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The microbial community colonized on microplastics (MPs), known as the 'plastisphere', has attracted extensive concern owing to its environmental implications. Coastal salt marshes, which are crucial ecological assets, are considered sinks for MPs. Despite their strong spatial heterogeneity, there is limited information on plastisphere across diverse environments in coastal salt marshes. Herein, a 1-year field experiment was conducted at three sites in the Yancheng salt marsh in China. This included two sites in the intertidal zone, bare flat (BF) and Spartina alterniflora vegetation area (SA), and one site in the supratidal zone, Phragmites australis vegetation area (PA). Petroleum-based MPs (polyethylene and expanded polystyrene) and bio-based MPs (polylactic acid and polybutylene succinate) were employed. The results revealed significant differences in bacterial community composition between the plastisphere and sediment at all three sites examined, and the species enriched in the plastisphere exhibited location-specific characteristics. Overall, the largest difference was observed at the SA site, whereas the smallest difference was observed at the BF site. Furthermore, the MP polymer types influenced the composition of the bacterial communities in the plastisphere, also exhibiting location-specific characteristics, with the most pronounced impact observed at the PA site and the least at the BF site. The polybutylene succinate plastisphere bacterial communities at the SA and PA sites were quite different from the plastispheres from the other three MP polymer types. Co-occurrence network analyses suggested that the bacterial community network in the BF plastisphere exhibited the highest complexity, whereas the network in the SA plastisphere showed relatively sparse interactions. Null model analyses underscored the predominant role of deterministic processes in shaping the assembly of plastisphere bacterial communities across all three sites, with a more pronounced influence observed in the intertidal zone than in the supratidal zone. This study enriches our understanding of the plastisphere in coastal salt marshes. [Display omitted] • Plastisphere bacterial community in salt marshes differs from that in sediment. • Differences in bacterial communities vary by geographic location. • MP polymer types affect the composition of plastisphere bacterial communities. • Plastisphere network characteristics exhibit variability with environmental change. • Deterministic processes primarily shape plastisphere bacterial communities. [ABSTRACT FROM AUTHOR]

Pollution status and ecological risks associated with sediment heavy metals (Cu, Pb, Zn, Cd, and Cr) were investigated around Xincun Bay, assessing their spatial variations and relationship with sediment physiochemical factors. Higher concentrations and associated risks were observed in the central region, where mariculture activities were concentrated, compared to non-maricultured areas. Despite with overall low concentrations, Cd had a higher ecological risk. Correlation and principal component analyses revealed similar sources for all metals in Xincun Bay. Heavy metal concentrations varied with expansion of mariculture operations in terms of quantity and scale, confirming the influence of mariculture activities. Sediments around mariculture had higher contents of clay, silt, and total organic carbon (TOC), and finer particle sizes. Quantitative analyses through correlation and linear regression indicated that TOC significantly regulated heavy metal concentration and distribution (p < 0.05). Considering its significant association with TOC, the influence of mean grain size should not be overlooked. [Display omitted] • Increased heavy metal pollution is observed near the mariculture area. • At lowest heavy metal contents, cadmium has the highest contamination risk. • TOC may control abundance and distribution of sediment heavy metal pollution. • Heavy metals of lagoon sediments have similar sources. • Mariculture is the primary source of heavy metal pollution in Xincun Bay. [ABSTRACT FROM AUTHOR]

Highlights • The original spatial pattern of the natural geographical attributes was changed by human activities. • Different ecosystem components have different responses to human activities. • The establishment of reserved areas has a positive effect on the protection of Marine biodiversity. Abstract Using the marine biological valuation method, we selected five ecosystem components, namely, phytoplankton, microzooplankton, macrozooplankton, macrobenthos, and nekton, to evaluate the marine biodiversity value of Jiangsu's offshore areas in 2006 (early-term coastal development) and 2014 (mid-term coastal development), and the impact of human activities on the values were analyzed based on the differences between the two time periods. In general, the biological value (BV) of the Jiangsu offshore area changed in the context of high-intensity human activities, disrupting the original spatial pattern of the natural geographical attributes indicated by the BV in 2006. From the perspective of various ecosystem components, the impact on macrobenthos is long-lasting and significant, the impact on plankton is temporary and recoverable, and the presence of offshore structures leads to the formation of new habitats that attract new species and more predators (fishes), with the BV of nekton in the radial sand ridge area being higher than that in other marine areas. The results of our approach confirm the importance of areas that were previously identified for protection (particularly in the central regions). Our results also highlight the value of currently unprotected sites, mainly in the northern and southern regions. Highlighting the impact of high-intensity human activities on the BV of Jiangsu lays a foundation for developing future marine spatial plans and provides a scientific reference and basis for administrative departments to develop marine management decisions. [ABSTRACT FROM AUTHOR]

