Irrigation Period Research Articles

Comparison of the Ameliorating Effects of Valsartan and Amlodipine on Vascular Endothelial Dysfunction and Oxidative Stress in Elderly Patients with Type H Hypertension.

Objective To explore whether long-term administration of valsartan or amlodipine can improve vascular endothelial function and reduce the production of reactive oxygen species in patients with H-type hypertension, so as to provide a reference for clinical treatment. Methods A total of 82 elderly patients with type H hypertension who were admitted to our hospital from March to August 2017 were selected as the research subjects. The study included a 4-week continuous irrigation period followed by a 24-week randomized treatment period. Forty patients in the valsartan group and 42 in the amlodipine group were treated with 5 mg amlodipine or 80 mg valsartan for 24 weeks. Clinical efficacy, 24 h mean DBP, SBP, and 24HSBP, DBP coefficient of variation, cardiac fatty acid-binding protein (H-FABP), vascular pseudohemophilia factor (VWF), nitric oxide (NO), endothelium-dependent vasodilation function (FMD), nonendothelium-dependent vasodilation function (NMD), malondialdehyde (MDA), GSH-Px, and SOD levels were observed. Results The total effective rate was 80.0% (32/40) in the valsartan group and 85.71% (36/42) in the amlodipine group, and the difference was not statistically significant (P > 0.05). After 24 weeks of treatment, the 24 h mean SBP, SDP, 24HSBP, and DBP variation coefficients of the two groups were significantly decreased, and there was no statistical significance between the two groups (P > 0.05). After treatment, the values of H-FABP, VWF, NO, and MDA in both groups decreased compared with before treatment, while the values of FMD%, NMD%, SOD, and GSH-Px increased compared with before treatment (P > 0.05), and the levels of H-FABP, VWF, and NO in the valsartan group were lower than those in the amlodipine group. Meanwhile, FMD%, NMD%, SOD, and GSH-Px levels were higher than those in the amlodipine group (P > 0.05). Conclusion Valsartan and amlodipine reduce blood pressure, improve vascular endothelial function, and inhibit oxidative stress in elderly patients with H-type hypertension on average. However, valsartan has a better effect on vascular endothelial dysfunction and oxidative stress in elderly patients with H-type hypertension.

Evaluation of Biobed Bio-Mixture from Olive Oil Mill Wastewater Treatment as a Soil Organic Amendment in a Circular Economy Context

This study, based on circular economy principles and sustainable development practices, aims to present the results of soil samples analysis after their mixture with a biobed bio-mixture of straw, soil and compost, used for two consecutive years as organic bio-filter of olive oil mill wastewater. So far, exhausted bio-mixtures used in biobeds to minimize pesticide point-source contamination turned out to contain residues of pesticides, and they are considered hazardous wastes; thus, they require special treatment before their disposal. Contrariwise, saturated bio-mixtures from bio-bed systems utilized for olive mill wastewater (OMWW) treatment not only do not require any special treatment before their final disposal but also can be exploited as a soil amendment. To this end, the effects of the used bio-mixture application in three different proportions as a soil amendment on the physical and chemical properties of medium-texture soil were investigated. The application of water simulating a typical irrigation period during a growing season took place. Upon completion of the water application, soil samples were collected from two different depths of the columns and analyzed, and leachates collected from the columns were also analyzed. Soil texture, organic matter, calcium carbonate, electrical conductivity (EC), pH, total nitrogen, nitrates, nitrites, ammonium, available phosphorus, exchangeable potassium, sodium, calcium and magnesium, exchangeable sodium percentage (ESP), cation exchange capacity (CEC), available iron, manganese, copper, zinc and boron were monitored in the soil samples as indexes of potential soil amendment, and EC, pH, nitrates, potassium, sodium, calcium, magnesium, sodium adsorption ratio (SAR), total hardness, iron, manganese, copper, zinc and boron were monitored in the leachates as indexes of potential groundwater contamination.The study demonstrated the effective use of saturated bio-mixture as an organic soil amendment, while the impact of selected amendments on groundwater was the minimum.

