Seawater Source Research Articles

Thermal resistance capacity model for transient simulation of capillary-box heat exchangers

In this paper, a novel simplified hybrid model is developed to simulate the transient thermal behaviors of capillary-box heat exchangers (CBHEs) buried in the seabed, serving as the front-end heat exchangers in seawater source heat pump system (SWHPs). The thermal resistance and capacity (TRC) approach is applied for derivation of the governing equations inside and outside the heat exchangers. Also, an analytical solution is integrated to model heat transfer in the seabed base. The effects of seawater seepage on the thermal performance of CBHEs are taken into account in the present model. The state-space representation is used to solve the governing equations. The model is verified against experimental data, achieving very good agreement with the mean bias error (MBE) of 7.2 %. A comparison with a three-dimensional computational fluid dynamic (CFD) model indicates that the TRC model's maximum relative error and MBE are 0.7 % and 2.0 % lower than those of the CFD model. Additionally, the ratio of the time required by the CFD and TRC models for a 31-day run was 138. These results demonstrate that the TRC model is sufficiently accurate and fast in the thermal simulation of CBHEs. Furthermore, the thermal properties of CBHEs are examined using the present model. The model in this study provides practical implications for heat transfer analysis and design improvement of CBHEs utilized in SWHPs.

Innovative integration of sustainable technologies in educational programs: Fostering freshwater production and environmental preservation awareness

This study highlights the integration of sustainable desalination technologies into educational programs to raise awareness of freshwater production and environmental preservation. Through a comprehensive curriculum, students explore innovative methods such as pressure-retarded osmosis, multi-effect desalination, and seawater source heat pumps, all powered by renewable seawater thermal energy. The curriculum emphasizes the importance of reducing greenhouse gas emissions, lowering reliance on fossil fuels, and protecting aquatic ecosystems. Students engage in practical evaluations of energy efficiency, economic viability, and environmental impact. Sensitivity analyses are incorporated to help students identify critical factors affecting system performance and optimize operational conditions for various modes. Through hands-on experiments, students learn that components like the heat pump condenser contribute the most to energy loss (29 %), followed by the expansion valve (12 %), compressor (11 %), and seawater heat exchanger (8 %). Economic analyses reveal that while the heat pump condenser and seawater heat exchanger have the lowest financial impact (0.33 % and 2.48 %, respectively), the pressure-retarded osmosis and compressor units have the highest (100 % and 60.3 %, respectively). The findings demonstrate that an optimally designed desalination system can produce freshwater at 80 % lower costs compared to traditional plants, while also reducing carbon emissions by 15 %. Educational experiments also show that integrating pressure-retarded osmosis downstream of multi-effect desalination significantly reduces brine salinity and temperature, highlighting the system's potential for environmental sustainability. This approach not only fosters a deeper understanding of desalination technologies but also equips students with the tools to address future global water challenges.

Unraveling microbial community variation along a salinity gradient and indicative significance to groundwater salinization in the coastal aquifer

Saltwater intrusion poses a global environmental challenge in coastal regions, profoundly influencing groundwater microbial communities and biogeochemical processes. This study aims to elucidate the origin of groundwater salinity and understand the response of microbial interactions to groundwater salination through stable isotopes and 16S rDNA gene sequencing. The findings reveal a significant increase in groundwater TDS from inland to the coastline, ranging from 0.5 g/L to 144.6 g/L. Ionic relationship and isotopic fractionation indicate that the high salinity in groundwater originates not only from paleo–seawater but also from the dissolution of halite. Salty groundwater exhibits lower species richness and diversity than fresh groundwater. TDS, SO42–, and NO2– are the pivotal factors shaping the microbial community of salty groundwater, while NO3– and H2SiO3 are dominant variables influencing fresh groundwater community. This study identifies the order Alteromonadales, family Alteromonadaceae, and genus Marinobacter as potential biomarkers of seawater or paleo–seawater sources. Phylogenetic molecular network analysis of microbial communities illustrates that groundwater salinization results in a more compact microbial network but enhances microbial interactions. Predicted functional genes indicate that sulfate reduction genes (sat, met3, aprA, aprB, dsrA, and dsrB) are more abundant in salty groundwater than in fresh groundwater, suggesting a high metabolic potential for sulfate. These results elucidate the pivotal role of groundwater salinization in microbial community evolution, shaping specific functional zones in coastal groundwater.

