Human activity factors have a significant impact on changes in ammonia nitrogen (NH3-N) content in rivers. Existing research mainly focuses on human activity factors as type factors, and lacks research on the key factors affecting river NH3-N among human activity factors. Therefore, this paper aims to study the key factors affecting human activities on NH3-N in the Huaihe River through various statistical analysis methods. The study found that changes in NH3-N content in the Huaihe River are mainly affected by land use patterns in the basin. There are two different ways in which land use affects NH3-N in rivers: direct effects and indirect effects. We also studied the main pathways through which changes in key factors in human activities affect NH3-N in the Huaihe River by constructing a structural equation model. The results showed that crop sowing area and afforestation area have a significant direct effect on NH3-N in the Huaihe River. In addition, crop sowing area and afforestation area can also affect river NH3-N by regulating the amount of nitrogen fertilizer and human excrement. This study is of great significance for understanding how human activities regulate NH3-N content in rivers.

From November 2021 to September 2022, we conducted four field surveys on macroinvertebrates and water environmental factors in Xinyang section of the Huaihe River main stream. We analyzed the structure and spatiotemporal distribution characteristics of the functional feeding groups of macroinvertebrates, and evaluated river water quality. A total of 73 macroinvertebrate species were collected in the basin, belonging to 42 families, 7 classes, and 3 phyla. The dominant species of macroinvertebrates changed significantly in different months, with Exopalaemon modestus being the absolute advantage species in the basin in July and September 2022. In different sampling months, the functional feeding group of macroinvertebrates was mainly dominated by shredders, accounting for 35.9%. The results of redundancy analysis showed that the main environmental factors affecting the distribution of functional feeding groups of macroinvertebrates varied across different months, with conductivity in February, temperature in July, and oxidation-reduction potential in September and November. The evaluation based on the biolo-gical index and Shannon index of macroinvertebrates indicated that water quality in the investigated section was at a light pollution level.
2021年11月至2022年9月对淮河干流信阳段的大型底栖动物和水环境因子进行了4次野外调查,分析了该段大型底栖动物功能摄食类群的结构与时空分布特征,并对河流水质进行了生物评价。流域内共采集到大型底栖动物73种,隶属于3门7纲42科,不同月份大型底栖动物的优势种存在明显变化,其中秀丽白虾在2022年7月和9月成为流域内的绝对优势种。在不同采样月份,流域内大型底栖动物的功能摄食类群以撕食者占据主要优势,为35.9%。冗余分析结果表明,不同月份中影响大型底栖动物功能摄食类群分布的主要环境因子有所差异,其中2月的主要环境影响因子为电导率,7月为温度,9月和11月均为氧化还原电位。基于大型底栖动物的生物指数和Shannon指数的水质评价结果表明,流域内水质整体处于轻污染水平。.

The comprehensive understanding of PCBs\' fate has been impeded by the lack of simultaneous monitoring of PCBs in multiple environmental media in the background areas, which were considered long-term sinks for highly chlorinated PCBs. To address this gap, this study analyzed soils, willow tree barks, water, suspended particulate matter (SPM), and sediment samples collected from the middle reach of the Huaihe River in China for 27 PCBs. The results showed that the levels of ∑27PCBs in the soils were comparable to or lower than the background values worldwide. There were no significant correlations between organic matter and ∑27PCB concentrations in the soils and sediments. Additionally, the contamination of dioxin-like PCBs in the aquatic environment of the study area deserves more attention than in the soils. Applying the level III fugacity model to PCB 52, 77, 101, and 114 revealed that the soil was the primary reservoir, and air-soil exchange was the dominant intermedia transfer process, followed by air-water exchange. Furthermore, simulated results of air-soil and air-water diffusion were compared with those calculated from the field concentrations to predict the potential environmental behaviors of PCBs. Results indicated that the studied river would be a \"secondary source\" for PCB 52, 77, and 101. However, PCB 52, 77, 101, and 114 would continue to transfer from the air to the soil. This study combines multimedia field measurements and the fugacity model, providing a novel approach to predicting the potential environmental behaviors of PCBs.

