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To explore the causes of red tides in Qinhuangdao coastal water, we conducted surveys on both water quality and red tides during April to September of 2022 and analyzed the relationships between main environmental factors and red tide organisms through the factor analysis and canonical correspondence analysis. The results showed that there were eight red tides along the coast of Qinhuangdao in 2022, with a cumulative blooming area of 716.1 km2. The red tides could be divided into three kinds based on the major blooming organisms and occurrence time, Noctiluca scintillans bloom, diatom-euglena (Skeletonema costatum, Eutreptiella gymnastica, Pseudo-nitzschia spp.) bloom, and dinoflagellate (Scrippsiella trochoidea and Ceratium furca) bloom. Seasonal factor played roles mainly during July to September, while inorganic nutrients including nitrogen and phosphorus influenced the blooms mainly in April and July. The canonical correspondence analysis suggested that N. scintillans preferred low temperature, and often bloomed with high concentrations of ammonium nitrogen and dissolved inorganic phosphorus. S. costatum, E. gymnastica, and Pseudo-nitzschia spp. could tolerate broad ranges of various environmental factors, but favored high temperature and nitrogen-rich seawater. C. furca and S. trochoidea had higher survival rate and competitiveness in phosphate-poor waters. Combined the results from both analyses, we concluded that the causes for the three kinds of red tide processes in Qinhuangdao coastal areas in 2022 were different. Adequate diet algae and appropriate water temperature were important factors triggering and maintaining the N. scintillans bloom. Suitable temperature, salinity and eutrophication were the main reasons for the diatom-euglena bloom. The abundant nutrients and seawater disturbance promoted the germination of S. trochoidea cysts, while phosphorus limitation caused the blooming organism switched to C. furca and maintained the bloom hereafter.

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For the frequent occurrence of harmful algal blooms (HABs) in the Qinhuangdao coastal sea (QCS) of the Bohai Sea in summer, we tested the hypothesis that high-biodiversity HAB species exist in the area, and a series of censuses of HAB species were conducted in the QCS in the summers of 2014-2019. Through morphological identification, we found 100 algae species representing 42 genera in 3 phytoplankton phyla in this study, among which Bacillariophyta was the most dominant phylum. We also found that the population density of Dinoflagellata increased from 2016 to 2019. In total, 59 HAB species were annotated in this study, including 39 of Bacillariophyta, 18 of Dinoflagellata and 2 of Ochrophyta, of which 13 HAB species were reported in the Bohai Sea for the first time, and most HAB species were widely distributed in the QCS in summer. Notably, four dominant HAB species displayed unique temporal and spatial distribution characteristics, while their distribution ranges and population densities increased from 2014 to 2019. The distributions of five environmental factors were different in the QCS, while the temperature, salinity, and dissolved inorganic nitrogen might be the key environmental factors influencing the distribution of dominant HAB species in the summer. In conclusion, this study provides a detailed evaluation of phytoplankton diversity and interannual variation in the QCS. The existence of a high level of biodiversity of algal bloom species suggests the need for long-term monitoring in order to further study and prevent potential HABs.

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In recent years, paralytic shellfish toxins (PSTs) have been prevalent in the coastal waters of Qinhuangdao, the west coast of the Bohai Sea, China. The content of PSTs in shellfish often exceeded the regulatory limit of 800 µg STX equivalent (eq.) kg-1, which poses a serious threat to human health. In this study, two surveys were conducted in May 2021 and May 2022 to investigate the distribution of PSTs in the coastal waters of Qinhuangdao. Seawater, surface sediment, phytoplankton, zooplankton, and other marine organism samples were collected, and the composition and concentration of PSTs were analyzed by liquid chromatography with tandem mass spectrometry (LC-MS/MS). Results showed that multiple PST components were detected in all seawater samples collected at different depths, mainly including GTX1/4, GTX2/3, dcGTX2, STX and C1/2, and the highest concentration of PSTs reached 244 ng STX eq. L-1. The sediment samples also contained low levels of C1/2 and GTX2/3. Trace amounts of C1/2 and GTX1-4 were detected in phytoplankton and zooplankton. Moreover, all bivalve shellfish samples were found to contain PSTs, and the scallop Azumapecten farreri and the ark clam Anadara kagoshimensis showed relatively high concentrations of 607 and 497 µg STX eq. kg-1, respectively. In addition, low levels of PSTs were also found in some non-traditional PST vectors, including whelk Rapana venosa, octopus Amphioctopus ovulum, goby Ctenotrypauchen chinensis, and greenling Hexagrammos agrammus. Results of this study improve the understanding of the distribution of PSTs in seawater and marine organisms and the potential risk of persistent PSTs in seawater to marine ecosystems and human health.