Chromium phytoextraction using Phyllostachys pubescens (Moso Bamboo)

In this study, a bamboo species, the Phyllostachys pubescens – Moso Bamboo (MB) -, was selected for its heavy metals accumulation and translocation potential to restore Chromium (Cr)-contaminated soil. In order to evaluate the MB Chromium growth, tolerance and the potential for phytoremediation using MB to restore Cr-contaminated soil, pot experiments were carried out in simulated Mediterranean conditions in a laboratory, in a controlled environment, at a temperature of 20 °C. The results showed that MB growth rate was 4.28 cm/week on average, with an irrigation flow of 1.644 mm/d. MB tolerance was tested over a 12-week irrigation period with the addition of Cr-contaminated water. Cr removal from soil was 43% starting from a Cr content of approx. 200 mg/kg dry weight (dw) and the quantity of Cr per gram of root and rhizome was equal to 1.31 mg/g dw, while the quantity of Cr per gram of stem and leaves was equal to 0.86 mg/g dw, after 12 weeks. Pot experiments confirm that phytoremediation using plants such as MB provides an alternative approach for handling Cr-contaminated soil.

Performance Evaluation of Drip Irrigation System in Grapes Field

A commercial drip irrigation system was evaluated at farmer’s field under grapes to study the various parameters viz emission uniformity, emitter flow variations and statistical uniformity during the year 2019. The soil characteristics of the experiment field at different profile depths was analyzed and sandy loam soil is available at 0 to 15 cm depth and sandy clay loam is available from 15 cm to 60 cm depths, Irrigation was given daily based on potential evaporation. The soil moisture status during the crop growth period at various depths under the emitter was studied. The soil moisture in the field was maintained in a range of 21 to 23% under drip irrigation in the 60 cm depth irrespective of the duration. During the rainy season when no irrigation was given, the soil moisture fluctuated depending upon the intensity of rainfall. The system performance was good as indicated by high uniformity coefficient (93%) which indicates that the field is irrigated in a highly uniform manner. The yield was estimated as 27500 kg/ha and water use efficiency was found to be 566 kg.ha/cm The study revealed that superiority of drip irrigated soil regime and moisture content in the soil in 60 cm depth was more or less maintained constantly during the irrigation period.

Características físico-químicas de frutos de tomateiro para processamento industrial em função de manejos da irrigação

ABSTRACT This study was carried out to evaluate the postharvest quality of processing tomato fruits, submitted to irrigation depths and periods of suspension of irrigation before harvest, irrigated by subsurface drip in Cerrado areas in the southern region of Goiás State, Brazil, in 2015 and 2016. The experiments were established under a randomized block design, with four replicates arranged in a split plots scheme. In the plots, five irrigation depths were evaluated (50, 75, 100, 125 and 150% of the crop evapotranspiration) and, in the subplots, five periods of suspension of irrigation (0, 7, 14, 21 and 28 days before harvest) were assessed. After harvesting, which occurred at 125 days after transplanting the seedlings, the average fruit mass, fruit shape (longitudinal and transversal diameter), total soluble solids content, titratable acidity, pH, firmness, pulp yield, and water productivity for pulp yield were evaluated. Irrigation deficit, with the replacement of less than 100% of crop evapotranspiration, allowed to save water but significantly reduced the size of the fruits and the production of concentrated pulp. The suspension of irrigation before harvest decreased pulp yield and fruit size. The highest water productivity for pulp yield of tomato fruits occurred under water deficit with 50% of crop evapotranspiration. Irrigation depths from 50 to 150% of crop evapotranspiration and suspension before harvest does not influence total soluble solids content, pH, and fruit firmness.

Effect of the Forecast Air Temperature Change on the Water Needs of Vines in the Region of Bydgoszcz, Northern Poland

The climatic changes observed in Poland are manifested by an increase in air temperature, but not an increase in rainfall, which causes an increase in the water needs of plants, and hence the necessity to develop irrigation systems for crops. The aim of this study was to assess the water needs of grapevines in 2021–2050 in the Bydgoszcz region (northern Poland), an area with high requirements for supplementary irrigation. The calculations were based on the expected changes in air temperature according to the climate change scenario for Poland: the 4th Intergovernmental Panel on Climate Change—Special Report on Emissions Scenarios: balanced scenario (A1B). The average monthly temperature in 1981–2010 was used in the calculations. The water needs of grapevines were estimated using the reference evapotranspiration calculated using the Blaney–Criddle equation, and then using the crop coefficient and potential (crop) evapotranspiration. It was found that in 2021–2050, the water needs of grapevines, both during the growing season (May–September) and during the irrigation period (June–August), will increase by 6%. The highest and significant increase in water needs, by 10%, should be expected in August. The estimated increase in water needs of grapevines indicates the need to development sustainable irrigation systems for vineyards in northern Poland.

