Effects Of Anthropogenic Activities Research Articles

Distribution and potential provenance of trace elements in a 120-year dated sediment core from west Daya Bay, northeastern South China Sea

Eighteen trace elements were analyzed in a 120-year sediment core from Daya Bay. Burial flux history and potential provenance, the relationships among trace elements, and biogenic compositions were analyzed for determining the trend and extent of trace element accumulation and identifying corresponding anthropogenic effects. Additionally, the effects of anthropogenic activities on Daya Bay were reconstructed, and a baseline/background estimation was provided for Daya Bay. The burial fluxes of V, Cr, Cd, Cu, Zn, Mn, Fe, Co, Ni, Pb, Hg, Zn, Mo, Ag, As, Se, and Tl increased from 1960 to 2010, especially after the late 1980s. Our results are useful for understanding pollution and land-sea interactions along the coasts of the South China Sea, especially in the Guangdong-Hong Kong-Macao Greater Bay Area.

Sources and features of particulate organic matter in tropical small mountainous rivers (SW China) under the effects of anthropogenic activities

Small mountainous rivers (SMRs), particularly those in the tropics, play a disproportionate role in global carbon cycling and have been heavily disturbed by anthropogenic activities during the Anthropocene. Identifying the sources of particulate organic matter (POM) in SMRs and their influencing factors have crucial scientific significance in terms of filling a cognitional gap concerning the fate of POM in tropical land–ocean ecosystems and practical values regarding environmental management and ecological evaluation. In this study, total suspended solids concentration, particulate organic carbon and particulate nitrogen contents, stable carbon isotope (δ13C), and C/N ratio of suspended particulates were investigated from five SMRs (Fangcheng, Maoling, Qin, Dafeng, and Nanliu) in Guangxi Province, southwest China. The soil (OMsoil), C3 plants (OMC3), and autochthonous production (OMauto) were identified as potential POM sources, and their relative contributions were quantified via the use of end-member mixing models that were based on the classic indicators of δ13C and C/N. The results showed that soil was the biggest POM contributor in Nanliu, Qin, and Maoling rivers, whereas OMC3 was more important in Fangcheng River. Compared to other watersheds, the OMauto accounted for a very minor proportion of the POM sources in Fangcheng River. Nanliu and Fangcheng, as typical representatives of agricultural and forest watersheds, respectively, exhibited remarkable differences in terms of POM sources. Land use patterns that were dominated by agricultural expansion, the soil erosion that resulted from the destruction of vegetation and engineering construction, and hydrological characteristics such as flow velocity and nutrient concentration were all found to vastly impact the sources of POM reaching the different types of SMR. These influencing factors are mainly derived from anthropogenic activities, whose effects on the tropical SMRs ecosystems and even the global biogeochemical cycle, may exceed our expectation.

Effects of organic matter addition on chronically hydrocarbon-contaminated soil.

Soil is the recipient of organic pollutants as a consequence of anthropogenic activities. Hydrocarbons are contaminants that pose a risk to human and environmental health. Bioremediation of aging contaminated soils is a challenge due to the low biodegradability of contaminants as a result of their interaction with the soil matrix. The aim of this work was to evaluate the effect of both composting and the addition of mature compost on a soil chronically contaminated with hydrocarbons, focusing mainly on the recovery of soil functions and transformations of the soil matrix as well as microbial community shifts. The initial pollution level was 214ppm of polycyclic aromatic hydrocarbons (PAHs) and 2500ppm of aliphatic hydrocarbons (AHs). Composting and compost addition produced changes on soil matrix that promoted the release of PAHs (5.7 and 15 % respectively) but not the net PAH elimination. Interestingly, composting stimulated AHs elimination (about 24 %). The lack of PAHs elimination could be attributed to the insufficient PAHs content to stimulate the microbial degrading capacity, and the preferential consumption of easily absorbed C sources by the bacterial community. Despite the low PAH catabolic potential of the aging soil, metabolic shift was driven by the addition of organic matter, which could be monitored by the ratio of Proteobacteria to Actinobacteria combined with E4/E6 ratio. Regarding the quality of the soil, the nutrients provided by the exogenous organic matter contributed to the recovery of the global functions and species diversity of the soil along with the reduction of phytotoxicity.

