River Water Research Articles

A Study on Distribution of Characteristics of Microplastic in the Han-River Watershed

Microplastic pollution in the marine environment is a global issue. Recently, in South Korea, there has been active research on the establishment of testing methods and investigation of distribution characteristics of microplastics not only in marine environments but also in freshwater systems. In particular, it is necessary to study the distribution of microplastics such as rivers and lakes, which are drinking water sources, to affect the water quality environment, management, and countermeasures. This study identified the distribution of microplastics in the mainstream and tributary of the Han River water system. The freshwater, sediment, and biological species samples were pre-treated accordingly, and microplastics larger than 20 µm were analyzed using μ-FT-IR. As a result of the inter-laboratory study, in the same way as in this study, it was possible to confirm that the trusted recovery rate was 63.6%. The survey results indicated that the number of microplastics per location ranged from 1,173 to 8,940 particles/L in freshwater samples, 3,800 to 192,000 particles/kg in sediment samples, and 34 to 384 particles/individual in fish samples. The most commonly found microplastic materials were PP, PE, and PTFE. The size distribution of plastics appeared in the following order: 45~100 µm, 100~300 µm, 20~45 µm, and greater than 300 µm, with predominantly fragmented shapes observed.

Jenis-jenis Makrozoobentos yang Ditemukan di Batang Kuantan Kawasan Wisata Geopark Silokek Kabupaten Sijunjung

The Kuantan River in the Silokek Geopark Tourism Area, Sijunjung Regency, shows that the condition of the Kuantan River in the Silokek Geopark Tourism Area is a natural and potential tourism area, because the Kuantan River in the Silokek Geopark Tourism Area has become a tourist attraction due to its abundant natural wealth. However, gold mining has caused the Kuantan River water to be categorized as polluted, indicated by its turbidity. This study aims to determine the types of macrozoobenthos found in the Kuantan River within the Silokek Geopark Tourism Area, Sijunjung Regency. This research was conducted from August to December 2023. The research used a descriptive survey method, which included direct observation and sampling at the research site. The sampling technique used was purposive sampling, selecting three research stations. Sample identification was conducted at the Biology Education Laboratory, Universitas PGRI Sumatera Barat. Physicochemical water measurements were carried out at the Laboratory of Standardization and Industrial Services in Gadut, Padang, West Sumatra. The results of the research on the types of macrozoobenthos found in the Kuantan River within the Silokek Geopark Tourism Area, Sijunjung Regency, identified 10 species belonging to 2 classes: Gastropoda and Pelecypoda. Eight species of Gastropoda were found: Tarebia granifera, Thiara scabra, Brotia costula, Tryonia clathrata, Pleurocera acuta, Thiara scabra, Goniobasis livescens, Brotia sp., and 2 species of Pelecypoda: Corbicula manilensis and Pilsbryoconcha exilis.

Investigation of the impact of municipal solid waste disposal site leachate on surface water resources in Hosanna Town, Ethiopia.

Surface water resources are the most precious, yet they are also the most vulnerable to pollution. Consequently, maintaining the sustainability of water supplies is critical for livestock support to achieve SDG goals. Landfill leachate poses a significant threat to water resources in developing countries. This study aims to determine how the Hosanna town landfill site affects the Jewie River by analysing the quality of the Alela and Ajew streams and the landfill leachate in both wet and dry seasons. Furthermore, assess the suitability of the water quality for agricultural purposes. The leachate pollution index (LPI), Canadian Council Member of the Environment Water Quality Index (CCMEWQI), and irrigation water quality indices (IWQI) were computed for both seasons using two composite leachate samples and five flow-pace composite river samples. In the wet season, the leachate pollution indices for L1 and L2 ranged from 20.87 to 22.47, respectively. During the dry season, the leachate pollutant index of L1 and L2 was found to be 24.42 and 27.98. Only the Ajew River stream was affected during the dry season because the landfill site is only 46m away. Both the Ajew and Alela River streams are infested during the rainy season. Irrigation index concentrations revealed that the river water is suitable for cultivation. The early stages of landfill waste maturation are evident from the LPI results. Relocating the dump site is necessary to safeguard water resources because leachate has entered the river streams.

Comparison of river and coastal water as potential sources of bioavailable iron

The assimilation of dissolved iron by phytoplankton depends on its chemical speciation and/or oxidation state. In this study river and coastal water was irradiated with a sunlight simulator and monitored for photoproduction of bioavailable reduced iron using a colorimetric method. The 0.01 μΜ steady-state concentration of ferrous ion was detected in river water during irradiation. The apparent quantum yield, an estimate of process efficiency, suggests qualitative differences between organic iron complexes in river and coastal water. The amount of photoproduced bioavailable iron may be of importance in relieving iron stress in potentially toxic diazotrophs in the area affected by the river plume.