Dolostone-barite-phosphorite sequence in the basal Doushantuo Formation: Origin and implications for post-Marinoan ocean chemistry and phosphogenesis

Barite (BaSO4) represents a major component of many post-Marinoan cap dolostones worldwide, recording important information on climate upheavals during the terminal Neoproterozoic. However, its origins and relations with other lithofacies remain to be explored. Here we report new occurrences of barite in the basal Ediacaran Doushantuo Formation at a major phosphate mine in Weng'an, South China, and present results of detailed petrographic and geochemical investigations on the barites and related phases. At the outcrop scale, barite is mainly present as a 1–2 cm-thick layer at the contact of the cap dolostones and overlying phosphorites. Detailed petrographic observations reveal a lithofacies transition from dolostone through a mixture of barite, dolomite and apatite to barite and finally to granular phosphorite. The barites can be categorized into three generations in stratigraphic order, which are present as loose, randomly-oriented blades (B1), dense aggregates (B2), and radially aligned crystal fans (B3), respectively. B1 is dispersed in a matrix of apatite and dolomite, which has an average δ13Ccarb of −0.61‰. This, along with the common presence of organic matter (OM) in this barite, point to a possible source of Ba from organic degradation. B3 forms a centimeter-scale layer of barite fans that laterally extends over the entire mining pit, whereas B2 is locally distributed between B1 and B3, and occurs as relatively unoriented aggregates. δ34S values of B3 show a narrow range between +25.9‰ and +30.9‰, which is similar to that of contemporaneous seawater and indicate a seawater source of sulfate in barite. Based on the present investigation and a compilation of published data, we propose that B1 is diagenetic barite with a main source of Ba from degradation of organic matter and possibly also from dissolution of previous pelagic barite, whereas B2 and B3 represent seafloor precipitates that resulted from interactions between deep, anoxic Ba-rich waters and oxic, sulfate-rich surface waters during the post-glacial transgression. This episode of barite precipitation was immediately followed by massive accumulations of phosphorites in Weng'an and many areas of South China. The consecutive deposition of cap dolostone, barite and phosphorite signifies the transition from an alkalinity-rich, stagnant anoxic ocean to a dynamic marine regime featuring oxygenated surface waters and upwelling currents. These pH and redox changes likely facilitated the cycling and enrichment of phosphate in the shallow waters that was necessitated by the unprecedented accumulation of Ediacaran phosphorites in South China.

ANALISIS EFISIENSI BIAYA DALAM PENYEDIAAN AIR LAUT UNTUK OCEANARIUM KOTA: STUDI KASUS BXSea BINTARO

This research focuses on assessing how to procure seawater for the BXSea Bintaro Oceanarium, which is located far from natural seawater sources. The two main options analyzed were the purchase of seawater directly from the coast and the creation of artificial seawater. The research method used in this study was conducted through a qualitative, case study approach by combining literature study, field observation, and the researcher's experience as an oceanarium designer, to gain an in-depth understanding of the technical, economic, and environmental aspects associated with both ways of seawater procurement. The results show that the use of native seawater is more economical and environmentally friendly than artificial seawater. Analysis of the initial costs, long-term operational costs, and logistical and environmental implications of both methods showed the superiority of direct seawater procurement. This method is not only efficient in reducing logistical complexity and initial investment, but also has minimal environmental impact. The conclusions of this study confirm that natural seawater procurement is a cheaper option than the use of artificial seawater. Artificial seawater is significantly up to 5.58 times higher than natural seawater. This study makes an important contribution to the literature of seawater resource management in educational and recreational facilities, and underscores the importance of a sustainable approach in oceanarium development.

Enhancing Molecular Characterization of Dissolved Organic Matter by Integrative Direct Infusion and Liquid Chromatography Nontargeted Workflows.

Dissolved organic matter (DOM) in aquatic systems is a highly heterogeneous mixture of water-soluble organic compounds, acting as a major carbon reservoir driving biogeochemical cycles. Understanding DOM molecular composition is thus of vital interest for the health assessment of aquatic ecosystems, yet its characterization poses challenges due to its complex and dynamic chemical profile. Here, we performed a comprehensive chemical analysis of DOM from highly urbanized river and seawater sources and compared it to drinking water. Extensive analyses by nontargeted direct infusion (DI) and liquid chromatography (LC) high-resolution mass spectrometry (HRMS) through Orbitrap were integrated with novel computational workflows to allow molecular- and structural-level characterization of DOM. Across all water samples, over 7000 molecular formulas were calculated using both methods (∼4200 in DI and ∼3600 in LC). While the DI approach was limited to molecular formula calculation, the downstream data processing of MS2 spectral information combining library matching and in silico predictions enabled a comprehensive structural-level characterization of 16% of the molecular space detected by LC-HRMS across all water samples. Both analytical methods proved complementary, covering a broad chemical space that includes more highly polar compounds with DI and more less polar ones with LC. The innovative integration of diverse analytical techniques and computational workflow introduces a robust and largely available framework in the field, providing a widely applicable approach that significantly contributes to understanding the complex molecular composition of DOM.

