Single Factor Evaluation Research Articles

Hydrodistillation Optimization for Borago officinalis L. Essential Oil and Its Chemical Composition Analysis.

The essential oil extracted from Borago officinalis L. aerial parts using hydrodistillation contains several compounds, although it yields low amounts. For the first time, this study investigated the effects of hydrodistillation parameters and optimized conditions to maximize the yield of B. officinalis essential oil while characterizing its chemical composition using gas chromatography-mass spectrometry. A single-factor evaluation of three extraction parameters-extraction time, liquid-to-solid ratio, and soaking time-revealed optimal conditions of 4h, 10:1mL/g, and 2h, respectively. Subsequently, the Box-Behnken response surface method produced a significant polynomial model, determining optimal conditions of an extraction time of 5h, a liquid-to-solid ratio of 11.06:1mL/g, and a soaking time of 2h, 17min, and 34s, resulting in an essential oil yield of 0.42%. A total of 21 compounds were identified in B. officinalis essential oil, predominantly nonacosane (29.15%) and phytol (27.92%).

Analysis of heavy metal characteristics and health risks of edible mushrooms in the mid-western region of China

This study determined the content of metal elements (As, Cd, Cr, Hg, Pb) in 9 edible mushrooms using ICP-MS, and evaluated the harm of long-term consumption of edible mushrooms to human health. The results showed that the concentrations of metal elements decreased in the order of Cd > As > Cr > Pb > Hg in edible mushrooms. The concentrations of Cd, As, Pb, and Hg were 22.95%, 8.20%, 1.64%, and 3.28% higher, respectively, than the maximum standards in China, whereas Cr did not exceed the limit. The detection rate of metal elements in Morchella esculenta (L.) Pers (M. esculenta), and Agaricus blazei Murill (A. blazei) were relatively high. The results of single factor evaluation and target hazard coefficient (THQ, HI) indicated that Dictyophora indusiata (Vent.ex Pers) Fisch (D. indusiata), A. blazei and M. esculenta were the main sources of risk. In addition, the HI values in ascending order were: Pb (0.43) < Cr (0.68) < Hg (0.92) < Cd (7.21) < As (14.02), indicating that Cd and As were the primary sources of health risks in edible mushrooms. To ensure food safety, it is recommended to strengthen the supervision of edible mushrooms, make reasonable choices, and reduce exposure levels of heavy metal pollution.

An Evidential Reasoning Method of Comprehensive Evaluation of Water Quality Based on Gaussian Distribution

This study provides an evidential reasoning method for water quality evaluation based on Gaussian distribution to handle the problem of comprehensive water quality evaluation for a region across a period (multiple sections and multiple time points). The method turns the collection of observed water quality indicator values into a probability distribution of water quality grades by using the Gaussian distribution to compute the confidence assessment of water quality grades over one period. It eliminates the subjectivity involved in determining confidence levels and the problem of information loss during data fusion that arises with conventional approaches. The probability distribution of each assessment grade is then determined by repeatedly synthesizing evidence of the same water quality grade using the improved evidential reasoning synthesis rule. To avoid the subjectivity included in experience-based weight settings, principal component analysis (PCA) is utilized to calculate the weights of water quality indicators based on contribution rates and load coefficients. In the end, utility theory is presented to modify the discrete probability distribution of precise numerical expressions, offering thorough results for the evaluation of water quality and facilitating the comparison of various water quality grades. Using the Xiangjiang River Basin as a case study, the proposed evaluation method is contrasted with popular techniques for assessing water quality, including the Single-Factor Evaluation Method, the Fuzzy Comprehensive Evaluation Method, and the Evidential Reasoning Comprehensive Evaluation Method. The findings suggest that the evidence reasoning approach for evaluating water quality that is based on Gaussian distribution is more rational, accurate, and scientific. Additionally, empirical studies on the annual water quality trends in various regions, the upstream, midstream, and downstream trends, and the water quality trends during wet and dry periods are conducted using this method to assess and analyze changes in water quality in the Xiangjiang River Basin during the “11th Five-Year Plan” and “12th Five-Year Plan” periods. The analysis findings demonstrate that, even if the rate of progress has slowed, the Xiangjiang River Basin’s overall water quality has been steadily improving since management and protection measures were put in place. This shows that the preventive and control efforts implemented in the “11th Five-Year Plan” and “12th Five-Year Plan” periods were successful; nevertheless, carrying out the current tactics might only have a limited impact. As a result, more advanced and creative approaches are required to encourage the ongoing enhancement of the water quality in the Xiangjiang River Basin.

