Selenium in surface and irrigation water in the Kendrick irrigation district, Wyoming

High selenium (Se) concentrations have been found in surface waters in the Kendrick Reclamation Project, Wyoming. Precipitation and irrigation water moving over seleniferous soils are contributing causes, and drought may exacerbate this. This study surveyed Se concentrations and discharges in local surface streams, irrigation drains, and the delivery canal. Sites were sampled monthly and analyzed for Se and total suspended solids (TSS). A completely randomized design with two factors (soil parent material and location, inside or outside irrigation district) was used. Mean Se concentrations were 64 μg L^???1 inside the irrigation district on shale soils, 17 μg L^???1 inside the district off shale soils, 5 μg L^???1 outside the district on shale soils, and 3 μg L^???1 outside the district off shale soils. Correlations between discharge and Se concentrations were generally negative, while correlations between discharge and Se load were generally positive. There was little correlation between load and concentration, and little correlation between TSS and Se. A comparison of Se concentrations in streams and drains showed Se concentrations were significantly higher (p?<?0.001) in streams during the irrigation season, but not in the off-season (p?=?0.515). We conclude that higher discharges decrease Se concentration, but increase load. Conversion from flood to sprinkle irrigation may increase Se concentrations by reducing discharge, but decrease Se loads going into the N. Platte River, and will likely alter the timing and magnitude of flows. Both load and concentration should be considered when implementing Se regulations and standards.     

Analysis of agricultural drought using vegetation temperature condition index (VTCI) from Terra/MODIS satellite data

The most commonly used normalized difference vegetation index (NDVI) from remote sensing often fall short in real-time drought monitoring due to a lagged vegetation response to drought. Therefore, research recently emphasized on the use of combination of surface temperature and NDVI which provides vegetation and moisture conditions simultaneously. Since drought stress effects on agriculture are closely linked to actual evapotranspiration, we used a vegetation temperature condition index (VTCI) which is more closely related to crop water status and holds a key place in real-time drought monitoring and assessment. In this study, NDVI and land surface temperature (T _s) from MODIS 8-day composite data during cloud-free period (September–October) were adopted to construct an NDVI–T _s space, from which the VTCI was computed. The crop moisture index (based on estimates of potential evapotranspiration and soil moisture depletion) was calculated to represent soil moisture stress on weekly basis for 20 weather monitoring stations. Correlation and regression analysis were attempted to relate VTCI with crop moisture status and crop performance. VTCI was found to accurately access the degree and spatial extent of drought stress in all years (2000, 2002, and 2004). The temporal variation of VTCI also provides drought pattern changes over space and time. Results showed significant and positive relations between CMI (crop moisture index) and VTCI observed particularly during prominent drought periods which proved VTCI as an ideal index to monitor terminal drought at regional scale. VTCI had significant positive relationship with yield but weakly related to crop anomalies. Duration of terminal drought stress derived from VTCI has a significant negative relationship with yields of major grain and oilseeds crops, particularly, groundnut.     

Reuse of municipal effluent with drip irrigation and evaluation the effect on soil properties in a semi-arid area

Irrigation with municipal effluent was evaluated during 25 months in Southern Iran from 2003 to 2005 in which 14 tree species were irrigated with effluent and borehole water at an annual supply rate of 3,940 and 5,395 m(3) ha(-1), respectively. To mitigate the environmental effects, a drip irrigation system was designed and the amount of applied water based on pan evaporation was measured by flow meters and soil properties were monitored. The statistical results showed that the applied effluent had no adverse effect on soil properties. The soil salinity was reduced from 8.2, 6.8 and 7.0 dSm(-1) to 1.07, 1.12 and 3.5 dSm(-1 )in the soil layers 0-30, 30-60 and 60-90 cm, respectively. The SAR decreased significantly, while soil pH increased by 0.8 and 0.6 units in the layers 0-30 and 30-60 cm. A total application of 9,335 m(3)ha(-1 )of effluent with a nitrogen and phosphorus concentration of 7.9 and 10.3 mg l(-1), added 73 and 101 kg ha(-1) of nitrogen and phosphorus to the soil. Organic carbon also increased significantly. Twenty-five months irrigation with effluent caused a slight increase in soil bulk density and a slight decrease in mean permeability. Because of an efficient filtration and high discharge rate of bubblers (drippers), no considerable sign of clogging was observed.     

