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51.
The potential risk of pesticides to cause harm to humans and other organisms even at trace levels calls for sensitive and accurate analytical techniques for their simultaneous qualitative and quantitative determinations. In this study, a sensitive binary dispersive liquid-liquid microextraction (B-DLLME) strategy was developed for the simultaneous determination of phorate and oxyfluorfen by gas chromatography mass spectrometry after extraction/preconcentration from aqueous solution. An experimental design was used to optimize parameters of the B-DLLME method to obtain maximum outcome. Under the optimum conditions of B-DLLME, the limit of detection (LOD) for phorate and oxyfluorfen were found to be 0.41 μg L?1 and 0.54 μg L?1, respectively. The detection limits correlate to about 37 and 73 folds enhancement in detection powers when compared to direct GC-MS determination of phorate and oxyfluorfen, respectively. In order to find out the applicability of developed method to real samples, recovery tests were performed for 20 μg L?1 of phorate and oxyfluorfen spiked in well water samples. Percent recovery values were found to be 94.5% for phorate and 101.9% for oxyfluorfen.  相似文献   
52.

Purpose

Riparian zone contamination is a growing problem for several European catchments due to high anthropogenic pressures. This study investigates As, Cd, Cr, Cu, Ni, Pb, and Zn concentrations in the Sava River riparian zone, characterized by wide agricultural areas, various geological substrates, and different types of industrial pollution. The accumulation and mobility of these elements were studied because they are listed as priority substances in the Water Framework Directive and environmental objectives for surface waters.

Materials and methods

Sampling was performed during the sampling campaign of the EU 7th FW-funded GLOBAQUA project in September 2015 during a low-water event. Soil samples were collected along the Sava River at 12 selected sampling sites, from a depth of 0–30 cm, at a distance of 10–15 m from the river bank. The extent of pollution was estimated by determining total and readily soluble element concentrations in the soils. Potential ecological risk and the source of the selected elements in the soils was determined using the enrichment factor (EF), potential ecological risk index (RI), and statistical methods such as the principal component analysis (PCA) and multiple linear regression analysis (MLRA).

Results and discussion

This study showed that concentrations of the selected elements increase along the Sava. In terms of origin, PCA and MLRA indicated that Cr and Ni in soils are predominantly lithogenic, while As, Cd, Pb, and Zn are both lithogenic and anthropogenic (ore deposits, industry, and agriculture). PCA singled out Cu since its origin in soil is most probably from specific point-source pollution. EF was generally minor to moderate for most of the examined elements, apart from Cu, for which the EF was significant at one sampling site. Overall ecological risk (RI) fell within the low-risk category for most sites, apart from Belgrade sampling site (BEO), where high total Cd content affected individual and overall ecological risk indicators, indicating Cd could represent a considerable ecological risk for the downstream riparian zone.