Molecular Characterization and Phylogenetic analyses of Rotaviruses Circulating in Municipal Sewage and Sewage-Polluted River Waters in Durban Area, South Africa.

Globally, rotavirus continues to be the leading etiology of severe pediatric gastroenteritis, and transmission of the disease via environmental reservoirs has become an emerging concern in developing countries. From August to October 2021, a total of 69 samples comprising 48 of raw and treated sewage, and 21 surface waters, were collected from four Durban wastewater treatment plants (DWWTP), and effluent receiving rivers, respectively. Rotaviruses recovered and identified from the samples were subjected to sequencing, genotyping, and phylogenetic analysis. Of the 65 (94.2%) rotavirus-positive samples, 33.3% were from raw sewage, 16% from activated sludge, 15.9% from final effluents, and 29.0% were from the receiving river samples. A total of 49 G and 41 P genotypes were detected in sewage while 15 G and 22 P genotypes were detected in river samples. G1 genotype predominated in sewage (24.5%) followed by G3 (22.4%), G2 (14.3%), G4 (12.2%), G12 (10.2%), G9 (8.2%), and G8 (6.1%). Similarly, G1 predominated in river water samples (33.3%) and was followed by G2, G4 (20.0% each), G3, and G12 (13.3% each). Rotavirus VP4 genotypes P[4], P[6], and P[8] accounted for 36.6%, 29.3%, and 9.8%, respectively, in sewage. Correspondingly, 45.5%, 31.8%, and 13.6% were detected in river samples. The G and P genotypes not identified by the methods used were 2.1% versus 24.3% and 0.1% versus 9.1% for sewage and river water samples, respectively. Sequence comparison studies indicated a high level of nucleotide identity in the G1, G2, G3, G4, G8 VP7, and P[4], P[6], and P[8] VP4 gene sequences between strains from the environment and those from patients in the region. This is the first environmental-based study on the G and P genotypes diversity of rotavirus in municipal wastewater and their receiving rivers in this geographical region. The high similarity between environmental and clinical rotavirus strains suggests both local circulation of the virus and potential exposure risks. In addition, it highlights the usefulness of sewage surveillance as an additional tool for an epidemiological investigation, especially in populations that include individuals with subclinical or asymptomatic infections that are precluded in case-based studies.

Floating on groundwater: Insight of multi-source remote sensing for Qaidam basin

Situated in the north of the Qinghai-Tibet Plateau, the Qaidam Basin experiences limited precipitation and significant evaporation. Despite these conditions, it stands out as one of the most densely distributed lakes in China. The formation of these lakes is controversial: whether the lake water primarily originates from local precipitation or external water sources. To address this issue, this paper explores the recharge sources of lakes in the Qaidam Basin and the circulation patterns of groundwater from a remote sensing perspective. Based on deep learning networks, we optimized the soft object regions of the Object-Contextual Representations Network (OCRNet) and proposed the Remote·Sensing Adaptive-Improved OCRNet (RSA-IOCRNet). Compared with seven other networks, RSA-IOCRNet obtained better experimental results and was used to construct an area sequence of 16 major lakes in the Qaidam Basin. Combined with multi-source data, the comprehensive analysis indicates no significant correlation between climatic factors and lake changes, while an obvious correlation between lakes and groundwater changes in the eastern Qaidam, consisting with the results of the field survey. Deep-circulating groundwater recharges numerous Qaidam lakes through upwelling from fault zones, such as Gasikule Lake and Xiaochaidan Lake. Groundwater in the Qaidam Basin is more depleted in hydrogen-oxygen isotope characteristics than surface water in the basin, but similar to some river water in the endorheic Tibetan Plateau. This indicates that Tibetan seepage water, estimated at approximately 540 billion m3/a, is transported through the Qaidam Basin via deep circulation. Moreover, it rises to recharge the groundwater and lakes within this basin through fracture zones, extending to various arid and semi-arid regions such as Taitema Lake. This work provides a new perspective on the impact of deep groundwater on lakes and water circulation in these areas.

