Distribution,characteristics, and research status of microplastics in the trunk stream and main lakes of the Yangtze River: A review

Microplastic pollution has become an environmental issue of great concern owing to the persistence of microplastics and their potential adverse effects on biota.The Yangtze River is the longest river in China and the third-longest river in the world,and the microplastics in this river will affect the health of a large population living along with it.To ensure the survival safety of people,it is essential to plan ahead and investigate in advance in order to understand the microplastic pollution in the river and work out countermeasures.This paper reviews the literature concerning the microplastic pollution in the Yangtze River basin and analyzes the abundance,shapes,colors,and composition of microplastics in the water bodies and sediments in the trunk stream and main lakes of the Yangtze River.The results are as follows.Compared to other river basins in China and abroad,the microplastics in the Yangtze River basin have a moderate abundance and high spatial heterogeneity.Owing to the barrier effect of the Three Gorges Dam on microplastics,the abundance of microplastics in the Three Gorges Reservoir is generally an order of magnitude higher than that in other sections of the river.Most microplastics in the water bodies and sediments are less than 1 mm in size and are transparent and colorful.In terms of shapes,they are dominated by fibers,followed by fragments and films.In terms of composition,the microplastics in the source region of the Yangtze River are mainly composed of nylon and polyethylene,while the microplastics in the surface water from the lower reaches of the Jinsha River to the Yangtze River estuary are dominated by polypropylene and polyethylene.The microplastics are primarily derived from the secondary microplastics in the environment,and relatively intensive human activities increase the abundance of microplastics.These results serve as bases for understanding and preventing microplastic pollution in the Yangtze River.     

Microplastic contamination in lacustrine sediments in the Qinghai-Tibet Plateau: Current status and transfer mechanisms

This paper aims to investigate the present situation and transfer mechanisms of microplastics in lacustrine sediments in the Qinghai-Tibet Plateau. The study surveyed the average abundance of microplastics in sediments. The abundance of microplastics in sediments of lakes from the Qinghai-Tibet Plateau is 17.22–2643.65 items/kg DW and 0–60.63 items/kg DW based on the data of the Qinghai Lake and the Siying Co Basin. The microplastic abundance in sediments from small and medium lakes is very high compared to that in other areas in the world. Like microplastics in other lakes of the world, those in the lakes in the Qinghai-Tibet Plateau mainly include organic polymers PA, PET, PE, and PP and are primarily in the shape of fibers and fragments. The microplastic pollution of lacustrine sediments in the Qinghai-Tibet Plateau is affected by natural changes and by human activities, and the concentration of microplastics in lacustrine ecosystems gradually increases through food chains. Furthermore, the paper suggests the relevant administrative departments of the Qinghai-Tibet Plateau strengthen waste management while developing tourism and pay much attention to the impacts of microplastics in water environments. This study provides a reference for preventing and controlling microplastic contamination in the Qinghai-Tibet Plateau.©2022 China Geology Editorial Office.     

Microplastic pollution in Yellow River,China: Current status and research progress of biotoxicological effects

This study aims to comprehensively assess the environmental risks of microplastics in the Yellow River, achieving the following results through comprehensive research. The average microplastic abundances in the river waters and sediments are 5358–654000 n/m³ and 43.57–615 items/kg, respectively, and there are fewer microplastics in water samples than in sediments. Microplastics in the study area can be divided into five types according to their occurrence morphologies, namely fragments, foams, films, fibers, and particles. The most widely distributed pollution types in sediments include debris, fibers, and particles. In contrast, fibers are the dominant type in water samples, accounting for 68.18% –98.93%. The chemical components of the microplastics include polyethylene, polypropylene, polystyrene, polyethylene terephthalate, and polyvinyl chloride. The microplastics are in four colors, with white accounting for a higher proportion. The grain size of the microplastics in tributaries or lakes of the Yellow River is less than 2 mm, which makes them liable to enter organisms for enrichment. Furthermore, the sources of the microplastics are closely related to agricultural and industrial production and biological activities in habitats and exhibit seasonal and hydrological characteristics. The microplastics in the study area show the adsorption of metals and nonmetals to different degrees, which increases the pollution risks of heavy metals combined with microplastics. In addition, microplastics can accumulate in organisms in the Yellow River and cause physical, biochemical, and other damage to aquatic organisms, thus further posing carcinogenic risks to human beings. Therefore, it is necessary to study, monitor, and control the pollution and effects of microplastics in the Yellow River, in order to provide theoretical references for the control of pollution and ecological risk of microplastics in the river.©2021 China Geology Editorial Office.     