Conclusions

At downstream sites, there was a noticeable increase in PTE content, with Cd, Cr, Ni, and Zn exceeding the proposed threshold values for European soils, indicating rising contamination in riparian soils. In terms of the ecological risk, only Cd could pose a potential ecological threat for the downstream riparian zone.
  相似文献   
53.
A field experiment has been conducted to determine the effects of different irrigation water and AMF (Arbuscular Mycorrhizal Fungi) biofertilizer, photosynthesis activator and traditional fertilizer dry bean (Phaseolus vulgaris L.) on yield and growth parameters in Nevsehir Province of Turkey in 2015. The experiment has been carried out using three replications in a split plot design with three different irrigation types as main plots and AMF biofertilizer (ERS), photosynthesis activator (Multigreen-Mg), traditional fertilization (TF-Control), ERS + Mg, ERS + TF and TF + Mg applied as subplots. The number of pods per plant, the length of pods, the number of grains per pod, the weight of grains per plant, the yield of grains, 1000 seed weight, the number of grains per plant, protein yield, arbuscular mycorrhizal fungi rate have been evaluated as yield and growth criteria in the study. In the experiment, as well as the treatment x irrigation interaction, the plant height, pod number per plant, pod lenght, grain number per pod, grain weight per plant, grain yield, 1000 seed weight, grain number per plant, protein rate/grain, protein yield, root weight and AMF colonization parameters, were the other studied properties that were found to be significant. The results obtained were 877.6 mm for I100 irrigation treatment, 512.2 mm for I50 irrigation treatment and 40.19 mm water for I30 irrigation treatment. Regarding the growth parameters of dry bean, the highest PH was in ERS + Mg (67.66 cm), the lowest PH was in ERS (54.33 cm); In I50, the highest Plant Height (PH) was in ERS + Mg (65.66 cm), the lowest PH was in TF-Control (53.00 cm); and in I30, the highest PH was in TF-Control (50.66 cm), and the lowest PH was again in ERS + Mg (44.33 cm). For protein yield (PY) value, ERS + Mg, ERS + TF, TF + Mg have been placed in the same group, in I100 and I50 irrigation treatment. The highest value was ERS + TF (34.90 kg da?1) in I100, The lowest value was TF-control (19.90 kg da?1) in I30 irrigation treatment. In terms of mycorrhiza colonization ratio, ERS has been ranked first in all irrigation treatments, while the highest mycorrhiza colonization has been observed in I30 irrigation treatment (26.30%). ERS was followed by ERS + Mg (23.33%). As expected, the lowest mycorrhiza colonization ratio in all irrigation treatments have been observed in TF-control treatment, while the highest mycorrhiza colonization ratio has been respectively observed in I30 and I50 irrigation topics. The highest root weight (RW) in I100 irrigation treatment was observed in ERS (15.06 g plant?1) and it was observed in ERS (19.05 g plant?1; 26.30 g plant?1) in I50 and I30 irrigation treatments. The lowest RW in all irrigation treatments has been observed in TF + Mg (4.43 g plant?1, 6.40 g plant?1, 10.26 g plant?1), respectively.  相似文献   
54.
In this experiment, four cadmium (Cd) hyperaccumulator species (Crassocephalum crepidioides, Galinsoga parviflora, Sigesbeckia orientalis, and Solanum nigrum) were intercropped with grape (Vitis vinifera) cuttings together in Cd-containated soil to study the effects of intercropping with the Cd-hyperaccumulator plants on growth and Cd accumulation of grape seedlings. Compared with the monoculture, intercropping with S. nigrum increased the biomass of grape seedlings, but intercropping with the other three hyperaccumulator species decreased the grape seedling biomass. Intercropping with S. nigrum increased chlorophyll a and total chlorophyll contents in leaves of grape seedlings compared with the monoculture, whereas intercropping with the other three hyperaccumulator species showed either a decrease or no effect. Intercropping with hyperaccumulator plants had no significant effects on chlorophyll b and carotenoid contents in leaves of grape seedlings compared with the monoculture. Compared with the monoculture, intercropping with C. crepidioides, G. parviflora, S. nigrum and S. orientalis significantly decreased Cd contents in shoots of grape seedlings by 78.7%, 12.7%, 29.8% and 26.5%, respectively. Therefore, intercropping with hyperaccumulator plants can decrease Cd accumulation in grape, and intercropping with S. nigrum can also promote grape seedling growth.  相似文献   
55.
不同有机肥对有机茶园茶叶产量及开花量影响的研究   总被引:2,自引:0,他引:2  
为了研究不同有机物料在有机茶园中的施用效果,在八年生有机茶园内设置4种无害化有机物料、3个不同水平的处理,研究这些处理对福鼎种茶树生产性状、鲜叶生化品质及开花量的影响。试验结果表明:与空白对照相比,各种无害化有机物料处理均可显著改善茶树的生长,提高茶叶的产量,改善茶叶的品质,降低开花量,提高经济效益。芽重增加17.06%~42.06%,茶芽密度提高20.9%~36.4%,茶青的产量提高41.26%~93.4 9%,开花量降低2 1.6 7%~4 6.8%,产值增加1 757~3 223元/6 6 7 m2不等;茶叶的水浸出物、茶多酚、氨基酸、咖啡碱等品质成分含量比对照有明显增加。  相似文献   
56.

