Field measurements of dissolved organic carbon (DOC) concentration and remote-sensing reflectance were conducted to develop a regional, empirical red-blue algorithm to retrieve surface DOC from Geostationary Ocean Color Imager (GOCI) data for Lake Taihu, China. The auxiliary data (in-situ observations of the optical properties and water quality, buoy measurements of hydrodynamic data and water chemical parameters) were used to investigate the spatial and temporal variations in DOC. GOCI was shown to be capable of successfully obtaining hourly variations in DOC, with a root mean square error percentage (RMSP) of 17.29% (RMSE = 0.69 mg/L) for the match-up data. The GOCI-derived DOC in Lake Taihu confirms that the highest DOC concentration is in northwest Lake Taihu, followed by Meiliang Bay, Gonghu Bay and northeast Lake Taihu. Hourly DOC variation is significant and presents a different trend for each lake segment due to the variety of influencing factors. Discharge of DOC from surrounding rivers is an important factor to the variation of DOC in northeast Lake Taihu. However, organic products of algae will be the primary contributor to DOC when algal bloom occurred. During the period of algal bloom, high DOC levels in Lake Taihu can lead to hypoxia when coupled with high temperatures and low disturbance. 相似文献
AbstractThe impact of Brown Carbon (BrC) to aerosol light absorption has been paid more attention recently and there are a large number of studies showing that the influence of BrC on radiative forcing should not be ignored. BrC also acts as an important component of haze pollution which is occurring frequently in Wuhan, China. Therefore, it is essential to estimate their optical properties, composition, and mass concentration. Considering most haze pollution happens during the coldest time, we retrieved BrC columnar content during winter in Wuhan for the first time. Our method bases on the fact that BrC showed the strong spectral dependence on UV-light absorption. Using this method, we found that BrC makes up the small proportions of total aerosol volume (less than 10%). In the winter of 2011, we retrieved the daily-averaged columnar-integrated mass concentration of BrC on clear day is 4.353 mg/m2 while that of haze day is 12.750 mg/m2. According to the sensitivity study, we found that the results highly relied on the assumed aerosol refractive index. To reduce the uncertainty of this approach, we need to gain a better understanding of the temporal variability of the radiation absorbing components of these aerosols in the future. 相似文献
ABSTRACTThe “subsumption of nature” framework focuses on productivity increases and extractive innovations in nature-based industries. In this article, we argue that it can also be employed beyond that context in order to capture the convoluted dynamics of market environmentalism. To substantiate our argument, we draw on recent fieldwork on “Trees for Global Benefits,” a forestry-based offsetting project in western Uganda. Like industrial tree plantations, this project relies on the subsumption of carbon sequestration to market imperatives in order to guarantee the quality of its carbon credits. The ecological and socioeconomic difficulties this process engenders give rise to unintended consequences and set in motion the disciplining of the carbon offset producers themselves. The application of the subsumption framework to nonindustrial sectors in this way calls attention to the interlinked socioecological dynamics involved in the subsumption of nature, and highlights potential synergies with previous work on the subsumption of labor. 相似文献
Land-use systems are characterized by complex interactions between human decision-makers and their biophysical environment. Mismatches between the scale of human drivers and the impacts of human decisions potentially threaten the ecological sustainability of these systems. This article reviews sources of complexity in land-use systems, moving from the human decision level to human interactions to effects over space, time and scale. Selected challenges in modeling such systems and potential resolutions are discussed, including strategies to empiricize complex models and methods for linking models across human and natural systems. Illustrative examples from published literature and an ongoing research project focused on timber harvest and carbon sequestration are used throughout the paper. The paper concludes with a brief discussion of remaining challenges to modeling indirect and cross-scale linkages and of the potential utility of complex models of land systems. 相似文献
The redox sensitive elements, molybdenum (Mo) and uranium (U), in marine sediments from the latest Permian Dalong (大隆) Formation at the Shangsi (上寺) Section, Northeast Siehuan (四川), South China, were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) to determine their response to a range of redox conditions, and to estimate the organic carbon burial rate. On the basis of the correlation between authigenic Mo abundance and organic carbon content in modern oceans, the organic carbon burial rates were calculated for the rocks at Dalong Formation, ranging from 0.48-125.83 mmol/(m2-d), which shows a larger range than the mineralization rate of organic carbon at the continental margins (1.6-4.23 mmol/(m2.d)). The Zr-normalized Mo and U abundances show large fluctuations in the entire section. The maxima of Zr-normalized Mo abundance and thus the maxima of the organic carbon burial rates were observed at the interval between the 155th and 156th beds (404-407 m above the base of Middle Permian). A decrease (the minimum) in U/Mo ratios is present in this interval. It is speculated that the oxygen-limited conditions and ultimately anoxia or euxinia may develop within this depth interval. In contrast, an enhanced enrichment of Zr-normallzed U abundance is found, in association with less enrichment in Zr-normnllzed Mo abundance in the interval from the I51st to 154th beds (395-404 m above the base of Middle Permian), inferring the dominance of a suboxic/anoxic depositional condition (denitrifying condition), or without free H2S. The presence of small quantities of dissolved oxygen may have caused the solubilization and loss of Mo from sediments. It is proposed that the multiple cycles of abrupt oxidation and reduction due to the upwelllng at this interval lead to the enhanced accumulation of authigenic U, but less enrichment of Mo. A decrease in the contents of U, Mo, and TOC is found above the 157th bed (407 m above the base of Middle Permian), in association with the enhanced U/Mo ratio, suggesting the overall oxic conditions at the end of the Dalong Formation. 相似文献