Microplastic pollution in surface water and sediments of Qinghai-Tibet Plateau: Current status and causes

To study the current status and causes of the microplastic pollution in surface water of the Qinghai-Tibet Plateau, this paper compared the average microplastic abundance in sediments and surface water of the Qinghai-Tibet Plateau and the results are as follows. First, the average microplastic abundance in surface water of the independent rivers and the whole area is 247–2686 items/m³ and 856 items/m³, respectively. The average microplastic abundance in sediments of independent rivers or lakes and the whole area is 0–933 items/m² and 362 items/m², respectively. Meanwhile, the degree of microplastic pollution in river sediments is higher than that in lake sediments, and the rivers suffering from microplastic pollution mainly include the Brahmaputra River, Tongtian River, and Nujiang River. Second, compared with the microplastic pollution in other areas of the world, the levelof microplastic pollution in the lakes and rivers of the Qinghai-Tibet plateau is not lower than that of well-developed areas with more intensive human activities. Finally, this study suggests that relevant government departments of the Qinghai-Tibet Plateau should strengthen waste management strategies while developing tourism and that much attention should be paid to the impacts of microplastics in the water environment.©2021 China Geology Editorial Office.     

Research Progress on Source-to-Sink Transport Processes of Marine Microplastics

Microplastics in marine environment are global environmental issue and challenge and have received an extensive international concern. At present, most of researches focus on the investigation of microplastic abundance in the ocean surface water, and there is insufficient understanding of the distribution and transport processes of microplastics in the deep-sea environment. This paper reviewed marine microplastic studies carried out in the last decade, and summarized the source, global distribution and transport processes of microplastics. Field investigations showed that both surface water and water column were important accumulation areas for microplastics, while deep-sea surface sediments were final sinks for microplastic deposition and accumulation. Transport of microplastics to the deep sea included two modes: vertical settlement and lateral transport. Laboratory simulation showed that the sinking rate of microplastic particles in the ocean changed between 300 and 1 000 meters per day, and the sinking process was not solely controlled by particle physical properties such as particle density, but also influenced by ocean dynamic process, biological action and marine snow aggregation. Microplastics deposited on the seafloor could migrate laterally towards the deep sea with resuspended sediments, which were related to internal waves, deep-sea turbidity current or climatic events. However, there remain the key knowledge gaps in uncertain speed and quantity of microplastics moving to the deep sea, which is not conducive to the comprehensive understanding of the microplastic transport process from source to sink. Therefore, it is recommended to observe the vertical sinking flux of microplastics with layered sediment traps in order to study the source-to-sink transport processes of microplastics in deep-sea environment.     

