Long‐term monitoring of a mercury contaminated estuary (Ria de Aveiro,Portugal): the effect of weather events and management in mercury transport

The main aim of this research was to assess the mercury transport from an estuarine basin with a background of anthropogenic contamination during a spring tidal cycle (year 2009) and compare it with two previous tidal cycles (years 1994 and 1999), as part of a long‐term monitoring program. Results showed that effective mercury transport occurs both in the dissolved and particulate fractions (0.18 and 0.20 kg per tidal cycle, respectively), and despite an overall decrease in environmental contamination, results more than double previous findings on particulate transport in the system. These findings result essentially from changes in the tidal prism (net export of 2 million m³ of water), given that both dissolved and particulate concentrations did not increase over time. Hydrodynamic simulations were performed to evaluate the effect of physical disturbance (dredging) and weather events (increased freshwater flow) in these processes, and results suggest the increased freshwater flow into the system as the main forcing function for the mercury transport increment. These results highlight the importance of long‐term monitoring programs, since despite an overall improvement in local contamination levels, the enhancement of transport processes through hydrological changes increases environmental pressure away from the contamination source. Copyright © 2012 John Wiley & Sons, Ltd.     

Simulation of site-scale water fluxes in desert and natural oasis ecosystems of the arid region in Northwest China

The study of water fluxes is important to better understand hydrological cycles in arid regions. Data-driven machine learning models have been recently applied to water flux simulation. Previous studies have built site-scale simulation models of water fluxes for individual sites separately, requiring a large amount of data from each site and significant computation time. For arid areas, there is no consensus as to the optimal model and variable selection method to simulate water fluxes. Using data from seven flux observation sites in the arid region of Northwest China, this study compared the performance of random forest (RF), support vector machine (SVM), back propagation neural network (BPNN), and multiple linear regression (MLR) models in simulating water fluxes. Additionally, the study investigated inter-annual and seasonal variation in water fluxes and the dominant drivers of this variation at different sites. A universal simulation model for water flux was built using the RF approach and key variables as determined by MLR, incorporating data from all sites. Model performance of the SVM algorithm (R² = 0.25–0.90) was slightly worse than that of the RF algorithm (R² = 0.41–0.91); the BPNN algorithm performed poorly in most cases (R² = 0.15–0.88). Similarly, the MLR results were limited and unreliable (R² = 0.00–0.66). Using the universal RF model, annual water fluxes were found to be much higher than the precipitation received at each site, and natural oases showed higher fluxes than desert ecosystems. Water fluxes were highest during the growing season (May–September) and lowest during the non-growing season (October–April). Furthermore, the dominant drivers of water flux variation were various among different sites, but the normalized difference vegetation index (NDVI), soil moisture and soil temperature were important at most sites. This study provides useful insights for simulating water fluxes in desert and oasis ecosystems, understanding patterns of variation and the underlying mechanisms. Besides, these results can make a contribution as the decision-making basis to the water management in desert and oasis ecosystems.     

Money for nothin’ and coal for free: ‘Technology neutrality’ and biomass development under the Flemish tradable green certificate scheme

Recent literature has highlighted the creation of multiple equivalences as an important factor underpinning the rise of market-based mechanisms for environmental regulation. Extending these insights into the field of renewable energy policy, this article focuses on one example of this trend – namely the principle of technology neutrality as applied under the Flemish tradable green certificate scheme – and analyzes the concrete ways in which it has shaped the evolution of the Flemish renewable energy landscape. Concretely, the article shows that technology neutrality played a key role in promoting the uptake of biomass combustion in old coal power plants in Flanders, which led to a number of undesirable outcomes and gave rise to significant opposition. Correcting these shortcomings required a number of policy interventions on the part of the Flemish government that fundamentally moved the scheme away from the principle of technology neutrality and towards a more hybrid RE support system, suggesting that the promotion of technology neutrality was fundamentally misguided. Together with similar experiences from related market-based instruments, this suggests that the promotion of technology neutrality has far-reaching implications for the environmental effectiveness of climate and energy policies. In light of the continued promotion of the principle, the article calls for full recognition of the inherent technological choices that are being made through the promotion of policies that purport to be technology-neutral.     

