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191.
Mini-review on river eutrophication and bottom improvement techniques, with special emphasis on the Nakdong River 总被引:4,自引:0,他引:4
Water quality in rivers is vital to humans and to maintenance of biotic and ecological integrity.During the Four Major Rivers restoration of South Korea, remarkable attempts have been made to decrease external nutrient loads and moveable weirs were designed to discharge silt that may deposit in pools. However, recently eutrophication of the Nakdong River, which was limited to the lower reaches, is seen to be spreading upstream. The reduction of external nutrient loads to rivers is a long-term goal that is unlikely to lead to reductions in algal blooms for many years because of the time required to implement effective land management strategies. It would therefore be desirable to implement complementary strategies. Regulating the amount of water released is effective at preventing algae blooms in weir pools; so, the relationship between discharge, stratification and bloom formation should be understood in this regard. However, pollutants are likely to accumulate in the riverbed upstream from release points. Thus, to control phosphorus levels, total phosphorus density should be lowered by applying in-river techniques as well. As many ecosystem properties are controlled by multiple processes, simultaneous river bottom improvement techniques, such as combined dissolved oxygen supply and nutrient inactivation, are likely to be effective. The purpose of this review is to present a series of technological approaches that can be used to improve the river bottom area and hence sediment nutrient release, and to illustrate the application of these techniques to the Nakdong River. 相似文献
192.
Textile mill waste can be vermicomposted if it is mixed in the range of 20–30% with cow dung. This article reports the effect
of inoculation, of nitrogen fixing Azotobacter chroococcum strain; Azospirillum brasilense strain and phosphate solubilizing Pseudomonas maltophila, on nitrogen and phosphorus content of vermicomposts prepared from cow dung (CD) and cow dung spiked textile mill sludge
(CD + STMS). The CD vermicompost was more supportive to the growth and multiplication of all the three bacteria than CD + STMS
vermicompost. In Azotobacter chroococcum treated vermicomposts maximum nitrogen content was recorded between 45 and 60 days [CD␣vermicompost (25.9 ± 0.45 g kg−1) and CD + STMS vermicompost (20.6 ± 0.62 g kg−1)] followed by Azospirillum brasilense inoculation [CD vermicompost (19.4 ± 0.60 g kg−1) and CD + STMS vermicompost (18.6 ± 0.17 g kg−1)]. Phosphorus content in Pseudomonas maltophila inoculated CD vermicompost was 20.8 ± 0.20 g kg−1 and CD + STMS vermicompost was 13.4 ± 0.45 g kg−1 after 75th day of inoculation. 相似文献
193.
基于物质流分析的密云水库上游流域磷循环特征 总被引:5,自引:3,他引:5
运用物质流分析方法,对北京市地表饮用水源地--密云水库流域进行了磷循环特征的研究;分析了研究区域内种植业、畜牧业、人口和简单子系统内部及子系统间的磷输入输出状况,以及系统整体的代谢效率特征,讨论了流域水体磷污染负荷的影响因素.研究结果表明:①化肥、饲料添加剂和农药是流域磷输入的主要来源,占直接物质磷输入总量的52.9%;整个系统向环境输入磷2868.44t,其中的26.5%直接进入水体.②在水体磷负荷中,畜牧业系统的贡献最大,为1800.26 t,达到输出总量的82%,其次为种植业系统,占9.4%.③系统整体结构不协调.呈现单向和开放状态.研究区种植业系统运行出现磷亏缺,并具有区域性和不均衡性的特点;而畜牧业系统则出现磷盈余,整体结构不协调;畜禽的排泄物未能得到有效处置和循环再生,其中进入水体的量占畜禽粪尿磷总量的40.9%,从而造成严重的资源浪费和广泛的生态环境影响.④水体污染负荷与城市化率密切相关. 相似文献
194.
太湖氮磷浓度与水质因子的关系 总被引:6,自引:2,他引:4
在2003年10月27、28日和2004年8月19日的太湖水质试验数据基础上,研究与探讨了氮浓度、磷浓度与叶绿素a浓度、悬浮物浓度和CDOM(Colored Dissolved Organic Matter)浓度之间的定量关系。研究结果表明:①在2003年10月份和2004年8月份,太湖梅梁湾地区水体的氮、磷浓度介于1~4mg/L和0.1~0.3mg/L,该浓度恰好处于易发生水华的营养物质浓度供应区间;②与2004年8月19日相比,2003年10月27、28日的太湖藻类处于低增长、高消亡状态;③在太湖梅梁湾地区,氮、磷浓度与CDOM浓度、叶绿素a浓度和悬浮物浓度之间存在较强的线性相关性,其相关系数大于0.557;④在太湖水体中,磷浓度、CDOM浓度、叶绿素a浓度和悬浮物浓度的四因子关系模型比氮浓度、CDOM浓度、叶绿素a浓度和悬浮物浓度的四因子关系模型的相关系数高。 相似文献
195.
Numerous recent studies discuss phosphate rock extraction, and some even propose that a peak in production could be reached in coming decades. This would have great consequences as phosphate rock based fertilizers are irreplaceable in modern agriculture. Studies suggesting an impending peak commonly use curve fitting models where mathematical functions are fitted to historical world production data, while studies using other methods reach completely different results. Also, a sudden increase in global reserve estimates is commonly used to dismiss these warnings, and has somewhat altered the debate. The recent multiplication of estimated reserves is mostly based on an increase of the Moroccan reserve estimate, leading to Morocco currently making up most of the global reserves. This study models global phosphate rock production using a disaggregated curve fitting model based on the production in individual major producing countries, providing a somewhat different view than most studies, and show that the global trade of phosphate rock could be completely dependent on Morocco in the future. There are several different factors that can potentially limit global production and these factors should be considered for the individual producing countries. Society's total dependence on phosphate rock should be further investigated despite claims of large resource occurrences. 相似文献
196.
Assessment of nutrient distributions in Lake Champlain using satellite remote sensing 总被引:3,自引:0,他引:3
The introduction of nutrients to lakes causing eutrophic conditions is a major problem around the world. Proper monitoring and modeling are important to effectively manage eutrophication in lake waters. The goal is to develop remote sensing models for nutrients, total phosphorus and total nitrogen, in Lake Champlain. The remote sensing models were created using multivariate linear regression with the unique band combinations of Landsat Enhanced Thematic Mapper Plus (ETM+) imagery based on the empirical relationship with the field observations. The resulting models successfully showed nutrient distributions in the most eutrophic part of Lake Champlain, Missisquoi Bay, with reasonable adjusted coefficient of determination values (R2 = 0.81 and 0.75 for total phosphorus and total nitrogen, respectively). The results show the feasibility and the utility of satellite imagery to detect spatial distributions of lake water quality constituents, which can be used to better understand nutrient distributions in Lake Champlain. This approach can be applicable to other lakes experiencing eutrophication assisting decision making when implementing Best Management Practices and other mitigation techniques to lakes. 相似文献
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200.
Declining worldwide phosphate rock reserves has driven a growing interest in exploration of alternative phosphate supplies. This study involved phosphorus recovery from swine wastewater through precipitation of struvite, a valuable slow-release fertiliser. The economic feasibility of this process is highly dependent on the cost of magnesium source. Two different magnesium sources were used for phosphorus recovery: pure magnesium chloride and nanofiltration(NF) saline water retentate. The paper f... 相似文献