土壤中微塑料的来源、生态环境危害及治理技术

【研究目的】近年来，由微塑料造成的生态环境污染问题引起了广泛关注。【研究方法】本文通过查阅大量土壤微塑料方向的文献，综述了国内外关于土壤中微塑料的来源、危害及检测治理技术最新研究进展。【研究结果】主要包括：（1）土壤中微塑料的主要来源是没有高效回收的农用地膜的裂解，此外还有农业生产活动中使用含有微塑料的污水污泥、空气中的微塑料沉降到地表等；（2）土壤中的微塑料能吸附重金属、抗生素等污染物，改变土壤pH、容重等理化性质，影响蚯蚓等土壤动物的发育，降低参与土壤养分循环过程中关键微生物的活性，对土壤环境造成危害；（3）目前还没有统一的微塑料分离检测技术标准，目检法、光谱法和热分析技术是微塑料主要的分析方法。【结论】土壤中的微塑料会给环境及动植物健康带来不同程度的风险，进一步通过食物链威胁人类健康。未来的研究重点包括阻隔土壤微塑料的来源、 土壤微塑料与重金属的复合污染机制和新兴的土壤微塑料检测技术。创新点：（1）目前关于土壤微塑料方面的研究刚刚起步，本文综述了土壤微塑料对农作物、土壤环境的影响及在食物链中传播的风险，对今后有关环境污染和人体健康方向的研究有一定的帮助； （2）本文较为全面地整理了以农业生产活动为主的土壤微塑料来源，由于已被微塑料污染的土壤治理难度较高，笔者提出关于土壤微塑料源的阻断建议，希望能有效降低未来土壤中微塑料的输入量。     

Current status and cause analysis of microplastic pollution in sea areas in China

As a new type of pollutants in the marine environment,microplastics have attracted increasing attention from scientific researchers and environmental protection workers in China and abroad.However,for the microplastic pollution in sea areas in China,there are a very limited number of studies on its current status and few reviews of research on the microplastics.This paper reviews the surveys and researches of microplastics in the Bohai Sea,the Yellow Sea,the East China Sea,the South China Sea,and main estuaries in China carried out in recent years and proposes an outlook for future work,aiming to provide research suggestions and solutions for ecological protection against microplastic pollution in sea areas in China.Previous studies have shown that microplastics are widely distributed in water bodies and sediments in sea areas and major estuaries in China.The Pearl River Estuary,in the South China Sea suffers the most serious microplastic pollution,followed by the Bohai Sea.In contrast,the microplastic pollution in the Yellow Sea and the East China Sea is comparatively slight.Microplastics in sea areas in China are mainly fibrous and are concentrated in offshore areas with developed industry and a dense population(especially around estuaries and bays).In addition,they are widely affected by human activities,such as shipping,aquaculture,industry,and sewage discharge.Here the authors suggest unifying measurement units and research methods and developing related standard systems to carry out researches related to microplastics.Furthermore,this paper also suggests further deepening researches on both the source-sink process of microplastics and nanoscale microplastics while enhancing the development and implementation of related policies,aiming to promote researches and control of microplastics in sea areas in China.     

Holocene estuarine sediments as a source of arsenic in Pleistocene groundwater in suburbs of Hanoi,Vietnam

Groundwater pollution by arsenic is a major health threat in suburban areas of Hanoi, Vietnam. The present study evaluates the effect of the sedimentary environments of the Pleistocene and Holocene deposits, and the recharge systems, on the groundwater arsenic pollution in Hanoi suburbs distant from the Red River. At two study sites (Linh Dam and Tai Mo communes), undisturbed soil cores identified a Pleistocene confined aquifer (PCA) and Holocene unconfined aquifer (HUA) as major aquifers, and Holocene estuarine and deltaic sediments as an aquitard layer between the two aquifers. The Holocene estuarine sediments (approximately 25–40 m depth, 9.6–4.8 cal ka BP) contained notably high concentrations of arsenic and organic matter, both likely to have been accumulated by mangroves during the Holocene sea-level highstand. The pore waters in these particular sediments exhibited elevated levels of arsenic and dissolved organic carbon. Arsenic in groundwater was higher in the PCA (25–94 μg/L) than in the HUA (5.2–42 μg/L), in both the monitoring wells and neighboring household tubewells. Elevated arsenic concentration in the PCA groundwater was likely due to vertical infiltration through the arsenic-rich and organic-matter-rich overlying Holocene estuarine sediments, caused by massive groundwater abstraction from the PCA. Countermeasures to prevent arsenic pollution of the PCA groundwater may include seeking alternative water resources, reducing water consumption, and/or appropriate choice of aquifers for groundwater supply.     