Nitrate source analysis of underground drinking water sources in Zhangjiakou main urban area and its health risk assessment

&lt;p style="line-height:200%;text-align:justify;text-justify:inter-ideograph;"&gt;&lt;span lang="EN-US"&gt;In order to investigate the main pollution factors of underground drinking water sources in semi-arid agricultural areas in China, and to reveal the threatening influence of pollutants on the normal water security of local society. Single-factor evaluation index, principal component analysis, basic data statistics are used to clarify the main pollution indicators of underground drinking water sources in Zhangjiakou main city and discuss the main influencing factors of the change of their pollution concentration, and evaluate the degree of health threat of its pollution to the drinking water of local residents. The results show that: the water sources of Taobeiying and Gushi are deeply affected by human activities, and nitrate, as the only exceeding substance under drinking water standards, is the most important indicator of groundwater pollution; and the nitrate con-centration of groundwater is higher in the pasture and nearby agricultural activities; nitrate contamination levels in groundwater are within the health acceptability range for the vast majority of the population, with only newborns in the Taobeiying drinking water source being exposed to a non-carcinogenic risk of nitrate. The results of the study will help to maintain a stable groundwater environment.&lt;/span&gt;&lt;/p&gt;

Assessment of surface water quality in the Sai Gon and Dong Nai Rivers, Vietnam

The Sai Gon and Dong Nai Rivers are important for the social and economic development of Southern Vietnam. They also serve as crucial water supply sources for Ho Chi Minh City and its surrounding provinces. The objectives of the present study are to evaluate the surface water quality of these rivers and to detect the possible sources of pollutants between 2015 and 2019. The study utilized various methods, including single factor evaluation, water quality index (WQI), and principal component analysis (PCA). Water quality data, such as pH, dissolved oxygen (DO), chemical oxygen demand (COD), biochemical oxygen demand (BOD5), ammonia (N-NH4 +), phosphate (P-PO4 3-), and Coliform, from eight monitoring sites along the rivers were used for the evaluation. The results stated that the water quality of the study region generally varied from ‘moderate’ to ‘good’ and had a decreasing trend from the upstream to the downstream during the study period. In addition, PCA results indicated that domestic sewage and industrial wastewater were significant factors affecting water quality in the middle stream of the rivers. The findings of this study can be used by local environmental management authorities to gain insights into water pollution and propose potential solutions for better protection and management of water resources.

Characteristics of the vertical variation in water quality indicators of aquatic landscapes in urban parks: A case study of Xinxiang, China.

The quality of landscape water directly impacts the recreational and leisure experiences of the public. Factors such as water clarity, color, and taste can influence public perception, while contaminants like heavy metals, algae, and microorganisms may pose health risks. Stratified monitoring can reveal variations in the physical, chemical, and biological properties of water at different depths, thereby providing a more comprehensive understanding of water quality and aiding in the identification of pollution sources. This study examined aquatic landscapes at five parks in Xinxiang, China, monitoring thirteen indicators including Water Temperature (WT), Chroma (Ch), Turbidity (Tu), Suspended Solids (SS), Electrical Conductivity (EC), pH, Dissolved Oxygen (DO), Total Nitrogen (TN), Total Phosphorus (TP), Chemical Oxygen Demand (COD), Fe, Zn, and Cu. Utilizing the single-factor evaluation method, the water quality level of each indicator was assessed in accordance with the Water Quality Standard for Scenery and Recreation Area of the People's Republic of China (GB12941-91). The findings revealed significant vertical variations in the levels of TN, TP, COD, Fe, Zn and Cu of aquatic landscapes at parks, while WT, Ch, Tu, SS, EC, and DO showed no marked differences (P>0.05). The monthly dynamics of the water quality indicators indicated generally consistent trends for WT, Ch, Tu, SS, EC, DO, TN, TP, Zn, and Cu, albeit with varying degrees of fluctuation; however, the trends for EC, pH, COD, and Fe exhibited greater variability. These results offer valuable insights for the environmental protection and management of aquatic landscapes in urban parks. Stratified monitoring can capture the dynamic changes in water quality, assisting managers in developing more effective water quality management strategies.