Carbon isotope chemostratigraphy has been used for worldwide correlation of Precambrian/Cambrian (Pc/C) boundary sections, and has elucidated significant change of the carbon cycle during the rapid diversification of skeletal metazoa (i.e. the Cambrian Explosion). Nevertheless, the standard δ13C curve of the Early Cambrian has been poorly established mainly due to the lack of a continuous stratigraphic record. Here we report high-resolution δ13C chemostratigraphy of a drill core sample across the Pc/C boundary in the Three Gorge area, South China. This section extends from an uppermost Ediacaran dolostone (Dengying Fm.), through a lowermost Early Cambrian muddy limestone (Yanjiahe Fm.) to a middle Early Cambrian calcareous black shale (Shuijingtuo Fm.). As a result, we have identified two positive and two negative isotope excursions within this interval. Near the Pc/C boundary, the δ13Ccarb increases moderately from 0 to + 2‰ (positive excursion 1: P1), and then drops dramatically down to − 7‰ (negative excursion 1: N1). Subsequently, the δ13Ccarb increases continuously up to about + 5‰ at the upper part of the Nemakit–Daldynian stage. After this positive excursion, δ13Ccarb sharply decreases down to about − 9‰ (N2) just below the basal Tommotian unconformity. These continuous patterns of the δ13C shift are irrespective of lithotype, suggesting a primary origin of the record. Moreover, the obtained δ13C profile, except for the sharp excursion N2, is comparable to records of other sections within and outside of the Yangtze Platform. Hence, we conclude that the general feature of our δ13C profile best represents the global change in seawater chemistry. The minimum δ13C of the N1 (− 7‰) is slightly lower than carbon input from the mantle, thus implying an enhanced flux of 13C-depleted carbon just across the Pc/C boundary. Hence, the ocean at that time probably became anoxic, which may have affected the survival of sessile or benthic Ediacaran biota. The subsequent δ13C rise up to + 5‰ (P2) indicates an increase of primary productivity or an enhanced rate of organic carbon burial, which should have resulted in lowering pCO2 and following global cooling. This scenario accounts for the cause of the global-scale sea-level fall at the base of the Tommotian stage. The subsequent, very short-term, and exceptionally low δ13C (− 9‰) in N2 could have been associated with the release of methane from gas hydrates due to the sea-level fall. The inferred dramatic environmental changes (i.e., ocean anoxia, increasing productivity, global cooling and subsequent sea-level fall with methane release) appear to coincide with or occur just before the Cambrian Explosion. This may indicate synchronism between the environmental changes and rapid diversification of skeletal metazoa. 相似文献
To effectively address the root causes of carbon lock-in across developing countries, Nationally Appropriate Mitigation Actions (NAMAs) with transformational change characteristics are being supported by donors and finance mechanisms as a means to achieve ambitious nationally determined contributions (NDCs). However, there is still a scarcity of empirical studies on how transformational change policies and actions are designed and supported in practice. This article addresses such a gap in knowledge by combining theoretical insights from the multi-level perspective and transitions management literature to examine a donor-supported cement sector NAMA in Tunisia developed during 2012–2013. A narrative is constructed to analyse the adequacy of the NAMA design to promote structural shifts towards low carbon development in the cement sector. Data collection is based on semi-structured interviews and documentation gathered during field work in Tunisia 2014–2015. The study finds that the NAMA design is not likely to lead to transformational change of the cement sector, since underlying factors accounting for lock-in are not properly tackled. Although the NAMA has enabled new and promising sectoral partnerships across the cement sector, the analysis suggests that the NAMA’s transformational potential is currently limited by a number of factors not being adequately addressed. Measures are proposed to reorient the NAMA towards promoting system innovation, building on further research and experimentation with the policy entrepreneurial role of donors.
Key policy insights
Underlying factors such as the absence of local finance institutions and the lack of reflexivity features in project design restrict the potential of the Tunisian cement NAMA to spur transformation to low carbon development.
To tackle underlying causes of carbon lock-in and reorient policies and actions for transformational design, the promotion of feedback loops and self-contemplation needs to be based on a long-term vision, experimentation, social learning and information gathered during implementation.
Donors need to re-think their existing modalities to better support unpredictable and highly political changes for sustainability transitions in developing countries.
This article outlines a critical gap in the assessment methodology used to estimate the macroeconomic costs and benefits of climate and energy policy, which could lead to misleading information being used for policy-making. We show that the Computable General Equilibrium (CGE) models that are typically used for assessing climate policy use assumptions about the financial system that sit at odds with the observed reality. These assumptions lead to ‘crowding out’ of capital and, because of the way the models are constructed, negative economic impacts (in terms of gross domestic product (GDP) and welfare) from climate policy in virtually all cases.
In contrast, macro-econometric models, which follow non-equilibrium economic theory and adopt a more empirical approach, apply a treatment of the financial system that is more consistent with reality. Although these models also have major limitations, they show that green investment need not crowd out investment in other parts of the economy – and may therefore offer an economic stimulus. Our conclusion is that improvements in both modelling approaches should be sought with some urgency – both to provide a better assessment of potential climate and energy policy and to improve understanding of the dynamics of the global financial system more generally.
POLICY RELEVANCE
This article discusses the treatment of the financial system in the macroeconomic models that are used in assessments of climate and energy policy. It shows major limitations in approach that could result in misleading information being provided to policy-makers. 相似文献