Nitrogen pollution of groundwater is becoming more and more serious due to intense and extensive industrial and agricultural activities. This may exert great influence on human health. In this paper, ...human health risk due to groundwater nitrogen pollution in Jinghui canal irrigation area in Shaanxi Province of China where agricultural activities are intense was assessed. Forty-seven groundwater samples were collected from shallow wells and analyzed for physicochemical indices in the study area. Water samples were analyzed for pH, total dissolved solids (TDS), total hardness (TH), major ions (Na
+
, K
+
, Ca
2+
, Mg
2+
, HCO
3−
, CO
3
2−
, Cl
−
and SO
4
2−
), nitrate (NO
3
–N), nitrite (NO
2
–N) and ammonia nitrogen (NH
4
–N). General groundwater chemistry was described by statistical analysis and the Piper diagram. Water quality was quantified via comprehensive water quality index (CWQI), and human health risk was assessed considering the age and exposure pathways of the consumers. The results show that the shallow groundwater is slightly alkaline and groundwater types are HCO
3
·SO
4
·Cl–Mg and HCO
3
·SO
4
·Cl–Na. Rock weathering and evaporation are main natural processes regulating the groundwater chemistry. The CWQI indicates that groundwater in the study area is seriously polluted by TH, TDS, SO
4
2−
, Cl
−
and NO
3
−
. Human health risk is high because of high concentrations of nitrate in drinking water. The results also show that children are at higher risk than adults. The health risk through dermal contact is much lower than that through drinking water intake and can be ignored.
Assessment of groundwater quality and health risk was conducted in the Shenfu coal mine area in Ordos basin, northwestern China. Statistical analysis, Piper and Chadha diagrams were used to reveal ...the hydrogeochemical characteristics of groundwater via physicochemical analysis of 44 collected samples. The suitability of groundwater was assessed for domestic and irrigation purposes, and the fuzzy comprehensive method was adopted to assess the overall groundwater quality for further discussion on groundwater management. The model recommended by the USEPA was selected to estimate the non-carcinogenic risks caused by NO
3
−
, NO
2
−
, NH
4
+
, F
−
, Fe and Mn through oral ingestion and direct dermal contact. The results revealed that the predominant hydrochemical types of groundwater were SO
4
∙Cl–Ca∙Mg and HCO
3
–Ca∙Mg types and the major cations and anions followed the orders of Ca
2+
> Na
+
> Mg
2+
>K
+
and HCO
3
−
> SO
4
2−
> Cl
−
, respectively. Groundwater is generally acceptable for irrigation. However, for domestic purposes, 47.73% of the collected samples are of excellent and good quality and are suitable for direct consumption. Both adults and children face non-carcinogenic risks because of exposure to contaminants such as nitrate, nitrite and fluoride. The risk to children is higher than that to adults, which is consistent with other studies. Nitrite contributes most to the risks, followed by nitrate and fluoride. Home-use water quality improvement devices and rainwater harvesting are suggested to enhance the groundwater quality protection and management in this area. The research also indicates that health risk assessment should always accompany general water quality assessment to ensure the reliability of the water quality assessment.
The objective of the study is to determine the distribution and origin of fluoride in two confined aquifers within the depth of 80–240 m (mid-deep confined aquifers) in Shizuishan City, an arid area ...in Northwest China. Based on geological and hydrogeological conditions, the distribution patterns of fluoride in the two confined aquifers were studied. Correlation analysis was used to reveal the mechanisms and reactions influencing the groundwater chemistry. The control of aquifer leakage induced by intense groundwater abstraction on fluoride concentrations was also discussed. The results show that the concentration of F⁻in some locations of the study area is beyond the limit of the Standards for Drinking Water Quality of China. Correlation analysis shows that the major reactions occurring in the confined aquifers are dissolution of gypsum, fluorite and halite, and precipitation of calcite and dolomite. Groundwater leakage from shallow aquifers is also responsible for the elevation of fluoride in mid-deep confined aquifers. The research is a scientific basis for the rational development and utilization of groundwater in this area, and it may be referenced by international scholars for similar research in other parts of the world.