Atmospheric palaeo-CO2 estimates based on the carbon isotope and stomatal data of Cheirolepidiaceae from the Lower Cretaceous of the Jiuquan Basin,Gansu Province

The stable carbon isotope compositions and the stomatal parameters (stomatal density and stomatal index) of four Cheirolepidiaceae species, Brachyphyllum ningxiaensis, Brachyphyllum obtusum, Pseudofrenelopsis dalatzensis and Pseudofrenelopsis gansuensis, were analyzed to recover the late Early Cretaceous atmospheric CO₂ levels. The fossil plants were collected from 5 consecutive sedimentary members of the uppermost Zhonggou Formation. Based on the stomatal data, the estimated palaeo-atmospheric CO₂ concentrations in the Jiuquan Basin during the late Early Cretaceous were 1060–882 ppmv based on the carboniferous standardization and were 641–531 ppmv based on the recent standardization; the pCO₂ values present at first a decreasing and then an increasing trend within the sedimentary time of the five members. The δ¹³Cp values based on the 21 Brachyphyllum specimens showed a large variation, which ranged from −20.98‰ to −25.69‰, with an average of −24.2‰. The values also identified a C3 photosynthetic pathway for the Brachyphyllum specimens. The predicted δ¹³Ca values varied from −2.1‰ to −6.38‰, with an average of −5.03‰. These two proxies were irregular within the different members; therefore, the correlation with the change in atmospheric CO₂ concentrations was not significant. Moreover, a water-stressed environment was proposed based on the δ¹³C values of the present fossil plants, a proposal that was also supported by the previous palaeobotanical, palynological and stratigraphical evidence. In the present study, an inconsistent relationship between the stable carbon isotope and the stomata values was apparent, which most likely indicated that the stomata numbers of the plant were more sensitive to the variation in the concentration of the atmospheric CO₂, whereas the δ¹³C values were sensitive to the moisture conditions.     

Late Cenomanian environmental conditions at the submerged Tatric Ridge,Central Western Carpathians during the period preceding Oceanic Anoxic Event 2 – A palaeontological and isotopic approach

Micropalaeontological and isotopic studies of the upper Cenomanian turbiditic/hemipelagic sediments from the High-Tatric unit (Central Western Carpathians; Polish part of the Tatra Mountains) has been undertaken to characterize the sedimentary conditions in the Tatric basin, a part of the Western Tethys, related to the interval preceding the late Cenomanian oceanic anoxic event (OAE2). The deposition of these sediments, including organic-rich layers (TOC up to 0.7%), corresponds to the Rotalipora cushmani foraminiferal Zone. Microfacial, foraminiferal and palynological analyses show that the sea floor was located at upper bathyal depths and the water column was poorly oxygenated. The intrabasinal carbonate material indicates moderate primary productivity with rare periods of upwellings. The scarcity of marine fossils in redeposited material and features of carbonate lithoclasts suggest very low productivity in the nearshore surface water, most probably due to a low-density hyposaline cap as surface runoff from the southern margin of the basin. The carbon isotopic study documents the negative values of δ¹³C_carb in the whole section as an effect of transfer of isotopically light carbon sourced from various sources. Such negative values of δ¹³C_carb are characteristic of the upper Cenomanian sediments, deposited in relatively shallow water basins, characterized by input of terrestrial organic matter and/or carbonate particles known from the Western Interior sections, the Atlantic coastal plain, the northwestern African margin, the eastern margin of the Apulian Platform and shelf sediments in the NW Europe and Tethyan Himalayas. Most probably, all of these events could be related to the global sea level fluctuations that occurred ca. 95.5–94.5 Ma comparing with the Haq (2014) eustatic curve.     

青藏高原晚始新世干旱化事件：改则盆地康托组碳酸盐岩碳氧同位素的记录

改则盆地位于青藏高原腹地,盆地内沉积物记录了高原古环境变化的重要信息。本文对改则盆地康托组碳酸盐岩碳氧同位素进行研究,结果显示改则盆地中-晚始新世的演化分为两个阶段:1中始新世湿润气候下开放湖盆阶段:虽然碳酸盐岩δ~(18)O值在43层处向正值偏移,但整体~(18)O和~(13)C强烈亏损,并且该时期碳酸盐岩δ~(18)O值和δ~(13)C变化相关系数为R~2=0.082。表明该阶段的研究区虽然经历过短期蒸发作用增强或补给水减少,但整体是气候湿润条件下补给水丰富的开放型湖盆。2晚始新世干旱气候下封闭湖盆阶段:经过中新世晚期(63层)气候和湖泊水文状态的过渡,晚始新世~(18)O和~(13)C同位素富集,δ~(18)O值和δ~(13)C值变化相关系数为R~2=0.7762。表明该阶段气候干旱,蒸发作用强烈,湖盆萎缩成为封闭湖盆。综合前人研究,认为青藏高原腹地及北缘、东北缘在晚始新世存在明显的区域性干旱化事件。对比分析青藏高原隆升、全球气候记录、全球海水Sr和大气CO_2记录,认为青藏高原腹地和北部的干旱化事件主要受青藏高原隆升的影响。     

Study on the Global Carbon Assimilation System Based on Multisource Remote Sensing Data