Plateau lake ecological response to environmental change during the last 60 years: a case study from freshwater Lake Yangzong, SW China

The effects of anthropogenic activity and climate change on lake ecosystems for nine large plateau lakes in Yunnan Province have recently received much attention; however, most studies have focused on the deepest lake sediments and ignored the lake sediments adjacent to the populated area. To evaluate the sedimentation rates and ecological changes, four 210Pb- and 137Cs-dated sediment cores were collected along the long axis of Yangzong Lake, a fault-controlled north-south strike lake located in Yunnan Plateau in July 2006 and July 2016, respectively. We combined a biological indicator (diatom assemblage) with geochemical indicators (total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP)) for core S0 in the southern part of the lake to examine the ecological changes in response to anthropogenic disturbances within the lake over the last 60 years. The results showed that the sedimentation rate in the southern part of the lake (S1) was significantly higher than that in the central (S2) and northern (S3) parts of the lake. Redundancy analysis (RDA) and Pearson correlation analysis identified significant correlations between TP and Aulacoseira granulata, Cyclotella ocellata, and Cyclotella rohomboideo-elliptica (correlation coefficients: − 0.66, − 0.63, and 0.81, respectively, p < 0.01). There was a clear shift in the diatom community from oligotrophic to eutrophic species becoming dominant after the 1990s, coinciding with the intensifying human activities around the lake. Furthermore, there were two periods of diatom absence in core S0, which was associated with two periods of rapid depositional events. These are likely associated with the intensification of industry, mining, road construction, and agriculture within the lake catchment. These findings highlight the sensitivity of freshwater ecosystems in the shallow-water area of a lake to human activities, with implications for future water quality in fault-controlled lakes.

Effects of anthropogenic activities on microplastics in deposit-feeders (Diptera: Chironomidae) in an urban river of Taiwan

The presence of microplastics (MPs) in the environment has generated global concerns. However, the explicit assessment of the effect of multiple anthropogenic activities on the existence of MPs in the freshwater system is scarcely reported. This study quantified anthropogenic activities and analyzed their relationship with MPs on a freshwater organism: the midge larvae (Diptera: Chironomidae). The study took place in an urban river and consisted of comparing the abundance and types of MPs. Our results highlight that, while industrial area was the most important variable contributing to the total MP concentration in midge larvae, residential area also influenced the concentration of microfibers in midge larvae. The impact of a residential area on the relative abundance of microfibers in each sample site was diluted by the proximity to an industrial area. In conclusion, we suggest that industrial areas are a potential source of MP pollution in river sediment, and midge larvae can be a good indicator of the MP concentrations in urban river systems. Quantifying anthropogenic activities can help discern their effects on MP concentration in a river system and promote management strategies.

Effects of Anthropogenic Activities on the Physicochemical and Microbiological Characteristics of Aba River and Sediment

Effects of Anthropogenic Activities on the Physicochemical and Microbiological Characteristics of Aba River and Sediment

Age estimation and growth of striped dolphins Stenella coeruleoalba stranded along the coasts of south-western Italy

The knowledge of demographic traits such as longevity, growth rates and age at sexual maturity is crucial for understanding the structure of a population in its natural environment and implementing appropriate strategies for its management and conservation. Based on counts of growth layer groups in sections of decalcified teeth using the paraffin technique, we estimated the age and growth of 25 individuals of striped dolphin (Stenella coeruleoalba) found dead stranded along the coast of Campania and Calabria (south Italy, central-western Mediterranean) from 2013 to 2018. Seven individuals, with TL of 100–110 cm, were calves under 1 year old. The oldest male and female individuals were 19 and 14 years old, respectively. Growth curve estimated using the Gompertz growth model (GGM) showed that in S. coeruleoalba male growth trajectories are partly in accordance with those reported in other studies on the same species from different Mediterranean areas. The high frequency (28%) of calves strongly suggests that females of this species use the marine area all around the south-western Italian coasts to give birth to their offspring. Furthermore, a comparison with the estimated age of striped dolphins from other Mediterranean marine areas shows that the longevity of the individuals examined in this study is much lower. Our study provides information toward understanding the demographic traits of S. coeruleoalba from Mediterranean Sea. The results reported here can be useful for future research aimed at understanding population structure, mortality patterns and the effects of anthropogenic activity on the survival of this species in this marine area.