Effects of Irrigation Regimes on Soil Water Dynamics of Two Typical Woody Halophyte Species in Taklimakan Desert Highway Shelterbelt

Freshwater resources are in a shortage in arid regions worldwide, especially in extremely arid desert areas. To solve this problem, highly saline groundwater is used for drip irrigation of desert plants. Since more irrigation infiltrating into the deep soil cannot be absorbed and utilized by desert plants, it is crucial to determine optimal water-saving irrigation regimes. In this study, we examined the effects of irrigation regimes on the soil water dynamics of two typical woody halophyte species (Haloxylon and Calligonum), and quantified the irrigation intervals and periods based on a field test of precision irrigation control in the Taklimakan Desert Highway shelterbelt. Results showed that the change in soil moisture of two species in the shallow 0–60 cm layer could be divided into a rapid decline period (1–9 d), a slow decline period (9–19 d), and a relatively stable period (19–39 d) after irrigation. The decrease rate of soil moisture at the 0–60 cm depth was significantly higher than that at the 60–200 cm depth. The irrigation regime combining 35 mm irrigation with 10 days was beneficial to soil water storage and plant use with respect to Calligonum, while the irrigation regime combining 35 mm irrigation with 40 days was best for Haloxylon. Increasing the single irrigation amount and prolonging the irrigation period can further enable the more effective use of irrigation water. This study highlights that saline groundwater irrigation provides potential advantages for desert plants’ survival under reasonable irrigation regimes.

Research on soil physical characteristics and dynamic response of groundwater to irrigation in typical irrigation area of Huangshui River Basin

Under the influence of the natural and human factors, water table of irrigated area Changes frequently, but it is mainly affected by irrigation water infiltration replenishment. Basic physical properties of different soil layer of the typical field were determined and analyzed, and 5 groundwater observation wells were constructed to carry out the experiment of the response of groundwater to irrigation. The results showed that the upper vertical 0-40 cm is loose, the 40-60 cm layer is relatively tight, and the lower part 60-200 cm tend to loose again. Soil saturated water holding capacity, capillary water holding capacity and field capacity showed increased first and then decreased trend with the increase of soil depth. They almost showed the same nearly evenly spaced degressive trend. The groundwater stage dynamic change rule of spring and seedling irrigation stage in the typical plot was fit to the hydrological geology condition of grade-Iterrace of Huangshui river valley. Lateral canal water direction formed a line effect. The rangeability of water table of spring irrigation period was significantly higher than that of seedling irrigation period.

Exploration of Water-Saving and High-Yield Irrigation Model for Tomato under Microsprinkler Irrigation with Plastic Film in a Greenhouse Based on Spatial Analysis

The purpose of this study was to analyse the suitability of the frequency and amount of microsprinkler irrigation under plastic film technology (MSPF) in a greenhouse. This study was aimed at determining the effects of different irrigation frequency and irrigation amount of the MSPF on the quality, yield (Y), and water use efficiency (WUE) of tomato, and the optimal irrigation period and irrigation amount of tomato with MSPF were determined by spatial analysis method. Irrigation frequency was set 3 levels, 3 d (F1), 5 d (F3), and 7 d (F3), respectively. Irrigation amount was set 3 levels, 0.7 E pan (I1), 1.0 E pan (I2), and 1.2 E pan (I3) ( E pan is the diameter of 20 cm standard pan evaporation, mm), respectively. The results show that increase in the single fruit weight (SFW), transverse diameter (TD), vertical diameter (VD), total soluble solids (TSS), total soluble sugar (TSU), soluble solid content (SSC), sugar-acid ratio (SAR), soluble protein (SP), vitamin C (VC), lycopene (L), Y, and WUE of spring and autumn tomatoes was observed initially with decreasing irrigation frequency; however, decrease in all these variables was observed thereafter. Similarly, SFW, TD, VD, and SAR of spring and autumn tomatoes first added and then reduced with increasing irrigation amount, whereas TSS, SP, TSU, VC, L, and WUE exhibited an overall decreasing trend. On the basis of spatial analysis, the comprehensive score, Y, and WUE of F2I2 tomato were predicted to simultaneously reach more than 95% of the maximum, which is consistent with the earlier studies on comprehensive evaluation of yield and WUE.