The Paris agreement signed in April, 2016 aims to balance global anthropogenic carbon emissions and terrestrial carbon sinks by the middle of the 21^st century. To fulfill this goal, it is necessary to calculate carbon fluxes of different regions reliably. The global carbon assimilation system is an effective technique for achieving this goal. The Ministry of Science and Technology of China supports the project entitled as study on the global carbon assimilation system based on multisource remote sensing data through the national key research and development programs for global change and adaptation during the thirteen-five period. This project will develop synergic inversion techniques for retrieving key parameters of biological and atmospheric cycles and for assimilating multisource remote sensing and ground based data. Then, the high resolution global carbon assimilation system coupled with an ecological model will be constructed. This system is able to assimilate jointly multisource observation data and to optimize key model parameters, photosynthesis and respiration carbon fluxes of global terrestrial ecosystems, and anthropogenic carbon emission fluxes of key regions. This system will be used to study quantitatively the spatial and temporal patterns of carbon fluxes of global terrestrial ecosystems and anthropogenic carbon emission fluxes of key regions and to identify the mechanisms driving the global terrestrial carbon sinks and sources. The outputs of this study will be helpful for the fulfillment of the key research and development programs for global change and adaptation and provide valuable data and technical support for the decision-making in China.     

Comparative Study of the Carbon Emission Situation and Goals between China and India

As the two large developing and populous countries, China and India face the dual challenges of economic development and climate change. Both of them are active in carbon emissions reduction, while India also bears the pressure of being “benchmarked” against China. With taking China and India as the sample of a comparative analysis, and the statistical value of a long sequence as the basic analysis data, based on the detailed analysis and comparison of carbon emissions history, the carbon emissions situation of the two countries from various dimensions including economic development, energy reserves and consumption, etc. were comparatively analyzed. The carbon intensity and energy structure after achieving the objectives were measured and compared by focusing on the carbon emissions reduction targets in China and India. The comparative results show that: China’s total carbon emissions are greater than India’s, but the growth rate of emissions, per capita emissions are significantly lower than India’s, while the carbon intensity decreases significantly faster than that of India. China has taken more efforts to make commitments to carbon reduction than India. With India’s energy structure adjustment, the situation will be gradually better than that in China.     

Geochemical characteristics and isotopic reversal of natural gases in eastern Kopeh-Dagh,NE Iran

Natural gas samples from two gas fields located in Eastern Kopeh-Dagh area were analyzed for molecular and stable isotope compositions. The gaseous hydrocarbons in both Lower Cretaceous clastic reservoir and Upper Jurassic carbonate reservoir are coal-type gases mainly derived from type III kerogen, however enriched δD values of methane implies presence of type II kerogen related material in the source rock. In comparison Upper Jurassic carbonate reservoir gases show higher dryness coefficient resulted through TSR, while presence of C₁C₅ gases in Lower Cretaceous clastic reservoir exhibit no TSR phenomenon. Carbon isotopic values indicate gas to gas cracking and TSR occurrence in the Upper Jurassic carbonate reservoir, as the result of elevated temperature experienced, prior to the following uplifts in last 33–37 million years. The δ¹³C of carbon dioxide and δ³⁴S of hydrogen sulfide in Upper Jurassic carbonate reservoir do not primarily reflect TSR, as uplift related carbonate rock dissolution by acidic gases and reaction/precipitation of light H₂S have changed these values severely. Gaseous hydrocarbons in both reservoirs exhibit enrichment in C₂ gas member, with the carbonate reservoir having higher values resulted through mixing with highly-mature-completely-reversed shale gases. It is likely that the uplifts have lifted off the pressure on shale gases, therefore facilitated the migration of the gases into overlying horizons. However it appears that the released gases during the first major uplift (33–37 million years ago) have migrated to both reservoirs, while the second migrated gases have only mixed with Upper Jurassic carbonate reservoir gases. The studied data suggesting that economic accumulations of natural gas/shale gases deeper than Upper Jurassic carbonate reservoir would be unlikely.     

Coastal aquaculture,mangrove deforestation and blue carbon emissions: Is REDD+ a solution?

Globally, coastal aquaculture particularly shrimp farming has been under huge criticism because of its environmental impacts including devastating effects on mangrove forests. However, mangroves are ecologically and economically important forests, and the most carbon-rich forests in the tropics that provide a wide range of ecosystem services and biodiversity conservation. Carbon emissions are likely to have been the dominant cause of climate change and blue carbon emissions are being critically augmented through mangrove deforestation. Because of mangrove deforestation, different climatic variables including coastal flooding, cyclone, drought, rainfall, salinity, sea-level rise, and sea surface temperature have dramatic effects on coastal aquaculture. Mangrove forests have been instrumental in augmenting resilience to climate change. The “Reducing Emissions from Deforestation and forest Degradation (REDD)” program can help to restore mangroves which in turn increases options for adaptation to climate change. However, technical and financial assistance with institutional support are needed to implement REDD+.