Effects of water replenishment on lake water quality and trophic status: An 11-year study in cold and arid regions

Water replenishment is an important measure for maintaining and improving the aquatic environmental quality of lakes. The problems of water quality deterioration and water shortage can be alleviated by introducing water of higher quality. However, the mechanism of water replenishment in the improvement of the water quality and trophic status of lakes remains unclear. This study investigated water replenishment in Wuliangsuhai Lake (WLSHL) from 2011 to 2021 by collecting seasonal water samples and conducting laboratory analyses. Water replenishment was found to be capable of significantly improving lake water quality and alleviating eutrophication. It is worth noting that single long-term water replenishment measures have limitations in improving the water quality and trophic status. The whole process was divided into three stages according to the water quality and trophic status, namely the buffer period, decline period, and stable period. During the buffer period, the water quality and trophic status showed only slight improvement because of the small amount of water replenishment and the low proportion of higher-quality water from the Yellow River. In the decline period, with increasing water replenishment, the proportion of higher-quality water from the Yellow River gradually increased, leading to the most significant and stable degree of improvement. In the stable period, increases in the amount of water replenishment had little effect on improving the water quality and trophic status, which is attributable to the balance between internal pollutants (lake water–sediment), and the balance between internal-external pollutants (lake water–irrigation return flow + Yellow River water). On the premise of stable water quality, with eutrophication control as the management goal, the optimal water replenishment would be approximately 10.58 ×108 m3. Further necessary measures for solving aquatic environmental problems include the combination of sediment dredging, optimization of the water replenishment route, and implementation of quality management in water replenishment.

Effects of open dumping site on surrounding air, soil, and water: a case study of Biratnagar metropolitan city

Managing solid waste is one of the emerging challenges in urban areas, and open dumping and burning is common practices mostly in developing countries like Nepal. Which affects the overall surroundings. The study has investigated the effects of open dumping and burning in nearby air, soil, and river water in dumping site of Biratnagar metropolitan city. For studying the effects on air, the three samples of air were taken, at center and 100m upstream and downstream to the direction of wind flow. Soil samples were taken at 10m from the dumping site center, at 25m from the first sample and at 60m from the second sample, and the water samples were taken at leachate and 100 m upstream and downstream to the leachate. Soil and water were subjected to the physiochemical test, heavy metals test and microbes test whereas PM 2.5, and PM 10 were tested for air quality. The results showed that the air from upstream has been seen carrying particulate matter from the dumping site to downstream. Similarly, it is found that the quality of water at leachate and downstream is degraded compared to upstream. The soil quality has been found to have degraded due to the harmful and toxic material of the dumping site. Thus, this study shows that open dumping and burning have affected the nearby air, water, and soil.

Biodegradation of Photocatalytic Degradation Products of Sulfonamides: Kinetics and Identification of Intermediates.

Sulfonamides can be effectively removed from wastewater through a photocatalytic process. However, the mineralization achieved by this method is a long-term and expensive process. The effect of shortening the photocatalytic process is the partial degradation and formation of intermediates. The purpose of this study was to evaluate the sensitivity and transformation of photocatalytic reaction intermediates in aerobic biological processes. Sulfadiazine and sulfamethoxazole solutions were used in the study, which were irradiated in the presence of a TiO2-P25 catalyst. The resulting solutions were then aerated after the addition of river water or activated sludge suspension from a commercial wastewater treatment plant. The reaction kinetics were determined and fifteen products of photocatalytic degradation of sulfonamides were identified. Most of these products were further transformed in the presence of activated sludge suspension or in water taken from the river. They may have been decomposed into other organic and inorganic compounds. The formation of biologically inactive acyl derivatives was observed in the biological process. However, compounds that are more toxic to aquatic organisms than the initial drugs can also be formed. After 28 days, the sulfamethoxazole concentration in the presence of activated sludge was reduced by 66 ± 7%. Sulfadiazine was practically non-biodegradable under the conditions used. The presented results confirm the advisability of using photocatalysis as a process preceding biodegradation.

