Search Results (10)

Reducing fertilizer and pesticide use is a crucial path for the green transformation of agricultural production, which has garnered sustained attention in research on sustainable agricultural development. Based on the theoretical analysis, this article analyzes the spatiotemporal evolution characteristics of fertilizer and pesticide usage intensity (FUI and PUI) in the Yangtze River Delta (YRD) over the past 20 years and uses a Two-Way Fixed Effects Model to test their impacts and mechanisms. Findings show that agricultural development in the YRD shows a pattern of specialization and intensification with a significant north–south divide, with zero growth and reduction in fertilizer and pesticide use across the region from 2010 to 2015, but the current FUI and PUI are still nearly three and five times higher than the global average. Over the past 20 years, the FUI is high in the north and low in the south, high in the plains and low in mountainous-hilly areas, and high in suburban areas and low in remote counties. Adversely, the PUI is high in the south and low in the north, high in mountainous-hilly areas and low in plains, and high in suburban areas and low in remote counties. The FUI and PUI of characteristic agricultural areas of fruit, tea, and forestry in southern Anhui and southwestern Zhejiang, as well as the agroecological and facility agriculture clusters in southern Jiangsu and the suburbs of Shanghai, have approached the peak and successfully moved into the new green development stage earlier compared to other areas. In contrast, the grain and oil production plains areas along the Yangtze River, the coast, in northern Anhui, and in northern Jiangsu are relatively lagging behind. The combination of soil, water, light, and heat resource conditions and modes of agriculture production shape the absolute figures of FUI and PUI, and factors such as the level of local economic development and public fiscal expenditure significantly influence the trajectories of spatiotemporal differentiation in the progress of reducing fertilizer and pesticide in the YRD. Full article

Activities, particularly harbor construction, often exert significant and non-negligible impacts on coastal environments. Therefore, it is of great practical importance to quantitatively assess the effects of such construction on the surrounding topography, such as tidal flats. This study focuses on the coast of Jiangsu Binhai Harbor. Using multi-source and multi-temporal remote sensing images, digital elevation models of tidal flats surrounding Binhai Harbor were generated for the years 2013, 2015, and 2017 through the waterline method. A quantitative analysis was conducted utilizing GIS spatial analysis techniques to examine erosion–deposition patterns, contour changes, and typical cross-sectional comparisons. The findings reveal that, although the overall coastline is in a state of erosion, the localized impacts of harbor construction are evident. Between 2013 and 2017, the northern tidal flats experienced overall erosion, whereas deposition occurred near the harbor’s root areas. Compared to 2013–2015, there was a significant decrease in erosion between 2015 and 2017, indicating that the construction of the project had a significant impact on the northern tidal flats. Throughout the five-year study period, the tidal flats within the breakwater underwent continuous adjustment, shifting from being close to the shoreline to being concentrated on both sides of the breakwater. Significant siltation was observed on the inner side of the breakwater at Binhai Harbor between 2015 and 2017, with an increase of 0.86 km² in the area above −2 m. This study demonstrates that remote sensing technology is highly effective in monitoring changes in coastal topography, especially under the influence of human activities. Full article

Since 2007, Ulva prolifera (U. prolifera) originating in northern Jiangsu (NJ) has consistently expanded to the southern coast of the Shandong Peninsula. However, the underlying reasons for the 2007 sudden bloom of U. prolifera on a large scale remain unknown. This study uses remote sensing data from MODIS/AQUA spanning the period 2003–2022 to investigate the sea surface temperature (SST) structure changes in the southern Yellow Sea (SYS) over the past 20 years. The results demonstrate the following. (1) Since 2007, the NJ northward current and the Yangtze estuary warm current have exhibited higher temperatures, earlier northward intrusions, and larger influence areas, leading to a faster warming rate in NJ before mid-May. This rapid increase in SST to a level suitable for early U. prolifera growth triggers large-scale blooms. (2) The change in temperature structure is primarily induced by a prolonged and intense La Niña event in 2007–2008. However, since 2016, under stable global climate conditions, the temperature structure of the SYS has returned to the pre-2007 state, corresponding to a decrease in the scale of U. prolifera blooms. Full article

In this study, columnar sediment samples were collected from north to south along the northern Jiangsu coast, China, under Spartina alterniflora vegetation in four sample areas: Chuandong Port (Area-1), Tiaozini Scenic Area (Area-2), Yangkou Town (Area-3), and Meiledi Marine Park (Area-4). Organic carbon (OC), nutrient elements including total nitrogen (TN), total phosphorus (TP), and total sulfur (TS), and physicochemical properties including pH, salinity (Sal), moisture content (MC), and bulk density (BD) were measured. Pearson’s correlation analysis was performed to explore the correlation between OC content and sedimentary physicochemical indexes, and the partial least squares regression (PLSR) model was used to analyze the factors affecting changes in OC content. The results found that the OC content of columnar sediments of S. alterniflora decreased with increasing depth in all four areas. The OC content in the four sample areas was mainly affected by the TN, pH, MC, TP, and burial depth. In particular, TN, MC, TP, TS, and clay content positively affected OC, whereas burial depth, pH, silt content, BD, sand content, and Sal negatively affected OC. The results of this study provide a valuable reference for evaluating the role of coastal wetlands in the global carbon cycle. Full article