The Relationship Between the Distribution of Water and Salt Elements in Arid Irrigation Areas and Soil Salination Evolution

Long periods of surface water irrigation and water and salt movement have slow and continuous influence on the evolution of soil salinization in a closed hydrogeological unit of arid irrigation areas. It is of more application value to study the evolution process of soil salinization from the perspective of regional medium and long terms in the regional scale for the sustainable development of irrigated areas. In this study, the spatial–temporal evolution of soil salinization and dominant factors for soil salination, and the relationship between soil salination and the groundwater buried depth were studied through spatial interpolation and statistical analysis with long-time observed data of a closed hydrogeological unit in the Jingtaichuan Electric-Lifting Irrigation Area in Gansu Province, China. The results showed that from 2001 to 2016, the soil salt content, the groundwater mineralization, and the surface irrigated water amount in the study area enhanced slowly, while the groundwater buried depth decreased; the salinization degree in the study area was increasing slowly; there was a positive correlation between the soil salt content and the groundwater mineralization, while a negative correlation existed between the soil salt content and either the surface irrigated water amount or the groundwater buried depth; the groundwater buried depth had the strongest impact on the spatial distribution of the soil salt content; the increase rate of the soil salt content lowered as the groundwater buried depth increased, which met the logarithmic relationship; soil salination was actively developed in regions with a low groundwater buried depth below 2.5 m, and soil salinization became evident in regions with a groundwater buried depth below 5 m; 15.0 m was a critical groundwater buried depth that caused the increase or the decrease in the soil salt content. The research results provide a new way to predict the development trend of soil salinization in the medium and long terms and provide a theoretical basis for the development of salinization prevention and control measures in irrigated areas, which is of great significance to maintaining a harmonious soil and water environment in irrigated areas.

Temporal and Spatial Variation Characteristics and Driving Factors of Nitrogen of Shallow Groundwater in Hetao Irrigation District

As an important food production area in the north of China, the Hetao plain is extremely vulnerable to nitrate pollution caused by agricultural production activities and additional factors. Thus, it is of great significance for the environmental protection and rational use of groundwater to detect the current situation of groundwater nitrate pollution, temporal and spatial evolution characteristics, and main influencing factors in the Hetao irrigation district. We selected the Wualte irrigation area as the study area, and the characteristics of temporal and spatial changes in groundwater nitrate concentration and the main influencing factors in this area were explored. We used statistical analysis to analyze the nitrogen content of groundwater in the study area, and the Piper three-line diagram was used to explore the characteristics of chemical composition and evolution; furthermore, we used ion ratio and correlation analysis methods to explore the source of NO3--N in groundwater. The results showed that NO3--N was the main existing form of nitrogen in the Wulate irrigation area, and its concentration varied from 0.01 to 60.00 mg·L-1, with an exceeding standard rate of 10.50%. In terms of time, the characteristic of time change was that the NO3--N concentration in August of groundwater was the highest (average 6.61 mg·L-1), followed by that in October (6.22 mg·L-1) and November (6.25 mg·L-1), and that in March (average value of 1.77 mg·L-1) was the lowest. With the influence of rainfall and irrigation, the NO3--N in the soil was infiltrated into the groundwater, showing the characteristic that wet season and concentrated irrigation periods were higher than those in other periods. Spatially, it appeared as southwest (8.87 mg·L-1)>northwest (4.25 mg·L-1)>east (0.89 mg·L-1), mainly due to the original geological conditions, land use, and domestic waste stacking. In addition, the concentration of NO3--N of groundwater in the study area was closely related to the depth of groundwater and redox conditions but was relatively less affected by the concentration of water chemical ions. Therefore, identifying the temporal and spatial distribution characteristics and main sources of groundwater nitrogen pollution can provide a scientific basis for scientific fertilization, groundwater nitrate pollution control, and water safety.