Assessment of atrazine contamination in the Sele River estuary: spatial distribution, human health risks, and ecological implications in Southern Europe

BackgroundOveruse of pesticides is a major worldwide problem for the environment and human health. Atrazine (ATR) is a synthetic triazine herbicide that is typically used to manage crops and although it was banned many years ago, it was detected frequently with a high persistence in the aquatic environments. This study assesses the human and environment health risks, temporal patterns and spatial distribution of ATR and its degradation products (DPs) in the Sele River estuary within the Southern European context.. It specifically investigates their occurrence in the water dissolved phase (WDP), suspended particulate matter (SPM), and sediment.ResultsSampling was conducted across 10 sites throughout the year’s four seasons. Amounts of ATR and its DPs detected ranged from 20.1 to 96.5 ng L−1 in WDP, from 5.4 to 60.2 ng L−1 in SPM, and from 4.7 to 19.8 ng g−1 in sediment samples, signifying some pollution levels. Spatial distribution mechanisms revealed a southward movement of ATR and its DPs pollution from the Sele River mouth, intensifying during the rainy season. In this study area, a risk evaluation was also carried out. No sample contained ATR or its DPs in concentrations above the recommended limits, which pose a Non-carcinogenic and Carcinogenic risk. The environmental risk was low. Additionally, the determined Incremental lifetime cancer risk (ILCR) value was within the allowable range.ConclusionDespite its long-standing prohibition, this study investigate ATR levels in the water and sediments of Sele River in Southern Europe. Beyond simply delineating the pollution status of Sele River, this research delineates its ecological repercussions on the Thyrrenian Sea, providing essential data for norms and laws related to water contamination.Graphical

Traceability of River Water Pollution Based on MFO and M-H Algorithms

Traceability of River Water Pollution Based on MFO and M-H Algorithms

Detection of some Biological Parameters and Heavy Metals Presence in Tigris River Water by Novel Designed Bacterial Efflux Pump Genes

Detection of some Biological Parameters and Heavy Metals Presence in Tigris River Water by Novel Designed Bacterial Efflux Pump Genes

Peroxysulfur species-mediated enhanced oxidation of micropollutants by ferrate(VI): Peroxymonosulfate versus peroxydisulfate

Many studies have shown that Peroxymonosulfate (PMS) works synergistically with ferrate (Fe(VI)) to remove refractory organic compounds in a few minutes. However, little has been reported on the combined effects of peroxydisulfate (PDS) and Fe(VI). Since PDS is stable and cost effective, it is of practical significance to study the reaction mechanism and conditions of the PDS/Fe(VI) system. The results of the study indicate that the intermediate Fe(II) is formed during the decomposition of Fe(VI), which is then rapidly oxidized. Due to the asymmetry of the PMS molecular structure, PMS can rapidly trap Fe(II) (kPMS/Fe(II)= 3 × 104 M−1∙s−1), whereas PDS cannot (kPDS/Fe(II)= 26 M−1∙s−1). Hydroxylamine hydrochloride (HA) can reduce Fe(VI) and Fe(III) to Fe(II) to excite PDS to produce SO4•−. Acetate helps to detect Fe(II), but does not help PDS to trap Fe(II). Active species such as SO4•−, •OH, 1O2, and Fe(IV), Fe(V) are present in both systems, but in different amounts. In the PMS/Fe(Ⅵ) system, all these active species react with ibuprofen (IBP) and degrade IBP within several minutes. The effects of the initial pH, PMS or Fe(VI) dosage, and different amounts of IBP on the removal rate of IBP were investigated. According to the intermediates detected by the GC-MS, the degradation process of IBP includes hydroxylation, demethylation and single bond breakage. The degradation pathways of IBP were proposed. The degradation of IBP in tap water and Songhua River was also investigated. In actual water treatment, the dosage needs to be increased to achieve the same results. This study provides a basis and theoretical support for the application of PMS/Fe(Ⅵ) and PDS/Fe(VI) system in water treatment.

Effect of Integrated Landscape Characteristics Around Chaohu Lake on River Water Quality Based on Watershed Units

Considering the impact of differences in watershed characteristics on river water quality, with the Chaohu Lake Basin as the research object, based on the data of water quality, meteorology, topography, soil, and remote sensing images of the river monitoring points from October 2019 to September 2020, the watershed unit at each monitoring point was divided through digital terrain analysis, and the comprehensive landscape characteristics based on the watershed unit were explored through the comprehensive use of correlation analysis, redundancy analysis, and multiple regression analysis to investigate the influence of comprehensive landscape characteristics based on watershed units (including land use, climate, topography, soil, etc.) on the water quality of rivers around Chaohu Lake. The results showed that:① the water quality of rivers around Chaohu Lake had large spatial differences, with the main pollutants being total nitrogen and ammonia nitrogen. Most of the rivers had total nitrogen concentrations exceeding the Class V water quality standards, and the areas with serious nitrogen and phosphorus pollution were concentrated in the urban area of Hefei and the surrounding rivers, as well as in the middle and lower reaches of the Fengle and Hangbu Rivers. ② The comprehensive landscape characteristics of the watershed unit had a significant impact on the river water quality. Among them, the proportion of built-up land, the density of patches, the dispersion and juxtaposition index, and the Shannon diversity index were positively correlated with the water quality indicators, whereas the proportion of forest and grassland and the spreading index were negatively correlated with the water quality indicators. ③ In different seasons, the effect of the integrated landscape characteristics of the watershed unit on river water quality was stronger in the wet season than in the dry season, which was mainly caused by the difference in precipitation in the dry and wet seasons.

