Identifying the Key Information and Land Management Plans for Water Conservation under Dry Weather Conditions in the Border Areas of the Syr Darya River in Kazakhstan

COVID-19 and urban rivers: Effects of lockdown period on surface water pollution and quality- A case study of the Zarjoub River, north of Iran

Due to the spreading of the coronavirus (COVID-19) in Iran, restrictions and lockdown were announced to control the infection. In order to determine the effects of the lockdown period on the status of the water quality and pollution, the concentrations of Al, As, Ba, Cr, Cu, Mo, Ni, Pb, Se, and Zn, together with Na+, Mg2+, Ca2+ and electrical conductivity (EC), were measured in the Zarjoub River, north of Iran, in both pre-lockdown and post-lockdown periods. The results indicated that water pollution and associated human health risk reduced by an average of 30% and 39%, respectively, during the lockdown period. In addition, the multi-purpose water quality index also improved by an average of 34%. However, the water salinity and alkalinity increased during the lockdown period due to the increase of municipal wastewater and the use of disinfectants. The major sources of pollution were identified as weathering, municipal wastewater, industrial and agricultural effluents, solid waste, and vehicular pollution. PCA-MLR receptor model showed that the contribution of mixed sources of weathering and municipal wastewater in water pollution increased from 23 to 50% during the lockdown period. However, the contribution of mixed sources of industrial effluents and solid wastes reduced from 64 to 45%. Likewise, the contribution of traffic-related sources exhibited a reduction from 13% in the pre-lockdown period to 5% together with agricultural effluent in the post-lockdown period. Overall, although the lockdown period resulted in positive impacts on diminishing the level of water pollution caused by industrial and vehicular contaminants, the increase of municipal waste and wastewater is a negative consequence of the lockdown period.

A review of water pollution arising from agriculture and mining activities in Central Asia: Facts, causes and effects

Central Asia is one of many regions worldwide that face severe water shortages; nevertheless, water pollution in this region exacerbates the existing water stress and increases the risk of regional water conflicts. In this study, we perform an extensive literature review, and the data show that water pollution in Central Asia is closely linked to human activities. Within the Asian Gold Belt, water pollution is influenced mainly by mining, and the predominant pollutants are heavy metals and radionuclides. However, in the irrigated areas along the middle and lower reaches of inland rivers (e.g., the Amu Darya and Syr Darya), water pollution is strongly associated with agriculture. Hence, irrigated areas are characterized by high concentrations of ammonia, nitrogen, and phosphorus. In addition, the salinities of rivers and groundwater in the middle and lower reaches of inland rivers generally increase along the flow path due to high rates of evaporation. Soil salinization and frequent salt dust storms in the Aral Sea basin further increase the pollution of surface water bodies. Ultimately, the pollution of surface water and groundwater poses risks to human health and deteriorates the ecological environment. To prevent further water pollution, joint monitoring of the surface water and groundwater quantity and quality throughout Central Asia must be implemented immediately.

Appraisal of metallic pollution and ecological risks in agricultural soils of Alborz province, Iran, employing contamination indices and multivariate statistical analyses

The current study was done to evaluate the pH, electrical conductivity, bulk density, sand, silt, clay, available K and P, organic carbon, Zn, Cu, Mn, and Fe in agricultural soils of Alborz province, Iran. A total of 46 samples were collected as composite samples from 0-20 and 20-40 cm soil depths. The average values of Fe, Cu, Mn, and Zn were found lower than the European limits, Indian limits, and Earth's crust. Pearson's correlation analysis found that pH effects Zn retention and, Cu and Mn retention in soil samples. Cluster analysis and Principal component analysis established that HMs are originated from different sources. Contamination factor (CF) and ecological risk index (RI) results showed less contamination and ecological risk in soil samples. Enrichment factor (EF) and modified ecological risk index (MRI) results indicated high enrichment and ecological risk of Cu, Mn, and Zn in surface and sub-surface soil samples.