Multiple datasets related to pond and marine aquaculture have been published using diverse remote sensing technologies, yet a comprehensive dataset detailing spatial distribution on both land and sea sides is lacking. Firstly, a meticulous comparison of datasets which we selected related to aquaculture ponds and marine, ensuring consistency in trends. Subsequently, the datasets published by our team were edited and integrated to illustrate aquaculture activities on both sides of China’s coastal zone. Finally, a spatial differentiation of coastal aquaculture in major provinces was analyzed. This analysis also utilizes the types of coastline and statistical data, guiding coordinated resource management efforts. The results unveil a distinctive spatial distribution pattern, concentrating aquaculture in the northern regions—Bohai Sea, Jiangsu, Fujian, and Pearl River coasts in Guangdong. The provinces rich in aquaculture resources, such as Shandong, Guangdong, and Liaoning, exhibit extensive coastlines. However, remote sensing monitoring suggests an underestimation of Liaoning’s marine aquaculture compared to statistical yearbook data. Furthermore, southern provinces like Guangdong and Fujian exhibit significantly higher aquaculture output than Liaoning. Zhejiang leads in fishing output. The paper outlines the future development direction of coastal aquaculture, emphasizing a strategic, integrated land–sea approach for sustainable development. Full article

Tidal flats are accumulations of fine-grained sediment formed under the action of tides and play a very important role in coastal protection. The northern part of Jiangsu coast, as a typical example of muddy coasts found all over the world, has experienced serious erosion since the Yellow River shifted northward, and the range of erosion has been gradually extending southward, now reaching the south of the Sheyang River estuary (SYRE). In order to address coastal erosion near the SYRE through protective measures, there is an urgent need for research on the spatial and temporal variation of coastal erosion processes and their control mechanisms in the SYRE and adjacent coastal areas. For this study, the tidal flats on the south side of the SYRE were selected as the study area, and the sediment dynamics in the upper and lower intertidal flat were observed in different seasons to investigate the erosion processes and their dynamic mechanisms. The results show that the tidal current and wave action in the observed intertidal flats are stronger in winter than in summer, and these intertidal flats erode under the combined action of waves and currents. During winter, the net transport of the near-bottom suspended sediment and bedload is primarily towards the southeast, while in summer, the direction tends toward the north and northeast. The net transport fluxes are larger in the lower part of the intertidal flat than in the upper part in summer and also larger in winter than in summer within the lower intertidal flat. Furthermore, the tidal flat erosion in the study area manifests as shoreline retreat and flat surface erosion. The average shoreline retreat rate increased from 23.3 m/a during 2014–2019 to 43.5 m/a during 2019–2021, and the average erosion depth of the lower and upper parts of the intertidal flat over a tidal cycle is, respectively, 1.98 cm and 0.24 cm in winter and 1.65 cm and 0.26 cm in summer. The ratio of the wave-induced bottom shear stress to the tidal current-induced bottom shear stress is 0.40~0.46 in the lower intertidal flat and increases to 0.66~0.67 in the upper intertidal flat, indicating that the intertidal flat erosion in the study area is primarily driven by tidal currents, with significant contributions from wave action, especially in the upper intertidal flat. Full article

The Sheyang estuary is located on the northern Jiangsu muddy coast, in the western South Yellow Sea, and in the transition area between the eroded coast of the abandoned Yellow River delta and the silted coast of the central Jiangsu. This area is also one of the key areas of interactions between the paleo-Yellow River and paleo-Changjiang River during the late Quaternary. In order to investigate deeply the late Quaternary sedimentary sequence models of coasts and continental shelves under the interactions of the above two large rivers, the sedimentary sequence and age of the core NTCJ1 drilled at the Sheyang estuary were re-examined and re-interpreted recently, based on the existing data on lithology, grain size, ostracods, foraminifera, clay minerals, geochemical elements, and Electron Spin Resonance (ESR) dating, together with other adjacent key cores and shallow seismic profiles. The three new perspectives were summarized as follows: Firstly, the 22.00 m-long core NTCJ1 recorded the evolution of the sedimentary environments since Marine Isotope Stage 5 (MIS 5), and the first continental facies layer formed in MIS 4-2 is supposed to be missing; therefore, the MIS 1 marine facies layer directly overlays on the MIS 5 marine facies layer. Furthermore, the second continental facies layer formed in MIS 6 and/or the stage of the relatively low sea-level of MIS 5 has not been drilled yet. Secondarily, the middle-upper part of the NTCJ1 core sediments (0.00–17.95 m) are characterized by a finer grain, with a predominantly silty texture and dark yellow tone, and from bottom to top it shows a change from fine to coarse and then to fine in grain size, which could be substantially interpreted as the abandoned Yellow River deltaic deposits mainly formed in 1128–1855 CE, and may contain a small amount of Holocene coastal-shallow marine deposits at the bottom; however, it is difficult to identify them currently. Thirdly, the lower part of the NTCJ1 core sediments (17.95–22.00 m) have not yet been drilled through and are characterized by a coarser grain, with a predominantly fine sandy texture and dark grey tone, which could be interpreted as a delta front deposit in the MIS 5 tidal estuary and were obviously influenced by the paleo-Yellow River. Full article