Stability and Degradation of Opioids in River Water.

As the level of consumption of opioids continues to rise globally, there is increasing concern over the potential impacts of continuous opioid discharges into aquatic ecosystems. Opioids are psychoactive compounds that are not completely removed during wastewater treatment, and little is known about their stability and fate in the environment. In the present study, we evaluated the stability of four highly used opioids, buprenorphine, codeine, fentanyl, and tramadol, in river water via batch degradation experiments. The opioids were spiked at environmentally relevant concentrations into 150 mL of river microcosms designed to distinguish among hydrolysis, abiotic degradation, biodegradation, and sorption. All opioids exhibited relatively high stability in river water, with removal rates of only 15% (tramadol) to 26% (buprenorphine) after 6 days. Biodegradation was the most important attenuation pathway for all four opioids, with first-order biodegradation constants ranging from 0.011 d-1 (tramadol) to 0.018 d-1(buprenorphine). Overall, degradation rates were 1-4 orders of magnitude lower compared to the reported rates for wastewater systems. These results offer insights into the stability of opioids in freshwater systems and raise questions about the potential effects of their pseudopresence in surface waters on aquatic organisms.

A dual-signaling surface-enhanced Raman spectroscopy ratiometric strategy for ultrasensitive Hg2+ detection based on Au@Ag/COF composites

Heavy metal ion pollution poses significant risks to human health and ecological systems, and its monitoring is important. A sensitive and accurate surface-enhanced Raman spectroscopy (SERS) detection assay for Hg2+ was developed using Au@Ag/COF substrates and Y-shaped DNA labeled with two Raman reporters. The Au@Ag NPs in the COF produced robust and uniform E-fields, improving their detection reproducibility. The Y-shaped DNA design increased sensitivity with a low detection limit of 5.0 × 10−16 M by bringing the Raman reporter closer to the substrate surface. Additionally, the use of two Raman reporters allowed for a ratiometric method, improving detection accuracy by detecting both “signal-off” and “signal-on” signals. This selective sensor exhibited excellent recovery in river water, tap water, and milk samples, showcasing its robust biosensing capability for the detection of Hg2+ and its potential for sensing other heavy-metal ions in food and environmental applications.

Persistent organic pollutants in sediment of a tropical river: the case of N’djili River in Kinshasa (Democratic Republic of the Congo)

Surface sediments collected in several areas along the N’djili River, in the Kinshasa Province, Democratic Republic of the Congo, were analyzed for persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), organochlorine, polycyclic aromatic hydrocarbons (PAHs), and also organophosphorus and pyrethroid (PYR) pesticides. High values of POPs were determined in the DIGUE area of the river reaching 710 µg kg−1 for ∑12 PCBs, 397 µg kg−1 for ∑6 DDTs, 1138 µg kg−1 for ∑16 PAHs, and 23 µg kg−1 for ∑6 PBDEs. Regarding toxic effects on aquatic biota, the Total PCBs (∑7 × 4.3) were above the Threshold Effect Level (TEL) value of 34.1 μg kg−1 and above the Probable Effect Level (PEL) value of 277 μg kg−1 in most sampling sites. ∑16 PAHs values were, in general, below the TEL value of 610 μg kg−1, but with exceptions for several sampling sites where values exceeded the TEL value. The ∑6 DDTs in all sampling sites were higher than both TEL and PEL values of 6.15 and 20.03 μg kg−1, respectively. These values above TEL and PEL indicate potential adverse effects on benthic organisms. In general, the ratio values of (DDD + DDE)/DDT were higher than 0.5 reflecting past DDT use mostly, and Fluo/(Fluo + Pyr), IDP/(IDP + BghiP) and BaA/(BaA + Chry) ratios indicated several PAHs origins including petrogenic and pyrolytic sources, petroleum, grass, wood and coal combustion. Globally, the results of this research showed high contamination of N´djili River sediments by a plethora of organic pollutants and at toxic levels to the aquatic biota. Furthermore, the river water quality might be not suitable for human consumption.