Effects of COVID-19 pandemic lockdown on microbial and metals contaminations in a part of Thirumanimuthar River, South India: A comparative health hazard perspective

Twenty-two water samples from the Thirumanimuthar River course in southern India were collected before COVID-19 lockdown and during COVID-19 lockdown periods and were analyzed for microbiological parameters (fecal coliform bacteria, total coliform bacteria, Escherichia coli, and fecal streptococci) and heavy metals (Fe, Mn, Zn, Cu, Cd, Ni, Pb and Cr). The lockdown has decreased microbial populations and heavy metals. Fe, Cu, Cd, Ni, Pb and Cr exceeded the drinking water limits, respectively, in 77%, 45%, 27%, 18%, 9% and 91% of the pre-lockdown samples. During the lockdown period, Fe, Cu and Cd concentrations in 23% and Cr in 50% of the samples exceeded the limits. Heavy Metal Pollution Index (PI) expressed that 27%, 64% and 9% of the pre-lockdown samples represented 'low', 'medium' and 'high' pollution categories, respectively, but 68% and 32% of the lockdown period samples represented 'low' and 'medium' categories, respectively. The Metal Index (MI) exposed that all samples of pre-lockdown were under the seriously affected category, whereas 54% and 46% of lockdown samples were under strongly and seriously affected categories, respectively. Health risk evaluation predicted that 95%, 91% and 86% of pre-lockdown samples and 45%, 36% and 33% of lockdown period samples were at risk among children, teenagers and adults, respectively. As there is no integrated study on river water quality of COVID-19 lockdown this work is uniquely carried out by combining heavy metal pollution, microbial contamination and human health risk evaluation.

Another insight into the contamination levels at Ogoniland in Niger Delta, Nigeria, with focus on Goi Creek

Environmental pollution arising from crude oil exploratory activities has adversely impacted both the living and non-living components of the ecosystem. An insight into the impact of such activities with focus on Goi Creek in Ogoniland was provided in this study. We generated reliable data for physicochemical, heavy metal, and total hydrocarbon levels in the creek via a total of 40 samples collected across 4 stations designated within the creek in a duration of 10 months. With the exception of temperature, total dissolve solid, dissolved oxygen, chloride, sulfate, nitrate, zinc, and vanadium, the levels of other regulated parameters in the samples were not compatible with the national and international guidelines and standards for surface water quality including Federal Ministry of Environment Guidelines and standards for water quality in Nigeria and Environmental Protection Agency National recommended water quality criteria, respectively. The principal components (PCs) 1 and 2 of principal component analysis biplot revealed that the concentrations of the physicochemical parameters showed a mixed distribution among the stations; however, the heavy metals were more localized to station 4. Moreover, the dataset was subjected to water quality index (WQI), contamination index (C_d), heavy metal evaluation index (HEI), trace element toxicity index (TETI), and environmental water quality index (EWQI) to determine the extent of contamination. The result showed poor WQI, high contamination for C_d, and low-to-medium contamination for HEI. Although, there were variations among the stations on the contamination level, uniform remediation method should be adopted due to the similarity of the contaminants in all the stations.

Environmental monitoring and impact assessment of Prut River cross-border pollution

The cross-border rivers management is a challenge for the involved countries, especially if they do not have the same type of legislation. The negative effects on water quality are quantified by using environmental impact assessment tools. Thus, the quantification of impacts that could affect the human health, ecosystem equilibrium, and biodiversity is based on monitoring of the water quality indicators. An increased attention should be paid to the toxic pollutants resulted from various activities that may affect the aquatic environment and human health on short and long term. This study approaches the cross-border impact assessment of heavy metals, organic, and nutrient pollution in the case of two countries (Romania and Republic of Moldova), the Prut River being the natural border. The methodology considered a specific area of the Prut River on both river sides, based on specific water quality indicators. The studied area covers sampling points from North to South within Iasi County and Republic of Moldova, in the Prut River cross-border section. To assess the pollutants' impacts, the improved Leopold Matrix and the Rapid Impact Assessment Matrix were adapted and applied. The results offered an overview on water pollution level and impacts on the Prut River cross-border area, for the 5-year period (2015-2019). There is a major negative impact generated in the Southern part of the studied area, in the case of the following indicators: copper, selenium, organic substances, with an increased level of pollution recorded in the last 2 years (2018, 2019). The conclusion of this research is that even if both countries follow the international protocols concerning cross-border pollution, they still have to comply to different environmental standards which approach differently the pollution levels and the significant impacts on water quality.