Abstract To assess the impact of offshore wind farms (OWFs) on the structure and energy flow of coastal ecosystems, Ecopath models of the Jiangsu coastal ecosystem (JCE) based on biological field data collected before and after the establishment of the Rudong OWFs in 2007 and 2015, respectively, were constructed and compared. The results indicated that after OWF construction, detritus, phytoplankton, zooplankton, anchovies, and some benthic fish were positively impacted. The increased primary production and detritus resulted in the increased food supply for zooplankton, which made it possible for planktivorous species (particularly anchovies) to be fed. Consequently, the biomass and production of some benthic fish increased, which indicates a potential reef effect. Other groups with decreased biomasses and productions may have been negatively impacted by the OWFs. Herbivory flows dominated the pre- and post-construction JCE despite their low transfer efficiencies; however, the proportion of detritivory flow increased after OWF construction, and this was especially prominent at high trophic levels. The post-construction JCE was immature with lower system connectivity, trophic flow utilisation, and transfer efficiency. However, the ecosystem tended to develop towards higher maturity with higher energy throughput, ecosystem activity, and recycling capability. Highlights • Positively impacted functional groups: detritus, phytoplankton, zooplankton, anchovies, and other benthic fish. • Proportion of detritivory flow increased and this was especially prominent at high trophic levels. • Immature: lower system connectivity, trophic flow utilisation, and transfer efficiency. • Developing towards maturity: higher energy throughput, ecosystem activity, and recycling capability. [ABSTRACT FROM AUTHOR]

Abstract At present, the study of microplastic sources is in a relatively preliminary stage due to the complexity of microplastic features in the environment. Based on a literature review, we developed a source-specific classification system for the quantitative analysis of microplastic sources. The classification system includes ten types of microplastics based on morphology and composition and can identify their main sources and the associated probabilities. To reflect the complexity of types and sources in the regional combination of microplastics, we first propose a microplastic diversity index (D 1-D '(MP)). We use the South China Sea as an example to carry out quantitative source analysis and calculate the diversity index. Eight types of microplastics were found, mainly consisting of maritime coatings (type "Gran_coat") (33.0%) and synthetic fibers (type "Fib_thin") (29.6%). We also found that the diversity increased with offshore distance. In addition, we partitioned surface microplastics globally according to a two-dimensional microplastic abundance-diversity index. We believe that these indicators can effectively reflect pollution status and ultimately lead to different types of control measures. In the future, additional indicators for the characterization of microplastics must be included in the classification system to establish a one-to-one source analysis system for microplastic characteristics and source apportionment. In general, our study may provide new insights into the establishment of more accurate and quantitative source apportionment techniques and effective pollution control. Graphical abstract Image 1 Highlights • We proposed a classification system for the source apportionment of microplastics. • The classification includes ten types of microplastics based on morphology and polymer type. • To reflect the complexity of types and sources, we first propose a microplastic diversity index. • We selected floating microplastics in the South China Sea as an example. [ABSTRACT FROM AUTHOR]

Abstract Little data are available on the bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) in coral reef fish from the South China Sea (SCS). In this study, we collected 21 coral reef fish species from the Xisha and Nansha Islands in the SCS to investigate the occurrence of 16 US-EPA PAHs. The total PAH concentrations (ΣPAH) in the collected fish ranged from 12.79 to 409.28 ng/g dry weight (dw, Xisha Islands) and from 32.71 to 139.09 ng/g dw (Nansha Islands), respectively. The ΣPAH concentration of Scarus niger collected from the Xisha Islands (237.13 ng/g dw) was about twofold higher than that of Scarus niger collected from the Nansha Islands (139.09 ng/g dw). The dominant compounds were found to be 2-ring and 3-ring PAHs. Based on qualitative and quantitative analyses, the main PAH sources were found to be coal and biomass combustion (50.43%), petroleum sources (25.86%), and vehicular emissions (16.10%). Highlights • The first report on PAH contamination in coral reef fish from the South China Sea • PAH levels from the Xisha Islands were higher than those from the Nansha Islands • Low molecular weight PAHs were dominant in coral reef fish • PAHs mainly originated from biomass combustion, petroleum sources, and vehicular emissions [ABSTRACT FROM AUTHOR]

Abstract This study analyzes the distribution and transportation of heavy metals in surface sediments by determining the concentrations of 6 heavy metals (Cr, Zn, Ni, Pb, Cu, and Cd) based on 164 surface sediments collected from the East China Sea (ECS). The results indicated that concentrations of heavy metals were higher in the south than the north with a clear boundary near 30° N. The distributions of the six heavy metals could be divided into four groups that corresponded well with different sediment components, suggesting that hydrodynamic sorting processes play an important role in the selective transportation of sedimentary heavy metals. In addition, the spatial distributions of heavy metals were more consistent with fine-grained sediments having a grain size lower than 32 μm. Heavy metal concentrations were slightly higher than found in previous studies conducted from 2002 to 2010. In addition, their spatial patterns have changed drastically compared to data from 2006, suggesting that intensive inland human activities have had a profound impact on heavy metal transportation and distribution in the estuarine & inner-shelf regions of the ECS. Graphical abstract Unlabelled Image Highlights • Distribution patterns of heavy metals in the East China Sea are depicted. • Hydrodynamics and sediment properties are the main factors affecting heavy metal distribution. • Spatial patterns have drastically changed in the context of intensive human activities. [ABSTRACT FROM AUTHOR]