Soil biodiversity and fuction have been altered by the increasing levels of nitrogen as a result of fertilization and atmospheric deposition. Although soil microarthropods are a crucial component of soil biodiversity and play a key role in a diverse range of soil functions, our understanding of the mechanisms by which N addition affects them remains limited. Using a long-term nitrogen addition experiment (2012–2016) in poplar plantations (Populus deltoides L. CL‘35′) located along the coast of Yellow Sea Forest Park in northern Jiangsu, eastern China (32°52′ N and 120°49′ E), where the soil was entisols, we examined the response of soil microarthropods across three soil depths (0–15 cm, 15–25 cm, 25–40 cm) to five N input levels (0, 5, 10, 15, 30 g N m⁻² year⁻¹) over four seasons. We found that the number of microarthropods per unit area initially grew and then dropped as more nitrogen was added to soils. Soil organic carbon (positive correlation, R² = 0.53) and pH (negative correlation, R² = 0.19) were the two dominant factors driving the effects of nitrogen addition on soil microarthropod densities at all soil depths. These results suggest that nitrogen input enhances the density of soil microarthropods via the increase in fresh organic matter input. However, the increase in organic matter may be offset by an indirect increase in acidity under high levels of N addition, providing one possible explanation for the reduced density of microarthropods in heavily fertilized soils.71 Full article

Tidal flats play an important role in promoting coastal biodiversity, defense against flooding, land reclamation and recreation. Many coastal tidal flats, especially the tide-dominant ones, are muddy. However, the number of studies on the profile shape and surficial sediment distribution of muddy tidal flats is small compared to sandy beaches. Based on high spatial-resolution measurements along the tide-dominant Jiangsu Coast, China, we analyzed the morphology and sediment characteristics of the unvegetated intertidal flats along the Jiangsu Coast. The Jiangsu Coast can be divided into an eroding northern part (north coast) and an accreting southern part (south coast). The beach slope of the north coast shows a southward flattening trend, apart from some outliers related to rocky parts of the coastline. We found alternating very fine and coarse sediment (depending on the local clay content) for different locations along the north coast, which can be explained from consolidation and armoring-induced erosion resistance. In the south coast, we found gradual coarsening of bed surface sediment and gradual flattening of beach slopes to the south. This seemingly unexpected pattern is explained by the flood-dominant current causing landward sediment transport, larger tidal range in the south part, sheltering effect of the Radial Sand Ridges, and contribution of different sediment sources, viz. the Abandoned Yellow River Delta and the Radial Sand Ridges. In the cross-shore direction, the sediment grain size decreases landward. Waves are only of secondary importance for the sediment dynamics at the unvegetated tidal flats along the Jiangsu Coast. Full article

Mass concentration data for particulate matter with an aerodynamic diameter less than or equal to 2.50 μm (PM_2.5) combined with backward trajectory cluster analysis, potential source contribution function (PSCF), and concentration weighted trajectory (CWT) methods were used to investigate the transport pathways and potential source regions of PM_2.5 on the west coast of Bohai Bay from 2009 to 2018. Two pathways responsible for the transportation of high PM_2.5 levels were identified, namely a southerly pathway and a northwesterly pathway. The southerly pathway represented the major transport pathway of PM_2.5 for all seasons. As a regional transport pathway, it had the greatest impact in winter, followed by autumn. The southerly transport pathway passed over the Shandong and Hebei provinces before reaching Tianjin: Air masses were transported within the boundary layer (below 925 hPa), representing a slow-moving air flow. The northwesterly pathway mostly occurred in winter and autumn and passed over desert and semidesert regions in Outer Mongolia, the sand lands of Inner Mongolia, and Hebei. The air masses associated with the northwesterly pathway represented fast-moving airflows responsible for long-range transportation of PM_2.5. Two potential source regions that contributed to high PM_2.5 loadings on the west coast of Bohai Bay were identified, “southerly source regions” and “northwesterly source regions”. The southerly source regions, with weighted CWT (WCWT) values in winter greater than 140.00 μg/m³, were anthropogenic source regions, including southern Hebei, western Shandong, eastern Henan, northern Anhui, and northern Jiangsu. The northwesterly source regions, with WCWT values in winter of 80.00–140.00 μg/m³, were natural source regions, encompassing central Inner Mongolia and southern Mongolia. In addition, the southerly transport pathway passed though anthropogenic source regions, while the northwesterly transport pathway passed though natural source regions. The impacts of anthropogenic source regions on PM_2.5 loadings on the west coast of Bohai Bay were greater than those of natural source regions. Full article