sea area, and the average relative error is approximately 11.15%; 2) The suspended sediment content lies between 0.45-12.15 mg/L over the study area, and the main input source is land-based input from the west coast of Huangmao Sea, the ecological impact on the dolphin reserve can be neglected; 3) Combined with MODIS-based remote sensing images of suspended sediment in the Pearl River Estuary, it is found that there is an obvious branching phenomena when the sediment is transported from the Huangmao Sea to the outside of the mouth. The main axis of runoff is transported along the northeast direction of Dajin Island to the southeast direction of Dajin Island in the estuary area, while the coastal current is transported along the northeast direction of Dajin Island to the southwest direction of Dajin Island. As a result, there are low suspended sediment and high transparency sea areas in the north of Dajin Island, which are suitable for aquaculture.
Data simplification is an important factor of the spatial data generalization. In this paper, the principle of the 3D D-P algorithm was introduced firstly, and aiming at the low computational efficiency of this algorithm, the first base plane was artificially designated instead of the loop search in the tight method, this improvement makes the computational efficiency to improve dozens of times , but the result of generalization of 3D discrete point is very similar to the generalized result by the tight method. This process was validated by experiments and this algorithm has a certain overall characteristics,therefore it has wide application prospect.
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