Measuring the Levels of Heavy Metal Pollution in Al - Diwaniyah River Water Using Oomycetes Fungus

The research included, for a period of 6 months, a study of two aspects. The first was the isolation and diagnosis of oomycetes in the water of Al-Diwaniyah River in five sites. The sites where pollution increased were chosen, namely textile, rubber factories, and sites before water treatment, compared to two sites: Sadr Al-Daghara and a site under Al-Diwaniyah Bridge, which had little pollution, as the percentage of pollution increased. Ovomycetes in pollution sites in order to increase the organic matter in them and to provide many nutrients, knowing that these fungi were isolated from control areas, but in small proportions, in addition to other groups of non-oomycetes and the previously dominant types of Oomycetes. Some physical tests were conducted on the water of the Diwaniyah River in the study sites to observe the suitability of the physical characteristics for the presence of these fungi, namely temperature, PH, alkalinity, hardness, and others. The second aspect is to consider these fungi as indicators of pollution in the river water when they are present in polluted areas by analyzing the enzymatic filtrate to measure The percentages of presence of heavy metals, such as cadmium, mercury, lead, and selenium, which appeared in high percentages that exceeded the permissible limits for their presence, whether in river water or in the bodies of living organisms. The percentages of cadmium were (0.012)% in Saprolegnia sp. and Pythium sp., while the percentages of lead were (1.5, 1.3).)% in Saprolegnia sp and Fusarium sp, while mercury recorded a percentage of (0.3, 0.05, 1.2)% in Achlya., Apodachlya sp.,. Fusarium sp. Selenium appeared at a rate of (0.2)% in Apodachlya sp, Arsenic in Pythium sp. At a rate of (0.02%) also for the purpose of comparison of these results, tests were conducted for heavy metals in the water at the selected sites (L3, L2, L1) (fabric, rubber, and site before treatment) respectively. The results showed the appearance of heavy metals (cadmium, lead, mercury, arsenic, selenium). In high percentages compared to sites L4 and L5, their percentages were very small, almost reaching zero.

Evaluation of the Effect of Agricultural Return Flow on Water Quality, Water Quantity and Aquatic Ecology in Downstream Rivers

Agricultural water serves various functions, including public interest purposes, beyond its primary role in agricultural production. In order to evaluate the various public interest purposes of agricultural water, a quantified study of the effect of agricultural water on river flow, water quality, and aquatic ecosystems is needed. Therefore, this study quantified the impact of agricultural water on the environmental and ecological maintenance function of downstream rivers, taking into account the return flow of agricultural water in rural areas. To this end, first, the effect of agricultural return flow on river maintenance function was evaluated by comparing the return flow quantity calculated using the reservoir supply data with the simulated river flow rate through the SWAT model. Second, the effect of the agricultural return flow on the downstream river environmental ecological function was analyzed using the optimal flow rate results calculated through the PHABSIM model. The lastly, the effect of agricultural water by farming period on the water quality of downstream rivers was analyzed. As a result of the analysis, it was found that the return flow of agricultural water had a large effect on the river flow rate in the case of the non-rainy season, but the optimal ecological flow rate was not satisfied. In the case of river water quality, it was confirmed that the effect of agricultural water (mainly considered as a pollutant) was not significant, except for the drainage duration of rice paddies. Therefore, it can be understood that agricultural water is not only used for the purpose of production but can also have a positive impact on the aquatic ecology of downstream rivers.

Environmental effects of river ice, The Saint John (Wolastoq) River, New Brunswick, Canada

ABSTRACT The Saint John (Wolastoq) River (SJR) is a major international river flowing through the State of Maine, USA, and the Province of New Brunswick, Canada. In terms of river length and basin area, it is one of the largest rivers on the eastern seaboard of North America south of the St. Lawrence River system. Subject to seasonal ice cover, ice conditions vary along the SJR due to natural differences in climate and terrain, and due to anthropogenetic changes, such as the construction of dams. Ice formation, growth, and breakup along the SJR affects its hydraulic and ecological regimes and leads to the potential for ice jamming that has caused severe flooding and ice runs. Ice affects river erosion, flooding, ecology, water quality, and recreational uses of the SJR. An overview of typical winter climate and ice season characteristics along the SJR from Dickey, Maine, USA to Saint John, New Brunswick, and some of its environmental consequences are summarized in this review paper. Ice processes and phenomena that occur along the SJR occur along other northern rivers, and can cause similar environmental concerns and consequences that should not be ignored in river engineering and basin management.