河北邯邢铁矿区矿山环境生态地球化学评价

在河北邯邢西石门及周边铁矿区系统地采集了各类生态环境地球化学样品,包括土壤（n=242）、玉米（n=110）、地表水（n=37）、地下水（n=31）和水系沉积物（n=81）。通过对矿区各样品元素含量特征和元素富集程度的研究,利用区域地球化学基准值和地质累积指数定量评价了矿山污染扰动程度。研究表明,矿区土壤、玉米、地表水、地下水、水系沉积物中相对富集较高的与成矿作用有关的元素及主要的伴生元素,部分重金属元素超标,土壤和水系沉积物中Se、As、Cd、Cu、As、Cd、Cu、Co元素超标,玉米中F、Cr、Cd元素接近食品卫生限值,地表水和地下水部分指标浓度接近三类水质限值。研究表明,造成污染的主要来源是铁矿尾矿沙和煤矸石中的硫化物发生氧化作用,导致重金属淋滤转移,另一来源是燃煤降尘的积聚。     

Characterization and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in sediments in the Yellow River Estuary, China

Concentrations and sources of polycyclic aromatic hydrocarbons (PAHs) were investigated in surface sediments of the Yellow River Estuary (YRE). The isobath-parallel tidal and residual currents play important roles in the variation of PAH distribution, such that the contamination level of PAHs in fine-grained sediments is significantly higher than in the relatively coarse grain size sediments. Both diagnostic ratios and principal component analysis (PCA) with multivariate linear regression (MLR) were used to apportion sources of PAHs. The results revealed that pyrogenic sources are important sources of PAHs. Further analysis indicated that the contributions of coal combustion, traffic-related pollution and mixed sources (spills of oil products and vegetation combustion) were 35, 29 and 36 %, respectively, using PCA/MLR. Pyrogenic sources (coal combustion and traffic-related pollution) contribute 64 % of anthropogenic PAHs in sediments, which indicates that energy consumption could be a predominant factor in PAH pollution of YRE. Acenaphthylene and acenaphthene are the two main species of PAHs with more ecotoxicological concern in YRE.     

Distribution and impacts on the geological environment of antiviral drugs in major waters of Wuhan,China

This study investigated water samples collected from the surface water and groundwater in Wuhan City, Hubei Province, China in different stages of the outbreak of the coronavirus disease 2019 (hereinafter referred to as COVID-19) in the city, aiming to determine the distribution characteristics of antiviral drugs in the city’s waters. The results are as follows. The main hydrochemical type of surface water and groundwater in Wuhan was Ca-HCO₃. The major chemical components in the groundwater had higher concentrations and spatial variability than those in the surface water. Two antiviral drugs and two glucocorticoids were detected in the surface water, groundwater, and sewage during the COVID-19 outbreak. Among them, chloroquine phosphate and cortisone had higher detection rates of 32.26% and 25.80%, respectively in all samples. The concentrations of residual drugs in East Lake were higher than those in other waters. The main drug detected in the waters in the later stage of the COVID-19 outbreak in Wuhan was chloroquine phosphate, whose detection rates in the surface water and the groundwater were 53.85% and 28.57%, respectively. Moreover, the detection rate and concentration of chloroquine phosphate were higher in East Lake than in Huangjia Lake. The groundwater containing chloroquine phosphate was mainly distributed along the river areas where the groundwater was highly vulnerable. The residual drugs in the surface water and the groundwater had lower concentrations in the late stage of the COVID-19 outbreak than in the middle of the outbreak, and they have not yet caused any negative impacts on the ecological environment.©2022 China Geology Editorial Office.     