The ecological impact of thermal discharge has become an important issue in the field of marine and environmental protection. We focused on the effects of thermal discharge on seawater temperature and biological communities based on data from before (2006) and after (2013–2014) the construction of a power plant. The thermal discharge induced stratification, which resulted in changes in the vertical hydrodynamic conditions. Stratification combined with elevated temperatures significantly affected the phytoplankton abundance and community structure. Elevated seawater temperatures decreased the chlorophyll- a concentrations by 34% and 63%, at the surface and bottom, respectively. The elevated seawater temperature at the bottom might not be high enough to significantly affect the macrobenthos, but significantly affected the phytoplankton and zooplankton communities. Because these communities serve as food for the macrobenthic community, their changes resulted in growth of the macrobenthos. Furthermore, this effect induced macrobenthic community succession, resulting in decreased species diversity and increased dominance. [ABSTRACT FROM AUTHOR]

Despite the rapid construction of offshore wind farms, the available information regarding the risks of this type of development in terms of emerging pollutants, particularly microplastics, is scarce. In this study, we quantified the level of microplastic pollution at an offshore wind farm in the Yellow Sea, China, in 2016. The abundance of microplastics was 0.330 ± 0.278 items/m 3 in the surface water and 2.58 ± 1.14 items/g (dry) in the sediment. To the best of our knowledge, the level of microplastic pollution in our study area was slightly higher than that in coastal areas around the world. The microplastics detected in the surface waters and sediments were mainly fibrous (75.3% and 68.7%, respectively) and consisted of some granules and films. The microplastics in the samples might originate from garments or ropes via wastewater discharge. The abundance of plastic in the water and sediment samples collected from the wind farm area was lower than that in the samples collected from outside the wind farm area. The anthropogenic hydrodynamic effect was the main factor affecting the local distribution of microplastics. The presence of a wind farm could increase the bed shear stress during ebb tide, disturbing the bed sediment, facilitating its initiation and transport, and ultimately increasing the ease of washing away the microplastics adhered to the sediment. This study will serve as a reference for further studies of the distribution and migration of microplastics in coastal zones subjected to similar marine utilization. [ABSTRACT FROM AUTHOR]

The estuarine-inner shelf mud regions of the East China Sea (ECS) are valuable for studying the source-to-sink processes of fluvial sediments deposited since the Holocene. In this study, we present evidence of the provenance and environmental evolution of two cores (S5-2 and JC07) from the estuarine-inner shelf regions of the ECS over the past 100 years based on 210 Pb dating, high-resolution grain size measurements and clay mineral analyses. The results indicate that the clay mineral assemblages of cores S5-2 and JC07 are dominated by illite, followed by kaolinite and chlorite, and present scarce amounts of smectite. A comparison of these clay mineral assemblages with several major sources reveals that the fine sediments on the estuarine-inner shelf of the ECS represent a mixture of provenances associated with the Yangtze and Yellow Rivers, as well as smaller rivers. However, the contribution of each provenance has varied greatly over the past hundred years, as indicated by the down-core variability due to strong sediment reworking and transport on the inner shelf and the reduction of the sediment load from the Yangtze River basin. In the mud region of the Yangtze River estuary, the sediment from 1930 to 1956 was primarily derived from the Yangtze River, although the Yellow River was also an important influence. From 1956 to 2013, the Yellow River contribution decreased, whereas the Yangtze River contribution correspondingly increased. In the Zhe-Min mud region, the Yangtze River contributed more sediment than did other rivers from 1910 to 1950; however, the Yangtze River contribution gradually decreased from 1950 to 2013. Moreover, the other small rivers accounted for minor contributions, and the East Asian winter monsoon (EAWM) played an important role in the sediment transport process in the ECS. Our results indicate that the weakening/strengthening of the EAWM and a decrease in the sediment load of the Yangtze River influenced the transport and fate of sediment on the estuarine-inner shelf of the ECS. [ABSTRACT FROM AUTHOR]