Ecological risk assessment and source apportionment of heavy metals contamination: an appraisal based on the Tellus soil survey

It is imperative to comprehend the level and spatial distribution of soil pollution with heavy metals to find sustainable management approaches for affected soils. Selected heavy metals (Mn, Zn, Pb, Cu, Cr, Ni, As, Co, and Cd) and physiochemical parameters were appraised for 620 samples from industrial, agricultural and urban sites in Northern Ireland using the Tellus database. The findings of this study showed that among the analyzed heavy metals, Mn content was the highest and Cd content the lowest. Pearson's correlation analysis revealed that heavy metals were highly correlated with each other, signifying similar sources for the heavy metals. Mixed factors (anthropogenic and lithogenic) were responsible for the contribution of heavy metals as revealed by multivariate statistical analysis. The results of contamination factor and enrichment factor analyses suggest that As, Cd, and Pb showed very high risk for pollution in the study area. The geoaccumulation index revealed that with the exception of Cd, all analyzed heavy metals showed severe accumulation in the soils. The potential and modified ecological risk indices inferred that Cd, As, and Pb represented ecological threats in the soils of Northern Ireland. The findings of this study will aid in forming approaches to decrease the risks associated with heavy metals in industrial, urban and agricultural soils, and help create guidelines to protect the environment from long-term accumulation of heavy metals.

Impact assessment of metal contamination in surface water of Sutlej River (India) on human health risks

The Sutlej river in Indian Punjab is getting contaminated by industrial waste, sewage, and agricultural runoff. Most of the previous studies on metal contamination of water are mainly confined to the small stretch of river. Therefore, a systematic study was carried out to assess the spatial and temporal variability of metal contamination in water from the entry point of Sutlej River in Indian Punjab to its tail end when it leaves the country. The likelihood of cancer risk was also estimated though human health risk assessment. The water samples (between 76 and 91) were collected from Sutlej river during pre- (April) and post-monsoon (September-October) seasons of the years 2017 and 2018. There samples were analyzed for 10 metals (Zn, Cu, Fe, Mn, Ni, Cd, Pb, Co, Cr and As) using Atomic Absorption Spectrophotometer. Results showed that metal concentration in water was higher along the transboundary during both the seasons. The concentration of metals in water was higher in pre-monsoon season than post-monsoon season. Multivariate analysis in different seasons showed that biophysical variables and social drivers (including anthropogenic activities) have great influence on the concentration of metals. Spatial distribution of all the metals in water and heavy metal pollution index showed that metal contamination was higher along the transboundary followed by the area from the confluence of contaminated drain with river to transboundary along with localized spots in the river flowing in Indian Punjab. The likelihood of cancer risk due to ingestion of metals through water was in the order: Cd > Ni > Cr > As and the risk is higher in the areas along the transboundary. These results are useful for formulating the action plan to improve the water quality of Sutlej river and its environs including water-soil-plant continuum which affect human health.

Increased crop water requirements have exacerbated water stress in the arid transboundary rivers of Central Asia

Water scarcity and ecological degradation as a result of the expansion of irrigated agriculture in arid regions have become global issues. A better understanding of the changes in crop water requirements (CWRs) is important for promoting sustainable development, particularly the water resource management of transboundary rivers. In this study, the latest and complete meteorological station and crop area data, the CropWat model, and the slope method were used to estimate the CWR in the Syr Darya Basin (SDB) of Central Asia from 2000 to 2018. The spatiotemporal variation of the water requirements for primary crops at the city scale was first assessed. The impacts of climate and cultivated land change on the CWR were quantified, and the associated impacts of the CWR on the water resources and environment were discussed. The results revealed that the mean unit area CWR of the SDB was 944.1 mm and the rate of increase was 7.6 mm/a from 2000 to 2018. The area of the primary crops expanded by 5851.6 km², and the total CWR increased at a mean rate of 2.0 × 10⁸ m³/a, with the majority of this change being concentrated between 2010 and 2018. By 2018, the total CWR reached 194.8 × 10⁸ m³. The lower reaches of the SDB were associated with a high CWR and a high rate of increase. Along with the reduction in basin water resources, the increased CWR has exacerbated the water stress in the SDB. Sensitivity analysis indicated that the dominant factors influencing the change in the CWR are cultivated land change (65.0%) and climate change (35.0%). Owing to a reasonable crop planting structure, the middle reaches maintained a relatively low CWR and rate of increase. Given the predicted changes in climate, optimizing crop planting structure and controlling the expansion of cultivated land in order to reduce the CWR can help to mitigate water scarcity.