The Construction and Application of the Effectiveness and Dynamic Teaching Evaluation Model of Big Civic and Political Science Courses

Abstract How to make the teaching quality of the Civics and Political Science class continuously improve, the teaching effectiveness is highlighted in the growth of students, and the comprehensive development of students is effectively promoted, which has become an important part of the educational evaluation reform of the Civics and Political Science class in colleges and universities. Based on the construction concept of the objectivity evaluation index system, this paper determines the evaluation index system of the effect and dynamic teaching of the big Civic and Political Science class. It adopts expert knowledge to pre-process the research data. According to the judgment affiliation degree and weight set, determine the single-factor evaluation matrix of evaluation indexes, calculate the weight value of evaluation indexes, and then complete the construction of a fuzzy comprehensive evaluation model oriented to the effect of big Civic and Political Science teaching and dynamic teaching and based on the data analysis software, carry out the comprehensive evaluation and analysis. The results show that the size of the weight value of the first-level indexes in order of magnitude, dynamic teaching process A2 (0.5478) &gt; teaching preparation A1 (0.2353) &gt; big Civics effect A3 (0.2169), indicating that the weight accounted for by the dynamic teaching and teaching preparation is relatively large and there is a not-so-small gap between the weight value of the big Civics effect A3, so the teaching of big Civics courses should focus on teaching preparation and dynamic teaching. This study can not only enrich the teacher’s Civics teaching method, but also improve the students’ Civics level, which has a promoting effect on promoting the development of the teaching of Big Civics courses in colleges and universities.

Application and comparison of four assessment methods for water quality of Sancha Lake in Central Sichuan Province, China

Abstract In order to analyze and compare the characteristics and applicability of different water quality evaluation methods applied to lake water quality evaluation, four monitoring sections were set up in Sancha Lake in 2019, 2020, and 2021, and 20 water quality parameters were selected. The single factor index method, the comprehensive pollution index method, the Nemerow pollution index method, and the improved Nemerow pollution index method were used to comprehensively evaluate water quality. The research results showed that the single factor index evaluation method is simple to operate and can quickly determine the water quality category by identifying the worst single water quality indicator. The comprehensive pollution index method and the Nemerow pollution index method determine the degree of water pollution based on the numerical values representing the overall pollution level of the representative water body. The evaluation results showed that except for the evaluation results of the single factor evaluation method with categories II and III, the results of other evaluation methods were all category I, indicating that the water quality was good.

Study on seasonal floating treatment wetland combination water purification based on numerical simulation

The North Canal Basin, Tianjin, section in Wuqing urban area is subject to multi-source pollution from its surroundings and exhibits characteristics of a stagnant water body. As an urban landscape water body, there is immense pressure to improve its water environment and quality. During the 13th Five-Year Plan, China's “Major Special Project for Water Pollution Control and Treatment Technology” conducted research and demonstration of remediation technologies for this river section. Three water quality indexes, ammonia nitrogen (NH3-N), total phosphorus (TP), and chemical oxygen demand (COD) were improved to some extent. In this study, based on the experimental results of the water special project and the achievements of the two-dimensional hydrodynamic water quality model of this river section, nine different Floating Treatment Wetland (FTW) combination schemes were designed for the summer, autumn, and winter without changing the original ratio of FTW in the demonstration project. The scenario simulation results indicate that the optimal FTW combination schemes for the three seasons are A3, B1, and C2, respectively; the water purification effects of each optimal FTW combination scheme are superior to those of the original demonstration project, with the removal rate performance of the optimal scenario simulations for the three seasons being B1 > C2 > A3. Further single-factor evaluation of water quality under the nine FTW combination schemes reveals that each scheme significantly improves the water quality of North Canal Basin in different seasons, with the best removal effect achieved in autumn, reaching Class IV water quality, followed by winter and summer, both achieving Class V water quality. The results of this study can provide guidance for devising aquatic plant arrangements that meet water quality standards in different regions and offer a theoretical basis for the sustainable development of water quality purification in different seasons for northern rivers, taking the example of North Canal Basin.

