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471.
A transgenic approach to enhance phosphorus use efficiency in crops as part of a comprehensive strategy for sustainable agriculture 总被引:1,自引:0,他引:1
Concerns about phosphorus (P) sustainability in agriculture arise not only from the potential of P scarcity but also from the known effects of agricultural P use beyond the field, i.e., eutrophication leading to dead zones in lakes, rivers and coastal oceans due to runoffs from fertilized fields. Plants possess a large number of adaptive responses to Pi (orthophosphate) limitation that provide potential raw materials to enhance Pi scavenging abilities of crop plants. Understanding and engineering these adaptive responses to increase the efficiency of crop capture of natural and fertilizer Pi in soils is one way to optimize Pi use efficiency (PUE) and, together with other approaches, help to meet the P sustainability challenge in agriculture. Research on the molecular and physiological basis of Pi uptake is facilitating the generation of plants with enhanced Pi use efficiency by genetic engineering. Here we describe work done in this direction with emphasis on the up-regulation of plant proton-translocating pyrophosphatases (H+-PPases). 相似文献
472.
Assessment of typical pollutants in waterborne by combining active biomonitoring and integrated biomarkers response 总被引:1,自引:0,他引:1
Organic pollutants, heavy metals and pharmaceuticals are continuously dispersed into the environment and have become a relevant environmental emerging concern. In this study, a situ assay to assess ecotoxicity of mixed pollutants was carried out in three typical sites with different priority contaminations in Guangzhou, China. Chemical analysis of organic pollutants, metals and quinolones in three exposure sites were determined by GC-ECD/MS, ICP-AES and HPLC, as well as, a combination of biomarkers including: ethoxyresorufin O-deethylase (EROD); aminopyrine N-demethylase (APND); erythromycin N-demethylase (ERND); glutathione S-transferase (GST); malondialdehyde (MDA); CYP1A; and P-glycoprotein (P-gp) mRNA expressions were evaluated in Mugilogobius abei. Results of chemical analysis in sediment samples revealed that the dominant chemicals were organic pollutants and heavy metals in Huadi River while quinolones in the pond. Bioassays indicated that differences among sites were in relation to some specific biomarkers. EROD and GST activities significantly increased after 72 h in situ exposure, but no difference was observed among the exposure sites. APND, ERND and MDA exhibited dissimilar change patterns for different priority pollutants. CYP1A and P-gp mRNA expressions were significantly induced at all exposure sites, whilst P-gp activity was typical for S2 with the highest levels of quinolones. The molecular biomarkers seemed to be more susceptible than enzyme activities. These assays confirmed the usefulness of applying a large array of various combined biomarkers at different levels, in assessing the toxic effects of mixed pollutants in a natural aquatic environment. 相似文献
473.
474.
Köhler HR Sandu C Scheil V Nagy-Petrică EM Segner H Telcean I Stan G Triebskorn R 《Environmental monitoring and assessment》2007,127(1-3):47-54
Along a downstream stretch of River Mureş, Romania, adult males of two feral fish species, European chub (Leuciscus cephalus) and sneep (Chondrostoma nasus) were sampled at four sites with different levels of contamination. Fish were analysed for the biochemical markers hsp70
(in liver and gills) and hepatic EROD activity, as well as several biometrical parameters (age, length, wet weight, condition
factor). None of the biochemical markers correlated with any biometrical parameter, thus biomarker reactions were related
to site-specific criteria. While the hepatic hsp70 level did not differ among the sites, significant elevation of the hsp70
level in the gills revealed proteotoxic damage in chub at the most upstream site, where we recorded the highest heavy metal
contamination of the investigated stretch, and in both chub and sneep at the site right downstream of the city of Arad. In
both species, significantly elevated hepatic EROD activity downstream of Arad indicated that fish from these sites are also
exposed to organic chemicals. The results were indicative of impaired fish health at least at three of the four investigated
sites. The approach to relate biomarker responses to analytical data on pollution was shown to fit well the recent EU demands
on further enhanced efforts in the monitoring of Romanian water quality. 相似文献
475.
采用Claassen的养分吸收机理模型探讨了玉米与大豆幼苗磷吸收过程中的参数敏感性,结果表明:在一般土壤与施肥条件下,玉米与大豆幼苗吸收磷的高度敏感性参数或重要限制因素为根系伸长速率与根半径;在相同土壤供磷条件下,供试大豆幼苗根系的磷摄取能力远低于玉米幼苗根系的磷摄取能力,其原因归结于两者在根系最大养分流Imax与根系伸长速率K两个敏感性参数上的差异;玉米与大豆幼苗磷吸收过程中三种根毛参数的敏感性均较低,这主要与土壤供磷水平较高有关;土壤含水量在玉米幼苗磷吸收过程中表现了极高的敏感性,当土壤含水量降低时,土壤养分供应参数对玉米幼苗磷吸收的敏感性与限制作用均增大。 相似文献
476.