Impact of haze events on airborne bacterial consortia\u2013a case study

Transboundary haze events received a noticeable attention recently, due to their frequent occurrences. They are mainly, consequences of anthropogenic activities. Sri Lanka experienced a haze event parallel to India in November 2019, the first air pollution event in Sri Lanka linked to a haze event in India. Due to the limited availability of information on haze-related microorganisms, we conducted this study in Kandy, Sri Lanka, aiming to explore the airborne bacterial consortia during a haze event. The natural sedimentation method was used for air sampling. Bacterial identification and the total bacterial load were determined using Sanger sequencing and qPCR. Notably, the total bacterial load was elevated by ~ 40% with the haze and decreased with decreasing haze intensity. The highest bacterial load was reported during the day time of the most intense hazy day (1.89 × 106 cells/µl) compared to non-hazy days (lowest; 1.12 × 105 cells/µl). Twelve bacterial species were identified and the most abundant phylum was Proteobacteria. The most common species observed during haze was Acinetobacter modestus. The percentage of culturable bacterial species was also high during the haze event (75% during day time of the most intense hazy day compared to 25% on the control). Two human pathogenic bacteria Burkholderia multivorans and Chryseobacterium gleum were found only during the haze event. Therefore, haze events could be hazardous to humans by means of the presence and fluctuating amounts of pathogenic bacteria. Thus, these findings are important in developing policies and guidelines to monitor and minimize the negative impact of haze events.

Efecto de las actividades antropogénicas sobre la cobertura de mangle en la cuenca baja del río Coatzacoalcos

Los manglares son uno de los tipos de humedales costeros presentes en la cuenca baja del río Coatzacoalcos que, a pesar de su creciente deterioro, conservan importancia ecológica y económica. El objetivo del presente estudio fué identificar la principal actividad antropogénica que ha contribuído a reducir la cobertura de manglar en la cuenca baja del río Coatzacoalcos, mediante dos métodos: 1) comparando las áreas de los manglares y el desarrollo urbano, entre los años 1986 y 2016, con imágenes Landsat y Sentinel (escala 1:250,000), utilizando Q-Gis versión 2.14.2; y 2) mediante una matriz de máximos y mínimos, donde se asignaron valores para calificar el grado de afectación de las acciones antrópicas a cada componente del ecosistema. De acuerdo con el análisis espacial realizado, entre 1986 y 2016, se registró una pérdida del 86% de manglares, asociado al aumento de los asentamientos humanos en la cuenca baja del río Coatzacoalcos. Las acciones que más afectaron los componentes ambientales fueron los asentamientos humanos, desmontes y rellenos, ganadería y emplazamientos industriales con porcentajes de afectación de 15.9, 15.7, 15.5 y 13.5%, respectivamente. Los componentes ambientales más afectados fueron el suelo, la flora y el agua, con porcentajes de afectación del recurso de 17, 17 y 16%, respectivamente. Los asentamientos humanos son la principal causa de pérdida de manglares en la cuenca baja del río Coatzacoalcos, en particular los asentamientos irregulares que se dan en la región.

New Insights into Impacts of Toxic Metals in Aquatic Environments

Chemical contamination of the aquatic environment, as a consequence of anthropogenic activities, remains of major worldwide concern [...]