Exploring the relationship between land use change and landscape patterns can provide a basis for regional ecological management. In this paper, based on remote sensing images of the Huaihe River Ecological and Economic Zone for the years 2000, 2005, 2010, 2015 and 2020, the spatial and temporal evolution patterns of land use in the region were quantitatively described by using the methods of land use shift matrix and landscape pattern analysis. The relationship between land use change and landscape pattern was analyzed with the Grey Relation Analysis (GRA) model. The results show that: (1) the land use of the Huaihe River Ecological and Economic Zone has changed significantly in the past 20 years, with the conversion of arable land into construction and forest lands, in addition to the growth of water areas and a decline in the areas of arable land, grassland and unused land. (2) The landscape pattern fragmentation of each type of land in the study area from 2000 to 2020 fluctuated and decreased, and the landscape connectivity and landscape diversity increased significantly. (3) The GRA model shows that construction, arable and forest lands played the most significant role in the change of landscape pattern of the Huaihe River Ecological and Economic Zone. Countermeasures are proposed to better coordinate and optimize the relationship between spatial development and landscape pattern for the Huaihe River ecological and economic Zone.

Distributions, souces, ecological risks as well as environmental behaviors of 20 organochlorine pesticides (OCPs) in riparian soils and sediments of the middle reach of the Huaihe River, a traditional agricultural area of China, were investigated. ∑OCPs in riparian soils and sediments were 1.8-63 ng g-1 (mean = 19 ± 12 ng g-1) and 1.2-9.9 ng g-1 (mean = 3.0 ± 1.8 ng g-1), respectively. HCHs were the dominant OCPs in both soils and sediments, while high concentrations of ∑HEPTs and ∑DDTs were also detected in some soils and sediments. No correlations were found between concentrations of OCPs and organic matter contents in both soils and sediments. Based on the source analysis, most OCPs in the riparian soils were mainly from historical residues, such as historical usage of technical HCH, DDT, chlordane and endosulfan. OCPs in sediments were influenced not only by surface runoff by also by other factors, e.g. in-situ contamination (DDT-containing antifouling paints in ships) and/or hydraulic transport from some tributaries. Some never-used OCPs, such as heptachlor and aldrin, were widely detected in soils and sediments. This might be attributed to some unknown usages or long-range atmospheric transport of them from other source regions. Ecological risk analysis suggested that DDTs and HCHs in soils would not lead to an adverse effect on soil ecological environment as well as agricultural production, and OCP residues in sediments also would not pose a threat to the sediment-dwelling organisms.

Fifty-four surface sediments from the typical coal mining area were analyzed for pristane, phytane and C8-C40 n-alkanes using gas chromatography-mass spectrometry (GC-MS). The spatial distribution, homolog profiles and source apportionment of aliphatic hydrocarbons were investigated. Bimodal distribution pattern, centered at C16-C20 and C27-C33 n-alkanes, were observed in all sediment samples with an obvious dominance of low molecular weight homologues. Principal component analysis-multiple linear regression (PCA-MLR) was used to predict the contributions of different sources. The result implied that natural input was the main source, contribution of which accounted for 60.8%, and the contributions of different sources were estimated as follow: 21.8% for terrestrial higher plants, 24.1% for algae and photosynthetic bacteria, 14.9% for submerged/floating macrophytes, 23.5% for fossil fuel combustion and 15.7% for petroleum hydrocarbons. Moreover, relatively high median concentrations of fossil fuel combustion were observed in Shou County and Fengtai County, indicating the high contribution of fossil fuel combustion in these two areas.