Bishwo B. Pokharel Alemu Regassa Charles M. Nyachoti 《Journal of environmental science and health. Part. B》2017,52(6):395-401
A study was conducted to examine the effects of different dietary levels of available phosphorus (aP) on P excretion, bone mineralization, performance and the mRNA expression of sodium-dependent P transporters in growing pigs. Sixty-day old growing pigs (n = 54) with an average initial BW of 19.50 ± 1.11 kg were randomly allocated to a control diet (C) containing 0.23% available phosphorus (aP), T1 containing 0.17% aP and T2 containing 0.11% aP. There were 6 pens per treatment with 3 pigs per pen. Body weight and feed intake were measured weekly. At the end of each week, one pig from each pen was housed in a metabolic crate for 24 h to collect fecal and urine samples and then sacrificed to obtain third metacarpal (MC3) bones and jejunal and kidney samples. Bones were scanned by Dual Energy X-ray Absorptiometry (DEXA). Fecal and urine samples were sub-sampled and analyzed for P content. The expression of P transporter mRNA in jejunum and kidney samples was measured using quantitative real-time polymerase chain reaction (qRT-PCR). Data were analyzed using GLM procedure of the Statistical Analysis System (SAS Institute version 9.2). Pigs fed the T2 diet had reduced (P < 0.05) average daily gain (ADG) and gain to feed (G:F) compared to those fed the C diet during week 2. Overall, ADG and G:F were also reduced (P < 0.05) in pigs fed the T2 diet compared to those fed the C and T1 diets. Bone mineral density (BMD) and bone mineral content (BMC) were reduced (P < 0.05) in pigs fed the T2 diet compared to those fed the C diet throughout the experiment. At week 1, jejunal mRNA expression of Na (+)-dependent phosphate transporter 2 (SLC34A2) was increased (P < 0.01) in pigs fed the T2 diet compared to C diet. Renal mRNA expression of Na(+)-dependent phosphate transporter 1 (SLC34A1) and SLC34A3 were increased (P < 0.05) in pigs fed the T2 diet compared to those fed the C diet at week 2 and was accompanied by lower (P < 0.05) urinary P in pigs fed the T2 diet during week 2 and week 3. In conclusion, growing pigs are highly sensitive to low dietary P as shown by reduced ADG, bone mineralization and urinary P level, but moderate reduction in dietary P up to 0.17% aP in the diet has the potential to reduce environmental pollution by reducing P concentration in swine manure and without compromising performance. 相似文献
477.
The emergence of Corporate Social Responsibility (CSR) in the extractive industries represents a bid to legitimize the sector after decades of environmental disasters and the trampling of indigenous rights. But whilst the rise in CSR has meant safer technologies and better stakeholder engagement, there is little evidence of any real socio-economic development at the grassroots. This paper examines the uneasy relationship existing between the strategic ‘business model’ of CSR and the brand of development it delivers. Using evidence from two multinational extractive industries in Papua New Guinea, we show how weaknesses in CSR practice come from greater emphasis on meeting global ‘performance standards’ than on the specificities of the social contexts in which strategies are implemented. These weaknesses, we argue, lead to ill-conceived and inappropriate development programmes that generate inequality, fragmentation, and social and economic insecurity. We conclude that greater engagement with affected communities will facilitate the development of more mutually beneficial and appropriate CSR strategies. 相似文献
478.
In the mineral rich but arid Pilbara region of Western Australia, managing water constraints represents a significant challenge to the mining sector where local depletion is a growing problem. Conversely, the expansion of pit dewatering is creating surface water excess in localised areas of potentially high social and ecological significance. Indigenous people are by far the longest term residents of the Pilbara region and express a range of strong concerns about past, current and future water-related developments in the area. They also have proprietary interests in water recognised by the common law and protected by federal native title legislation. Rio Tinto Iron Ore (RTIO), commissioned the authors to undertake research to improve corporate understanding of Indigenous interests in water and to provide advice on its consultation processes. We argue here that a more sophisticated account of Indigenous water values is a necessary but, on its own, insufficient measure to achieve RTIO’s desired long-term goals. We suggest an equivalent process of understanding and documenting corporate water values and interests, actions to improve trust and credibility in the relationship between the parties, and leadership in wider catchment management as necessary complementary actions. These actions follow logically from internal corporate commitments regarding water and Indigenous people and from recognition of their property rights, but also align directly with major trends in the National Water Initiative, the key water policy framework for Australia. Therefore significant synergies exist between internal corporate aspirations, the evolving legal regime, and wider governance agendas for a key limiting resource. Our analysis is relevant to a range of CSR and water resource contexts across the wider mining sector. 相似文献
479.
氮、磷在湿地基质中降解的机理研究 总被引:1,自引:0,他引:1
湿地基质被看成是人工湿地处理污水的核心部分,通过科学实验,文章分析了人工湿地运行中氮、磷在沿程方向和纵向的基质中的分布,重点研究湿地基质对于氮、磷的净化作用,有利于进一步理清湿地基质降解氮、磷的机理。 相似文献
480.
Cancer has become a critical health issue in the world heritage city Kandy, Sri Lanka. Polycyclic aromatic hydrocarbons (PAHs), one of persistent organic pollutants, in the atmosphere may be a major etiological factor in lung carcinogenicity. Over the very high concentrations of ambient air PAHs reported in Kandy, this paper is focused on setting priorities to control human exposure to PAHs in prevention of cancer.On re-appraisal of the classical indicator benzo(a)pyrene (B[a]P) for atmospheric PAHs-related carcinogenicity, B[a]P failed to reflect the toxicity completely and may not be the sole indicator for risk assessment studies in complex multi-sourced urban environments. The excess lifetime lung cancer risks of atmospheric PAHs with ‘less than lifetime exposure’ were assessed based on both ‘B[a]P toxic equivalents’ and ‘B[a]P surrogate epidemiological’ approach of risk quantification, over emissions characterized urban, suburban, and rural areas of Kandy. In urban heavy traffic areas, PAH-related additional cancer burden has been 942 million−1 over 30 y of exposure. Over the whole study area, ∑p-PAHs show strong correlation (r = 0.8) to the predicted risk levels. While the urban and suburban predicted cancer risk levels could not show significant correlation to their emission sources indicating the real complexity in mega urban environments, the rural lung cancer risk levels correlated perfectly with the source, firewood combustion.Policy decisions on environment and health could be based on established correlations among ‘emission sources-exposures-health effects’. The priority for “analysis of options and policy formulation to reduce inhalation PAHs exposure of population in Kandy” was considered “moderate to high”. 相似文献