Seawater source heat pump system based on capillary heat exchanger for seepage in submarine tunnel: a case study

Abstract The discharge of seepage water from undersea tunnel structures, often treated as wastewater, inherently carries a substantial reservoir of untapped low-grade thermal energy. Unfortunately, comprehensive investigations into harnessing this latent potential remain notably limited. This study introduced an innovative strategy through the design of an undersea tunnel seepage seawater source heat pump system. Distinguished by the integration of a capillary front-end heat exchanger, this system aimed to effectively exploit the frequently disregarded low-grade thermal energy present in the seepage water of undersea tunnel structures. The seawater seepage from the tunnel is transported to the car park at the tunnel entrance, and a seawater energy pool is constructed by storing seawater in its underground space. The use of capillary network placed in the energy pool in the front heat exchanger, water source heat pump units, circulating water pumps and fan coil end device composed of underground undersea tunnel seepage seawater source heat pump system for the building heating and cooling. Furthermore, a comparative assessment was conducted, contrasting this novel system with the traditional air-conditioning setup that utilizes chillers and gas boilers as cooling and heating sources. The aim was to evaluate its capacity for energy conservation and emission reduction. The findings from the study strongly affirmed the viability of the proposed seepage seawater source heat pump system within undersea tunnels. It boasted the potential to achieve annual savings of 53.55 tce, highlighting a noteworthy energy-saving rate of 21.2%. Concurrently, reductions in CO2, SO2, and particulate emissions amounted to 132.28 t/a, 1.07 t/a, and 0.54 t/a, respectively. This study not only stands as a reference for the strategic utilization of seepage seawater from undersea tunnel structures, prioritizing energy conservation and emission reduction, but also pioneers innovative approaches toward resource optimization and environmental sustainability, meeting the inherent needs of carbon peaking and carbon neutrality goals.

Research on the matching relationship of multi-energy collaborative temperature control in factory farming system based on TRNSYS

In light of the escalating energy crisis and the imperative to address climate change, there exists a pervasive global consensus advocating the reduction of carbon emissions and the exploration of novel energy sources. Despite this consensus, the realm of factory farming continues to rely upon conventional energy sources for heating purposes. This study focuses on the investigation into the multi-energy heating system employed by an aquaculture company in Dalian City. We undertook the optimization of critical parameters within this system and formulate a comprehensive model for the multi-energy system using the TRNSYS transient simulation platform. The optimization process employs the Hooke-Jeeves algorithm, implemented through GenOpt software, with the system annual value cost serving as the objective function. Optimization variables include solar collector area, solar collector slope, thermal storage tank volume, seawater source heat pump power, and wastewater plate heat exchanger area. The findings of this investigation reveal a marked enhancement in the Coefficient of Performance (COP) and overall system performance after optimization. The resultant annual operating cost was $3133.61, indicating a substantial reduction of $1151.86 compared to the pre-optimization period’s cost. The static payback period is determined to be 9.43 years. During the heating period, in contrast to traditional boiler heating, the optimized system manifests a reduction in coal consumption of 4485.03 kg, accompanied by a cumulative decrease in pollutant emissions totaling 11544.46 kg. This substantiates the system’s cumulative economic and environmental viability.