Сучасний екологічний стан поверхневих вод р. Трубіж

The problem of environmental safety of water bodies is relevant today, especially for the basins of small and medium-sized rivers, which are clear indicators of the environment state. One of them is the Trubizh River. The water resources of this river are formed under the anthropogenically changed conditions of the drainage and humidification complex of the Trubizh reclamation system. These resources are also receivers of effluents from point and diffuse sources. Thus, there is a need for constant monitoring of the ecological condition of the river. The water quality of it is a consequence of anthropogenic activities in the watershed. The aim of the work is a comprehensive assessment of the Trubizh River ecological condition under the modern conditions of water quality formation. The analysis has been conducted using official data from the state monitoring of water quality for 2015-2019 years and our own research for 2015-2016 years. 7 observation points have been considered from souse to mouth of the river: border areas of Brovary and Baryshivka; Baryshivka – 1 km above and 0.9 km below the village, Pereyaslav-Khmelnytsky – 0.5 km above and 1 km below the town, the mouth of the Alta and Trubizh rivers). We used such methods as analytical (determination of water quality indicators according to generally accepted standardized methods); analysis, systematization and generalization of the monitoring database; method of calculation of integrated block indices and complex ecological index of water quality (IE). It is established that during the five-year period (2015-2019) according to the weighted average and the worst values of the complex ecological index (IEworst 4.2) the waters are characterized as "satisfactory", "slightly polluted" of the III class quality 4 category. In 2018 and 2019 years, there was a deterioration in water quality by one category (III quality class 5 category) - "mediocre", "moderately polluted" water. This is due to a set of conditions of natural and climatic (insufficient rainfall and rising air temperature) and anthropogenic nature (water pollution, unauthorized surface water abstraction, runoff obstruction, etc.). It is noted that Trubizh river is characterized by stable uniform spatial water pollution. The largest values of IE are recorded in the area of influence of the village Baryshivka (IE worst 3.7-3.8) and Pereyaslav-Khmelnytskyi in the sampling points: the Alta river mouth (IEworst 4.0) and the Trubizh river mouth (IEworst 3.7). The water quality in these sampling points corresponded to class III of category 4 and was generally characterized as "satisfactory", "polluted". In general, the deterioration of water quality is caused by organic pollution (according to the indicator of dichromate oxidation (IV class, 6 category), BOD5 (Biochemical oxygen demand) (III class, 5 category), nitrogen compounds (ammonium, nitrite and nitrate) – V class, 7 category) and phosphorus compounds (phosphate ions – III class, 5 category), total iron and general chromium – III class, 5 category, phenols and SSAS (synthetic surfactants active substances) – IV class, 6 category. Thus, one of the main reasons for the degradation of the river is the anthropogenic conditionality of its development as a result of the urbanized and agricultural areas impact. The obtained data open the prospect of continuing work on monitoring and assessing the ecological status of aquatic ecosystems of the Trubizh River for the further development of scientifically based recommendations. It is necessary for making management decisions for sustainable use and protection of surface waters and restoration of aquatic ecosystems of Trubizh River Basin.

Habitat fragmentation shapes natal dispersal and sociality in an Afrotropical cooperative breeder.

It remains poorly understood how effects of anthropogenic activity, such as large-scale habitat fragmentation, impact sociality in animals. In cooperatively breeding species, groups are mostly formed through delayed offspring dispersal, and habitat fragmentation can affect this process in two opposite directions. Increased habitat isolation may increase dispersal costs, promoting delayed dispersal. Alternatively, reduced patch size and quality may decrease benefits of philopatry, promoting dispersal. Here, we test both predictions in a cooperatively breeding bird (placid greenbul, Phyllastrephus placidus) from an Afrotropical cloud forest archipelago. Males born in fragmented forest dispersed about 1 year earlier than those born in continuous forest. Contrary to females, males also started to reproduce earlier and mostly settled within their natal patch. Females only rarely delayed their dispersal for more than 1 year, both in fragmented and continuous forests. Our results suggest that early male dispersal and reproduction is jointly driven by a decrease in the value of the natal territory and an increase in local breeding opportunities in fragmented forest. While plasticity in dispersal strategies of cooperative breeders in response to anthropogenic change is believed to optimize reproduction-survival trade-offs, to what extent it shapes the ability of species to respond to rapid environmental change remains to be studied.

