The Yongding River is the mother river of Beijing. However, due to the environmental pollution caused by the economic development, the water and coastal environment of this river has suffered from great destruction. The ecological restoration of the Yongding River is imperative. In this paper, we analysed seven basic water quality indicators in Yongding River based on Information Entropy and found that the main factors for affecting water quality were ammonia and CODMn. Then the basic water quality indicators were predicted, based on Grey System GM(1,1) model and we concluded that turbidity and conductivity would grow fastest in the next 20 years. Finally, we made some reasonable ideas and methods in Yongding River ecological restoration.

The subject in this paper is the surface water of Yuecheng Reservoir in Handan. On the premise of analysing variation characteristics of sulphate of Yuecheng Reservoir, we recognized reasons of increased sulphate concentration value resulting in water pollution. It drew conclusions that sulphate concentration in Yuecheng Reservoir varied significantly during winter and reached maximum. At the same time, there was a significant correlation between sulphate concentration of atmospheric precipitation in urban areas and sulphate concentration of Yuecheng Reservoir, which was because that the sulphate of atmospheric precipitation reached to the reservoir by surface runoff, having a certain degree of influence on the sulphate concentration of Yuecheng Reservoir.

Based on the migration and transformation features of pollution sources in wide and shallow rivers, several monitoring points of water quality were set in the downstream to obtain a series of monitoring information. The changes of source intensity were, therefore, determined to present the problems in the inversion of instantaneous pollution sources during sudden pollution accidents. The research employs a differential evolution (DE) algorithm to inverse the location and number of emissions of pollutants discharged. The results show that the DE algorithm can accurately identify the sizes and locations of pollution sources and provide technical support for the identification of pollution sources. The research explored the impact of monitoring schemes on the accuracy of inversion results. It is of technical significance for manipulating and optimizing the emergency monitoring plans.

Nitrate nitrogen (N-NO3-), the most common pollutant in groundwater, is a result of the effect of diffuse sources of pollution like agriculture and animal husbandry intensive. The land use for these economic activities is very common in the Los R?os sub-region in the state of Tabasco, Mexico, where the Los R?os and Boca del Cerro aquifers are located. The aim of this research was to assess the concentrations of nitrate-nitrogen (N-NO3-) in groundwater, determine the quality in agreement with the maximum permissible limits established by national and international regulations, and the risks to the public health and aquatic life. The spatial distribution of N-NO3- was determined using the inverse distance weighted (IDW) interpolation technique. The average nitrate-nitrogen concentration was 0.76 mg.L-1, while the maximum concentration observed was 3.98 mg.L1. This does not exceed the maximum permissible limit (MPL) established in the national and international normativity for drinking water. However, in 50% of the sampling sites, the concentrations of N-NO3- exceed the MPL established in Mexico for the protection of the life of seawater. Relatively low concentrations of N-NO3- have shown to be toxic to certain aquatic organisms, and the aquifers studied discharge a third of the water to the rivers in the area, which flow into the Laguna de T?rminos Campeche and the Gulf of Mexico. Laguna de T?rminos Campeche is one of the most diverse and rich environmental systems on earth, where numerous ecosystems converge such as coastal lagoons, wetlands, mangroves, seagrasses, and coral reefs.

In India, festivals like Ganesh Chaturthi, Durga Puja form an integral part of its rich and diverse cultural heritage. The ritual of idol worshipping and immersion into water bodies signifies the cycle of creation and dissolution, acknowledging the rhythm of nature that all things come from nature and go seamlessly back to it for a cycle to begin. But, in recent times the practice of immersing Plaster of Paris (POP) made idols along with other decorative material into natural water bodies has immensely raised the severe issue of water pollution and creating an uncongenial aquatic ecosystem. In this purview, a pilot project for chemical disintegration of POP idols during Ganesh festival was run in Bhopal, Madhya Pradesh, India to study the effective application of a chemical method developed by CSIR-NCL, Pune by using ammonium bicarbonate. Water samples were collected before and after idol immersion activity from the tank. The detailed chemical analysis of the aqueous phase was carried out to study the effect on various parameters and application of residues. The analytical results reveal that the method has its practical utility as both the products of the reaction can further be used in chalk making and as fertiliser with dilution. The concentration of heavy metals was found minimal and in the limits in the treated aqueous phase. This paper also supports the sustainable management of such functions rather than the use of artificial materials.