We examined the source-to-sink sediment transport processes from the Changjiang River to the estuarine coastal shelf area by analyzing the clay mineral assemblages in suspended sediment samples from the Changjiang River catchment and surface samples from the estuarine coastal shelf area following the impoundment of the Three Gorges Dam (TGD) in 2003. The results indicate that the clay mineral compositions throughout the study area are dominated by illite, with less abundant kaolinite and chlorite and scarce smectite. The clay minerals display distinct differences in the tributaries and exhibit obvious changes in the trunk stream compared with the periods before 2003, and the source of sediment has largely shifted to the mid- to lower reaches of the river after 2003. Spatially, the clay mineral assemblages in the estuarine area define two compositionally distinct provinces. Province I covers the mud area of the Changjiang River estuary and the Zhe-Min coastal region, where sediment is primarily supplied by the Changjiang River. Province II includes part of the Changjiang River estuary and the southeastern portion of the study area, where the sediment is composed of terrestrial material from the Changjiang River and re-suspended material from the Huanghe River carried by the Jiangsu coastal current. Moreover, the other smaller rivers in China (including the Oujiang and Minjiang rivers of mainland China and the rivers of West Taiwan) also contribut sediments to the estuarine and inner shelf areas. In general, the clay mineral assemblages in the Changjiang River estuarine area are have mainly been controlled by sediment supplied from upstream of the Changjiang River tributaries. However, since the completion of the TGD in 2003, the mid- to downstream tributaries have become the main source of sediments from the Changjiang catchment into the East China Sea. These analyses further demonstrate that the coastal currents and the decrease in the sediment load of the river have the greatest impacts on the distribution and transport of clay minerals assemblages in the sediments. [ABSTRACT FROM AUTHOR]

The water discharge and sediment load of rivers are changing substantially under the impacts of climate change and human activities, becoming a hot issue in hydro-environmental research. In this study, the water discharge and sediment load in the mainstream and seven tributaries of the Yangtze River were investigated by using long-term hydro-meteorological data from 1953 to 2013. The non-parametric Mann-Kendall test and double mass curve (DMC) were used to detect trends and abrupt change-points in water discharge and sediment load and to quantify the effects of climate change and human activities on water discharge and sediment load. The results are as follows: (1) the water discharge showed a non-significant decreasing trend at most stations except Hukou station. Among these, water discharge at Dongting Lake and the Min River basin shows a significant decreasing trend with average rates of − 13.93 × 10 8 m 3 /year and − 1.8 × 10 8 m 3 /year ( P < 0.05), respectively. However, the sediment load exhibited a significant decreasing trend in all tributaries of the Yangtze River. (2) No significant abrupt change-points were detected in the time series of water discharge for all hydrological stations. In contrast, significant abrupt change-points were detected in sediment load, most of these changes appeared in the late 1980s. (3) The water discharge was mainly influenced by precipitation in the Yangtze River basin, whereas sediment load was mainly affected by climate change and human activities; the relative contribution ratios of human activities were above 70% for the Yangtze River. (4) The decrease of sediment load has directly impacted the lower Yangtze River and the delta region. These results will provide a reference for better resource management in the Yangtze River Basin. [ABSTRACT FROM AUTHOR]

Intensive anthropogenic activities have a serious negative effect on the Jiangsu coastal area of China, especially on the distinctive intertidal zone. Humans are trying to eliminate this effect by taking protection and eco-compensation measures. However, when trying to determine the ecological status and quantify the anthropogenic impact for this area, the complex relationship between ecosystems and environmental stress leads to difficulties in reflecting general environmental quality. This study assessed the benthic ecological status of 10 transects (three stations/transect) across six different typologies over six years (2007, 2009–2013) in the Jiangsu intertidal zone. A unitary assessment of each transect was conducted using the multivariate AZTI Marine Biotic Index (M-AMBI), along with a radar chart (and its parameters). In the Jiangsu intertidal zone, the ecological status was noted as good or moderate at most sampling stations. Among the six assessed years, 2010 had the highest ecological status, while 2007 had the lowest. As for transects, transect 1 had the highest ratings, and transect 3 had the lowest ratings. Various stresses and advantageous human intervention and contributed to the ecological status for the different areas. The M-AMBI could be used in the future as a suitable index to assess the benthic ecological status of the Jiangsu intertidal zone. In addition, the new unitary method validated in this study could be used to assess ecosystems with several small biotopes, while accurately reflecting environmental quality. [ABSTRACT FROM AUTHOR]

To assess the environmental risks of polycyclic aromatic hydrocarbons (PAHs), 48 and 45 sediments were collected from the Yangtze River Estuary (YRE) and Pearl River Estuary (PRE), respectively. The toxicity equivalency concentration (TEQ) in the YRE and PRE were ranged from 1.68 to 76.13 and 9.28 to 129.24 ng TEQ g − 1 , respectively. Results of risk quotient suggest that ecological risks of two estuaries are at a moderate level, but are higher in the PRE than YRE. The increment lifetime cancer risks (ILCR) from the YRE via ingestion and dermal contact were 1 × 10 − 6 to 5.6 × 10 − 5 and 4 × 10 − 6 to 1.6 × 10 − 4 , and ranged from 7 × 10 − 6 to 9.4 × 10 − 5 and 2 × 10 − 5 to 2.8 × 10 − 4 in the PRE. ILCR results suggest that some low and moderate cancer risk exists in the YRE and PRE. Therefore, monitoring and control measures should be carried out immediately to reduce or eliminate the risks to human health from environmental exposure. [ABSTRACT FROM AUTHOR]