Removal of Contaminants from Water by Bacterial Activity

High concentration of sulphates and metals in waters is often as a consequence of anthropogenic activity and industry. The principlesof the biological-chemical methods for pollution removal include various processes. The most widely metabolic pathway of sulphate-reducing bacteria - overall dissimilatory reduction - is the complete reduction of sulphate to hydrogen sulphide. Two major metabolicgroups are known, depending on whether or not they can oxidize acetate. One group utilizes lactate, fumarate, propionate, butyrate,pyruvate, and aromatic compounds, which they typically oxidize to acetate, while the other group oxidizes acetate to CO₂ and H₂O.Sulphate is reduced to H₂S through a series of intermediate reactions. The end product of this reaction, hydrogen sulphide, can reactwith metal ions to form insoluble metal sulphides or reduce soluble toxic metals, often to less toxic or less soluble forms. This way,sulphate-reducing bacteria are utilizable in bio-elimination of sulphate and metal from water.

Greenhouse gas balance in global pasturelands and rangelands

Grassland ecosystems play an essential role in climate regulation through carbon (C) storage in plant and soil. But, anthropogenic practices such as livestock grazing, grazing related excreta nitrogen (N) deposition, and manure/fertilizer N application have the potential to reduce the effectiveness of grassland C sink through increased nitrous oxide (N2O) and methane (CH4) emissions. Although the effect of anthropogenic activities on net greenhouse gas (GHG) fluxes in grassland ecosystems have been investigated at local to regional scales, estimates of net GHG balance at the global scale remains uncertain. With the data-model framework integrating empirical estimates of livestock CH4 emissions with process-based modeling estimates of land CO2, N2O and CH4 fluxes, we examined the overall global warming potential (GWP) of grassland ecosystems during 1961–2010. We then quantified the grassland-specific and regional variations to identify hotspots of GHG fluxes. Our results show that, over a 100-year time horizon, grassland ecosystems sequestered a cumulative total of 113.9 Pg CO2-eq in plant and soil, but then released 91.9 Pg CO2-eq to the atmosphere, offsetting 81% of the net CO2 sink. We also found large grassland-specific variations in net GHG fluxes, with pasturelands acting as a small GHG source of 1.52 ± 143 Tg CO2-eq yr−1 (mean ± 1.0 s.d.) and rangelands a strong GHG sink (−442 ± 266 Tg CO2-eq yr−1) during 1961–2010. Regionally, Europe acted as a GHG source of 23 ± 10 Tg CO2-eq yr−1, while other regions (i.e. Africa, Southern Asia) were strong GHG sinks during 2001–2010. Our study highlights the importance of considering regional and grassland-specific differences in GHG fluxes for guiding future management and climate mitigation strategies in global grasslands.

226Ra, 210Po and lead isotopes in a pit lake water profile in Sweden

A pit lake arises as a consequence of anthropogenic activities in opencast mining areas. These water bodies may be enriched in hazardous stable contaminants and/or in naturally occurring radionuclides depending on the local geological conditions. Mining legacy in Sweden produced hundreds of these pit lakes and most of them are used for recreational purposes in the southern part of the country. In this paper, one pit lake was selected for having enhanced levels of natural radionuclides. Physico-chemical parameters (temperature, pH, oxidation-reduction potential, dissolved oxygen and depth), elemental composition (via Inductive Coupled Plasma Mass Spectrometry) and radiometric characterization (via alpha spectrometry of 226Ra, 210Po and 210Pb) were carried along the depth of a 60 m depth pit lake, with the main aim to describe how natural radionuclides and elements behaves with depth in a non-uraniferous pit lake.Based on observed changes in physico-chemical parameters, a thermocline and a chemocline region were identified at around 10 and 30 m depth respectively. Concerning radionuclides, 226Ra ranged from 75 ± 3 up to 360 ± 12 mBq/kg while 210Po ranged from 11 ± 1 up to 71 ± 3 mBq/kg. 210Pb distribution with depth was also determined via secular equilibrium with 210Po after 2 years and also stable Pb was measured. Disequilibrium 226Ra-210Pb was found and the residence time of 210Pb in the water column was assessed. Additionally, different vertical distributions between 210Pb and Pb were found which points out different sources for different lead isotopes in the water body.