Real-time fine-scale data was collected along the Bagmati River, in Kathmandu Valley, using mobile and fixed sensor system during the winter season. The water quality parameters; pH, conductivity, total dissolved salt (TDS), salinity, oxygen reduction potential (ORP), dissolved oxygen (DO), and turbidity were measured in the space domain using a fixed sensor and mobile sensor (small rafting boat loaded with sensor) systems. The water quality parameters from the fixed sensor system revealed that the Bagmati River was comparatively less polluted upstream from Gokarna to Tilganga sites and molecular oxygen present in the water was enough to decompose organic pollutants. However, the water quality downstream from Tinkune to Balkhu sites was degraded drastically making it unfit for living organisms. Temporal variation of water quality attributes that human activity significantly enhanced pollutants which severely degraded the water quality in the daytime. The fine-scale space domain heat map data of the mobile sensor system also suggested that the water quality continuously deteriorated from Shankhamul to Sundarighat sites. The ORP value was always negative and decreased with downflow and becomes -263 mV near the Sundarighat Bridge. The mixing of tributaries and increment of solid waste and untreated sewer along the river enhanced pollutants excessively and decreased oxygen level to zero. The results attributed that decomposition of the sewer by microorganism consumed almost all oxygen which produced volatile compounds and generated malodorous odor downstream of Bagmati River.

The pollution of the river by man-made sewage and waste disposal is not only harmful to animals and plants in it but also for animals higher in the food chain including those close to the food chain. Water is the most vital natural substance, as it plays a role in nearly every aspect of human life. Therefore, there is a great need to ensure that the water used by humans should not contain hazardous substances. Water quality is directly linked to biological life. The Nag River flows from the Lava village of north Ambazari Lake and flows into the center of Nagpur city. As a result of rapid and unstoppable development, significant changes have taken place in the water quality of the Nag River. Because the Nag River’s water is frequently used for irrigation, it should be tested for cytotoxicity and genotoxicity. Since the rate of cancer and genetic disorders has recently increased in the Nagpur region, the Nag River’s water could be a source of carcinogens in the food chain, affecting the population. This study was conducted to analyze the impact of water collected from various points of the Nag River using Allium cepa as a model organism. The results of this study showed that all water samples from the Nag River cause a cytotoxic effect (20-23%) and genotoxic effects (23-28%) in Allium cepa cells. Therefore, before the use of Nag River water, it must be treated to diminish its harmful effect.

Groundwater is the most important resource for human consumption and the support of habitat and for maintaining the feature of base flow to river courses, while its quality is necessary to ensure sustainable safe exploit of the resources for all purposes. The untreated or inappropriate industrial effluents discharge on the surface causes harsh groundwater pollution in the industrial area of the nation. Sixty groundwater samples have been collected from boreholes and water samples were analysed to examine the groundwater quality of Avinashi-Tirupur-Palladam region. The samples were examined for the physico-chemical parameters like pH, electrical conductivity (EC) and total dissolved solids (TDS), major cations like calcium (Ca2+), magnesium (Mg2+), sodium (Na+), potassium (K+) and major anions like bicarbonate (HCO3-), carbonate (CO32-), chloride (Cl-), nitrate (NO3-) and sulphate (SO42-), along with fluoride. The abundance of major cations and anions was investigated. Spatial distribution map based on total dissolved solids indicates that the Noyyal and Nallar river basins, central regions of the study area, are more affected. The chemical parameter data of groundwater samples of the study area are plotted in Gibbs’s diagram. Based on the Piper diagram, different water types were identified. Hydro-chemically, the quality of the groundwater for human consumption was determined. The ion concentration distribution indicates that most of the groundwater sample locations in the study area are not suitable for domestic use.

Dissolved oxygen (DO), NH4+-N, total phosphorus (TP), CODMn and BOD5 in water in the Hechuan segment of Fujing River were monitored to assess water pollution in the river scientifically. Water pollution indexes were analysed and their pollution load-sharing ratios were calculated by using single pollution index method and Nemerow comprehensive pollution index method, respectively. Results show that the water quality in 25% of the monitored sections can be considered clean and the water quality of 75% of the sections can be considered slightly polluted in two water functional zones in the Hechuan segment of Fujiang River with water quality control targets of Level III and Level IV, respectively. Water quality declines from upstream to downstream. DO does not exceed standards in all the sections. NH4+-N significantly contributes to water pollution in all the sections | as a consequence, NH4+-N is a major pollution index in the entire Fujiang River. In some sections, TP, CODMn and BOD5 yield high pollution load sharing ratios. The distribution of the main pollution sources of different sections shows that the pollution indexes exceeding standards are mainly influenced by various pollution factors, such as cultivation, industrial wastewater, urban and rural domestic sewage, and agricultural non-point sources. Therefore, relevant preventive measures and recommendations are provided as a reference of the comprehensive control of water pollution in the Hechuan segment of Fujiang River.