In this study, an ecological vulnerability assessment indicator system was constructed using the “exposure–climate sensitivity–adaptive capacity” framework according to the theory of ecological vulnerability. An improved ecosystem service value calculation model was proposed based on empirical parameters. Using Yancheng Nature Reserve in China as an example, we employed remote sensing data to conduct an empirical analysis of the changes in the spatiotemporal pattern, ecological vulnerability, and ecosystem services of typical landscape types over the period from 1987 to 2013. The statistical results derived from landscape pattern indices (LPIs) showed that during the investigation period, three natural wetland landscape types (i.e., Spartina alterniflora , Suaeda glauca , and Phragmites australis ) showed gradually increased fragmentation in the study area. The ecological vulnerability scores of the major landscape types (in descending order) were P. australis (0.053), farmland (0.047), S. alterniflora (0.042), S. glauca (0.031), and bare mud flat (0.002). The results derived from the ecosystem service value fluctuation index ( ESVFI ) showed that from 1987 to 1997, the value of the ecosystem services provided by S. glauca and P. australis wetlands decreased, whereas that of S. alterniflora wetlands increased continuously. From 2002 to 2013, the value of the ecosystem services provided by all three types of natural wetland showed a downward trend. In conclusion, the combined effects of human and natural factors, including the expansion of farmland and the invasion of S. alterniflora , and changes in seawater erosion and deposition led to changes in the landscape patterns, ecological vulnerability, and ecosystem services of the Yancheng Nature Reserve during the investigation period. The results indicate that a “dual adaptive” management system based on natural succession and supplemented by appropriate manual intervention should be implemented, and the management efficiency and flexibility should be improved to meet the common needs of biodiversity conservation and economic development. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are mainly produced by incomplete combustion and are used as indicators of anthropogenic activities on the environment. This study analyses the PAHs level in the Yangtze River Estuary (YRE), an important component of Yangtze River and a developed and populated region in China. Surface sediments were collected from 77 sites at the YRE and its adjacent coastal zone (IACZ) for a comprehensive study of PAHs. Kriging interpolation technology and Positive matrix factorization (PMF) model were applied to explore the spatial distribution and sources of PAHs. Concentrations of 16 PAHs (ΣPAHs) varied from 27.2 ng g −1 to 621.6 ng g −1 dry weight, with an average value of 158.2 ng g −1 . Spatially, ΣPAHs exhibited wide fluctuation and exhibited an increasing tendency from north to south. In addition, ΣPAHs exhibited a decreasing trend with increasing distance between the estuary and IACZ. The deposition flux of PAHs indicated that more than 107.8 t a −1 PAHs was deposited in the study area annually. The results of the PMF model revealed that anthropogenic activities were the main sources of PAHs in the study area. Vehicle emissions and marine engines were the most important sources and accounted for 40.9% of the pollution. Coal combustion, petrogenic sources, and wood combustion were other sources that contributed 23.9%, 23.6%, and 11.5%, respectively. The distribution patterns of PAHs in the YRE and IACZ were influenced by many complicated factors such as sediment grain size, hydrodynamics and so on. [ABSTRACT FROM AUTHOR]

Marine microplastic pollution is a major environmental challenge that threatens marine ecosystems and human health. Several models have been used to calculate and predict the theoretical amount of plastic waste discharged into the sea by coastal countries. Unlike earlier theoretical models of source discharge, we used the method of data normalisation to focus on the actual distribution of microplastics and their potential ecological risk in offshore surface waters. Our findings indicate that the average normalised abundance of microplastics in near-shore region of Bohai Sea was greater than the average normalised abundance of microplastics in the seas near the Yangtze River Delta urban agglomeration and the Pearl River Delta urban agglomeration. Moreover, the average amount of plastic waste discharged from terrestrial sources to the ocean per kilometre exhibited the following order: Bohai Rim urban agglomeration (150.90) (tonnes km−1) < the Pearl River Delta urban agglomeration (274.30) (tonnes km−1) < Yangtze River Delta urban agglomeration (577.44) (tonnes km−1). Further, the average microplastics abundance in offshore areas of different countries and the amount of plastic discharged per kilometre of the coastline were significantly negatively correlated, implying that microplastics were not necessarily abundant in coastal areas where large amounts of plastic are discharged into the sea. Hydrodynamic conditions had the greatest influence on the distribution of microplastics in offshore surface waters. The transport of nutrient salts from terrestrial areas to offshore waters was also influenced by hydrodynamics, with enrichment patterns in offshore areas exhibiting similar to those of microplastics. Therefore, when the offshore microplastic accumulation area overlapped with the nutrient salt enrichment zone, the health risk associated with the consumption of edible fish from offshore communities increased. In view of these findings, coastal countries must implement policies to reduce marine plastic waste emissions and develop management strategies based on their local pollution levels. [Display omitted] • There's a mismatch between theoretical plastic discharges and MPs distribution. • MPs aren't necessarily abundant where large amounts of plastic input into the sea. • Hydrodynamic conditions had the greatest influence on the MPs distribution. • Health risk of offshore fish consumption increases when MPs overlaps with nutrient. [ABSTRACT FROM AUTHOR]