Carbon Outwelling and Uptake Along a Tidal Glacier‐Lagoon‐Ocean Continuum

AbstractTidewater glaciers are highly vulnerable to climate change due to warming from both atmospheric and seawater sources. Most tidewater glaciers are rapidly retreating, but little is known about how glacial melting modifies coastal biogeochemical cycles. Here, we investigate carbonate and nutrient dynamics and fluxes in an expanding proglacial tidal lagoon connected to Europe's largest glacier in Iceland (Vatnajökull). The lagoon N:P:Si ratios (2:1:30) imply a system deficient in nitrogen. The large variations in the freshwater endmembers highlighted the complexity of resolving sources and transformations. The lagoon acted as a sink of dissolved inorganic carbon (DIC). Floating chamber incubations revealed a CO2 uptake of 26 ± 15 mmol m−2 d−1. Lagoon waters near the glacier had a 170% higher CO2 uptake than near the lagoon mouth, likely driven by primary production stimulated by nitrogen‐rich bottom water upwelling. The lateral DIC and total alkalinity (TA) flux rates (outwelling) from the lagoon to the ocean were −1.5 ± 0.1 (export to ocean) and 23 ± 5 mmol m−2 d−1 (import into the lagoon) respectively. All samples were undersaturated with respect to aragonite due to glacial meltwater dilution of TA and CO2 uptake. This implies dilution of oceanic alkalinity, lowering the nearshore buffering capacity against ocean acidification.

Analysis of energy-saving effects of recirculation aquaculture system using seawater source heat pumps and solar power generation

Analysis of energy-saving effects of recirculation aquaculture system using seawater source heat pumps and solar power generation

Halophiles and their adaptations: A comprehensive review on recent progress and prospects in biodesalination applications

AbstractWorldwide climate change, rising population, and industrialization have raised the global demand for freshwater. Desalinating brackish water has become a sustainable technology for drinking and agriculture to overcome global water scarcity. Thriving biodesalination technology has become more attractive and eco‐friendly than the present physicochemical desalination methods, which are expensive and energy‐intensive. Researchers are exploring the bioutilization of nature's potential for desalination using halophiles like haloarchaea, halobacteria, halophytic algae, and plants. Biomimetic desalination membranes have been developed, inspired by the desalination mechanism in animals. This comprehensive review explores recent advancements and potential applications of halophiles in biodesalination to exploit them effectively. It provides an overview of the opportunities and challenges associated with harnessing halophiles for the removal of salts from brackish and seawater sources. This review also focuses on insights into biomolecules produced by the halophilic microorganisms and halophytes in the desalination process. Understanding the mechanism of action of these biomolecules will edify the effective unexplored research areas in biomimicry and bioutilization to overcome the existing limitations in water treatment.

Efficient Method for Solving Underwater Electromagnetic Fields Generated by Radiation Sources in Seawater

Efficient Method for Solving Underwater Electromagnetic Fields Generated by Radiation Sources in Seawater

Techno-economic evaluation of a seawater source heat pump system with auxiliary heat source in cold region of China

The utilizing of renewable seawater energy through seawater source heat pumps (SWHPs) in coastal areas is considered as a sustainable technology with minimal environment impact. Promotion of this technology needs clear understanding of its techno-economic performance but there are limited relevant studies. An empirical study was conducted in Qingdao, China, based on a practical installation comprising SWHPs supplemented by electric boilers. On-site measurements revealed considerable COP of 3.81 for SWHP and COPs of 2.87 for the whole system, implying SWHP as a viable and efficient solution for space heating in mild winter in this region. Results from TRNSYS simulations showed SWHP with auxiliary gas boilers (SWHP-GB) achieved the lowest annual primary energy demand and best economic and environmental benefits compared with other three schemes, namely SWHP with electric boilers (SWHP-EB), chillers with gas boilers (Chiller-GB) and air source heat pumps with gas boilers (ASHP-GB). SWHP played important roles in energy efficiency of the whole system with a considerable seasonal COP of 3.72 and 3.22 respectively for heating and cooling. Annual primary energy demand of SWHP-GB accounted for 55 %, 78 % and 56 % of SWHP-EB, Chiller-GB and ASHP-GB, respectively. SWHP-GB achieved the lowest life cycle costs and a rapid payback period of 10.9 years. Moreover, using direct or indirect heat exchange with seawater was found with limited impact on techno-economic performance of the system. To conclude, SWHP-GB could be used as an efficient solution for building heating and cooling in northern coastal cities in China.

