Measurement report: Vehicle-based multi-lidar observational study of the effect of meteorological elements on the three-dimensional distribution of particles in the western Guangdong–Hong Kong–Macao Greater Bay Area

The distribution of meteorological elements has always been an important factor in determining the horizontal and vertical distribution of particles in the atmosphere. To study the effect of meteorological elements on the three-dimensional distribution structure of particles, mobile vehicle lidar and fixed-location observations were collected in the western Guangdong–Hong Kong–Macao Greater Bay Area of China during September and October in 2019 and 2020. Vertical aerosol extinction coefficient, depolarization ratio, and wind and temperature profiles were measured using a micro pulse lidar, a Raman scattering lidar, and a Doppler wind profile lidar installed on a mobile monitoring vehicle. The mechanism of how wind and temperature in the boundary layer affects the horizontal and vertical distribution of particles was analysed. The results show that particles were mostly distributed in downstream areas on days with moderate wind speed in the boundary layer, whereas they were distributed homogeneously on days with weaker wind. There are three typical types of vertical distribution of particles in the western Guangdong–Hong Kong–Macao Greater Bay Area (GBA): surface single layer, elevated single layer, and double layer. Analysis of wind profiles and Hybrid Single-Particle Lagrangian Integrated Trajectory Model (HYSPLIT) backward trajectory reveals different sources of particles for the three types. Particles concentrating near the temperature inversion and multiple inversions could cause more than one peak in the extinction coefficient profile. There were two mechanisms affecting the distribution of particulate matter in the upper and lower boundary layers. Based on this observational study, a general model of meteorological elements affecting the vertical distribution of urban particulate matter is proposed.

Nutrient Distribution in Eastern Indonesian Waters

Nutrients are needed for the growth of phytoplankton as a basic component in the marine food web. The concentration of nutrients in waters relates to primary productivity and it will influence fisheries stocks. So far, research on nutrients in the deep sea is rarely carried out in Indonesia. This study aims to determine water quality, horizontal and vertical distribution of nutrients in eastern Indonesian waters, which can be used as baseline data for deep-sea nutrients in Indonesia. The study was conducted from October 29 to November 15, 2017. Sampling was carried out in 20 stations with seven layers. Nutrient measurements were conducted based on Strickland and Parsons (1972). Our results showed that the concentrations of phosphate, nitrate, nitrite, ammonium, and silicate ranged from 0.000-0.060 mg/l, 0.001-0.321 mg/l, 0.000-0.009 mg/l, 0.004-0.024 mg/l and 0.085-1.090 mg/l, respectively. In general, the highest concentration of nutrients was found in Maluku Sea. The vertical distribution of nitrate, phosphate, and silicate shows that the increasing concentrations as increasing depth, except for nitrite and ammonium. The maximum nitrite concentration appears in the northern area, while the ammonium distribution has homogenous pattern.

Measurement report: Vehicle-based and In Situ Multi-lidar Observational Study on the Effect of Meteorological Elements on the Three-dimensional Distribution of Particles in the Western Guangdong–Hong Kong–Macao Greater Bay Area

The distribution of meteorological elements has always been an important factor in determining the horizontal and vertical distribution of particles in the atmosphere. To study the effect of meteorological elements on the three-dimensional distribution structure of particles, mobile vehicle lidar observations, and in situ observations were presented in the western Guangdong–Hong Kong–Macao Greater Bay Area of China during September and October of 2019 and 2020. Vertical aerosol extinction coefficient, depolarization ratio, wind and temperature profiles were measured by using a micro pulse lidar, a Raman scattering lidar, and a Doppler wind profile lidar installed on a mobile monitoring vehicle. The mechanism of how wind and temperature in the boundary layer affects the horizontal and vertical distribution of particles was analyzed. The result showed that particles were mostly distributed in downstream areas on days with moderate wind speed in the boundary layer, while they presented homogeneously on days with weaker wind. There are three typical types of vertical distribution of particles in the western Guangdong–Hong Kong–Macao Greater Bay Area (GBA): surface single layer, elevated single layer, and double layer. Analysis of wind profiles and Hybrid Single-Particle Lagrangian Integrated Trajectory Model (HYSPLIT) backward trajectory revealed different sources of particles for the three types. Particles concentrated near the temperature inversion and multiple inversions could cause more than one peak in the extinction coefficient profile. There are two mechanisms that affected the distribution of particulate matter in the upper and lower boundary layers. Based on observational study, a general model of meteorological elements affecting the vertical distribution of urban particulate matter was made.

