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151.
Sang N 《Journal of environmental management》2008,88(4):1161-1174
In principle the protection of environmental resources is in every ones interest, yet it is evident that this is not what often occurs. In some cases there is an identifiable person or corporation, whose environmental impact can be tractably regulated either politically or via market forces. In other cases there is cumulative impact on a commonly held or "common pool" resource, from a variety of users, making establishing rights and responsibilities for resource management more difficult. The water of the Ythan catchment is one such 'Common Pool Resource' (CPR). An intensively farmed catchment also sustaining a sizable population, the consequent nitrate inputs to the water are believed to be the cause of algal matting at the estuary mouth, an internationally designated wildlife reserve. This led to its designation as Scotland's first Nitrate Vulnerable Zone (NVZ). Supported by the EU Life Environment fund, the Ythan Project attempted to foster co-operation between farmers and the wider community of the Ythan catchment to protect and restore the river environment. Throughout the project surveys were undertaken concerning the popularity of the Ythan Project's voluntary approach compared with more individualist or state-organised approaches. Taking CPR theory as a framework, key findings from those surveys are presented and discussed as to their implications for organisational intervention in CPR problems. 相似文献
152.
Elevated nitrate concentrations in streamwater are a major environmental management problem. While land use exerts a large control on stream nitrate, hydrology often plays an equally important role. To date, predictions of low-flow nitrate in ungauged watersheds have been poor because of the difficulty in describing the uniqueness of watershed hydrology over large areas. Clearly, hydrologic response varies depending on the states and stocks of water, flow pathways, and residence times. How to capture the dominant hydrological controls that combine with land use to define streamwater nitrate concentration is a major research challenge. This paper tests the new Hydrologic Landscape Regions (HLRs) watershed classification scheme of Wolock and others (Environmental Management 34:S71-S88, 2004) to address the question: Can HLRs be used as a way to predict low-flow nitrate? We also test a number of other indexes including inverse-distance weighting of land use and the well-known topographic index (TI) to address the question: How do other terrain and land use measures compare to HLR in terms of their ability to predict low-flow nitrate concentration? We test this for 76 watersheds in western Oregon using the U.S. Environmental Protection Agency’s Environmental Monitoring and Assessment Program and Regional Environmental Monitoring and Assessment Program data. We found that HLRs did not significantly improve nitrate predictions beyond the standard TI and land-use metrics. Using TI and inverse-distance weighting did not improve nitrate predictions; the best models were the percentage land use—elevation models. We did, however, see an improvement of chloride predictions using HLRs, TI, and inverse-distance weighting; adding HLRs and TI significantly improved model predictions and the best models used inverse-distance weighting and elevation. One interesting result of this study is elevation consistently predicted nitrate better than TI or the hydrologic classification scheme. 相似文献
153.
154.
Mike Hutchins Carlo Fezzi Ian Bateman Paulette Posen Amelie Deflandre-Vlandas 《Environmental management》2009,44(2):256-267
A case study of the Yorkshire Derwent (UK) catchment is used to illustrate an integrated approach for assessing the viability
of policy options for reducing diffuse nitrate losses to waterbodies. For a range of options, modeling methods for simulating
river nitrate levels are combined with techniques for estimating the economic costs to agriculture of modifying those levels.
By incorporating spatially explicit data and information on catchment residence times (which may span many decades particularly
in areas of groundwater discharge) a method is developed for efficient spatial targeting of measures, for example, to the
most at-risk freshwater environments. Combining hydrological and economic findings, the analysis reveals that, in terms of
cost-effectiveness, the ranking of options is highly sensitive to both (i) whether or not specific stretches of river within
a catchment are regarded as a priority for protection, and (ii) the criterion of nitrate concentration deemed most appropriate
as an indicator of the health of the environment. Therefore, given the focus under European legislation upon ecological status
of freshwaters, these conclusions highlight the need to improve understanding of mechanistic linkages between the chemical
and biological dynamics of aquatic systems. 相似文献
155.
