Evaluation of groundwater quality using water quality index and its suitability for assessing water for drinking and irrigation purposes: Case study of Sistan and Baluchistan province (Iran)

The present study evaluates the groundwater quality for drinking and agricultural purposes and determines physicochemical characteristics of groundwater in the Sistan and Baluchistan province in Iran. In order to investigate the water quality, sampling was done in 654 open dug wells, the chemical parameters were analyzed, and water quality index was determined. In this regard, Langelier saturation index (LSI), Ryznar Stability index (RSI), Puckorius scaling index (PSI), Larson–Skold index (LS), and Aggressiveness index (AI) were considered to determine water suitability for industrial purposes. Finally, the analytical results were taken to generate the numerical spatial distribution of the parameters using the geographic information system (GIS) environment. According to the results, water sources were less corrosive based on AI and PSI, low and light corrosion according to RSI, and corrosion according to the Larsson–Sckold index. The results of the drinking water quality index showed that 1.2% shared extraction wells were classified as excellent, 52.1% as good, 39% as poor, 6% as very poor, and 1.7% as unsuitable for drinking purpose classes. In addition, irrigating water quality index illustrated that 19.9% and 80.1% wells were placed in the “excellent” and “Good” classes, respectively. Also, the quality of water in this study was categorized as brackish.     

灌溉方法与施氮对土壤水分、硝态氮和小麦生长发育的调控效应

为探明玉米秸秆还田下小麦的合理灌溉与施肥方法,于田间研究了漫灌(FI)、微喷灌(SI)、滴灌(DI)和灌水施氮模式(N₁, 基施纯N 157.5 kg·hm^-2+拔节期施纯N 67.5 kg·hm^-2; N₂, 基施纯N 157.5 kg·hm^-2+拔节期施纯N 45.0 kg·hm^-2+灌浆期施N 22.5 kg·hm^-2)对土壤水分、硝态氮(NO₃^--N)含量和小麦生长发育的影响.结果表明: 灌溉方法和灌水施氮模式共同影响土壤含水量和贮水量的变化.其中,灌溉方法对越冬期和返青期0～60 cm、孕穗期和灌浆期0～160 cm、成熟期100～160 cm土层含水量影响相对较小,对越冬期和返青期80～160 cm、成熟期0～80 cm土层含水量影响大;FI对含水量和贮水量影响最大,DI次之,SI最小;SI和DI的灌水施氮模式中灌水量多,则土层含水量高、贮水量多,变化大.NO₃^--N含量受灌溉方法和施氮的影响,施氮对0～20 cm土层影响大,SI生育期NO₃^--N含量变化大,DI越冬期至孕穗期NO₃^--N含量变化小,此后变化大,FI与DI相反;生育前中期灌水量对NO₃^--N含量影响大,后期施氮对NO₃^--N含量影响大;SI和DI的2种灌水施氮模式中冬前灌水量多的NO₃^--N含量变化大.灌溉方法中SI越冬期总茎数和单株分蘖高,成穗率高,成穗数多,产量、水分利用效率(WUE)和氮素利用效率最高,滴灌次之,漫灌最低;SI和DI中N₁生育期总茎数、成穗数多,但穗粒数和千粒重低,产量、WUE和氮素利用效率低于N₂.因此,玉米秸秆还田后播种小麦,微喷灌代替漫灌生育期灌4水,施足基肥,拔节期和灌浆期分次追氮,是山西南部小麦-玉米一年两熟区小麦节水高产高效栽培模式.     

Adult anopheline ecology and malaria transmission in irrigated areas of South Punjab, Pakistan

Surface irrigation in the Punjab province of Pakistan has been carried out on a large scale since the development of the Indus Basin Irrigation System in the late 19th century. The objective of our study was to understand how the population dynamics of adult anopheline mosquitoes (Diptera: Culicidae) could be related to malaria transmission in rural areas with intensive irrigation and a history of malaria epidemics. In this paper we present our observations from three villages located along an irrigation canal in South Punjab. The study was carried out from 1 April 1999 to 31 March 2000. Mosquitoes were collected from bedrooms using the pyrethroid spraycatch method and from vegetation and animal sheds using backpack aspirators. Overall, Anopheles subpictus Grassi sensu lato predominated (55.6%), followed by An. stephensi Liston s.l. (41.4%), An. culicifacies Giles s.l. (2.0%), An. pulcherrimus Theobald (1.0%) and An. peditaeniatus Leicester (0.1%). Most mosquitoes (98.8%) were collected from indoor resting-sites whereas collections from potential resting-sites outdoors accounted for only 1.2% of total anopheline densities, confirming the endophilic behaviour of anophelines in Pakistan. Anopheles stephensi, An. culicifacies and An. subpictus populations peaked in August, September and October, respectively. High temperatures and low rainfall negatively affected seasonal abundance in our area. There were interesting differences in anopheline fauna between villages, with An. culicifacies occurring almost exclusively in the village at the head of the irrigation canal, where waterlogged and irrigated fields prevailed. Monthly house-to-house fever surveys showed that malaria transmission remained low with an overall slide positivity rate of 2.4% and all cases were due to infection with Plasmodium vivax. The most plausible explanation for low transmission in our study area seems to be the low density of Pakistan's primary malaria vector, An. culicifacies. The role of other species such as An. stephensi is not clear. Our observations indicate that, in South Punjab, irrigation-related sites support the breeding of anopheline mosquitoes, including the vectors of malaria. As our study was carried out during a year with exceptionally hot and dry climatic conditions, densities and longevity of mosquitoes would probably be higher in other years and could result in more significant malaria transmission than we observed. To assess the overall importance of irrigation-related sites in the epidemiology of malaria in the Punjab, more studies are needed to compare irrigated and non-irrigated areas.     

