The 2009 M W 7.8 Fiordland （New Zealand） earthquake is the largest to have occurred in New Zealand since the 1931 M W 7.8 Hawke’s Bay earthquake, 1 000 km to the northwest. In this paper two tracks of ALOS PALSAR i...The 2009 M W 7.8 Fiordland （New Zealand） earthquake is the largest to have occurred in New Zealand since the 1931 M W 7.8 Hawke’s Bay earthquake, 1 000 km to the northwest. In this paper two tracks of ALOS PALSAR interferograms （one ascending and one descending） are used to determine fault geometry and slip distribution of this large earthquake. Modeling the event as dislocation in an elastic half-space suggests that the earthquake resulted from slip on a SSW-NNE orientated thrust fault that is associated with the subduction between the Pacific and Australian Plates, with oblique displacement of up to 6.3 m. This finding is consistent with the preliminary studies undertaken by the USGS using seismic data.展开更多
China is experiencing rapid urbanization that has changed the water quality of rivers, especially nutrient loads. In this study, a typical urban river located in a karst area, Chengguan River, was chosen to explore th...China is experiencing rapid urbanization that has changed the water quality of rivers, especially nutrient loads. In this study, a typical urban river located in a karst area, Chengguan River, was chosen to explore the influence of urbanization on river ecosystems based on nutrient concentration and nitrate isotopes. The results show monthly variability of water chemistry and nutrient concentration. Nutrient concentration in two tributaries and the mainstem showed significant spatial variability, with heavy N and P pollution in one tributary near a suburban area,indicating a response to different levels of urbanization.Measurements of nitrate dual isotopes suggest thatvolatilization, assimilation, nitrification, and denitrification all occur in the polluted river. Water chemistry and nitrate isotopes show that major nitrogen sources included domestic waste and agricultural input, such as chemical fertilizer and manure. The results suggest that urbanization increases nutrient concentrations and accelerates the riverine nitrogen dynamic, and point to the need to manage point sources of sewage effluents to improve the water quality of urban rivers in southwestern China.展开更多
Aims Grasslands are the world’s most extensive terrestrial ecosystem,and are a major feed source for livestock.Meeting increasing demand for meat and other dairy products in a sustainable manner is a big challenge.At...Aims Grasslands are the world’s most extensive terrestrial ecosystem,and are a major feed source for livestock.Meeting increasing demand for meat and other dairy products in a sustainable manner is a big challenge.At a field scale,Global Positioning System and ground-based sensor technologies provide promising tools for grassland and herd management with high precision.With the growth in availability of spaceborne remote sensing data,it is therefore important to revisit the relevant methods and applications that can exploit this imagery.In this article,we have reviewed the(i)current status of grassland monitoring/observation methods and applications based on satellite remote sensing data,(ii)the technological and methodological developments to retrieve different grassland biophysical parameters and management characteristics(i.e.degradation,grazing intensity)and(iii)identified the key remaining challenges and some new upcoming trends for future development.Important Findings The retrieval of grassland biophysical parameters have evolved in recent years from classical regression analysis to more complex,efficient and robust modeling approaches,driven by satellite data,and are likely to continue to be the most robust method for deriving grassland information,however these require more high quality calibration and validation data.We found that the hypertemporal satellite data are widely used for time series generation,and particularly to overcome cloud contamination issues,but the current low spatial resolution of these instruments precludes their use for field-scale application in many countries.This trend may change with the current rise in launch of satellite constellations,such as RapidEye,Sentinel-2 and even the microsatellites such as those operated by Skybox Imaging.Microwave imagery has not been widely used for grassland applications,and a better understanding of the backscatter behaviour from different phenological stages is needed for more reliable products in cloudy regions.The development of hyperspectral satellite instrumentation and analytical methods will help for more detailed discrimination of habitat types,and the development of tools for greater end-user operation.展开更多
Long-chain n-alkanes are one of the most common organic compounds in terrestrial plants and they are well-preserved in various geological archives.n-alkanes are relatively resistant to degradation and thus they can pr...Long-chain n-alkanes are one of the most common organic compounds in terrestrial plants and they are well-preserved in various geological archives.n-alkanes are relatively resistant to degradation and thus they can provide high-fidelity records of past vegetation and climate changes.Nevertheless,previous studies have shown that the interpretation of n-alkane proxies,such as the average chain length(ACL),is often ambiguous since this proxy depends on more than one variable.Both vegetation and climate could exert controls on the n-alkane ACL,and hence its interpretation requires careful consideration,especially in regions like the Qinghai-Tibet Plateau(QTP)where topography,biome type and moisture source are highly variable.To further evaluate the influences of vegetation and climate on the ACL in high-elevation lakes,we examined the n-alkane distributions of the surface sediments of 55 lakes across the QTP.Our results show that the ACL across a climatic gradient is significantly affected by precipitation,rather than by temperature.The positive correlation between ACL and precipitation may be because of the effect of microbial degradation during deposition.Finally,we suggest that more caution is needed in the interpretation of ACL data in different regions.展开更多