Groundwater is an important water source for agricultural irrigation in Penyang County. Some traditional methods such as irrigation coefficient, sodium adsorption ratio, total alkalinity, total ...salinity and total dissolved solids were employed to assess groundwater quality in this area. In addition, an improved technique for order preference by similarity to ideal solution model was applied for comprehensive assessment. The origin of major ions and groundwater hydrogeochemical evolution was also discussed. Groundwater in Penyang County contains relative concentrations of dominant constituents in the following order: Na
+
> Ca
2+
> Mg
2+
> K
+
for cations and HCO
3
−
> SO
4
2−
> Cl
−
> CO
3
2−
for anions. Groundwater quality is largely excellent and/or good, suggesting general suitability for agricultural use. Calcite and dolomite are found saturated in groundwater and thus tend to precipitate out, while halite, fluorite and gypsum are unsaturated and will dissolve into groundwater during flow. Groundwater in the study area is weathering-dominated, and mineral weathering (carbonate and silicate minerals) and ion exchange are the most important factors controlling groundwater chemistry.
In this paper, a novel reaching law for discrete-time sliding-mode control is proposed. The reaching law is established based on an exponential term that dynamically adapts to the variation of the ...switching function. The difference function is also employed to redefine the change rate as the second-order difference of the disturbance. Unlike existing works, the proposed reaching law is able to guarantee smaller width of the quasi-sliding-mode domain (QSMD) while decreasing the reaching time in the same time. The ultimate magnitude of the QSMD in proposed method is of the order O(T 3 ). Moreover, the reaching steps for the system to converge to the sliding surface are obtained and the system dynamics in and out the QSMD are theoretically analyzed. Both numerical simulations and experimental investigations on a piezoelectric actuator are employed to validate the effectiveness of the proposed method.
In this paper, a new discrete reaching law with improved quasi-sliding-mode domain (QSMD) is proposed and a sliding-mode controller is designed for discrete-time systems with uncertainties. By ...redefining the change rate as the second-order difference of the system uncertainties and adopting the continuous-approximate function, smaller width of the QSMD can be guaranteed. Moreover, the QSMD of the proposed reaching law is obtained and the system dynamics in and out the QSMD are theoretically analyzed. Perturbation estimation technique is employed to estimate the unknown uncertainties. Thus, no prior knowledge of the uncertainty bound is required. Both numerical simulations and experimental results on a piezoelectric actuator are presented to demonstrate the performance of the proposed method.
Fluoride (F⁻) has significant impacts on human health. High fluoride groundwater (up to 1.90 mg/L) has been found in upper confined aquifer underlying the first terrace of Weihe River during a ...hydrogeological investigation for water supply in 2005. To reveal the occurrence and hydrogeochemistry of high F⁻ groundwater, hydrogeochemical tools such as saturation index, ionic ratios and correlation analysis were used in this study. The study shows that the concentrations of most physiochemical parameters from phreatic water, influenced by intensive evaporation and anthropogenic activities such as unregulated sewage and excreta disposal and agricultural practices in the area, are higher than those of confined water. The F⁻ concentration in phreatic water is within the acceptable limits set by China and the World Health Organization (WHO), while that of upper confined water shows a decreasing trend northwestward as the Weihe River approaches, with F⁻ concentration in the first terrace beyond the national and the WHO standards. High F⁻ groundwater is observed in alkaline environment associated with high Na⁺, pH, HCO₃ ⁻ and low Ca²⁺ and Mg²⁺. The enrichment of F⁻ is controlled by geologic and hydrogeological conditions, fluorine-bearing minerals presented in alluvial formations and their dissolution/precipitation under the alkaline environment along groundwater flow. Ion exchange, human activities and the mixing of different recharge waters may influence the enrichment of F⁻ as well.
Groundwater quality which relates closely to human health has become as important as its quantity due to the demand for safe water. In the present study, an entropy-weighted fuzzy water quality index ...(WQI) has been proposed for performing groundwater quality assessment in and around an industrial park, northwest China, where domestic water requirements are solely met by groundwater. The human health risk was assessed with the model recommended by the United States Environmental Protection Agency. In addition, the sources of major ions and main contaminants were also analyzed. The study shows that groundwater in the study area has been contaminated conjunctively by natural processes and industrial and agricultural activities. Nitrate, manganese (Mn), fluoride, total dissolved solids, total hardness and sulfate are major contaminants influencing groundwater quality. Nitrate and heavy metals such as Mn are mainly affected by human agricultural activities and industrial production, while other contaminants are mainly originated from mineral weathering and water–rock interactions. The results of water quality assessment suggest that half of the groundwater samples collected are of medium quality thus require pretreatment before human consumption. The mean health risk caused by the consumption of contaminated groundwater in the area is 8.42 × 10⁻⁵ per year which surpasses the maximum acceptable level (5 × 10⁻⁵ per year) recommended by the International Commission on Radiologic Protection. The entropy-weighted fuzzy WQI proposed in this study can not only assign proper weights to parameters but also treat uncertainties associated with water quality classification. This study will be of interest to international environmentalists and hydrogeologists. It will also be useful in regional groundwater management and protection.