In recent decades, rapid development of industrialization and urbanization caused adverse impact on the aqueous ecology and environment of the Huaihe River basin, China. In this work, three 210Pb-dated sediment cores extracted from the middle reach of Huaihe River in Anhui Province, China were analyzed to elucidate the temporal trends and sources of polybrominated diphenyl ethers (PBDEs). Source diagnostics indicated that commercial Deca-BDE, Penta-BDE and Octa-BDE products and debromination of higher brominated BDE compounds were likely the PBDE sources in the Huaihe River. The prevalence of BDE-47 in the sediment cores was attributed to the extensive use of commercial Bromkal 70-5DE and Bromkal DE-71 in the region. BDE-28 was another congener that was prevalent in all sediment samples, suggesting that reductive debromination occurred in the sediments. Dramatic increase of PBDE concentrations in both three cores since the post-1980s could be attributed to the rapid expansion of production of electronic and telecommunication equipment and household usage in China. PBDE temporal trends in core S1 located at rural area mainly reflected the regional and national inputs deriving from long distance atmospheric transport, and the positive correlations between PBDE concentration in core S1 and gross domestic product (GDP) and household appliances production volumes (HPVs) were observed. PBDE inputs at site S3 mainly include the transport of contaminated water and re-suspended fine sediment particles from the upstream site S2, which was located in the industrial area and adjacent to e-waste recycling area. The government efforts to protect the environment and improve the e-waste management resulted in the progressive decrease trends in PBDE concentrations in cores S2 and S3.

This paper presented the historical data on the temporal trends of polybrominated diphenyl ethers (PBDEs) in the sediment cores collected from the Huaihe River, Yellow River and Chaohu Lake, China. Among the 40 targeted PBDE congeners, only 10, 6, and 9 of them were detected respectively in the samples from the Huaihe River, Yellow River and Chaohu Lake. On average, the total PBDEs concentrations in sediments were highest in Chaohu Lake followed by the Huaihe River and the Yellow River. As compared to other PBDE congeners, BDE-209 had higher concentrations and detection rates. The similar down core variation between PBDEs and total organic carbon (TOC) suggests that TOC is an important factor influencing PBDEs distribution in the sediments. The total PBDEs concentrations showed an increasing trend from bottom to upper sediments before a decreasing trend in the topmost sediments. The rapid urbanization and industrialization of these regions in recent decades may cause the historically increasing concentrations of sedimentary PBDEs, especially BDE-209. The decreasing PBDEs concentrations in topmost sediments was probably related to the strict environmental policies at present.

Surface water quality has been greatly affected by anthropogenic activities around the world in the past decades. Scientists and policymakers should pay close attention to quantify historical change in human impacts on aquatic environment. An effective method for reconstructing the historical input of anthropogenic organic matters in aquatic environment is urgently required. Here, five sediment cores from the Huaihe River were analyzed for n-alkanes (C8-C40) and isoprenoid alkanes (pristane and phytane) using gas chromatography-mass spectrometry (GC-MS). Sixty years (1955-2014) sedimentary history of n-alkanes was reconstructed using 210Pb method. The evaluation of wax n-alkanes percentage (WNA) indicated that the terrestrial higher plant input was predominant in most samples. The main anthropogenic sources were the petroleum hydrocarbon, fossil fuel combustion and the discharge of industrial wastewater and domestic sewage. The results of principal component analysis-multiple linear regression (PCA-MLR) indicated that the respective contributions of anthropogenic and biogenic sources to sedimentary organic matters were 47.8% and 48.1% in the Huaihe River. Furthermore, the anthropogenic contribution displayed a decrease trend from 1991 to 2014, which probably attributed to the effective pollution control measures taken by the local government. However, the anthropogenic contribution was still considerable during this period. Thus, the government should pay attention to organic pollution control in the Huaihe River sediments continuously. In summary, this study provides an effective method for reconstructing the historical change in anthropogenic contribution to sedimentary organic matters in rivers, which can probably be applied to other aquatic environment around the world.