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The relationships between environmental factors and fish density are closely related, and species distribution models (SDMs) have been widely used in exploring these relationships and predicting the spatial distribution of fishery resources. When exploring the prediction of the spatial distribution of species in different seasons, the method of choosing the appropriate approach to the season will help to improve the predictive performance of the model. Based on data collected from 2015 to 2020 during a survey off southern Zhejiang, the Tweedie-GAM was used to establish the relationship between the density of Decapterus maruadsi and environmental factors at different modeling approaches. The results showed that water temperature, salinity and depth were the main factors influencing D. maruadsi, and they operated through different mechanisms and even resulted in opposite trends of density in different seasons. Spatially, the two modeling approaches also differed in predicting the spatial distribution of D. maruadsi, with the seasonal model showing a higher density trend in inshore waters than in offshore waters in spring but showing the opposite trend in summer and autumn, which was more consistent with the actual spatial distribution of the resource. By analyzing the effects of two different approaches on the prediction of fishery resources, this study aims to provide research ideas and references for improving the predictive performance of SDMs. [ABSTRACT FROM AUTHOR]

In order to accurately explore the relationship between the density of Engraulis japonicus and environmental factors, five types of models, including Tweedie-Generalized Additive Model (GAM), two-stage GAM, Ad hoc-GAM, and Generalized Additive Mixing Model (GAMM), were compared based on the survey data in offshore waters of southern Zhejiang, China from 2015 to 2021 in this study. The results showed the best goodness of fit for two-stage GAM when processing the data of E. japonicus resource density. The deviance explained of GAM1 and GAM2 were 19.9 and 53.8%, respectively. According to this study, water temperature and salinity are important environmental factors affecting the distribution of E. japonicus, which are also closely related to latitude. In general, the resource density of E. japonicus decreases gradually with the increase in water temperature. When the salinity was between 26 ppt and 34 ppt, the resource density was higher. Also, there were some differences in the spatial distribution of E. japonicus in different seasons. The relationship between the resource density of E. japonicus and environmental factors was analyzed through various models to provide a scientific basis for the conservation management of E. japonicus in offshore waters of southern Zhejiang, China. [ABSTRACT FROM AUTHOR]

To effectively use the fishery count data containing zero values, Setipinna taty in the coastal waters of south inshore of Zhejiang in China from 2017 to 2019 was used in this study. Environmental factors, such as water temperature, water depth, and salinity, were selected to establish models and compare based on the generalized additive model (GAM) of the Tweedie distribution (Tweedie-GAM) and two-stage GAM, Ad hoc method, and generalized additive mixed model (GAMM). The results showed that each station accounted for a higher proportion of zero values and the two-stage GAM model had a higher deviation interpretation rate, and GAM I and GAM II had 19.6% and 60.4% deviation interpretation rates. The cross-validation results showed that the performance evaluation of the two-stage GAM model was the best and showed the highest R2 value, the lowest average absolute error, and the relatively small root mean square error. This study found that the abundance of S. taty in the south inshore of Zhejiang was highest at around 21°C and 18°C in spring and autumn, and the abundance reached the highest at a water depth of about 20 m. In spatial distribution, the high value of the abundance of S. taty was mostly distributed in the coastal waters in the south of 28°N. In future research, models should be fitted and compared for different sampling zero-value ratios, and more environmental factors should be included to accurately find an optimal model and provide references for the conservation of fishery resources. [ABSTRACT FROM AUTHOR]

Organophosphate flame retardants (OPFRs) are an emerging class of pollutants. In this study, 62 soil samples were collected from Zhejiang Province China, and screened for 8 typical OPFRs. All compounds were detected in soil at 100% detection frequency, except for triethyl phosphate (TEP) compounds (93.6%). The sum of the eight OPFR concentrations ranged from 9.15 to 132 ng/g dry weight (dw), with mean and median values of 24.9 and 19.0 ng/g dw, respectively. Triphenyl phosphate (TPHP) was identified as the most abundant analog, with a median concentration of 9.94 ng/g dw, followed by tris(2-ethylhexyl)phosphate (TEHP). Significantly higher OPFR concentrations were detected in northern Zhejiang; concentrations decreased sharply from the north to the south. OPFR concentrations in soils from cities or economically developed counties were much higher than those from rural areas. OPFR sources in Zhejiang Province mainly originated from PVC-made products and traffic emissions. Dermal absorption of OPFRs via soil was the primary pathway for human exposure. Health risks due to exposure to OPFRs through soil ingestion were found to be negligible. [ABSTRACT FROM AUTHOR]