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Thermal discharges from power plants elevate temperatures in the surrounding waters, and this warming of the marine environment inevitably influences phytoplankton communities. In this study, we conducted seasonal sampling in coastal waters of the Bohai Sea off Qinhuangdao, China. The results revealed that the coastal waters are notably affected by thermal discharge, with unseasonably-high water temperatures, particularly during winter. The change of phytoplankton community structure has been detected in the warmer coastal seawater. Although diatoms were the dominant species during field investigations, there were no significant seasonal changes in diatom abundance. In contrast, the density of dinoflagellates was low in all seasons due to the effects of thermal discharge. Consequently, the general trend in phytoplankton succession was interrupted. In general, the findings of this study may provide further insights into the warmer environmental impacts on phytoplankton communities in temperate regions.

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Objective:To analyze the distribution and composition characteristics of jellyfish stings in various coastal baths in Qinhuangdao City from 2017 to 2019, and to provide scientific basis for the prevention, control and early warning of jellyfish stings.Methods:Statistics and analysis of the age, gender, time of stings, location of injury, first symptoms, and playing time in the sea at the time of the sting, etc. of people with jellyfish stings in various bathing beaches along the coast of Qinhuangdao from 2017 to 2019 (July to August) were conducted.Results:The number of jellyfish stings in the coastal bathing beaches of Qinhuangdao City in 2017, 2018, and 2019 was decreasing year by year, with 1 890, 492, and 171 cases respectively. Among them, Qianshuiwan Bathing Beach and Dongshan Bathing Beach had more stings (60.90% and 35.08% respectively in 2017, 24.39% and 64.23% respectively in 2018, 16.96% and 16.42% respectively in 2019). There was no significant change in the gender and age distribution of jellyfish stings each year [57.99% males in 2017, with a median age of 13 (8, 31) years old; 63.21% males in 2018, with a median age of 25 (8, 29) years old; and 59.65% males in 2019, with a median age of 12 (7, 31) years old]. Stings were mainly located at the lower limbs (the proportion of lower limb injuries: 46.54% in 2018, 45.61% in 2019), followed by upper limbs (upper arm, elbow, forearm), trunk, etc. The first symptom was mainly pain (89.43% in 2018, 38.29% in 2019), followed by rash (64.43% in 2018, 59.43% in 2019), numbness, blisters, etc. Sting incidents mainly occurred from 13:00 to 17:59 (the proportion of sting incidents in this time period in 2018 and 2019 were 68.09% and 52.63%, respectively).Conclusions:Jellyfish stings in coastal baths in Qinhuangdao City are mainly distributed in Qianshuiwan Baths and Dongshan Baths. The management of these sea areas should be strengthened, and scientific publicity and medical rescue should be strengthened to prevent jellyfish stings in peak hours and related baths.

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The brown tides occurring in the coastal scallop cultivation area of Qinhuangdao, China, in recent years are caused by Aureococcus anophagefferens and significantly impact the scallop industry and the marine ecosystem in this region. Long-term investigations of phytoplankton and hydrological variables in the Qinhuangdao sea area were conducted in this study to understand the spatial-temporal variations of A. anophagefferens in relation to environmental factors. Samples were collected during twelve cruises from July 2011 to December 2013 and were analyzed for the temperature, salinity, dissolved oxygen (DO), nutrients and phytoplankton pigments. All diagnostic pigments of A. anophagefferens, such as chlorophyll c3 (Chl c3), Chl c2, 19'-butanoyloxyfucoxanthin (But-fuco), fucoxanthin (Fuco), and diadinoxanthin (Diad), were detected in the surface water by using high-performance liquid chromatography (HPLC). The highest concentrations of But-fuco (5.64 µg L-1), Fuco (37.94 µg L-1) and chlorophyll a (Chl a, 17.25 µg L-1) occurred in different seasons and sampling sites. The A. anophagefferens bloom (as indicated by But-fuco) usually expanded from the south to the north of the Qinhuangdao sea area, close to scallop-culturing regions. The bloom unusually starts in May, reaches its peak in June and almost disappears in August, with the temperature ranging from ca. 19 °C to 23 °C. The redundancy analysis (RDA) indicated that relatively high salinity (>29) and low inorganic nutrients were suitable for the development of the A. anophagefferens bloom. The ratios of diagnostic pigments to Chl a were not constant during different cruises and generally obeyed two different linear relationships, thus indicating the co-occurrence of the blooms of A. anophagefferens and other species, such as Minutocellus polymorphus. In summary, our work reports the long-term variation of A. anophagefferens blooms based on diagnostic pigments and environmental controls, which may provide more insights into the formation mechanisms of the brown tide in this region.