Marine microplastic pollution has become a major global concern in recent years and the fate of microplastics in the ocean is a hot issue of research. We investigated microplastic pollution in surface sediments in the northern South China Sea to explore its distribution characteristics and influencing factors across the continental shelf, continental slope, and deep-sea environments. It was found that the microplastic abundance of surface sediments was 130.56 ± 40.48 items/kg. The average abundance of microplastics in all three topographic areas gradually decreased with increasing distance offshore. However, the differences in microplastic diversity indices between the three areas were not significant and were higher than those in other seas of the world, indicating that the waters of the northern South China Sea are rich in microplastics from complex sources, with more pollution input channels. In the continental shelf, fibrous and low density microplastics accounted for the largest amount, with a low degree of microplastic aging, and were mostly transported by suspended-load. These microplastics were mainly influenced by human activities. In the deep sea, microplastics with higher density were the most abundant and the number of fibrous microplastics was fewer, while the average size was larger, mainly influenced by the bottom currents. These microplastics underwent long-term bedload transport. In the continental slope, the main factors affecting the distribution of microplastics were more complex. In addition to pollution by human activities, the slope also receives microplastic materials carried by bottom currents; therefore, the composition of microplastics in the slope combines those characteristics of microplastics in both the continental shelf and deep-sea areas. The findings of this study indicate that the South China Sea is affected by complex pollution sources under the dual effects of human activities and natural conditions; in particular, the pollution situation in the deep-sea area needs extensive attention. [Display omitted] • Distribution of microplastic and characteristics from the northern SCS are reported. • MPs distribution is mainly affected by human activities and bottom currents. • Continental shelf has higher abundance than continental slope and deep-sea areas. • Deep-sea areas potentially pool large amounts of microplastics. • Prominent MDI in northern SCS reflects the diversity of pollution input channels. [ABSTRACT FROM AUTHOR]

Based on data from the Datong hydrological station and 147 meteorological stations, the influences of climate change and human activities on temporal changes in water discharge and sediment load were examined in the Yangtze River basin from 1953 to 2010. The Mann–Kendall test, abrupt change test (Mann–Kendall and cumulative anomaly test), and Morlet wavelet method were employed to analyze the water discharge and sediment load data measured at the Datong hydrological station. The results indicated that the annual mean precipitation and water discharge exhibited decreasing trends of − 0.0064 mm/10 yr and − 1.41 × 10 8 m 3 /yr, respectively, and that the water sediment load showed a significant decreasing trend of − 46.5 × 10 6 t/yr. Meanwhile, an abrupt change in the water discharge occurred in 2003. The sediment load also exhibited an abrupt change in 1985. From 1970 to 2010, the climate change and human activities contributed 72% and 28%, respectively, to the water discharge reduction. The human-induced decrease in the sediment load was 914.03 × 10 6 t/yr during the 1970s and 3301.79 × 10 6 t/yr during the 2000s. The contribution from human activities also increased from 71% to 92%, especially in the 1990s, when the value increased to 92%. Climate change and human activities contributed 14% and 86%, respectively, to the sediment load reduction. Inter-annual variations in water discharge and sediment load were affected by climate oscillations and human activities. The effect of human activities on the sediment load was considerably greater than those on water discharge in the Yangtze River basin. [ABSTRACT FROM AUTHOR]

The main objective of ecosystem health management is to preserve the capacity of ecosystems to respond to disturbances and future changes. We proposed a set of ecological indicators for coastal ecosystem health assessment using physical stressors such as total suspended matter, chemical stressors including nutrients and heavy metal pollutants, community structure metrics including species richness, diversity and evenness, and ecosystem level eco-exergy indicators. The results of our case study indicate that the health status of the Jiangsu coastal ecosystem is limited by environmental stressors and factors that affect the community species diversity. The health status of nektonic and benthic communities is reflected by water quality and sediment physicochemical properties, respectively. The results of our case study demonstrate that the integrated ecological health indicator system can provide a comprehensive assessment that corresponds with the current health of coastal ecosystems and a reliable theoretical basis for regional coastal management. [ABSTRACT FROM AUTHOR]