Evaluation of agricultural drought in South Korea using socio-economic drought information

The effect of drought on agriculture is a complicated result of several factors. Several studies have been conducted to evaluate agricultural drought using facility monitoring or statistical data. However, the gap in awareness between the public monitoring of drought and local situations has not been sufficiently reduced. The objectives of this study were to analyze the correlation between a socioeconomic drought information (SEDI) based on Internet news articles and agricultural drought data and to determine whether the SEDI can provide reliable information regarding damage due to agricultural drought. The SEDI was subdivided into the following aspects: water deficit, water security and support, economic damage and impact, and environmental and sanitation impact. The correlation coefficient between SEDI and eight agricultural statistical datasets ranged from 0.74 to 0.89. In moderately dry irrigation and non-irrigation periods, the relationship between SEDI and the agricultural reservoir drought index (RDI) was evidenced by a receiver operating characteristic and an area under the curve of 0.60 and 0.68, respectively. The cross-correlation values between the SEDI and RDI ranged from −0.48 to −0.42. According to cross-correlation analysis, SEDI was able to detect drought one month earlier than the RDI was able to do. Thus, our proposed method can contribute to the development of an impact-based early warning system for agricultural drought management.

Relationship between drainage composition and clay minerals evolution under heavily irrigated sugarcane cultivation in southwest Iran

The present study was conducted to determine the concentration and total amount of some compounds excreted in the drainage water of two different records of soils cultivated with sugarcane and to compare the mineral evolution of these soils with that of uncultivated soils. Cultivation changed the soil class Typic Aquisalids in uncultivated soils to Fluventic Haplustepts in cultivated soils. Unlike other elements, Ca and Mg showed a storage trend in some months. Mn and Fe depletion was largely a function of reduction conditions due to intensive irrigation, leading to high depletion in the irrigation period (80–85% of the total amount discharged). Although Si removal was a function of the irrigation period, its amount was much higher than that of Fe and Mn. However, as the irrigation record increased, more Si was removed during the irrigation period. Except for Mg, Si, Fe, and K, removal through drainage water did not depend on the length of the cultivation period. It was argued that these compounds were released due to the evolution or dissolution of clay minerals. During the irrigation period, K was removed much more than all other elements because of wetting, drying, and increasing NH4 by applying fertilizers. Si > Mg > Ca > K > Fe > Mn and K≫Si ∼ Ca ∼ Mg > Fe > Mn were the trends observed in concentration and total excreted amount in drainage water, respectively. Furthermore, minerals such as palygorskite, illite, and chlorite were abundant in uncultivated lands, but decreased or almost disappeared in cultivated lands, leading to the formation of expandable minerals such as smectite and vermiculite.

Impacts of Irrigation Time and Well Depths on Farmers’ Costs and Benefits in Maize Production

In the North China Plain, drought usually occurs during the interval between wheat harvest and maize sowing in normal and dry years. The first irrigation for maize plays a critical role in guaranteeing seed germination and grain yields. Using experimental data from Xinxiang in 2019 and survey data of 641 farmers from the North China Plain in 2020, this study adopts a cost-benefit analysis method to investigate the impacts of irrigation time and well depths on farmers’ costs and benefits in maize production. The results showed that farms with well depth > 120 m accounted for 49% of total farms, especially in Hebei Province, and 38% wells had low water yield < 2.7 m3 kW−1 h−1. Delaying the time of the first irrigation made maize yields decline by up to 307 kg ha−1 day−1. Well depths increased irrigation costs and total maize production cost in an exponential manner, causing farmers’ benefits to decrease exponentially with well depths. With well depth > 180 m, the proportion of irrigation cost to total cost rose to 14%, whereas well depth > 230 m directly caused the farmers’ profits negative. A critical well depth of 230 m was put forward as the upper limit for farmers adopting maize planting in the NCP. The concept of ‘rotational irrigation strategy’ and suggestions of adopting drip irrigation, sprinkler irrigation, or hose-reel sprinkler irrigation were recommended to advance 6–8 days for the first irrigation period, compared with traditional flood irrigation.