Comparison of HPLC Pigment Analysis and Microscopy in Phytoplankton Assessment in the Seomjin River Estuary, Korea

The distribution of microalgal species in estuaries shows marked gradients because of the mixing of marine and fresh water during tidal exchanges. To assess the spatio-temporal distribution of phytoplankton in the Seomjin River estuary (SRE), Korea, we investigated the seasonal phytoplankton communities along a salinity gradient in the estuary using both high performance liquid chromatography (HPLC) pigment analysis and light microscopy. Both types of analysis indicated that marine planktonic diatoms generally dominated at downstream sites having salinities >10, whereas freshwater species dominated at upstream sites having salinities <5. High levels of the pigments fucoxanthin and alloxanthin were found at upstream sites in the SRE in late spring. During summer, relatively high levels of the pigment peridinin were present in downstream areas of the SRE, and relatively high levels of diatoms occurred in upstream areas. In autumn, small Cryptomonas species were found in high abundance based on microscopic analysis, while CHEMTAX analysis of photosynthetic pigments showed relatively high concentrations of the diatom pigment fucoxanthin, implying the co-occurrence of a small unidentified phytoplankton. During winter, when the estuarine waters were well mixed, both the microscopic and CHEMTAX analyses showed that diatoms dominated at most stations. Seasonal and horizontal gradients in environmental conditions were clearly influenced by the salinity and nutrient loadings, especially the nitrate+nitrite and silicate concentrations. In particular, the ratio of photoprotective carotenoid pigments (PPCs) to photosynthetic carotenoid pigments (PSCs) was relatively low during all four seasons. This was predominately because of the high productivity of diatoms, which have a very low ratio of PPCs to PPSs. The SRE is a favorable habitat for diatoms because it is a high turbulence area having rapid water movement as a result of tidal changes. Overall, there was consistency in the data derived from the microscopy and chemotaxonomy analyses, suggesting that both methods are useful for analysis of the phytoplankton community structure in this complex estuarine and coastal water ecosystem.

Global evaluation of heavy metal content in surface water bodies: A meta-analysis using heavy metal pollution indices and multivariate statistical analyses

Water is polluted by increasing activities of population and the necessity to provide them with goods and services that use water as a vital resource. The contamination of water due to heavy metals (HMs) is a big concern for humankind; however, global studies related to this topic are scarce. Thus, the current review assesses the content of HMs in surface water bodies throughout the world from 1994 to 2019. To achieve this goal, multivariate analyses were applied in order to determine the possible sources of HMs. Among the analyzed HMs in a total of 147 publications, the average content of Cr, Mn, Co, Ni, As and Cd exceeded the permissible limits suggested by WHO and USEPA. The results of the heavy metal pollution index, evaluation index, the degree of contamination, water pollution and toxicity load showed that the examined water bodies are highly polluted by HMs. The results of median lethal toxicity index showed maximum toxicity in As, Co, Cr and Ni in the surface water bodies. Results of ingestion and dermal pathways for adults and children in the current analyzed review showed that As is the major contaminant. Moreover, Cr, Ni, As and Cd showed values that could be considered as a high risk for cancer generation via the ingestion pathway as compared to the dermal route. It is recommended that remediation techniques such as the introduction of aquatic phytoremediation plant species and adsorbents should be included in land management plans in order to reduce human risks.

Soil and Water Conservation in Agricultural and Forestry Systems

This special issue includes six articles that cover a variety of issues about the topic of soil and water conservation in agricultural systems, including the following: a bibliometric analysis of soil and water conservation in the Loess Region of China; regarding croplands, one study evaluated the influence of vegetation covers on topsoil moisture and the effect of physiographic conditions on sediment yield in Spanish vineyards; another study evaluated the influence of plant age on soil water depletion in alfalfa pastures in the Tibet Autonomous Region; in a Chinese forest plantation, the effect of plant age and species on soil bulk density and pH was evaluated, and the most suitable afforestation species and stand age recommended to harvest maximum benefits were determined; regarding water pollution, a study evaluated soil water dynamics during two fallow years and three barley crop seasons in Spain and estimated the effect of the applied fertilizer (slurries or minerals) on nitrate leaching; and finally, another study identified the key information, including heavy metals, for water conservation in the border areas of the Syr Darya River in Kazakhstan. The proper use of soil and water resources is necessary to ensure the future well-being of humans and of the environment.