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Volatile organic compound (VOCs) emissions and control technologies of about 609 industrial enterprises in Qinhuangdao City were investigated in this study. The results showed that the exhausted emission flow rates from the industries of oil processing, coking, and nuclear fuel processing were found to be the largest sources of VOCs in Qinhuangdao City (normally above 105 m·h-1), whereas the other industrial emission flow rates were mainly within the range of 103-105 m3·h-1. The detected VOC concentrations for all the industries were less than 1000 mg·m-3. The VOCs emission rates were between 50-10000 g·h-1, but demonstrated different characteristics among the various industries. It was found that the industries of transportation equipment manufacturing, petroleum processing, coking, nuclear fuel processing, machinery and equipment manufacturing, printing and reproduction of recorded media, and chemical raw material and chemical product manufacturing had much higher concentrations and emission rates than other industries did. However, the overall VOCs emission level from this city was still lower when compared to previous reports for other regions of China. The investigation of the VOCs control technology application showed that there were 109 constructed or operated VOCs treatment facilities among the 609 industrial enterprises. Activated carbon adsorption technology accounted for the largest proportion among the various techniques, with 69%, followed by absorption technology (19%).

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This study established a VOC emissions inventory for Qinhuangdao City using the data on the product yield, raw material use, the concentration of VOCs, the discharge flow, and activities of 609 enterprises. The amount of annual VOC emissions obtained from direct measurements and emission factor methods was 8420.07 t; 48.9% of which was from the economechnological development district, which is the major industrial source of VOCs in the region. Benzene, lipids, alkanes, and ketones were the main industrial VOC components. For important VOC-emitting industries, processing of petroleum, coking, processing of nuclear fuel contributed 30.35% of total VOCs emissions in Qinhuangdao, and manufacture of chemical raw materials, chemical products contributed 14.42%. Solvent use was the most important emission link, which accounted for 37% of total industrial VOCs emissions. About 109 of 609 investigated plants have VOC treatment facilities, 69% of which are based on adsorption technology.

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The picoplanktonic pelagophyte Aureococcus anophagefferens could trigger harmful algal blooms (HABs) to discolor water in brown, known as brown tide. Since 2009, large-scale brown tides, caused by A. anophagefferens, had been occurred in early summer for three consecutive years in the coastal waters of Qinhuangdao, China and resulted considerable deleterious effects on the scallop mariculture industry. The causes for the occurrence of brown tides were not fully understood. Therefore, we conducted a one-year survey from June 2013 to May 2014 to study the seasonal succession of the phytoplankton community, including A. anophagefferens and its relationship with environmental variables in the area. The results revealed that the population dynamics of the phytoplankton community were significant variation with seasonal succession, in which A. anophagefferens played an important role during the entire year. The trend of the whole diversity index indicated that the community structure became more stable in winter. The results of principle component analysis (PCA) applied to the environmental factors indicated four major seasonal groups in the environmental variables. The water temperature, silicate and total nitrogen were contributed to the environment in summer, autumn and spring, respectively. In addition, a few another environmental factors commonly contributed to the winter waterbody, indicated that the aquatic environment is more complex in the cold season. The result revealed that the phytoplankton community structure and its variation were mainly affected by the hydrological factors, by using the redundancy analysis (RDA) for the relationship between dominant species and the environment. Furthermore, we inferred Chaetoceros decipiens as a potential species for the breakout of harmful algae blooms (HABs) by RDA ordination. We concluded that the key factor for the seasonal variations in the dynamics of phytoplankton community could be the hydrological parameters in Qinghuangdao coastal area. This research may provide more insight into the occurrence mechanism of brown tide.

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Many studies have been conducted focusing on the contribution of land emission sources to PM2.5 in China; however, little attention had been paid to other contributions, especially the secondary contributions from shipping emissions to atmospheric PM2.5. In this study, a combined source apportionment approach, including principle component analysis (PCA) and WRF-CMAQ simulation, was applied to identify both primary and secondary contributions from ships to atmospheric PM2.5. An intensive PM2.5 observation was conducted from April 2014 to January 2015 in Qinhuangdao, which was close to the largest energy output port of China. The chemical components analysis results showed that the primary component was the major contributor to PM2.5, with proportions of 48.3%, 48.9%, 55.1% and 55.4% in spring, summer, autumn and winter, respectively. The secondary component contributed higher fractions in summer (48.2%) and winter (36.8%), but had lower percentages in spring (30.1%) and autumn (32.7%). The hybrid source apportionment results indicated that the secondary contribution (SC) of shipping emissions to PM2.5 could not be ignored. The annual average SC was 2.7%, which was comparable to the primary contribution (2.9%). The SC was higher in summer (5.3%), but lower in winter (1.1%). The primary contributions to atmospheric PM2.5 were 3.0%, 2.5%, 3.4% and 2.7% in spring, summer, autumn and winter, respectively. As for the detailed chemical components, the contributions of shipping emissions were 2.3%, 0.5%, 0.1%, 1.0%, 1.7% and 0.1% to elements & sea salt, primary organic aerosol (POA), element carbon (EC), nitrate, sulfate and secondary organic carbon (SOA), respectively. The results of this study will further the understanding of the implications of shipping emissions in PM2.5 pollution.

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