Partitioning evapotranspiration of winter wheat based on oxygen isotope approach under different irrigation regimes

AbstractEvapotranspiration (ET), which is an elusive component of the hydrological cycle, comprises transpiration from plants (T) and evaporation from soil surface (E). In this regard, it is essential to know how much water is lost by T and E during the irrigation period. The overall aim of this study is to separate the ET components by stable oxygen isotopes of winter wheat at the field scale under different irrigation regimes. For this purpose, the field experiment was conducted under rain‐fed, deficit and full irrigation conditions. Soil–water–plant samples were taken for isotopic (18O/16O) analyses. According to the research results, a significant positive relationship was found between applied irrigation water and the average T/ET ratio with a correlation coefficient of 0.81. The T/ET ratios were, on average, 70, 75 and 84% for rain‐fed, deficit and full irrigation treatments, respectively. During the growing season, 231 and 78 mm of irrigation water were applied for full and deficit irrigation, respectively. This showed that water savings of 66% were achieved, although there was a slight (12%) change in transpiration in deficit irrigation. Also, in the use of the oxygen isotope content results indicated that T was the dominant source of total evapotranspiration.

Remote sensing devices as key methods in the advanced turfgrass phenotyping under different water regimes

Turfgrass phenotyping is a potential tool in different grass program breeding. The traditional methods for turfgrass drought phenotyping in field are time-consuming and labor-intensive. However, remote sensing techniques emerge as effective, rapid and easy approaches to optimize turfgrass selection under water stress. Remote sensing approaches are considerate as important strategies to select species of turfgrass tolerable to drought allowing green space sustainability and environment protection in regions with water limitation. Here we evaluated differences between six mixtures of C3-C4 turfgrass grown under two water regimes (limited and high irrigation). The performance of turf species was achieved using the green area (GA) vegetation index calculated from RGB (red green, blue) images obtained by ground camera and drone imagery, the normalized difference vegetation index (NDVI), the plant canopy temperature (CT) and soil moisture content (SM). Both vegetation (GA and NDVI) and water status (CT and SM) indices presented a significant difference in turfgrass growth under the two water regimes. Differences among turfgrass species were detected under limited and high irrigation using the vegetation indices. Both NDVI and GA allowed clear separation between drought-tolerant and susceptible turfgrass, as well as the identification of the mixtures with a rapid green regeneration after a period of limited irrigation. Moreover, the canopy temperature also discriminated between turfgrass species but only under limited irrigation, while soil moisture values did not differentiate between species. Furthermore, the regression and conceptual model using remote sensing parameters revealed the most adequate criteria to detect turfgrass variability under each growing condition. This study also highlights the usefulness of green area vegetation index derived from drone imagery. GA obtained by drone images in this study explained turfgrass variability better than that derived from ground RGB images or the NDVI.

The Aging Process of Cadmium in Paddy Soils under Intermittent Irrigation with Acid Water: A Short-Term Simulation Experiment.

Cadmium (Cd)-contaminated paddy soils are a big concern. However, the effect of irrigation with acid water on the migration and transformation of Cd and the effect of alternating redox conditions caused by intermittent irrigation on Cd aging processes in different depths of paddy soils are unclear. This study revealed Cd fractionation and aging in a Cd-contaminated paddy soil under four irrigation periods with acid water and four drainage periods, by applying a soil columns experiment and a sequential extraction procedure. The results showed that the dynamic changes of soil pH, oxidation reduction potential (ORP), iron (Fe) oxides and dissolved organic carbon (DOC) throughout the intermittent irrigation affected the transformation of Cd fractions. After 32 days, the proportion of exchangeable Cd (F1) to the total Cd decreased with a reduction of 24.4% and 20.1% at the topsoil and the subsoil, respectively. The labile fractions of Cd decreased, and the more immobilizable fractions of Cd increased in the different depths of soils due to the aging process. Additionally, the redistribution of the Fe and Mn oxide-bound Cd (F3) and organic matter and secondary-sulfide-bound Cd (F4) occurred at different depths of soils during the incubation time. Overall, the bioaccessibility of Cd in the subsoil was higher than that in the topsoil, which was likely due to the leaching and accumulation of soluble Cd in the deep soil. In addition, the aging processes in different depths of soils were divided into three stages, which can be mainly described as the transformation of F1 into F3 and F4.