Response of grassland productivity to climate change and anthropogenic activities in arid regions of Central Asia.

BackgroundQuantitative evaluations of the relative impacts of climate change and anthropogenic activity on grasslands are significant for understanding grassland degradation mechanisms and controlling degraded grasslands. However, our knowledge about the effects of anthropogenic activities and climate change on the grassland in a mountain basin system in arid regions of Central Asia is still subject to great uncertainties.MethodsIn this research, we have chosen the net primary productivity (NPP) as an index for revealing grassland dynamics processes. Moreover, the human appropriation of net primary production (NPPH), which was calculated as the potential NPP (NPPP) minus the actual NPP (NPPA), was applied to distinguish the relative influences of climate change and human activities on the grassland NPP variations in a mountain basin system of Central Asia from 2001–2015.ResultsThe results indicated that the grassland NPPA showed an increasing trend (35.88%) that was smaller than the decreasing trend (64.12%). The respective contributions of human activity, climate change and the two together to the increase in the NPPA were 6.19%, 81.30% and 12.51%, respectively. Human activity was largely responsible for the decrease in the grassland NPPA, with the area experiencing human-induced decreases accounting for 98.21% of the total decreased area, which mainly occurred during spring/autumn pasture and winter pasture. Furthermore, the average grazing pressure index (GPI) values of summer pastures, spring/autumn pasture and winter pastures were 1.04, 3.03 and 1.83, respectively, from 2001–2015. In addition, negative correlations between the NPP and GPI occupied most of the research area (92.41%).DiscussionOur results indicate that: (i) anthropogenic activities were the primary cause of the reduction in the grassland NPP, especially grazing activities. (ii) For areas where the grassland NPP has increased, precipitation was the dominant climatic factor over temperature in controlling the grassland NPP changes in the study area. (iii) The findings of the current research indicate that some measures should be taken to reduce livestock pressure, and artificial grasslands can be built along the Irtysh River and the Ulungur River to relieve grazing pressure on spring/autumn pastures and winter pastures. Our results could provide reliable information for grassland management and the prevention of grassland degradation in arid regions of Central Asia.

Effects of anthropogenic activities on land-use dynamics in an upland tropical evergreen forest in Ghana

ABSTRACT The Atewa Range Forest Reserve (ARFR) in Ghanais threatened by anthropogenic activities. This study used geospatial techniques to assess the effects of human activities on land use and land cover (LULC) dynamics in ARFR using Landsat satellite images of 1986, 1991, 2006 and 2016. Estimated Normalized Differential Vegetation Index showed a continuous decline in LULC, signifying increasing stress on vegetation in ARFR. Between 1986 and 2016, the rainforest reduced from 345.83km2 to 183.48km2; logged land declined from 324.52km2 to 186.21km2; farmland increased from 328.43km2 to 384.68km2; and settlement expanded from 110.48km2 to 354.91km2, respectively.

Effect of heavy metals on toxicogenetic damage of European eels Anguilla anguilla.