Cape Verde Frontal Zone in summer 2017: lateral transports of mass, dissolved oxygen and inorganic nutrients

The circulation patterns in the confluence of the North Atlantic subtropical and tropical gyres delimited by the Cape Verde Front (CVF) were examined during a field cruise in summer 2017. We collected hydrographic data, dissolved oxygen (O2) and inorganic nutrients along the perimeter of a closed box embracing the Cape Verde Frontal Zone (CVFZ). The detailed spatial (horizontal and vertical) distribution of water masses, O2 and inorganic nutrients in the CVF was analyzed, allowing for the independent estimation of the transports of these properties in the subtropical and tropical domains down to 2000 m. Overall, at surface and central levels, a net westward transport of 3.76 Sv was observed, whereas at intermediate levels, a net 3 Sv transport northward was obtained. We observed O2 and inorganic nutrient imbalances in the domain consistent with O2 consumption and inorganic nutrient production by organic matter remineralization, resulting in a net transport of inorganic nutrients to the ocean interior by the circulation patterns.

The Horizontal and Vertical Distribution of Deep-Sea Sediments Fungal Community in the South China Sea

Although diverse fungi have been found in the deep-sea habitats, the space distribution of fungi has not been well characterized. In this study, the fungal horizontal and vertical distribution of the deep-sea sediments, four locations, three depths each, in the South China Sea, were compared using ITS2 high-throughput sequencing. It was revealed that the South China Sea deep-sea sediments harbor diverse marine fungi, including 82.39% Ascomycota, 8.10% Basidiomycota, 0.55% Zygomycota and 8.96% unknown fungi. The results indicate that fungal community structure is not uniform among the different sediment habitats. Though surface sediments have similar fungal diversity across the 4 locations, the fungal abundance and diversity increase with the depth of the sediments from 0 to 2 m, and 1 and 2 m deep sediments show obvious location-dependent fungal community structure. This is the first time to compare the horizontal and vertical distribution of fungal community among different deep-sea sediments in the South China Sea by high-throughput sequencing, providing novel insights into the space distribution characteristics of deep-sea sediments fungi.

Horizontal and vertical distribution of cephalopod paralarvae in the Mesoamerican Barrier Reef System

Horizontal and vertical distribution of cephalopod paralarvae (PL) from the Mesoamerican Barrier Reef System (MBRS) in the Western Caribbean was studied during two oceanographic cruises in 2006 and 2007. A total of 1034 PL belonging to 12 families, 22 genera, 24 species, 5 morphotypes and a species complex were identified. Abralia redfieldi, Onychoteuthis banksii and Ornithoteuthis antillarum were the most abundant taxa. The taxonomic identification from these three species was corroborated with DNA barcoding (99.8–100% of similarity). Paralarvae of Octopus insularis were reported for the first time in the wild. Most PL occupied the Caribbean Surface Water mass in the 0–25 m depth stratum. Largest paralarval abundances were related to local oceanographic features favouring retention such as the Honduras Gyre and Cozumel eddy. No day-night differences were found in PL abundance, although Abralia redfieldi showed evidence of diel vertical migration. Distribution of PL in epipelagic waters of the MBRS was probably related to ontogenetic migration, hydrographic features of meso and subscale, and to the circulation regimes dominated by the Yucatan Current. The MBRS represents an important dispersion area for PL, potentially connecting a species-rich Caribbean community with the Gulf of Mexico and Florida waters.