Effects of irrigation and air humidity preconditioning on water relations, growth and survival of Rosmarinus officinalis plants during and after transplanting

The effect of different irrigation and air humidity conditioning treatments on the morphological and physiological responses of Rosmarinus officinalis in nursery conditions was investigated in order to evaluate the degree of hardening resulting from these conditions. Rosmarinus officinalis seedlings were pot-grown during 4 months in two greenhouses (nursery period), in which two irrigation treatments were used (control and deficit). In one of these greenhouses, air humidity was controlled using a dehumidifying system (low humidity), in the other greenhouse the air conditions were not artificially modified (control humidity). After the nursery period, the plants of all treatments were transplanted and well watered (100% water holding capacity for 1 month, transplanting period). After this period, they received no water (establishment period). At the end of the nursery period it was seen that deficit irrigation had altered the morphology of the R. officinalis plants by reducing plant height, stem diameter, leaf area, total dry weight, and root length, while humidity influenced the parameters related with plant water relations. Low air humidity and deficit irrigation-induced tissue dehydration and lower stomatal conductance values (gs). The plants subjected to deficit irrigation developed leaf osmotic adjustment, which was maintained during the transplanting period. At that time, the plants that had been exposed to deficit irrigation and low humidity showed efficient stomatal regulation (lower gs values). After transplanting and during the establishment period, these plants showed a better water status (higher psil and gs values). Their post-planting survival rate improved as a result of acclimation processes.     

Effect of organic and mineral fertilizers on N-use by wheat under different irrigation frequencies

A field trial was established in Errachidia, southern Morocco, to investigate the interaction between wheat residue management and mineral 15N-labelled ammonium sulphate, under different irrigation treatments, applied to wheat (Triticum durum var. Karim). In treatments I1, I2, I3 and I4, plots were irrigated every 10, 15, 21 and 30 days. Each plot contained three sub-plots that received three fertilization treatments: T1 received 42 kg N ha-1 of ammonium sulphate before seedling, 42 kg N ha-1 of ammonium sulphate labelled with 9.764 at % 15N excess at tillering and 84 N kg ha-1 of ammonium sulphate at flowering; T2 received 42 kg N ha-1 of ammonium sulphate labelled with 9.764 at % 15N excess at seedling, 42 kg N ha-1 at tillering and 42 kg N ha-1 at flowering; T3 received 4800 kg ha-1 of wheat residue labelled with 1.504 at % 15N excess and 42 kg N ha-1 of ammonium sulphate before seedling and 42 kg N ha-1 of ammonium sulphate at flowering. Nitrogen fertilization with 168 kg N ha-1 did no significantly increase grain and straw yields in comparison to the 126 kg N ha-1 application. The combination of the organic input and supplementary application of mineral fertilizer N has been found as a more attractive management option. For all irrigation treatments, the % recovery of N in the whole plant was higher in plants that received 15N at tillering (63%, 49% respectively for irrigation intervals between 10 and 30 d) than in plants that received 15N just after seeding (28% for irrigation each 10- and 30-d intervals). For the irrigation treatment each 10 and 15 days, the 15N was mainly recovered by the grain for all fertilization treatments, whereas for irrigation treatment each 30 days, the grain and straw recovered nearly equal amounts of fertilizer. For grain and straw of wheat, nitrogen in the plant derived from the fertilizer was low, while most of the N was derived from the soil for all irrigation and fertilization treatments. The % nitrogen in the plant derived from the fertilizer values showed no significant difference between the different plant parts. The results suggested a dominant influence of moisture availability on the fertilizer N uptake by wheat. Under dry conditions the losses of N can be allotted to denitrification and volatilisation.     