Assessing the impact of irrigation treatments on thiram residual trends: Correspondence with numerical modelling and field-scale experiments

The present study was undertaken to study the trends of transport of thiram, a dithiocarbamate pesticide, at different time and depth in the fields under real field conditions for wheat crop. Numerical simulations were carried out by solving the coupled soil–water content movement and mass transport equations using HYDRUS- 1D. The supplementary data used for paramaterization of HYDRUS-1D comprise of irrigation treatments, climatic conditions, and soil characteristics. Results focus on the effects and influence of irrigation treatments on pesticide persistence and mobility. Modelling results were in good agreement with the experimentally determined thiram concentrations. Application of the model to measured field data of thiram movement indicates that the modelling approach can provide reliable and useful estimates of the mass flux of water and non-volatile pesticide in vadose zone. For policy-makers and planners, some regulation strategies are suggested for controlling inappropriate pesticide application under deficit irrigation or rain-fed conditions.     

洋河下游农灌区农作物受灾与水质污染的关系

根据情况调查设计严密而合乎逻辑的监测方案：在农灌水质标准缺乏的情况下,根据监测数据和有关资料找出致害污染物;对本次监测数据和历年常规监测数据进行分析,确定污染源;最后提出防治污染的对策。结论是致死污染物为阿特拉津和乙草胺．而高锰酸盐指数、ｐＨ和悬浮物的超标是致害的重要有关因素;致害污染物主要来源了宣化区废水;严格监控农药厂废水、兴建污水处理厂和改善农灌措施是防治污染的途径。后来的事实完全证实了本结论和对策的正确性。     

Water quality assessment of Majhiaon block of Garwa district in Jharkhand with special focus on fluoride analysis

Fluoride in groundwater is known to contaminate the water sources globally. Jharkhand, one of the states in the eastern part of India, is known to have excessive fluoride content in groundwater sources. The present work involves assessment of water quality with special reference to fluoride in Majhiaon block of Garwa district in Jharkhand. Iron, nitrate and arsenic were also tested for the water samples collected from site. Eight hundred forty samples were tested for fluoride on site using colourimetry method, and one tenth of the samples were brought to laboratory for iron, nitrate, arsenic and fluoride analysis. Results show that 402 samples were having fluoride above permissible limit. Iron and nitrate were found to be beyond permissible limits in 302 and 286 water samples, respectively. More than 50% of samples collected from school had fluoride levels above permissible limits. Arsenic was well within the limits. However, few samples shown were excessive of iron and nitrate.     

对旱情的理性思考和构建新的监测、抗旱理念

对旱灾造成的损失,不能仅从农业粮食减产单方面估算,而应把旱灾造成的隐性损失科学评估出来。据此提出,抗旱要处理好农业用水、工业用水和城市用水及生态用水的关系,真正实现水资源的可持续利用,并应建立自动化的干旱监测和快速评估系统,以保证及时掌握旱情,将旱灾损失减至最小。     

Influence of drought and municipal sewage effluents on the baseflow water chemistry of an upper piedmont river

The Reedy River in South Carolina is affected by the urban area of Greenville, the third most populous city in the state, and by the effluents from two large-scale municipal wastewater treatment plants (WWTPs) located on the river. Riverine water chemistry was characterized using grab samples collected annually under spring season baseflow conditions. During the 4-year time period associated with this study, climatic variations included two severe drought spring seasons (2001 and 2002), one above-normal precipitation spring season (2003), and one below-normal precipitation spring season (2004). The influence of drought and human activities on the baseflow chemistry of the river was evaluated by comparing concentrations of dissolved anions, total metals, and other important water chemistry parameters for these different years. Concentrations of copper and zinc, common non-point source contaminants related to urban activities, were not substantially elevated in the river within the urban area under baseflow conditions when compared with headwater and tributary samples. In contrast, nitrate concentrations increased from 1.2–1.6 mg/l up to 2.6–2.9 mg/l through the urban stream reach. Concentrations of other major anions (e.g., sulfate, nitrate) also increased along the reach, suggesting that the river receives continuous inputs of these species from within the urban area. The highest concentrations of major cations and anions typically were observed immediately downstream from the two WWTP effluent discharge locations. Attenuation of nitrate downstream from the WWTPs did not always track chloride changes, suggesting that nitrate concentrations were being controlled by biochemical processes in addition to physical processes. The relative trends in decreasing nitrate concentrations with downstream distance appeared to depend on drought versus non-drought conditions, with biological processes presumably serving as a more important control during non-drought spring seasons.     