Purpose

Many efforts of restoring vegetation have ignored the feedbacks between biotic and abiotic factors that have developed in water-limited ecosystem. Dried soil layers (DSLs) have formed extensively on the Chinese Loess Plateau (CLP). The objective of this study was to identify the primary factors controlling spatial pattern of DSLs on the CLP.

Materials and methods

Two DSL indices (DSL thickness (DSLT) and soil water content in a DSL (DSL-SWC)) were estimated by measuring SWC to a depth of 5 m at 86 sites along a south-north transect on the CLP in 2013. The correlation between the spatial pattern of DSLs and environmental factors was determined with redundancy analysis (RDA).

Results and discussion

DSLs had formed at most of the sites (66 of the 86 sites) along the transect. The sites without DSLs were primarily in an irrigated agricultural zone. DSLT was >400 cm and generally increased from south to north, and DSL-SWC was 2.54% (v/v) in the semi-arid zone of the transect. The connected features of DSLs between connected neighboring sampling units exhibited a much wider extent. A total of nine environmental variables were the primary contributors to the spatial pattern of the DSLs, explaining approximately 47.3% of the variability. Local conditions were responsible for the higher proportion of explained variability than climatic factors. In addition, field capacity was the most important factor in all environmental factors, which may have influenced water-holding capacity.

Conclusions

This study concludes that spatial continuity and local conditions determine the spatial pattern of DSLs at a regional scale. Understanding the characteristic of DSLs is useful for efficiency of vegetation restoration and soil water management.
  相似文献   
57.
58.
深入认识和定量评价植被土壤层的水文调节功能,是干旱半干旱区生态工程建设和流域水土资源管理的重要科学依据。文中在宁夏六盘山北侧半干旱区的叠叠沟小流域,分析了4种典型植被(华北落叶松林、白桦林、沙棘灌丛和草地)100cm土层的土壤容重、持水能力和渗透性等土壤水文物理性质,运用坐标综合评定法定量评价了其土壤水文调节功能。结果表明:土壤容重(g/cm3)以沙棘灌丛(1.17)最高,白桦林、华北落叶松林和天然草地较接近(1.05~1.07);土壤总孔隙度表现为华北落叶松林(54.41%)>白桦林(53.30%)>天然草地(51.91%)>沙棘灌丛(50.11%);华北落叶松林和白桦林的蓄水性能和渗透性能要优于沙棘灌丛和草地。综合评价结果显示:白桦林地的土壤水文调节功能最强(0.0008),华北落叶松林地(0.0148)和沙棘灌丛(0.0678)次之,草地的土壤水文调节功能最差(0.2418)。  相似文献   
59.
膜下滴灌对水稻根系形态及生理性状的影响   总被引:2,自引:0,他引:2  
为探明水稻在膜下滴灌灌溉方式下根系生长发生的变化,设置小区试验与传统淹灌进行对比,以粳稻品种“T-04”和“T-43”为材料,研究了膜下滴灌灌溉方式对水稻根系形态、根系氧化力和硝酸还原酶的影响.结果表明:土表下20 cm深度,膜下滴灌水稻的根系长度、表面积、体积和平均直径都高于传统淹灌,并且差异具有统计学意义.土表下40 cm,膜下滴灌对水稻根系形态影响不具有统计学意义;水稻根系氧化力都是呈先增大,后减小的趋势,水稻根系氧化力最大期因品种而异.分蘖期膜下滴灌对水稻根系氧化力的影响因品种而异,但在拔节孕穗期、齐穗期和乳熟期,膜下滴灌水稻根系氧化力高于传统淹灌,并且差异具有统计学意义,膜下滴灌水稻后期根系具有较强的抗衰老能力;膜下滴灌水稻根系硝酸还原酶活性高于传统淹灌,但在分蘖期和乳熟期的差异不具有统计学意义,在拔节孕穗期和齐穗期差异具有统计学意义.  相似文献   
60.
Larvae of the cereal leaf minerSyringopais temperatella Led. (Lep.: Scythridae) collected from wheat and barley fields in the southeast Anatolian region of Turkey during 2005–2006, and their parasitization rates, were determined in the laboratory,Bracon (Habrobracon) stabilis Wesmael andApanteles sp. (Hymenoptera: Braconidae) were identified as its parasitoids for the first time.  相似文献   
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