Gupta DK Tripathi RD Rai UN Mishra S Srivastava S Dwivedi S Maathuis FJ 《Environmental monitoring and assessment》2007,134(1-3):479-487
Growth and metal accumulation were investigated in two Cicer arietinum L. varieties (var. CSG-8962 and var. C-235) when grown in various combinations of fly ash (FA) amended with garden soil (GS),
press mud (PM) or saw dust (SD). In addition, the levels of photosynthetic pigments, nitrate reductase (NR) activity, cysteine,
non-protein thiols (NP-SH), and ascorbic acid were studied. FA amended with GS or PM led to a 5–10 times increase in biomass
compared to FA control and was most pronounced in the less metal tolerant variety CSG-8962. Amendment of FA with either GS
or PM only moderately increased the contents of some essential metals whereas the non-essential Cd and Cr remained similar
or decreased slightly compared to FA control. FA combined with either GS or PM increased the amount of photosynthetic pigments
and was largely absent when SD was added to FA. Improved nitrogen availability led to increased nitrate reductase (NR) activity
with all amendments but less so with SD. Metal stress indicating parameters were generally reduced (cysteine and non-protein
thiols) or unchanged (ascorbic acid). In conclusion, of the tested ameliorants both GS and PM greatly improved growth of C. arietinum making FA a suitable component of plant growth substrates. 相似文献
156.
The urban landscape is comprised of many land uses, none more intensively managed than turfgrass; however, quantification of nutrient losses from specific land uses within urban watersheds, specifically golf courses is limited. Nitrate (NO(3)-N) and dissolved reactive phosphorus (DRP) were measured on a golf course in Austin, TX, USA from April 1, 1998 to March 31, 2003. NO(3)-N and DRP concentrations measured in storm flow were significantly greater exiting the course compared to those entering the course. Significant differences were also measured in baseflow NO(3)-N concentrations. The measured loading from the course was 4.0kg NO(3)-Nha(-1)yr(-1) (11% of applied) and 0.66kg DRPha(-1)yr(-1) (8% of applied). The resulting concentrations contributed by the course were 1.2mgL(-1) NO(3)-N and 0.2mgL(-1) DRP. At these levels, NO(3)-N poses minimal environmental risk. However, the DRP concentration is twice the recommended level to guard against eutrophication. 相似文献
157.
Measurements were conducted during 2004-2005 and 2009-2010 to characterize atmospheric nitrogen (N) deposition to the Jiulong River Estuary - Xiamen Bay area in southeast China. Isotopic analysis and long-term data (1990-2009) for inorganic N extracted from the national acid deposition dataset were used to determine the dominant source of atmospheric nitrate and N component dynamics. The results showed that the mean dissolved total N concentration in rain water for the three coastal area sites was 2.71 ± 1.58 mg N L(-1) (n = 141) in 2004. The mean dissolved inorganic N at the Xiamen site was 1.62 ± 1.19 mg N L(-1) (n = 46) in 2004-2005 and 1.56 ± 1.39 mg N L(-1) (n = 36) in 2009-2010, although the difference is not significant, nitrate turnover dominates the N component in the latter period. Total deposition flux over Xiamen was 30 kg N ha(-1) yr(-1), of which dry and wet deposition contributed 16% and 84%, respectively. Nitrate in wet deposition with low isotopic value (between -3.05 and -7.48‰) was likely to have mostly originated from combustion NO(x) from vehicle exhausts. The inorganic N in acid deposition exhibited a significant increase (mainly for nitrate) since the mid-1990s, which is consistent with the increased gaseous concentrations of NO(x) and expanding number of automobiles in the coastal city (Xiamen). The time series of nitrate anions and ammonium cations as well as pH values during the period 1990-2009 reflected an increasing trend of N emission with potential implication for N-induced acidification. 相似文献
158.
Lingyan Wu Xiaoye Zhang Junying Sun Yu Wang Junting Zhong Zhaoyang Meng 《环境科学学报(英文版)》2022,34(4):503-513
Air pollution in China is complex, and the formation mechanism of chemical components in particulate matter is still unclear. This study selected three consecutive heavy haze pollution episodes (HPEs) during winter in Beijing for continuous field observation, including an episode with heavy air pollution under red alert. Clean days during the observation period were selected for comparison. The HPE characteristics of Beijing in winter were: under the influence of adverse meteorological conditions such as high relative humidity, temperature inversion and low wind speed; and strengthening of secondary transformation reactions, which further intensified the accumulation of secondary aerosols and other pollutants, promoting the explosive growth of PM2.5. PM2.5/CO values, as indicators of the contribution of secondary transformation in PM2.5, were approximately 2 times higher in the HPEs than the average PM2.5/CO during the clean period. The secondary inorganic aerosols (sulfate nitrate and ammonium salt) were significantly enhanced during the HPEs, and the conversion coefficients were remarkably improved. In addition, it is interesting to observe that the production of sulfate tended to exceed that of nitrate in the late stage of all three HPEs. The existence of aqueous phase reactions led to the explosive growth sulfur oxidation ratio (SOR) and rapid generation of sulfate under high relative humidity (RH>70%). 相似文献
159.