Coastal saline wetlands are recognized as prominent sources of greenhouse gas emissions. However, insufficient attention has been paid to the effect of coastal wetlands in mitigating global warming caused by greenhouse gases in China. This study aims to investigate how vegetation and soil parameters affect greenhouse gas emissions in a coastal saline wetland. Fluxes of CO 2 , CH 4 , and N 2 O were measured simultaneously in situ using the closed static chamber technique in four different coastal tidal flats, namely, mud flat, Spartina alterniflora flat, Suaeda glauca flat, and grass flat. The measurements were obtained from September 2012 to August 2013 in the Yancheng coastal wetland, southeast China. The average fluxes across all seasons and flats varied from 10.7 to 2297.6 mg CO 2 m −2 h −1 (ecosystem respiration), from −0.368 to 4.959 mg CH 4 m −2 h −1 , and from 1.5 to 65.7 μg N 2 O m −2 h −1 . Higher CO 2 and CH 4 fluxes were observed during the summer and autumn seasons. However, the seasonal change of the N 2 O fluxes was complicated. For the S. alterniflora and grass flats, the highest emissions were observed during summer. For the mud and S. glauca flats, the emissions peaked during winter. The spatial variations of the three greenhouse gas fluxes in the coastal saline wetland primarily depended on vegetation type. The greenhouse gas fluxes from the three tidal flats with vegetation covers ( S. alterniflora , S. glauca , and grass flats) were higher than those from the mud flat. Higher CO 2 emissions were observed in the S. alterniflora flat than those in the other flats because of the higher carbon sequestration rate, together with higher net primary production and aboveground biomass. However, CH 4 and N 2 O emissions were highest in the grass flat, followed by the S. alterniflora flat. The effects of tidal flats on the CH 4 and N 2 O emissions differed according to the season. The S. alterniflora invasion increased the CO 2 emission while slightly lowering the CH 4 fluxes, compared with that of native plant communities dominated by Phragmites . Results also suggested that S. alterniflora had the highest global warming potential among the tidal flats in the coastal saline wetland. [ABSTRACT FROM AUTHOR]

Analyses of the spatial and temporal variation of reference evapotranspiration (ET 0 ) and aridity index (AI) can further understand climate change and its effect on hydrology. In this study, based on date from 58 standard meteorological stations, the spatio-temporal variations and trends of ET 0 and AI were calculated for the Loess Plateau Region (LPR) from 1961 to 2012 using the Mann–Kendall test, the moving t -test, and the Morlet wavelet methods. The results demonstrated: (1) the annual ET 0 displayed a statistically significant decrease of −10.3 mm/10 y ( P < 0.05) during 1961–2012. At that time, AI also had a decreasing trend of −0.013/10 y over the past 52 years. Compared with ET 0 , the inter-decadal variations of AI over the LPR seemed to show similar declined trends. (2) Spatially, about 81% stations displayed a decreasing trend for annual ET 0 during 1961–2012, and most of them were distributed in the western, northern and southeastern LPR. In addition, about 60% of stations showed statistically decreasing trends for AI, and the major decreases were mainly in the east Qinghai division and northern LPR. (3) Abrupt changes were detected in annual ET 0 series in the 1980s and in annual AI series in 1987. Wavelet analysis indicated significant 2 year and non-significant 7, 10 and 14 years in annual ET 0 series, and there existed periods of 4, 8 and 12 years for AI. (4) For ET 0 , wind speed was the most sensitive meteorological factor, followed by sunshine hours, precipitation, and relative humidity. For AI, ET 0 and precipitation were the sensitive factors. This study provides an understanding of the effect of recent climate change on hydrological cycle in the LPR. [ABSTRACT FROM AUTHOR]

Abstract: Based on daily precipitation dates at 42 meteorological stations in the Pearl River Basin, the spatial and temporal changes in precipitation index are analyzed during 1960–2012, eleven indices of precipitation extremes are studied. The results show that wet day precipitation, consecutive wet days and numbers of heavy precipitation days exhibit non-significant decreasing trends in the study area. Consecutive dry days and simple daily intensity index have increased and are significant at the 95% level, while other extreme precipitation indexes have non-significant increasing trends. Spatial changes of precipitation extreme indices show obvious differences, and they are not clustered either. On the whole, the number of rainy days has decreased over the Yunnan–Guizhou Plateau and hilly Guangxi, and the spatial distribution reflects the regional climatic complexity. Continuous wavelet transform analysis indicates that there are significant periodic variations with periods of ∼7 and ∼14 years in extreme precipitation, and that there is also a 6-year period and a 14-year period with the Pacific Decadal Oscillation (PDO) and Southern Oscillation Index (SOI), respectively, which are very consistent. The PDO and SOI are important influential factors for precipitation. In addition, except for consecutive dry days, the other extreme precipitation indices have significant correlations with annual precipitation. Large scale atmospheric circulation changes derived from NCEP/NCAR reanalysis reveals that a strengthening anticyclonic circulation, increasing geopotential height, weakening monsoonal flow, and vapor transportation over the Eurasian continent have contributed to the changes in precipitation extremes in southern China. [Copyright &y& Elsevier]