平原高速公路交通噪声对两侧敏感区域影响的探讨

针对目前平原高速公路交通噪声影响两侧敏感区域的状况,环评预测结果偏差过大的问题,应用声学传播理论,对交通噪声的衰减结果进行计算,并用实测数据进行验证。其结果对平原高速公路交通噪声的管理与治理提供相应的参考。     

Effects of irrigation with wastewater on the physiological properties and heavy metal content in Lepidium sativum L. and Eruca sativa (Mill.)

The purpose of this study was to determine the physiological properties of and heavy metal content in Lepidium sativum L. and Eruca sativa (Mill.) irrigated with municipal wastewater for 20 days. Wastewater was taken from a section where all wastewater of Adiyaman is collected. We analysed the soil for physicochemical properties, heavy metals and nutrient content and the plants for photosynthetic pigment content, dry weight and length. Irrigation wastewater increased the electrical conductivity and organic matter content in plant soil. In both plant soils, Cd and Ni content significantly increased with respect to control. Dry matter content decreased significantly in the edible parts, and the length of the edible parts increased significantly in E. sativa. Photosynthetic pigment content increased in L. sativum and decreased in E. sativa. Nutrient content changed significantly in both plants. In the edible parts of L. sativum, Cd and Ni content increased significantly compared to Pb and Cr. The edible parts of E. sativa also showed a higher Cd level than the control plant. The enrichment factor of the heavy metals in the edible parts of L. sativum followed this order: Cu?>?Pb?>?Cd?>?Ni?>?Cr and of E. sativa: Pb?>?Cd?>?Cu?>?Cr?>?Ni. The edible parts of both plants showed a high transfer factor (TF?>?1) for Cd, which points to high mobility of Cd from soil to plant. In conclusion, the use of wastewater for irrigation increased heavy metal content in both plants and affected their physiological and morphological properties.     

Assessment of long-term wastewater irrigation impacts on the soil geochemical properties and the bioaccumulation of heavy metals to the agricultural products

An extensive field survey was employed for assessing the impacts of long-term wastewater irrigation of forage crops and orange orchards in three suburban agricultural areas in Cyprus (areas I, II, and III), as compared to rainfed agriculture, on the soil geochemical properties and the bioaccumulation of heavy metals (Zn, Ni, Mn, Cu, Co) to the agricultural products. Both ryegrass fields and orange orchards in areas I and II were continuously wastewater irrigated for 10 years, whereas clover fields in area III for 0.5, 4, and 8 years. The results revealed that wastewater reuse for irrigation caused a slight increase in soil salinity and Cl^? content in areas I and II, and a remarkable increase, having strong correlation with the period in which wastewater irrigation was practiced, in area III. Soil salinization in area III was due to the high electrical conductivity (EC) of the wastewater applied for irrigation, attributed to the influx of seawater to the sewage collection network in area III. In addition, the wastewater irrigation practice resulted in a slight decrease of the soil pH values in area III, while a subtle impact was identified regarding the CaCO₃, Fe, and heavy metal content in the three areas surveyed. The heavy metal content quantified in the forage plants’ above-ground parts was below the critical levels of phytotoxicity and the maximum acceptable concentration in dairy feed, whereas heavy metals quantified in orange fruit pulp were below the maximum permissible levels (MPLs). Heavy metal phytoavailability was confined due to soil properties (high pH and clay content), as evidenced by the calculated low transfer factor (TF).     