Water quality improvement project for initial rainwater pollution and its performance evaluation

Efficiently addressing initial rainwater pollution is crucial for mitigating urban water pollution. However, the performance evaluation of initial rainwater pollution control project is rarely introduced. In this study, the architecture of effective comprehensive engineering measures for improving the water quality of initial rainwater in Anhui Province, China, was described. Three water quality indicators, ammonia nitrogen (NH3–N), chemical oxygen demand (COD), and total phosphorus (TP), were selected to explore the severity of urban pollution caused by initial rainwater under various rainfall scenarios. A single-factor evaluation method was used to contrast and assess the benefits of the initial rainfall interception project in terms of water quality enhancement. Results showed that initial rainfall pollution was gentler under light rainfall conditions but more prominent under moderate and heavy conditions. The percentages of NH3–N, COD, and TP in Lotus Pond that met the tertiary drinking water standard were 100%, 74.91%, and 100% with great improvement, and the average concentrations of NH3–N, COD, and TP in Fushan Road Drainage have decreased by 91.43%, 10.49%, and 57.33% respectively, after the construction of the interception project. These indicated that the nitrogen and phosphorus pollution were successfully controlled by the control techniques in both locations, but COD concentration has to be addressed with more specialized strategies. Overall, the water quality improvement project for initial rainwater pollution plays a great role in effectively governing initial rainwater pollution and improving river water quality, and provides an effective technical reference for urban water ecological environment management.

Water quality pollution assessment and source apportionment of lake wetlands: A case study of Xianghai Lake in the Northeast China Plain

Surface water pollution has always posed a serious challenge to water quality management. Improving water quality management requires figuring out how to comprehend water quality conditions scientifically and effectively as well as quantitatively identify regional pollution sources. In this study, Xianghai Lake, a typical lake-type wetland on the Northeast China Plain, was taken as the research area. Based on a geographic information system (GIS) method and 11 water quality parameters, the single-factor evaluation and comprehensive water quality index (WQI) methods were used to comprehensively evaluate the water quality of the lake-type wetland in the level period. Four key water quality parameters were determined by the principal component analysis (PCA) method, and more convenient comprehensive water quality evaluation models, the minimum WQI considering weights (WQImin-w) and the minimum WQI without considering weights (WQImin-nw) were established. The multiple statistical method and the absolute principal component score-multiple liner regression (APCS-MLR) model were combined to analyse the lake pollution sources based on the spatial changes in pollutants. The findings demonstrated that the WQImin-nw model’s water quality evaluation outcome was more accurate when weights were not taken into account. The WQImin-nw model can be used as a simple and convenient way to comprehend the variations in water quality in wetlands of lakes and reservoirs. It was concluded that the comprehensive water quality in the study area was at a “medium” level, and CODMn was the main limiting factor. Nonpoint source pollution (such as agricultural planting and livestock breeding) was the most important factor affecting the water quality of Xianghai Lake (with a comprehensive contribution rate of 31.65%). The comprehensive contribution rates of sediment endogenous and geological sources, phytoplankton and other plants, and water diversion and other hydrodynamic impacts accounted for 25.12%, 19.65%, and 23.58% of the total impact, respectively. This study can provide a scientific method for water quality assessment and management of lake wetlands, and an effective support for migration of migratory birds, habitat protection and grain production security.

Applicability analysis of different evaluation methods in groundwater quality evaluation: A case of Xi’an city

In order to find a suitable method for the evaluation of groundwater quality in Xi’an, the principles of single factor evaluation method, fuzzy comprehensive evaluation method and modified fuzzy comprehensive evaluation method are briefly described. Three methods are applied to the comparative analysis of water quality evaluation of 34 phreatic water samples in Xi’an. The results show that: (1) The results of fuzzy comprehensive evaluation method are more optimistic than those of single factor evaluation method. (2) The single factor evaluation method is simple in calculation and can directly reflect the degree of pollutants exceeding the standard in water, but the evaluation results are too one-sided to reflect the actual situation of water quality; The fuzzy comprehensive evaluation method and the modified fuzzy comprehensive evaluation method more comprehensively consider the comprehensive impact of evaluation factors on water quality, and their results are more objective than the single factor evaluation method. (3) The modified fuzzy comprehensive evaluation method improves the accuracy of the membership matrix by changing the critical value of Class V water. The weighted average calculation method avoids the error caused by the square term of concentration, so that the evaluation results will not be distorted. It is a very effective evaluation method, which should be promoted.