HYDRUS-2D simulations of typical pollutant migration in a soil aquifer system in the Zibo-Weifang funnel area of China

To clarify the removal trends of typical pollutants in recharged water samples during soil aquifer treatment (SAT), especially the recharging performances in the funnel areas of arid regions, the Zibo-Weifang funnel area of China was selected as an example where the effects of dry-wet ratio (DWR, the ratio of the dry period to irrigation period), wet period duration (WPD, duration of one irrigation period), irrigation side length (ISL) and irrigation depth (ID) on the 50-year SAT performance were simulated using HYDRUS-2D. Experimental results revealed that the operational parameters of the DWR, WPD, ISL and ID exhibited significant effects on the bulk removal of chemical oxygen demand (COD), nitrate (NO3−), ammonium (NH4+), total phosphorus (TP) and hexavalent chromium (Cr6+). Eventually, the optimal conditions with a DWR of 3, WPD of 7 d, ISL of 100 m, and ID of 200 cm were selected for the SAT based on the simulations, and irrigation loads as high as of 84.12 m/yr were obtained. During the 50-year irrigation simulation, as much as 256 Mm3/yr of new water would be recharged into the Shandong Plain, which would be accompanied by the effective removal of COD, NH4+, TP and Cr6+. In contrast, the NO3− concentrations within the obtained SAT effluent (50 m depth) were higher than those of the influent, which were closely related to the insufficient carbon sources in the deep soil and poor soil adsorption capacity. Thus, a more stringent threshold value for the nitrate reinjection concentration (e.g., 12 mg/L) was proposed. In addition, the pollutants, NO3−, NH4+, TP and Cr6+ all exhibited a penetration potential and posed potential pollution threats, especially under higher irrigation loads. Therefore, appropriate pretreatment measures should be strongly considered for the practical operation of SAT systems.

A CLINICAL STUDY ON DRY EYE AFTER CATARACT SURGERY.

Introduction: Dry eye as dened by the International Dry eye workshop is a multifactorial disease of the tears and ocular surfaces. Cataract surgery can cause dry eye as surgery can damage ocular surface. To nd out various factors Aims: responsible for dry eye after cataract surgery in presenile patients and the incidence of dry eye cases after cataract surgery. It was a Methods: prospective study on 100 patients Complete ocular examination and dry eye tests were done preoperatively and postoperatively. patients Results: who had longest tunnel incison, longer period of microscopic light exposure, vigorous irrigation, and eyedrops with preservatives had developed dry eye disease. As dry eye may develop after cataract surgery, so by decrea Conclusion: sing incision size of tunnel, minimizing microscopic light exposure and vigorous irrigation, using preservative free drops can decrease dry eye symptoms post operatively

Hydrological Effects of Agricultural Water Supplies on Paddy Fields using Surface–Groundwater Integrated Model

Agricultural water demands are mainly dependent on the supply from groundwater withdrawals and the supply from agricultural reservoirs. To understand the water cycle of the agricultural catchment, it is necessary to consider the actual situation of the water cycle of paddy fields in catchments through accurate hydrological modeling. In this study, streamflow simulations were implemented in consideration of the levee height of paddy fields and the irrigation period for one sub-catchment of the Boryeong Dam catchment using the integrated surface–groundwater model, CAT (Catchment Hydrologic Cycle Assessment Tool). To consider the agricultural reservoirs in modeling, the catchment was divided into the reservoir sub-catchments, upstream sub-catchments, downstream sub-catchments, and irrigated districts of each sub-catchment. This study aims to analyze the hydrological effects of agricultural reservoirs and groundwater pumping on the hydrological cycle of the catchment and on the soil moisture and groundwater level. As a result of the simulations, we found that the direct flow, baseflow, and groundwater recharge of the catchment increased with the agricultural reservoir supply water. In addition, the effect of drought on soil moisture content and groundwater level in the irrigated paddy fields from agricultural reservoirs was evaluated. The soil moisture increased by about 10% according to the water supply of agricultural reservoirs. The groundwater level rapidly decreased due to the groundwater abstraction during the irrigation period; however, it was analyzed that the water supply from agricultural reservoirs is significantly effective in preventing the decrease in the groundwater level in the irrigation season.