Quality of wastewater reuse in agricultural irrigation and its impact on public health

This study is planned to perform a sanitary survey of the largest sewage treatment plant in Riyadh, KSA, fortnightly for 6 months to examine its effluent quality as an example for the growing dependence on reuse of treated municipal wastewater in agricultural irrigation purposes to cope with increasing water shortage. The biological and physico-chemical parameters of 12 wastewater samples from the plant were examined using standard methods. The physico-chemical analysis indicated that the surveyed municipal wastewater treatment plant contained some of the studied parameters, such as turbidity, total suspended solids, biochemical oxygen demand, chemical oxygen demand and residual chlorine above the maximum permissible wastewater limits set by the Saudi Standards. However, heavy metal concentrations in all samples were lower than the recommended standards. Total and faecal coliform counts were above the permissible limits indicating poor sanitation level. Fifty percent of all wastewater samples were contaminated with faecal coliforms but, surprisingly, Escherichia coli were only detected in 8.3 % of the samples. Regular monitoring and enhancement of microbial and physico-chemical parameters of the wastewater quality served by different wastewater treatment plants for reuse in agricultural irrigation is recommended to preserve the environment and public health.     

Impacts of intensive agricultural irrigation and livestock farming on a semi-arid Mediterranean catchment

Irrigation return flows (IRF) are a major contributor of non-point source pollution to surface and groundwater. We evaluated the effects of irrigation on stream hydrochemistry in a Mediterranean semi-arid catchment (Flumen River, NE Spain). The Flumen River was separated into two zones based on the intensity of irrigation activities in the watershed. General linear models were used to compare the two zones. Relevant covariables (urban sewage, pig farming, and gypsum deposits in the basin) were quantified with the help of geographic information system techniques, accompanied by ground-truthing. High variability of the water quality parameters and temporal dynamics caused by irrigation were used to distinguish the two river reaches. Urban activity and livestock farming had a significant effect on water chemistry. An increase in the concentration of salts (240–541 μS·cm^???1 more in winter) and nitrate (average concentrations increased from 8.5 to 20.8 mg·l^???1 during irrigation months) was associated with a higher level of IRF. Those river reaches more strongly influenced by urban areas tended to have higher phosphorus (0.19–0.42 mg·l^???1 more in winter) concentrations. These results support earlier research about the significant consequences to water quality of both urban expansion and intensive agricultural production in arid and semi-arid regions. Data also indicate that salinization of soils, subsoils, surface water, and groundwater can be an unwelcome result of the application of pig manure for fertilization (increase in sodium concentration in 77.9 to 138.6 mg·l^???1).     

Analysis of the spatial-temporal variation characteristics of vegetative drought and its relationship with meteorological factors in China from 1982 to 2010

Drought is a complex natural phenomenon that can cause reduced water supplies and can consequently have substantial effects on agriculture and socioeconomic activities. The objective of this study was to gain a better understanding of the spatial-temporal variation characteristics of vegetative drought and its relationship with meteorological factors in China. The Vegetation Condition Index (VCI) dataset calculated from NOAA/AVHRR images from 1982 to 2010 was used to analyse the spatial-temporal variation characteristics of vegetative drought in China. This study also examined the trends in meteorological factors and their influences on drought using monitoring data collected from 686 national ground meteorological stations. The results showed that the VCI appeared to slowly rise in China from 1982 to 2010. From 1982 to 1999, the VCI rose slowly. Then, around 2000, the VCI exhibited a severe fluctuation before it entered into a relatively stable stage. Drought frequencies in China were higher, showing a spatial distribution feature of “higher in the north and lower in the south”. Based on the different levels of drought, the frequencies of mild and moderate drought in four geographical areas were higher, and the frequency of severe drought was higher only in ecologically vulnerable areas, such as the Tarim Basin and the Qaidam Basin. Drought was mainly influenced by meteorological factors, which differed regionally. In the northern region, the main influential factor was sunshine duration, while the other factors showed minimal effects. In the southern region and Tibetan Plateau, the main influential factors were sunshine duration and temperature. In the northwestern region, the main influential factors were wind velocity and station atmospheric pressure.     