Developing an Evaluation System Suitable for Coastal Rural Houses’ Characteristic Style and Its Inspiration for Rural Revitalization: Case Study of Rongcheng in Shandong Province

The characteristic style of rural houses is an important manifestation of the historical and cultural values of rural areas and is the key focus of the implementation of the strategy for the construction of beautiful China and the revitalization of rural areas. Taking 17 villages in the Rongcheng of Shandong as an example, this article integrated multidimensional data, including geospatial data, survey data and socio-economic data, and constructed a suitable index system to evaluate the characteristic style of coastal rural houses in 2018 and put forward the characteristic style regionalization of coastal rural houses. The results show that the characteristic style of coastal rural houses can be measured by the overall village environment, coastal architectural value and traditional folk culture, among which the coastal architectural value is the most critical. Two villages scored over 60 points in the comprehensive evaluation, namely the Dongchu Island village and Dazhuang Xujia Community. Different dominant characteristic styles of rural houses were identified according to single-factor evaluation. Based on the evaluation results and factors such as location, nature, social economy and the status quo of protection and development management, characteristic styles of rural houses in the research area can be divided into four continuous areas: historical and cultural characteristics, folk customs and industrial development characteristics, natural scenery characteristics and folk customs characteristics. Combined with regional positioning and development planning, the construction direction of different regional types was defined, and then the protection and improvement measures of rural residential features were put forward. This study not only provides a certain basis for the evaluation, construction and protection of the characteristic features of coastal rural dwellings in Rongcheng City but also provides guidance for the implementation of rural construction planning.

Spatial-Temporal Distribution Pattern and Tourism Utilization Potential of Intangible Cultural Heritage Resources in the Yellow River Basin

In this study, the spatial-temporal distribution pattern and tourism utilization potential of national ICH are analyzed based on GIS technology in the Yellow River Basin. The results show that: (1) The national ICH of the Yellow River Basin is distributed in an aggregated spatial pattern with the characteristic of “one belt and two cores”. The cities in Shanxi, Henan and Shandong provinces constitute the high-density and sub-high-density continuous belts. Haidong and Chengdu are the high-density and sub-high-density core areas, respectively. (2) The five batches of national ICH present a temporal distribution pattern of “Northeast to Southwest”. The distribution scope of national ICH in medium and high-density areas expands gradually and finally tends to be balanced. (3) For the single-factor evaluation of tourism utilization potential, there is an obvious gap in the evaluation grade among the cities. However, for the comprehensive evaluation of tourism utilization potential, there are 72 cities with an evaluation grade of three or above, accounting for 63%. This indicates that the tourism utilization potential of the national ICH in this basin is great. (4) The national ICH tourism in this basin can be developed from two aspects: regional differential development and regional linkage development.

Research on water resource carrying capacity of capital water conservation functional zone

Water resources are important for supporting regional economic development. A scientific and reasonable evaluation of the carrying capacity of water resources is of high significance to regional sustainable development. Zhangjiakou City is China’s first capital water conservation functional area, which plays a role in ensuring the safety of water resources and ecological environment in the capital. Considering Chicheng County, Zhangjiakou City, as a typical area, its water resource carrying capacity in the current year (2018) and the plan year (2025) is evaluated by constructing a water resource carrying capacity evaluation index system for the county, determining the threshold of the bearing capacity evaluation index, and using the single-factor evaluation method and cloud theory method. In addition, the main factors affecting the water resource carrying capacity of Chicheng County are analyzed. The results show that: Based on the single factor evaluation results, the critical state of water resources carrying capacity was evaluated comprehensively, and the factor carrying capacity of total water consumption in the predicted planning level year (38.0603 in normal water year and 41.3403 in dry water year) does not exceed the total water consumption index (51.14). Furthermore, The water resources carrying capacity level of the present level year (.45) and the planned level year (.46) belong to the third level of the evaluation index system. There is further scope for the carrying capacity of water resources in Chicheng County to satisfy its economic and social development. However, it is urgent to solve the problems affecting the water quality elements of rivers, such as heavy river water pollution, low sewage treatment capacity, and weak pollution monitoring and supervision. It is necessary to optimize the industrial economic structure of Chicheng County, accelerate the improvement of water resources management system and mechanism, and ensure the long-term safety of water resources and ecological environment in the capital.