Xuejun Liu Yangyang Zhang Aohan Tang Chen Wang Xin M Yunzhe Li Wen Xu Xiaoping Xi Aihua Zheng Wenqing Li Zengguo Fang Xiufen Zhao Xianlong Peng Yuping Zhang Jian Han Lijuan Zhang Jeffrey L. Collett 《环境科学学报(英文版)》2022,34(12):83-91
We investigated variations of PM2.5 and water-soluble inorganic ions chemical characteristics at nine urban and rural sites in China using ground-based observations. From 2015 to 2019, mean PM2.5 concentration across all sites decreased by 41.9 µg/m3 with a decline of 46% at urban sites and 28% at rural sites, where secondary inorganic aerosol (SIAs) contributed to 21% (urban sites) and 17% (rural sites) of the decreased PM2.5. SIAs concentrations underwent a decline at urban locations, while sulfate (SO42–), nitrate (NO3–), and ammonium (NH4+) decreased by 49.5%, 31.3% and 31.6%, respectively. However, only SO42– decreased at rural sites, NO3– increased by 21% and NH4+ decreased slightly. Those changes contributed to an overall SIAs increase in 2019. Higher molar ratios of NO3– to SO42– and NH4+ to SO42– were observed at urban sites than rural sites, being highest in the heavily polluted days. Mean molar ratios of NH3/NHx were higher in 2019 than 2015 at both urban and rural sites, implying increasing NHx remained as free NH3. Our observations indicated a slower transition from sulfate-driven to nitrate-driven aerosol pollution and less efficient control of NOx than SO2 related aerosol formation in rural regions than urban regions. Moreover, the common factor at urban and rural sites appears to be a combination of lower SO42– levels and an increasing fraction of NO3– to PM2.5 under NH4+-rich conditions. Our findings imply that synchronous reduction in NOx and NH3 emissions especially rural areas would be effective to mitigate NO3–-driven aerosol pollution. 相似文献
160.
A method for measuring gas entrapment in granular iron (Fe0) was developed and used to estimate the impact of gas production on porosity loss during the treatment of a high NO3- groundwater (up to approximately 10 mM). Over the 400-d study period the trapped gas in laboratory columns was small, with a maximum measured at 1.3% pore volume. Low levels of dissolved H2(g) were measured (up to 0.07+/-0.02 M). Free moving gas bubbles were not observed. Thus, porosity loss, which was determined by tracer tests to be 25-30%, is not accounted for by residual gas trapped in the iron. The removal of aqueous species (i.e., NO3-, Ca, and carbonate alkalinity) indicates that mineral precipitation contributed more significantly to porosity loss than did the trapped gases. Using the stoichiometric reactions between Fe0 and NO3-, an average corrosion rate of 1.7 mmol kg-1 d-1 was derived for the test granular iron. This rate is 10 times greater than Fe0 oxidation by H2O alone, based on H2 gas production. NO3- ion rather than H2O was the major oxidant in the groundwater in the absence of molecular O2. The N-mass balance [e.g., N2g and NH4+ and NO3-] suggests that abiotic reduction of NO3- dominated at the start of Fe0 treatment, whereas N2 production became more important once the microbial activity began. These laboratory results closely predict N2 gas production in a separated large column experiment that was operated for approximately 2 yr in the field, where a maximum of approximately 600 ml d-1 gas volumes was detected, of which 99.5% (v/v) was N2. We conclude that NO3- suppressed the production of H2(g) by competing with water for Fe0 oxidation, especially at the beginning of water treatment when Fe0 is highly reactive. Depends on the groundwater composition, gas venting may be necessary in maintaining PRB performance in the field. 相似文献