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261.
The paper reviews a number of challenges associated with reducing degradation and its related emissions through national approaches
to REDD+ under UNFCCC policy. It proposes that in many countries, it may in the short run be easier to deal with the kinds
of degradation that result from locally driven community over-exploitation of forest for livelihoods, than from selective
logging or fire control. Such degradation is low-level, but chronic, and is experienced over very large forest areas. Community
forest management programmes tend to result not only in reduced degradation, but also in forest enhancement; moreover they
are often popular, and do not require major political shifts. In principle these approaches therefore offer a quick start
option for REDD+. Developing reference emissions levels for low-level locally driven degradation is difficult however given
that stock losses and gains are too small to be identified and measured using remote sensing, and that in most countries there
is little or no forest inventory data available. We therefore propose that forest management initiatives at the local level,
such as those promoted by community forest management programmes, should monitor, and be credited for, only the net increase
in carbon stock over the implementation period, as assessed by ground level surveys at the start and end of the period. This
would also resolve the problem of nesting (ensuring that all credits are accounted for against the national reference emission
level), since communities and others at the local level would be rewarded only for increased sequestration, while the national
reference emission level would deal only with reductions in emissions from deforestation and degradation. 相似文献
262.
Eliška Rejmánková Ji?í Komárek Margaret Dix Jaroslava Komárková Nancy Girón 《Limnologica》2011,41(4):296-302
Lake Atitlan, one of the most important lakes not only in Central America but in the whole world, is facing serious problems with increasing water pollution. Over the last several decades, the uncontrolled nutrient input into the lake has lead to high P levels and low N:P ratios, initiating cyanobacterial blooms. The first bloom occurred in December of 2008, followed by more extensive bloom in October 2009. The blooms are formed by cyanobacteria from the rare planktic Lyngbya hieronymusii/birgei/robusta complex. Based on the species morphology, the Atitlan population corresponds to L. robusta and this is the first case of reported bloom of this species worldwide. Remote sensing images documented that at the maximum bloom development, 40% of the 137 km2 of the lake area were covered by dense patches of Lyngbya, with the chlorophyll a concentration reaching over 100 μg L−1. The only toxins detected in the 2009 bloom were trace levels of cylindrospermopsin and saxitoxin with 12 and 58 ng g−1, respectively. The nitrogen fixation followed a pattern expected in non-heterocytous cyanobacteria, i.e., the nitrogenase activity was minimal during the day, while during the night the activity reached 2.2 nmol C2H4 μg Ch a−1 h−1. Delta 15N of −0.86‰ was well in the range given for nitrogen fixing organisms. The cell C, N and P content was 36.7%, 5.9% and 0.9%, respectively, resulting in the molar ratio of 105:14.4:1. A well designed and executed lake monitoring program, strict control of nutrient input into the lake, and public education are the necessary prerequisites for potential prevention of even more severe blooms than the one from 2009. 相似文献
263.
264.
Katherine C. Filippino Margaret R. Mulholland Peter W. Bernhardt George E. Boneillo Ryan E. Morse Matthew Semcheski Harold Marshall Nancy G. Love Quinn Roberts Deborah A. Bronk 《Estuaries and Coasts》2011,34(2):269-280
Total maximum daily loads for nitrogen (N) are currently being established for the Chesapeake Bay watershed. While we know
inorganic N is bioavailable in the environment and therefore its input contributes to cultural eutrophication, the bioavailability
of organic N is unclear. Using bioassay experiments, we examined the impact of effluent-derived organic nitrogen (EON) from
wastewater treatment plants on natural water samples collected along an estuarine/salinity gradient within the lower Chesapeake
Bay watershed. All of the inorganic N and between 31% and 96% of the EON was removed during biotic bioassays within the first
2 days. Further, there was substantial abiotic reactivity of effluent N when it was added to natural water samples. Results
demonstrate that organic and inorganic N in effluent is removed to support the growth of microbial communities. These are
the first results aimed at assessing the reactivity of EON in natural waters along an estuarine/salinity gradient. 相似文献
265.