Analysis of Water Quality Around the Patancheruvu, Sangareddy, Telangana, India.

In nature, water quality affects the condition of ecosystems and altering the existence of living beings. In this paper the study of water quality is done for Patancheruvu block, Telangana, India. The main objective of this research is to find out the effect of different land use on water and protect it from contamination without hampering the environmental balance. The method used in this research to evaluated groundwater quality includes single factor evaluation method called Water Quality Index (WQI). The study area is divided in to 3 zones and collected bore water data from 16 sites around the study area. WQI analysis is done for two periods i.e., monsoon season and non-monsoon season. The results explained that, among the 16 sites,3 sites which are falling in the 3rd zone are not suitable for domestic purposes. Out of remaining 14 sites, 11 sites are satisfactory, and 2 sites are slightly modified. It is concluded that water quality of the Patancheruvu is degraded, fundamentally, by three factors: agricultural sewage discharges, industrial wastewater and urban wastage.

Study on Water Quality and Trophic Status of Subtropical Cascade Reservoirs in Dongjiang River Basin in Dry Season

The Dongjiang River Basin is an important water source for Guangdong Province, providing water for living, production and ecology for more than 40 million people. The three large reservoirs, Xinfengjiang Reservoir, Fengshuba Reservoir and Baipenzhu Reservoir, are the three largest reservoirs in the Dongjiang River Basin. The quality of the water environment in the three reservoirs plays an important role in ensuring the safety of drinking water and promoting the overall protection, systematic restoration and comprehensive management of the water ecosystem. 11 indicators, including water temperature, transparency, pH, DO, turbidity, conductivity, ammonia nitrogen, TN, TP, CODMn and chlorophyll a, were tested in October 2022 to study the water quality characteristics and trophic status of the three cascade reservoirs. The results of the single-factor evaluation of water quality showed that all three reservoirs reached the surface water class II level. TN is the primary pollutant in Fengshuba and Baipenzhu reservoirs. The concentration of Chla in Baekpongju Reservoir was 3.4 μg/L, with a mild risk of algal bloom. TLI (Σ) of the three cascade reservoirs were about 16.41~32.14.The results of the integrated nutrient status evaluation showed that Xinfengjiang Reservoir was in a depleted nutrient status, while Mapeshuba and Bailuanzhu Reservoirs were in a medium nutrient status. Factor analysis showed that 11 water quality factors can be classified into four categories. F1 represents the organic pollution. F2represents the phytoplankton biomass. F3 represents the concentration of nitrogen. F4 represents the suspended solids in water.

Comprehensive Evaluation of Surface Water Quality in the Flood Period of the Yellow River by Various Methods and Theories

Field monitoring of water quality during the autumn flood season in the middle and lower reaches of the Yellow River in 2021 was carried out. During this period, a host of methods, including the single-factor evaluation method, index evaluation method, and fuzzy mathematics method, were utilized to evaluate the water quality status. The relevant findings indicate that the water quality of the mainstream and tributaries in the middle and lower reaches of the Yellow River in the autumn flood season is excellent, which meets the water function zoning and water quality goals. In particular, the single-factor evaluation method emphasizes the use of the single index with the most serious pollution to represent the comprehensive water quality category, whereas the fuzzy mathematics method uses the multi-factor contribution rate to calculate the membership degree of water quality. Therefore, it is superior to the single-factor evaluation method in determining the water quality of the water functional zones within the evaluation scope. Meanwhile, the Nemerow index of the water quality of the tributaries of Yiluo River and Qinhe River at the section entering the Yellow River is lower than that of the mainstream, indicating that the water quality of tributaries is better than that of the mainstream during the monitoring period. Overall, the results of this research are conducive to the objective evaluation of the water quality of the Yellow River during the autumn flood season, thus providing more scientific technical support for the ecological conservation and restoration of the Yellow River basin.