Effects of 15N application frequency on nitrogen uptake efficiency in citrus trees

Two irrigation systems were used to compare nitrogen uptake efficiency in citrus trees and to evaluate the NO₃⁻ runoff in «Navelina» orange trees [Citrus sinensis (L.) Osbeck] on Carrizo citrange rootstock (Citrus sinensis × Poncirus trifoliata Raf.). These were fertilized with 125 g N as labelled K¹⁵NO₃ and grown outdoors in containers filled with a sand-loamy soil. Two groups of 3 trees received this N dose either in five equally split applications by a flooding irrigation system or in 66 applications by drip. Trees were harvested at the end of the vegetative cycle (December) and the isotopic ratios of ¹⁵N/¹⁴N were measured in the soil-plant system. The N uptake efficiency of the whole tree was higher with drip irrigation (75 percnt;) than with flooding system (64 percnt;). In the 0-90 cm soil profile, the N immobilized in the organic fraction was similar for both irrigation methods (around 13 percnt;), whereas the N retained as NO₃⁻ was 1 percnt; of the N applied under drip and 10 percnt; under flooding. In the last case, most of NO₃⁻ remained under root system and it could be lost to leaching either by heavy rainfalls or excessive water applications. These results showed that a drip irrigation system was more efficient for improving water use and N uptake from fertilizer, in addition to potentially reduced leaching losses.     

Breeding of Anopheles mosquitoes in irrigated areas of South Punjab, Pakistan

As part of investigations on potential linkages between irrigation and malaria transmission, all surface water bodies in and around three villages along an irrigation distributary in South Punjab, Pakistan, were surveyed for anopheline mosquito larvae (Diptera: Culicidae) from April 1999 to March 2000. Samples were characterized according to exposure to sunlight, substratum, presence of vegetation, fauna, inorganic matter and physical water condition (clear/turbid/foul). Also water temperature, dissolved oxygen (DO), electroconductivity (EC) and pH of sites were recorded. A total of 37982 Anopheles larvae of six morphological types were collected from 2992 samples taken from irrigation/agricultural and village/domestic aquatic habitats. Anopheles subpictus Grassi sensu lato was by far the most abundant (74.3%), followed by An. culicifacies Giles s.l. (4.1%), An. stephensi Liston s.l. (2.6%), An. pulcherrimus Theobald (1.8%), An. peditaeniatus Leicester (0.3%) and An. nigerrimus Giles (0.1%). The four most abundant species were significantly associated with waterlogged fields and communal village drinking-water tanks. Habitat characteristics most correlated with occurrence of anophelines were the physical water condition and the absence/presence of fauna, particularly predators. Occurrence and abundance of Anopheles immatures were not significantly correlated with water temperature, DO, EC or pH. Malaria vectors of the Anopheles culicifacies complex occurred at relatively low densities, mainly in irrigated and waterlogged fields. In South Punjab, where rainfall is very low, it should be possible to reduce anopheline breeding through water management, as larvae develop mainly in water bodies that are directly or indirectly related to the extensive canal-irrigation system.     

Phytophagous Mite Populations on Tahiti Lime, Citrus Latifolia, Under Induced Drought Conditions

In the nort-western region of Venezuela, Phyllocoptruta oleivora, Tetranychus mexicanus and Brevipalpus phoenicis are common plant-feeding mites on leaves, fruits and branches of Tahiti lime, Citrus latifolia. The population dynamics of these herbivores are affected by many factors, such as weekly treatments with wettable sulphur, particularly during the wet season, maintenance pruning of plants, irrigation with microsprinklers, induction of water stress by withholding irrigation and biotic and abiotic environmental factors. During October 1994-January 1995, 31 trees in a commercial orchard were sampled weekly in order to describe population fluctuations of plant-feeding mites (mean number of mites per leaf or fruit), before (4 weeks) and after (4 weeks) a period of 6 weeks of drought stress (no irrigation). The population density of P. oleivora increased progressively during the last 3 weeks of the irrigation period and reached a maximum of 24 mites per fruit. In contrast, the populations of the other two species, T. mexicanus and B. phoenicis, remained at the same low density as before the withholding-irrigation period. After 6 weeks without irrigation, only T. mexicanus increased, to a high mean value of 11 mites per leaf. The withholding-irrigation practice appears to affect the population size of P. oleivora towards the end of this period and that of T. mexicanus at the beginning of the re-establishment of the water supply. The highest proportion of trees (32%) was infested by T. mexicanus after the withholding-irrigation period, when irrigation was resumed, whereas the highest levels of infestation of trees by P. oleivora and B. phoenicis were 16 and 10%, respectively, during the last week of the water-stress period. Although factors affecting the dynamics of the mites in the orchard are likely to be complex, irrigation management apparently plays an important role.