Maria Falaleeva Cathal O'Mahony Stefan Gray Margaret Desmond Jeremy Gault Valerie Cummins 《Marine Policy》2011
Coastal environments are susceptible to a range of impacts arising from medium and long-term climate change. However, as Ireland's population and industrial centres are concentrated in coastal locations, Ireland's coastal communities will be particularly vulnerable to the impacts of climate change. Therefore, making the best use of existing knowledge to inform the establishment of governance structures capable of facilitating the measures and actions which may soon be required is a national imperative. Coastal communities worldwide have turned to integrated coastal zone management (ICZM) as a process to deliver sustainable development. This paper explores how experience gained from ICZM implementation can be harnessed to inform the development and implementation of climate adaptation policies, with a particular focus on the coastal zone. Using the principles and conceptual basis of Earth System Governance – an emerging approach to analyse complexity of governance under global environmental change – the paper maps the architecture of ICZM and climate governance in Ireland. The research identifies the main barriers to, and opportunities for, integrated application of the two policy domains. Barriers include the fragmentation of governance structures and responsibilities of key stakeholders, a lack of coordinated support for ICZM implementation at the national level, and a relatively weak awareness of the specifics of adaptation at the local level. Opportunities include the availability of expertise gathered from phases of ICZM implementation in Ireland, which encompasses mechanisms for science-policy integration, and invaluable experience of stakeholder participation and interaction. Current political and scientific support at national and EU levels give an additional impetus to climate research and actions which may bring additional opportunities and resources to coastal governance in Ireland. 相似文献
266.
Juan Reynerio Fagundo-Castillo Joel José Carrillo-Rivera Iñaki Antigüedad-Auzmendi Patricia González-Hernández Roberto Peláez-Díaz Rebeca Hernández-Díaz Dámaso Cáceres-Govea José Ramón Hernández-Santana Margaret Suárez-Muñoz Clara Melián-Rodríguez Mónica Rodríguez-Piña 《Environmental Geology》2008,55(2):247-267
Flows of different hierarchy, which travel through limestone, schist, sandstone and ultra-basic rocks, with ages from the
Paleocene to the Jurassic, at Sierra del Rosario, Pinar del Río, Cuba, were characterized. The waters were sampled from 1984
until 2004 and the data were statistically processed by means of chemical equilibrium and physico-chemical models, under a
flow system view of interpretation. Results demonstrate that the physico-chemical properties of the water are controlled by
water–rock interaction resulting from residence time since rainwater infiltrate and the path it follows to the discharge zone
and the type of aquifer material the different groundwater flows are in contact with. Geochemical indices allow the definition
of the different types of flow (local, intermediate, regional) to be characterized, permitting a further definition of the
different flow systems and rock type involved, as well as its use for water supply and medical use. The main geochemical processes
which control the chemical composition acquisitions mode are: congruent dissolution of calcite, dolomite, and halite; incongruent
dissolution of plagioclase and microcline minerals; pyrite oxidation, sulphate reduction, and silica dissolution at the surface
or silica precipitation at deep saturation and circulation zones. 相似文献
267.
Zoning of phosphorus in igneous olivine 总被引:2,自引:2,他引:0
Margaret S. Milman-Barris John R. Beckett Michael B. Baker Amy E. Hofmann Zachary Morgan Meghan R. Crowley Daniel Vielzeuf Edward Stolper 《Contributions to Mineralogy and Petrology》2008,155(6):739-765
We describe P zoning in olivines from terrestrial basalts, andesites, dacites, and komatiites and from a martian meteorite.
P2O5 contents of olivines vary from below the detection limit (≤0.01 wt%) to 0.2–0.4 wt% over a few microns, with no correlated
variations in Fo content. Zoning patterns include P-rich crystal cores with skeletal, hopper, or euhedral shapes; oscillatory
zoning; structures suggesting replacement of P-rich zones by P-poor olivine; and sector zoning. Melt inclusions in olivines
are usually located near P-rich regions but in direct contact with low-P olivine. Crystallization experiments on basaltic
compositions at constant cooling rates (15–30°C/h) reproduce many of these features. We infer that P-rich zones in experimental
and natural olivines reflect incorporation of P in excess of equilibrium partitioning during rapid growth, and zoning patterns
primarily record crystal-growth-rate variations. Occurrences of high-P phenocryst cores may reflect pulses of rapid crystal
growth following delayed nucleation due to undercooling. Most cases of oscillatory zoning in P likely reflect internal factors
whereby oscillating growth rates occur without external forcings, but some P zoning in natural olivines may reflect external
forcings (e.g., magma mixing events, eruption) that result in variable crystal growth rates and/or P contents in the magma.