A KAJIAN LOKASI UNTUK OCEANARIUM DI SURABAYA: KESEIMBANGAN ANTARA WISATA, PENDIDIKAN DAN RISET

This research examines the siting factors of an oceanarium in Surabaya, Indonesia. The research stems from the need to explore the optimal location for an oceanarium, taking into account the main objectives and functions of the development. The research aims to determine the most suitable location for an oceanarium, with recreation, education, conservation and research being the main considerations. The methodology involved a qualitative analysis of location factors, including accessibility, availability of natural resources, and environmental and socio-economic impacts. The discussion in this study emphasizes the importance of choosing a location that not only supports the oceanarium's objectives but also takes into account the availability of quality seawater resources. The ideal location recommended is an area adjacent to a clean source of seawater and protected from contamination, such as a location away from a river mouth. In addition, the location should be easily accessible to visitors and support recreation, education, conservation and research activities. The conclusion of this study shows that the best location for oceanarium development in Surabaya is the coastal area that fulfills these criteria, namely Kenjeran Lama beach and Ria Kenjeran Beach. This location stands out as the most strategic location in terms of access and travel time. These locations not only support the sustainability of the oceanarium in terms of ecology but also provide added value in terms of economy, education, recreation and research. This research provides valuable guidance for future oceanarium development, both in Surabaya and other locations in Indonesia.

Power consumption prediction model based on artificial neural networks for seawater source heat pump system in recirculating aquaculture system fish farm

Power consumption prediction model based on artificial neural networks for seawater source heat pump system in recirculating aquaculture system fish farm

Short- to Medium-Term Corrosion of Mild Steel in Highly Calcareous Seawaters: Effects of Calcium Carbonate Concentration, Coupon Orientation, and Nutrient Addition

Mild steels exposed to marine immersion conditions in which carbonate solubilities are exceeded, leading to deposition of calcareous material, have been shown to exhibit much-reduced corrosion rates compared with corrosion under conditions in which there is no exceedance of solubility limits and therefore no calcareous deposition. However, the differences in corrosion including the potential effect of microbiologically influenced corrosion (MIC) in these conditions have not been examined systematically in the literature. The study reported herein involves short- to medium-term marine immersion exposures (up to 18 month) of mild steel coupons in natural seawater (control) and in environments using the same seawater source dosed with (1) CaCO3, acting as an inorganic particulate suspension representative of that encountered in seawater with elevated calcareous content; and (2) a nitrate salt, acting as an industrial pollutant and bacterial nutrient source. The results show the extent to which the deposition of particulate CaCO3 from suspension in seawater onto and into the rusts reduces the rate of corrosion of mild steel; a rate that was found to be dependent on the coupon orientation within the seawater. Coupons that were permanently buried beneath a cap of settled CaCO3 particles exhibited a 70% reduction in corrosion rate compared with the representative control coupons. The results also show that for these exposure durations and conditions, while iron-related bacteria and sulfate-reducing bacteria populations were identified in high concentrations (respectively ∼1 × 106 cfu/g and ∼1 × 102 to 4 × 106 cfu/g, depending on coupon orientation) within the rust products themselves after 18 month of exposure, there was no clear evidence of MIC. These findings indicate that short and medium-term (nonaccelerated) studies of MIC for mild steel are insufficient or even misleading for the prediction of long-term corrosion rates in these environments.

Corrosion resistance and earth-abundance FeS-based heterojunction catalyst for seawater splitting at industrial grade density

The strategic progression toward highly efficient transition metal electrocatalytic electrodes is crucial to achieving efficiency and long-term stability in hydrogen production from authentic seawater sources. This work reports the development of a self-supporting, heterogeneous and corrosion-resistant iron sulfur-based catalytic electrode via a streamlined, one-step process involving sulfide etching and electroless plating on an iron foam substrate (IF). This new electrode, named NiS-FeS@IF, involves a nanostructured NiS-FeS catalytic material that combines in situ, resulting in a thin, ultrathin nanospherical layer on the IF. This construction has low overpotentials of merely 322 mV for the hydrogen evolution reaction (HER) and 563 mV for the oxygen evolution reaction (OER) with a current density of 500 mA cm−2 in alkaline simulated seawater electrolytes. Importantly, the NiS-FeS@IF electrode enduring more than 500 h at an industrial grade high current density of 1 A cm−2 without noteworthy performance deterioration. The unique and uniformly dispersed morphology of NiS-FeS facilitates intensified interfacial electron transfer, optimizes active site exposure and provides efficient channels for the rapid release and mass transfer of gas bubbles. This work introduces a novel approach for the facile preparation of efficient electrode materials.