Jiangsu and Zhejiang provinces, located in the Yangtze River Delta (YRD) core region, are the most economically developed regions in China, as well as the areas with serious soil pollution. The concentrations, sources, and distributions of heavy metal(loid)s in agricultural soils of the two provinces were studied; positive matrix factorization model (PMF) analysis and kriging interpolation were combined to compare the pollution characteristics of heavy metal(loid)s. The results showed that the degree of accumulation might be more serious in Zhejiang province than in Jiangsu province, especially in terms of Cd, Hg, and Pb. PMF results showed anthropogenic activities were the dominant factors affecting the concentrations of soil heavy metal(loid)s. The contributions of the three sources in Jiangsu province were 40.28% natural and traffic sources, 37.49% agricultural sources, and 22.22% industrial and coal combustion sources. The contributions of the three sources in Zhejiang province were 43.45% agricultural and industrial sources, 32.15% natural sources, and 24.40% industrial sources. The kriging interpolation results of the two provinces showed that the concentrations of As, Cr, and Ni were significantly higher in Jiangsu province than in Zhejiang province; the concentrations of Cu were similar in the two provinces, while other heavy metals had higher concentrations in Zhejiang province. These accumulations of heavy metal(loid)s in agricultural soil in both provinces cannot be ignored. This work will contribute to the development of effective policies aimed at protecting the soil environment from long-term accumulation of heavy metal(loid)s. Image 1 • Heavy metal(loid)s concentrations in agricultural soils of YRD varied greatly. • Heavy metal(loid)s accumulation degree was more serious in Zhejiang Province. • Anthropogenic activities influenced heavy metal(loid)s accumulation in soils. [ABSTRACT FROM AUTHOR]

Agricultural soil pollution in China poses a major threat to human health and food safety. There are no agricultural soil environmental standards based on human health in China, which prevents effective screening and assessment of risks. Jiangsu (JS) and Zhejiang (ZJ) provinces, located in the Yangtze River Delta (YRD) core region, have obvious differences in agricultural land conditions, which will result in differences in Generic Assessment Criteria (GAC). In this study, we derived and compared human health risk-based GAC using the Contaminated Land Exposure Assessment (CLEA) model for agricultural land scenarios in these two provinces. We found differences in the GAC between JS and ZJ due to differences in parameters. These differences are greatest for benzene, and cadmium (Cd). For Cd, the contribution of oral intake exceeds 90 %, and the vegetable consumption rate and mean daily intake (MDI) may be key parameters affecting GAC. For the volatile organic compound benzene, the inhalation of indoor vapor accounts for about 30 %, and the key parameters affecting the GAC for benzene may be the attenuation factor and soil organic matte (SOM). The derived GAC are generally lager (i.e., less stringent) than the GB15618-2018 and UK Suitable 4 Use Levels (S4ULs); however, the derived GAC for JS and ZJ were lower than the soil screening values (SSV) for residential land in China. This may be related to methods, land use types, and critical receptors. This work will contribute to the development of regional soil environmental standards in China. • GACs varied in ZJ and JS province due to their diversity of local parameters. • Agricultural land was very sensitive to human health, especially for farmers. • Vegetable consumption rate, MDI and SOM were key parameters affecting GAC. • Regional GACs are urgently needed in China based on local parameters. [ABSTRACT FROM AUTHOR]

Mercury exchange between soil and air is an important processe governing the biogeochemical cycling of Hg. This study investigated the in situ soil-air Hg fluxes in agricultural soils of Quzhou, Zhejiang Province, China, using a dynamic flux chamber coupled with a Hg vapor analyzer. Soil-air Hg exchange fluxes were overall emission for all seasons, indicating that agricultural soil was a Hg source for the atmosphere. Seasonal variations in soil-air Hg flux were observed, with low values in winter, elevated values in spring, peak values in summer, and a decline in autumn. Mercury emissions from soils showed a clear diurnal pattern where Hg released into the atmosphere reached a maximum at 11 a.m. and declined to a minimum at 2:00 and 20:00 in spring and summer, respectively. Meanwhile, soil-air Hg flux peaked at 1 p.m. and declined to a minimum at 6:00 and 23:00 in autumn and winter, respectively. The impact of each factor on the Hg exchange between soil and air varied in different seasons. Soil temperature was the major variable controlling the Hg flux in winter and spring; soil temperature and total gaseous Hg evidently affected the Hg flux in summer, and ozone (O 3) played a dominant role in influencing the Hg flux in autumn. Models for estimating the Hg evasive flux from soils were developed, and the atmospheric O 3 concentration was used for the first time as a parameter in these models. The measured and modeled Hg fluxes showed significant linear correlations (R 2 = 0.61; P < 0.001). Image 1 • O 3 was found to be a key factor that affected the soil-air exchange of Hg. • Seasonal variation was observed in soil-air exchange of Hg flux. • Hg flux from soil was modeled as a function of O 3 for the first time. • The impact of each factor on Hg exchange flux varied with season. [ABSTRACT FROM AUTHOR]