In experimental and some natural olivines, Al, Cr, and P concentrations are roughly linearly and positively correlated, suggesting
coupled substitutions, but in natural phenocrysts, Cr zoning is usually less intense than P zoning, and Al zoning weak to
absent. We propose that olivines grow from basic and ultrabasic magmas with correlated zoning in P, Cr, and Al superimposed
on normal zoning in Fe/Mg; rapidly diffusing divalent cations homogenize during residence in hot magma; Al and Cr only partially
homogenize; and delicate P zoning is preserved because P diffuses very slowly. This interpretation is consistent with the
fact that zoning is largely preserved not only in P but also in Al, Cr, and divalent cations in olivines with short residence
times at high temperature (e.g., experimentally grown olivines, komatiitic olivines, groundmass olivines, and the rims of
olivine phenocrysts grown during eruption). P zoning is widespread in magmatic olivine, revealing details of crystal growth
and intra-crystal stratigraphy in what otherwise appear to be relatively featureless crystals. Since it is preserved in early-formed
olivines with prolonged residence times in magmas at high temperatures, P zoning has promise as an archive of information
about an otherwise largely inaccessible stage of a magma’s history. Study of such features should be a valuable supplement
to routine petrographic investigations of basic and ultrabasic rocks, especially because these features can be observed with
standard electron microprobe techniques. 相似文献
268.
269.
Margaret R. Mulholland Ryan Morse Todd Egerton Peter W. Bernhardt K. C. Filippino 《Estuaries and Coasts》2018,41(6):1744-1765
A multi-year study was conducted in the eutrophic Lafayette River, a sub-tributary of the lower Chesapeake Bay during which uptake of inorganic and organic nitrogen (N) and C compounds was measured during multiple seasons and years when different dinoflagellate species were dominant. Seasonal dinoflagellate blooms included a variety of mixotrophic dinoflagellates including Heterocapsa triquetra in the late winter, Prorocentrum minimum in the spring, Akashiwo sanguinea in the early summer, and Scrippsiella trochoidea and Cochlodinium polykrikoides in late summer and fall. Results showed that no single N source fueled algal growth, rather rates of N and C uptake varied on seasonal and diurnal timescales, and within blooms as they initiated and developed. Rates of photosynthetic C uptake were low yielding low assimilation numbers during much of the study period and the ability to assimilate dissolved organic carbon augmented photosynthetic C uptake during bloom and non-bloom periods. The ability to use dissolved organic C during the day and night may allow mixotrophic bloom organisms a competitive advantage over co-occurring phytoplankton that are restricted to photoautotrophic growth, obtaining N and C during the day and in well-lit surface waters. 相似文献
270.
Margaret Skutsch Cecilia Simon Alejandro Velazquez José Carlos Fernández 《Global Environmental Change》2013,23(4):813-825
Mexico is relatively advanced in its preparation for international policy on Reduced Emissions from Deforestation and forest Degradation (REDD+) and has many of the pre-conditions needed to support a community approach in the implementation of a national REDD+ programme, particularly as regards tenure of forests and experience with community forest management and PES schemes, although these conditions do not pertain everywhere. One critical issue that is yet to be resolved concerns rights to carbon credits and distribution of the financial benefits flowing from REDD+. We demonstrate that attribution of carbon credits from reduced deforestation and degradation at the community level is virtually impossible from a technical viewpoint, since these credits are counterfactual. Payments based on assessment of performance of each community in terms of such reductions would moreover be inequitable and inefficient. Flat rate payments in return for agreed improvements in management are likely to be more motivating and much easier to administer. However, increases in carbon stock (forest enhancement) can be physically measured on site, and could be more easily attributed to each individual community. We therefore propose a system in which reduced deforestation and degradation are considered environmental services, with credits accruing to national government. The financial value of the credits may be used to finance flat rate payments to communities who agree to implement improved management. On the other hand, credits for forest enhancement, which reflect measurable increases in carbon in the communities’ trees, would be considered environmental goods. These should be considered the direct property of the owners of the forest (in the same sense as wood or poles) and it would be possible for communities to sell these credits themselves. We acknowledge however that many other problems face implementation of REDD+ in Mexico, and provide a number of important examples. 相似文献