Numerical Simulation of Transportation of Marine Microplastics A Review

The temporal and spatial discontinuity of microplastic sampling data restricts the investigation on their source, sink, transport pathway and trend. Numerical simulation combined with sampling investigation can comprehensively study the effects of microplastic characteristics, meteorology and hydrodynamics on the distribution and transportation of microplastics. In this paper, the studies of microplastic numerical simulation were reviewed from the aspects of numerical simulating research and their applications in microplastic tranportation, and the results were summarized as follows: The construction of the main driving force (current); the influence of environmental factors, such as wind, waves, topography and extreme sea conditions on the properties of microplastics with different characteristics (particle size, density, shape) and their tranportation; the application of numerical simulation in the study of microplastic removal. Based on progress on the study of numerical simulation of marine microplastics, the future directions were pointed out that the further simulating studies should focuson the spatio-temporal distribution and evolvement of microplastics by combining sampling data and numerical model, the simulating research on the relationship between microplastic parameters (roughness, wind drag coefficient, settling rate, resuspension rate and biofouling rate) and (meteorological and ocean) dynamic condition. Moreover, the results of simulating sensitivity experiments should be compared with sampling and laboratory testing data to improve the empirical parameters and formulas of numerical model.     

Spatial variations and ecological risk assessment of heavy metals in surface sediments on the upper reaches of Hun River, Northeast China

The distribution, accumulation, and ecological risk of heavy metals (Cu, Cd, Pb, Zn, Ni, Cr, and As) in the surface sediment were investigated in the upper reaches of Hunhe River, Northeast China. Sediment samples from 51 points throughout the upper reaches of Hunhe River were collected and measured for heavy metal concentrations, TN content, and TP content. Results showed that heavy metal concentrations at the vicinity of mines and towns were higher than those at other locations. According to sediment quality guidelines (SQGs), Cd and Zn were enriched in the sediments. The correlation analysis and principal component analysis (PCA) were conducted to assess the heavy metal sources. Close correlations between metal distribution and TP indicated that the sediments may be affected by application of phosphate fertilizer. Elements, Cu, Cd, Pb, Zn, and As, were grouped together, reflecting they were released from the same sources. PCA suggested that their primary sources were anthropogenic, namely mining and extensive use of fertilizers. Therefore, heavy metal pollution due to mining and agricultural intensification in the upper Hunhe River basin should be taken into account during the formation of regional management strategies for the water environment.     

Assessment of organic pollutants (PAH and PCB) in surface water: sediments and shallow groundwater of Grombalia watershed in northeast of Tunisia

Toxic organic compounds in wastewater are serious threats for both human and environment healthy states. This study investigates the potential sources of surface water, sediment and groundwater pollution by polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyl (PCBs) as discharged by wastewater into the River of Oued El bey in northeastern Tunisia. Analysis indicates that the concentration of PAHs and PCBs are high in wastewater and vary from 0.37 to 0.83 mg/L and from 0.28 and 1.18 mg/L, respectively. The spatial distribution of PAHs and PCB in surface water showed a variation between 0.37 to 9.91 mg/L and between 0.1 to 0.47 mg/L, respectively. However, the quality of surface water is changed after wastewater evacuation at Oued Tahouna. The determination of PAH and PCB pollutants in groundwater shows a great interest in the development of water resources. The Concentration of these pollutants varying from 0.0204 to 1.93 mg/L and from 0.0052 to 0.196 mg/L, respectively. For PAH, analysis reveals also that naphtelene, fluorene, anthracene and chrysene are the most detected PAHs compounds in water and sediment samples while benzo[b]fluoranthene and benzo[a]pyrene are less present and in trace level. Higher concentrations of PAHs and PCBs are found in samples taken close to industrial areas of Bouargoub and Soliman, and wastewater discharge locations in Soliman. Analysis of the spatial distribution of PAHs and PCBs clearly link their higher concentration in water and sediments to wastewater and manufacturing discharges in the study area. In surface sediment, the organic pollutants are present. The cluster analysis for organic pollutants in different state and different matrix highlight a relationship between the wastewater evacuation and the water qualities which confirmed the direct response of the pollution sources on the surface water and groundwater organic pollution quality.     