Effects of organic amendments and irrigation waters on the physical and chemical properties of two calcareous soils in Bahrain

The present investigation studies the effects of cow and chicken manure and sewage sludge at different rates of addition and with two irrigation waters of different salinities on two major calcareous soils in Bahrain. The aim was to quantify potential improvements in soil quality, the accumulation of trace metals, and quality of leachates.From the pot experiments it was found that soil waterholding capacity did not change significantly after addition of organic amendments, except in the case of sewage sludge. Total organic carbon and total Kjeldhal nitrogen content increased in the 0–5 cm layer. Low salinity water and sewage applications improved aggregate stability. Extractable phosphorus was enhanced by the chicken manure treatment more than others. Addition of different organic amendments did not affect exchangeable cations. pH values did not show appreciable changes and soils were neutral. Trace metals studied were present at non-toxic levels in the 0–5 cm layer. Zinc and copper were the only metal showing a tendency to leach to the lower soil layer. In all cases metal levels in the surface layer were proportional to the quantities added in the amendments and their levels in the leachate were very low.     

黄浦江水环境生物监测指标研究

对黄浦江进行了全面的生物监测及评价.通过相关性分析表明,底栖生物的Shnnon-Weaver指数和Coodnight指数与水质综合评价指数呈显著负相关;细菌总数和总大肠菌群数与水质综合评价指数呈显著正相关,R2值均＞0.9,能较敏感地反映水质变化的生态效应,构成了黄浦江水环境生物监测核心指标.     

滏阳河削减断面莲花口污染指数反弹的启示

根据地面水质常规监测中断面的功能特性,对监测数据中出市削减断面的石油类污染指数高于出市断面的现象进行了分析。通过研究当年其它主要污染指数的增长率和厉年石油类和其它主要污染指数的平均动态数列,证实削减断面石油类污染指数反弹属实。指明这是一种利用监测数据发现新污染源的方法。     

Land use impacts on river health of Uma Oya,Sri Lanka: implications of spatial scales

Human actions on landscapes are a principal threat to the ecological integrity of river ecosystems worldwide. Tropical landscapes have been poorly investigated in terms of the impact of catchment land cover alteration on water quality and biotic indices in comparison to temperate landscapes. Effects of land cover in the catchment at two spatial scales (catchment and site) on stream physical habitat quality, water quality, macroinvertebrate indices and community composition were evaluated for Uma Oya catchment in the upper Mahaweli watershed, Sri Lanka. The relationship between spatial arrangement of land cover in the catchment and water quality, macroinvertebrate indices and community composition was examined using univariate and multivariate approaches. Results indicate that chemical water quality variables such as conductivity and total dissolved solids are mostly governed by the land cover at broader spatial scales such as catchment scale. Shannon diversity index was also affected by catchment scale forest cover. In stream habitat features, nutrients such as N-NO₃ ^?, macroinvertebrate family richness, %shredders and macroinvertebrate community assemblages were predominantly influenced by the extent of land cover at 200 m site scale suggesting that local riparian forest cover is important in structuring macroinvertebrate communities. Thus, this study emphasizes the importance of services provided by forest cover at catchment and site scale in enhancing resilience of stream ecosystems to natural forces and human actions. Findings suggest that land cover disturbance effects on stream ecosystem health could be predicted when appropriate spatial arrangement of land cover is considered and has widespread application in the management of tropical river catchments.     

Application of the Morris algorithm for sensitivity analysis of the REALM model for the Goulburn irrigation system

The REALM modelling shell is widely used in Australia as a water allocation modelling tool. It has been used to develop the Goulburn System Model (GSM) of the Goulburn, Broken, Loddon and Campaspe Rivers in northeastern Victoria. REALM represents the river and irrigation system as a network of storages and carriers. The model has been optimised to best represent the water harvesting and allocation for use by water management authorities. The model is analysed to assess the sensitivity of a subset of the model outputs, to a subset of the system parameters. The New Morris algorithm uses sampling paths generated in the space of the parameters, to generate points at which the model is run (to generate the model outputs). These model runs are then used to estimate the first and second-order effects of the parameters on the outputs. The results illustrate the mild linkage of the Goulburn and Broken systems, and the Broken system also shows differences between minimum and average outflows. The Goulburn is more sensitive to some of the numerical convergence parameters used in the allocation software, while the Broken is less sensitive to these factors. The numerical convergence factors also lead to important second-order effects.