Ecological risk assessment of heavy metal pollutants and total petroleum hydrocarbons in sediments of the Bohai Sea, China.

Heavy metals and organic pollutants like total petroleum hydrocarbons (TPHs) in coastal marine sediments are receiving extensive attention, as they may pose a serious threat to the aquatic environment and ecosystem health. To date, however, data on the long-term variations in the levels of sedimentary heavy metals and TPHs as well as their ecological risks are relatively limited. Here, we conducted 12 cruises spanning 3years in the Bohai Sea and obtained ~1400 sediment samples to explore the long-term variations of heavy metals (i.e., Hg, As, Cu, Zn, Pb, Cd) and TPHs, and to assess their potential ecological risks. The results suggested that the ranges for the levels of Hg, As, Cu, Zn, Pb, Cd, and TPHs in sediments between 2019 and 2021 were <0.01-0.07, 0.23-10.72, 8.07-20.67, 25.52-46.55, 10.94-28.19, 0.14-0.56, and 9.14-18.41mgkg-1, respectively. Based on the single factor evaluation (Fi) for sediment quality, we found that most of the evaluation factors in the study area met the requirements of sediment quality standard (i.e., Fi<1), except for the factor of metal Cd in some cases. The implication is that the sediment in the Bohai Sea was fairly clean in terms of heavy metals and TPHs. However, the concentration of metal Cd exceeded the sediment quality standard during May 2019 and 2020 (i.e., Fi>1), indicating that Cd could be identified as a major pollutant in surface sediments. Also, based on the ecological risk assessment (Ei) of heavy metal pollutants, we found that the metal Cd had reached a level with potential ecological risk in some cases (80≤Ei<160). As such, we further suggested that the Cd contamination might have a potential risk on the Bohai Sea' ecosystem.

Hurricane wind disaster assessment methods on coastal structures based on area and radial distribution integration

Early studies have shown that hurricane disaster assessment indicators that only consider the intensity-related single factor cannot well represent the actual degree of damage caused by hurricanes to coastal structures. In the current study, for hurricane wind damage, in addition to the three wind disaster index formulas (corresponding to the wind resistance characteristics of infrastructures in developed, developing, and underdeveloped regions, respectively) that are related to hurricane intensity, the spatial scale characteristics of hurricanes are also considered. Thus, two kinds of hurricane wind disaster assessment methods by combing the wind disaster index and spatial scale of hurricanes are carried out, area and radial integration, respectively. Compared with the traditional single-factor evaluation index, the method based on area integral can more accurately characterize the degree of hurricane wind disaster. However, the peripheral small wind speed of the hurricane has a greater impact on wind disaster assessment; for medium-strength and intense hurricanes, the highest proportion is up to 61.5–67.7%; and that of weak hurricanes is up to 85.7–94.1%. To solve the challenging problems of hurricanes with small wind speed but the large size and large wind speed but small size, the area integral method with the concept of cut-in wind speed is introduced. The impact of small wind speed on wind disaster assessment is significantly reduced; the highest proportion of medium-strength and intense hurricanes is 14.5–22.5%, and that of weak hurricanes is 27.5–33.3%. Because the three-dimensional wind field is not easy to capture, the structure along the coastline is the most severely damaged, and the linear radial integral is less sensitive to small wind speeds than the quadratic area integral, a hurricane wind disaster assessment method based on radial integral is proposed. The results show that the method has good spatial region insensitivity. Both methods show that the numerical results can accurately represent the hurricane wind disaster when the horizontal grid size is 185 m or 555 m. However, the wind disaster assessment trends of the two methods are not linear because of the asymmetry of the hurricane structure. The two hurricane wind disaster assessment methods proposed in this study can better reflect the degree of disaster. For the comprehensive hurricane wind disaster assessment for large-scale wind farms in the deep sea, the area-based method can be used; for the infrastructure structures along the coastline, the radial-based method is more suitable. Since the measured meteorological data contain different characteristic radius and the corresponding wind speed of hurricanes, the method based on radial integral is more practical.