A temporary sampling technique for investigating groundwater quality near the ground surface

Improved knowledge of processes determining groundwater quality is an important precondition for the solution of various ecological and water management problems. In areas with highly fluctuating groundwater levels, time-limited access, local pollution sources or temporary interactions between surface water and groundwater, a temporary groundwater sampling technique could be of advantage. Furthermore, depth-specific sampling is of high value for investigating groundwater pollution related to seepage or surface water infiltration. A stainless steel core probe has been developed to obtain groundwater samples and to measure the hydraulic head distribution at various defined depths. The sampling technique is applicable only for non-volatile water constituents. An advantage of the core probe is that it can be driven into soil or sediments using ordinary low cost percussion equipment. The probe enables hydraulic head measurements and water sampling over vertical intervals of 0.3 m. Results from field experiments using the stainless steel core probe were in good correspondence with results from groundwater sampling at nearby observation wells. In the upper layer of the aquifer, the intrinsic spatial change in concentrations of sulphate, chloride and other water constituents is a function of distance between observation points and groundwater surface. Results indicate strong effects of a fluctuating groundwater level on groundwater quality at certain depths.     

雄安新区白洋淀湿地地表水和地下水转化关系及其对芦苇分布的影响

查明地表水和地下水作用关系对湿地生态保护与修复具有重要意义。采用地表水和地下水位监测、氢氧稳定同位素分析、湖床沉积物温度示踪等方法,研究了白洋淀渗漏对周边浅层地下水的影响范围和深度,评价了地表水垂向渗漏速率,并探讨了芦苇分布面积和地表水位以及地下水位埋深的关系。结果表明：白洋淀渗漏受地质结构和水力梯度等因素影响,对浅层地下水垂向上影响深度为20 m,水平向上影响范围存在较大空间变异。周边浅层地下水的补给来源为大气降雨和地表水,其中地表水渗漏的补给比例为0~90.5%。淀区渗漏速率0.01~0.59 mm/d,和含水层埋深关系密切,埋深越小,越有利于地表水渗漏。1976-2020年,白洋淀芦苇分布面积和地表水位关系密切。当地表水位为6.3~6.8 m时,芦苇分布面积最大,在水位小于6.3 m条件下芦苇面积随着水位增高而增加,大于6.8 m条件下随着水位增高而减少。芦苇台地下水位埋深和地表水位显著相关,在2020年4-9月芦苇生长期,除雨季前期外多数时段台地地下水埋深均适宜芦苇发育,建议在雨季前期实施生态补水,通过降低台地地下水位埋深促进芦苇生长发育。研究结果可为白洋淀生态补水、渗漏防治和生态保护提供参考。     

广西防城港地区浅层地下水pH值时空分布、成因及对生态环境的影响

【研究目的】查明防城港地区浅层偏酸性地下水时空分布、成因及环境影响。【研究方法】于2013—2015年间进行了浅层地下水pH值现场测试,枯水期214组,丰水期168组;讨论了其时空分布特征、成因和生态影响。【研究结果】结果表明,丰水期和枯水期偏酸性（pH <6.5）地下水样分别占79.3%和64.3%,pH值总体上丰水期低于枯水期。地下水pH值在低山区（均在5≤pH＜5.5范围,平均值5.18,n=4）＜丘陵区（大多数5≤pH＜6.5,平均值5.18,n=202）＜平原区（大多数6.5≤pH＜8.5,平均值6.77,n=8）。【结论】偏酸性地下水成因主要与偏酸性大气降水有关,其次与酸性的包气带介质及硫化物矿物的氧化有关。偏酸性大气降水入渗补给是丰水期pH值低于枯水期的主要原因。相比较而言,潮汐作用使得江平地区地下水pH值升高。偏酸性地下水影响饮水安全（研究区枯水期仅20.6%的样品pH值符合生活饮用水标准）,促进某些有害组分的释放,腐蚀地下管网和建筑桩基等设施。偏酸性地下水向地表水排泄亦可对地表水环境和地表生态系统产生影响。本研究有助于研究区水资源管理。创新点：本研究利用地质调查项目数据优势,系统阐述了防城港地区浅层偏酸性地下水时空分布特征;偏酸性地下水的成因与偏酸性大气降水、酸性包气带介质和硫化物矿物氧化有关;偏酸性地下水对人类健康、地下设施和生态环境具有潜在影响。     