We investigated microplastics (MPs) pollution in 349 Larimichthys polyactis specimens from the coastal area of Jiangsu Province, China. The MP abundance in L. polyactis was 1.03 ± 1.04 items/individual and 0.95 ± 0.92 items/10 g (wet weight). The MP abundance in specimens from the Haizhou Bay fishing ground was slightly higher than that in specimens from the Lvsi fishing ground. Spearman's correlation showed that MP abundance was positively correlated with body length when expressed as items/individual, but not items/10 g. The abundance in the gastrointestinal tract was slightly higher than that in the gills, but the differences were not significant for either measurement index. The MPs predominantly ingested by L. polyactis were <1 mm, fibrous, blue and had a cellophane composition. The MP pollution in L. polyactis in the coast of Jiangsu Province is at a medium to low level, as compared with other regions of China. [Display omitted] • We studied microplastics (MPs) in 349 Larimichthys polyactis specimens in Jiangsu. • MP abundance was 1.03 ± 1.04 items/individual and 0.95 ± 0.92 items/10 g. • MPs were positively correlated with body length when expressed as items/individual. • MP pollution in Jiangsu was medium to low compared with other coastal areas in China. • The impact of MP pollution on more trophic levels deserves further attention. [ABSTRACT FROM AUTHOR]

Marine fishes are consumed in large quantities by humans as nutritious food. However, the intake of fish polluted by chemicals may pose a severe threat to human health. This study measured the concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) in the muscles of 22 species of marine fish from two coastal regions, i.e. , Tanmen and Zhuhai, identified the source of PAHs, and assessed the human health risk by dietary exposure. Total PAH (Σ 16 PAHs) levels in Tanmen and Zhuhai fish were in the range of 24.29–684.83 ng g−1 dry weight (dw) and 13.74–42.59 ng g−1 dw, averaging 161.46 ng g−1 dw and 31.21 ng g−1 dw, respectively. Compared with other regions in the world, PAH concentrations in Tanmen fish were at median levels, and Zhuhai fish were at low levels. Low molecular weight PAHs (with 2- and 3-rings) were the predominant compounds detected. Molecular diagnostic ratios suggested that PAHs in Tanmen mainly originated from petrogenic sources such as vessel operations or tanker accidents, while Zhuhai fish were mainly polluted by pyrolytic sources such as combustion of coal and wood. The human health risk assessment results indicated that the risk of PAH intake via fish consumption from Zhuhai was negligible, while five species from Tanmen may pose potential health risks to local residents. • PAHs were detected in fish from two coastal regions. • Five species from Tanmen may pose potential health risks to local residents. • The risk of PAH intake via fish consumption from Zhuhai was negligible. [ABSTRACT FROM AUTHOR]

Atmospheric microplastics have been widely reported and detected in remote mountain areas and oceans, indicating that they can be transported over long distances through the atmosphere. Regional transport and deposition processes of atmospheric microplastics have a significant impact on the source and sink patterns, as well as the flux mechanisms of microplastics in terrestrial and marine environments. However, few studies have been conducted on the deposition of atmospheric microplastics. Thus, in this study, we collected atmospheric microplastic samples from the northwestern South China Sea and estimated that in the fall the dry deposition of atmospheric microplastics into the ocean was 1.4 × 103 t, which had a greater contribution than riverine inputs of microplastics in this region, suggesting that atmospheric microplastics are non-negligible sources of marine plastic litter with high environmental risk. Additionally, we reported on the abundance (0.035 ± 0.015 n/m3), morphological characteristics, composition, and sources of atmospheric microplastics in the northwestern South China Sea. Smaller-sized microplastics had a high abundance that decreased with increased proximity from the coast. Most of the detected microplastics were fibers, which accounted for approximately two-thirds of the total quantity. The spectral analysis detected seven polymer types, and polyester was predominant (29%). Combined with the cluster analysis of the backward trajectories of airflow, we demonstrated that the airflow affecting the northwestern South China Sea originated mainly from the northeast, potentially carrying microplastics from cities located in southeastern Chinese provinces to the South China Sea. • Dry deposition of atmospheric MPs into the northwestern SCS in the fall was 1400 t. • The number of MPs gradually increased and peaked as the particle size decreased. • The airflow may carry MPs over cities in southeastern China into SCS in the fall. • Long-term monitoring of atmospheric MPs and making evaluation standards are needed. [ABSTRACT FROM AUTHOR]