Development, 4E-analysis, and optimization of a seawater thermal energy-driven desalination system based on seawater source heat pump, multi-effect desalination, and pressure retarded osmosis with reduced effluent concentration

Development, 4E-analysis, and optimization of a seawater thermal energy-driven desalination system based on seawater source heat pump, multi-effect desalination, and pressure retarded osmosis with reduced effluent concentration

Emergence of the 2.1 Ga Francevillian biota was preceded by unprecedented hydrothermally driven seawater eutrophication

Recently, two independent studies suggest that the emergence of putative fossilized macro-eukaryotes in the Paleoproterozoic Francevillian Basin, ~2.1 billion years ago, may be related to a rise in seawater Zn bioavailability. This explanation is reliant on their extraordinary high Zn content and association with light Zn isotopes characteristic of eukaryotic enrichment. However, the trigger and origin of rising seawater Zn supply to the basin remains unknown. This study unravels a transient episode of intense submarine hydrothermal activity that triggered the weathering of a nutrient-rich oceanic crust reservoir, related to the collision of the Congo-São Francisco cratons during the Eburnean-Transamazonian orogeny, as the source of abundant seawater dissolved Zn, together with a suite of essential trace metals and phosphate to the continental margin waters. Surprisingly, the initiation of hydrothermal weathering coincided with the rapid onset of a rare Paleoproterozoic seawater eutrophication event. This transition is marked by basin-wide redox stratification, high sediment loading with organic carbon (Corg) and nitrogen, elevated C/N ratios, a steep negative Corg and positive bulk N isotope excursion, positive Ce anomalies, and low Mn/Fe ratios. Importantly, the transient eutrophication event ended with a reversal to lower seawater phosphate levels that coincided with rapid seawater ventilation and the appearance of macrofossil bearing sediments in Franceville. We suggest that these unexpected, localized conditions, set the stage for the emergence of the Francevillian biota.

Analysis of fast-growing culturable bacteria and pathogenic bacteria in the surface water of the northeast coast of Hainan Island in China

Objective: To obtain the diversity and abundance of fast-growing bacteria in the surface water of the northeast coast of Hainan Island in China, different cultivation methods were employed. This study also aims to provide a reference for isolating bacterial samples from seawater sources and preventing marine-derived pathogens. Methods: Based on the principles of taxonomic design, surface seawater samples were collected from six locations along the northeast coast of Hainan Island in China in March, June, October, and December 2021. Then, bacterial enrichment was performed based on traditional cultivation methods for Salmonella, Vibrio, Burkholderia pseudomallei, Actinomycetes, and general marine bacteria. After that, bacterial species identification was conducted by 16S rDNA amplicon sequencing and metagenomic sequencing. Results: A total of 1 151 fast-growing cultivable bacteria belonging to 66 genera and 213 species were identified using five different culture protocols. In different cultivation protocols, Bacillus and Klebsiella demonstrated extensive discriminatory advantages and ranked among the top genera in terms of abundance. Protocol 1 had Escherichia, Klebsiella, and Citrobacter as dominant genera. Pathogenic bacteria detected by protocol 1 included Klebsiella pneumoniae and Escherichia coli, with 37 and 29 strains respectively, while Salmonella enterica was uniquely detected with seven isolates. Proteus, Enterococcus, and Providencia were the dominant genera in protocol 2, and Proteus mirabilis was the most abundant pathogenic bacteria detected with 66 isolates. Vibrio cholerae was uniquely detected with six isolates at a higher abundance. Klebsiella, Escherichia, and Acinetobacter were the dominant genera in protocol 3, and Klebsiella pneumoniae was the most abundant pathogenic bacteria detected with 53 isolates, while Acinetobacter nosocomialis was uniquely detected with seven isolates. Vibrio and Pseudoalteromonas were the dominant genera in protocol 4, and they showed advantages in isolating and cultivating Marine-derived Vibrio. Exiguobacterium, Staphylococcus, and Bacillus were the dominant genera in protocol 5. Bacillus cereus and Lactococcus lactis were the most abundant pathogenic bacteria detected with 20 and 15 isolates, respectively, while Lactococcus lactis was uniquely detected at higher abundance. Metagenomic sequencing showed that Klebsiella pneumoniae was significantly dominant with a gene abundance of 51.11%, followed by Alcanivorax sp. at 12.57%. Conclusion: The surface water of the northeast coast of Hainan Island in China exhibits a rich diversity of bacteria, with Klebsiella pneumoniae being highly abundant in the studied area. Different cultivation methods demonstrate distinct selective advantages in culturing bacterial genera and pathogens. Therefore, it is necessary to optimize cultivation conditions for specific marine bacteria.