微塑料对水中甲基橙的吸附特征分析

以甲基橙(MO)为目标污染物,微塑料为载体,通过吸附动力学和等温吸附实验,比较通用塑料聚丙烯(PP)、通用工程塑料尼龙(PA)、聚甲醛(POM)和特种工程塑料聚四氟乙烯(PTFE)4种典型材质吸附MO的能力,并采用扫描电镜(SEM)、比表面积测试(BET)、显微拉曼光谱(Raman)、Zeta电位及傅立叶变换全反射衰减红外光谱(ATR-FTIR)技术手段对吸附前后PA进行表征,考察微塑料材质和PA粒径对MO吸附的影响,从而探究其可能存在的吸附机理。结果表明不同材质微塑料对MO的吸附能力具有明显差异性。其中,PA对MO的吸附量最大,可达7.39 mg/g,PA吸附MO的动力学过程包括起始的快速反应阶段和随后的慢速反应阶段,吸附过程符合二级动力学方程;等温吸附实验结果表明MO在PA上属于非均质化学吸附。静电作用及氢键的形成是造成不同材质微塑料吸附能力差异的主要原因,微塑料粒径大小与其对MO的吸附量呈显著负相关关系(R2=0.995, P<0.05),这与微塑料可提供的有效吸附位点息息相关。本研究可以为科学评价微塑料复杂的环境行为以及作为载体协同迁移污染物的能力提供依据。     

Review of water and soil contamination in and around Salihli geothermal field (Manisa,Turkey)

The town of Salihli is situated in Gediz Graben in the western Anatolia. This region is important in terms of industry, mining, geothermal energy, water sources, and agricultural production. Geothermal flow and anthropogenic activities in Salihli threaten the surrounding environment due to the contamination of cold groundwater, surface water, and soil. The goal of the present study is to determine the environmental effects of the geothermal and anthropogenic activities in Salihli on soil, stream sediments, and water. Stream sediments and farm soil have been contaminated by substances derived from geothermal and industrial effluents. To this end, the quality review of the water was completed and the heavy metal levels in stream sediment samples were measured to determine the extent of contamination. The elements As, B, Br, Fe, and Ni are the major contaminants present in surface water and groundwater in the study area. The concentrations of these elements excess tolerance limits of international water standards. Gibbsite, K-mica, kaolinite, sepiolite, halite, sulfur, willemite, and Pb(OH)₂ might be precipitated as scales at low temperatures on the soil; this could be interpreted as a resultant from soil contamination. The concentrations of 17 elements (As, Ba, B, Cd, Co, Cr, Cu, Fe, Hg, Li, Mo, Mn, Ni, Pb, Sb, Sr, and Zn) were measured in samples from stream sediments and surface soils. In the study area, especially geothermal and anthropogenic activities give rise to environmental pollution.     

Environmental impact of geothermal fluids on surface water, groundwater and streambed sediments in the Akarcay Basin, Turkey

In this study, the impact of geothermal water on ground and surface waters has been investigated in Akarcay Basin, Turkey. The release of thermal return water from district heating in the city of Afyon and from thermal baths has a considerable environmental impact on the main stream. Historical analyses of stream water quality data show that the present pollution is associated primarily with thermal return water of district heating system. Currently, about 6% of stream water comprises of thermal water. The pollution seems to degrade the water quality in Lake Eber. Streambed sediments were found to be in equilibrium with polluted water and may lead to additional pollution in lake water. Thermal groundwater intrusion to fresh water production wells was detected mainly at sites close to geothermal fields. Solutions to remove thermal water from surface environment are suggested.