Aquatic organisms are exposed to a variety of contaminants such as heavy metals introduced into the environment as a consequence of anthropogenic activities that usually cause genotoxic damage in aquatic organisms. DNA damage biomarkers for fish species detect genotoxic parameters for ecological risk assessment. In the present study, the effect of heavy metals (Cd, Cr, Cu, Fe, Ni, Pb, Zn, Co, and Mn) on DNA damage of Anguilla anguilla was examined by comet assay at reference site and three different sampling sites of the Orontes River. The relative mean heavy metal concentrations in water column were in the order of Fe>Cr>Pb>Zn>Ni>Cu>Mn>Cd>Co in all the sampling sites. Cr, Cd, and Pb concentrations at all sampling sites were above the values allowed by the EPA (1999, 2016). With these results, negative effects of Cr, Cd, and Pb appeared on ecosystem health. The comet assay showed a higher level of DNA damage in the gill cells in comparison with the liver cells of A. anguilla. The highest level of DNA damage as %T-DNA, tail moment, and tail migration in gill cells were 20.007 ± 1.744 %; 2.899 ± 0.341 μm, and 12.383 ± 01.040 TMi and 20.172 ± 1.944 %, 2.559 ± 0.265 μm, and 10.763 ± 0.910 TMi at Site 2 and Site 3, respectively. The correlations between heavy metals and DNA damage parameters revealed that both Cu and Co in water showed significant negative correlations (p < 0.05) with DNA damage levels. Consequently, this study revealed the genotoxic damage of A. anguilla due to pollution in Orontes River and lead to the better understanding of genotoxicity and heavy metal relationships.

Climatic water balance of mesophilic montane forest in the Huasteca region

We worked in areas of mesophilic mountain forest in the states of Puebla, Hidalgo and Veracruz, located within the Huasteca region. By its nature, the mountain mesophyll forest is a good water catcher. But its forest cover has decreased as a consequence of anthropogenic activities, negatively impacting water catchment. The temporal evolution (1979–2015) of the humidity index of the areas where mountain mesophyll forest exists was associated with the changes in its cover from 1997 to 2016. The results show that from 1979 to 2004, the humidity index decreased as a consequence of more than 29% deforestation. From 2005 to 2016, the deforestation rate did not exceed 1% and the humidity index presented an increasing trend. The conservation of this ecosystem is recommended as a priority to improve the amount of water in the region.

Effect of anthropogenic activities on the occurrence of polycyclic aromatic hydrocarbons in aquatic suspended particulate matter: Evidence from Rhine and Elbe Rivers

As carcinogenic and pervasive pollutants, polycyclic aromatic hydrocarbons (PAHs) in surface water are crucial to environmental policies, and the understanding of their trends and influencing factors is critical for achieving a good chemical and ecological status of water bodies. Based on long-term monitoring data from 1998 to 2017, this study systematically evaluated the spatiotemporal distribution, multimedia transport, fate, and source apportionment of PAHs adsorbed on suspended particulate matter (SPM) in Rhine and Elbe Rivers. The results of the Mann-Kendall test indicated that pollution levels of PAHs decreased from 2.81×105μg⋅s−1 to 9.80×104μg⋅s−1 on average in the Rhine and from 1.60×105 μg⋅s−1 to 5.21×104 μg⋅s−1 in the Elbe in the last 20 years. Spatially, SPM near urban areas had higher PAH mass fluxes (Rhine:3.07×105μg⋅s−1, Elbe: 1.73×105μg⋅s−1) and greater rates of decrease (slopes for Rhine and Elbe: −409, −323) than those near rural areas (Rhine:1.41×105 μg⋅s−1, Elbe: 9.35×104μg⋅s−1; slopes for Rhine and Elbe: −128, −89), indicating the significant influence of anthropogenic activities. Wavelet analysis showed that the pollution level of PAH had significant periodic oscillations for the Rhine and Elbe, and revealed several abrupt change points for the two rivers. A multimedia fugacity model demonstrated that impervious surfaces had the highest concentration (Rhine: 1.84g⋅m−3, Elbe: 0.15g⋅m−3), while soil (Rhine: 8.33×107g, Elbe: 2.53×106g) and sediments (Rhine: 4.85×106g, Elbe: 1.31×106g) had higher masses of PAHs. Furthermore, source apportionment computed using a self-organizing map and positive matrix factorization model suggested that the major sources of PAHs were vehicular emissions and coal combustion, which accounted for 51.86% of the total mass in the Rhine and 62.92% in the Elbe. The data revealed that the long-term trends of PAH variation were associated with changes in energy consumption and the implementation of vehicular emission standards. Therefore, the substitution of coal and petroleum with renewable energies could assist strategies of PAH mitigation in the environment and gradual reduction of pollution levels.