Glucocorticoids are widely used to reduce disease activity and inflammation in patients with a range of immune-mediated inflammatory diseases. It is uncertain whether or not low to moderate ...glucocorticoid dose increases cardiovascular risk. We aimed to quantify glucocorticoid dose-dependent cardiovascular risk in people with 6 immune-mediated inflammatory diseases.
We conducted a population-based cohort analysis of medical records from 389 primary care practices contributing data to the United Kingdom Clinical Practice Research Datalink (CPRD), linked to hospital admissions and deaths in 1998-2017. We estimated time-variant daily and cumulative glucocorticoid prednisolone-equivalent dose-related risks and hazard ratios (HRs) of first all-cause and type-specific cardiovascular diseases (CVDs). There were 87,794 patients with giant cell arteritis and/or polymyalgia rheumatica (n = 25,581), inflammatory bowel disease (n = 27,739), rheumatoid arthritis (n = 25,324), systemic lupus erythematosus (n = 3,951), and/or vasculitis (n = 5,199), and no prior CVD. Mean age was 56 years and 34.1% were men. The median follow-up time was 5.0 years, and the proportions of person-years spent at each level of glucocorticoid daily exposure were 80% for non-use, 6.0% for <5 mg, 11.2% for 5.0-14.9 mg, 1.6% for 15.0-24.9 mg, and 1.2% for ≥25.0 mg. Incident CVD occurred in 13,426 (15.3%) people, including 6,013 atrial fibrillation, 7,727 heart failure, and 2,809 acute myocardial infarction events. One-year cumulative risks of all-cause CVD increased from 1.4% in periods of non-use to 8.9% for a daily prednisolone-equivalent dose of ≥25.0 mg. Five-year cumulative risks increased from 7.1% to 28.0%, respectively. Compared to periods of non-glucocorticoid use, those with <5.0 mg daily prednisolone-equivalent dose had increased all-cause CVD risk (HR = 1.74; 95% confidence interval CI 1.64-1.84; range 1.52 for polymyalgia rheumatica and/or giant cell arteritis to 2.82 for systemic lupus erythematosus). Increased dose-dependent risk ratios were found regardless of disease activity level and for all type-specific CVDs. HRs for type-specific CVDs and <5.0-mg daily dose use were: 1.69 (95% CI 1.54-1.85) for atrial fibrillation, 1.75 (95% CI 1.56-1.97) for heart failure, 1.76 (95% CI 1.51-2.05) for acute myocardial infarction, 1.78 (95% CI 1.53-2.07) for peripheral arterial disease, 1.32 (95% CI 1.15-1.50) for cerebrovascular disease, and 1.93 (95% CI 1.47-2.53) for abdominal aortic aneurysm. The lack of hospital medication records and drug adherence data might have led to underestimation of the dose prescribed when specialists provided care and overestimation of the dose taken during periods of low disease activity. The resulting dose misclassification in some patients is likely to have reduced the size of dose-response estimates.
In this study, we observed an increased risk of CVDs associated with glucocorticoid dose intake even at lower doses (<5 mg) in 6 immune-mediated diseases. These results highlight the importance of prompt and regular monitoring of cardiovascular risk and use of primary prevention treatment at all glucocorticoid doses.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
An investigation of soil salinization was carried out in the Nanshantaizi area (Northwest China) with WET Sensor. This device can measure such soil parameters as bulk soil electrical conductivity, ...water content, and the pore water electrical conductivity that are important for soil salinization assessments. A distribution map of soil salinization was produced, and the factors influencing soil salinization and its processes were discussed in detail. The study shows that moderately salinized to salt soils are mainly observed in the alluvial plain, where groundwater level is high and lateral recharge water contains high salinity. Nanshantaizi is covered by slightly salinized soils. The soil salinization distribution estimated by WET Sensor is generally consistent with the actual levels of salinization. Soil salinity in Nanshantaizi is mostly of natural origin and accumulated salts could leach to deeper soils or aquifers by water percolation during irrigation. Groundwater evaporation, groundwater level depth and quality of recharge water are important factors influencing soil salinization in the alluvial plain.
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