The structure of upper crustal magma plumbing systems controls the distribution of volcanism and influences tectonic processes.Delineating the structure and volume of plumbing systems is,however,difficult because:(1)a...The structure of upper crustal magma plumbing systems controls the distribution of volcanism and influences tectonic processes.Delineating the structure and volume of plumbing systems is,however,difficult because:(1)active展开更多
Increased anthropogenic CO_(2) emissions are leading to an increase in CO_(2) uptake by the world's oceans and seas,resulting in ocean acidification with a decrease in global ocean water pH by as much as 0.3–0.4 ...Increased anthropogenic CO_(2) emissions are leading to an increase in CO_(2) uptake by the world's oceans and seas,resulting in ocean acidification with a decrease in global ocean water pH by as much as 0.3–0.4 units by the year 2100.The direct effects of changing pCO_(2) on important microalgal feedstocks are not as well understood.Few studies have focused on lipid composition changes in specific algal species in response to ocean acidification and yet microalgae are an indispensable food source for various marine species,including juvenile shellfish.Isochrysis galbana and Tetraselmis suecica are widely used in aquaculture as feeds for mussels and other shellfish.The total lipid contents and concentrations of I.galbana and T.suecica were investigated when grown under present day(400 ppm)and ocean acidification conditions(1000 ppm)to elucidate the impact of increasing pCO_(2) on an important algae feedstock.Total lipids,long-chain alkenones(LCAs)and alkenoates decreased at 1000 ppm in I.galbana.I.galbana produces higher lipids than T.suecica,and is perhaps as a result more impacted by the change in carbon available for lipid production under higher pCO_(2).I.galbana is an important feedstock,more easily assimilated for growth in juvenile shellfish and reductions in lipid composition may prove problematic for the growth of future shellfish aquaculture.Our findings suggest that higher pCO_(2) impacts on algal lipid growth are species specific and warrant further study.It is therefore vital to examine the impact of high CO_(2) on algal lipid production,especially those commercial shellfish feed varieties to predict future impacts on commercial aquaculture.展开更多
基金supported jointly by the GAS project (Ref: NE/H001085/1)a China 863 Project (No.2009AA12Z317)+2 种基金supported by the Natural Environmental Research Council (NERC) through the National Center of Earth Observation (NCEO) of which the Center for the Observation and Modelling of Earthquakesfunded by a general project of National Natural Science Foundation of China (NS- FC) (No. 40902081)a key project of the Ministry of Land & Resources, China (No. 1212010914015)
文摘The 2009 M W 7.8 Fiordland （New Zealand） earthquake is the largest to have occurred in New Zealand since the 1931 M W 7.8 Hawke’s Bay earthquake, 1 000 km to the northwest. In this paper two tracks of ALOS PALSAR interferograms （one ascending and one descending） are used to determine fault geometry and slip distribution of this large earthquake. Modeling the event as dislocation in an elastic half-space suggests that the earthquake resulted from slip on a SSW-NNE orientated thrust fault that is associated with the subduction between the Pacific and Australian Plates, with oblique displacement of up to 6.3 m. This finding is consistent with the preliminary studies undertaken by the USGS using seismic data.
基金financially supported by National Natural Science Foundation of China(Grant Nos.41571130072 and41130536)the Ministry of Science and Technology of China through Grant Nos.2016YFA0601000 and 2013CB956700
文摘China is experiencing rapid urbanization that has changed the water quality of rivers, especially nutrient loads. In this study, a typical urban river located in a karst area, Chengguan River, was chosen to explore the influence of urbanization on river ecosystems based on nutrient concentration and nitrate isotopes. The results show monthly variability of water chemistry and nutrient concentration. Nutrient concentration in two tributaries and the mainstem showed significant spatial variability, with heavy N and P pollution in one tributary near a suburban area,indicating a response to different levels of urbanization.Measurements of nitrate dual isotopes suggest thatvolatilization, assimilation, nitrification, and denitrification all occur in the polluted river. Water chemistry and nitrate isotopes show that major nitrogen sources included domestic waste and agricultural input, such as chemical fertilizer and manure. The results suggest that urbanization increases nutrient concentrations and accelerates the riverine nitrogen dynamic, and point to the need to manage point sources of sewage effluents to improve the water quality of urban rivers in southwestern China.
基金Teagasc Walsh Fellowship Program for funding this research.
文摘Aims Grasslands are the world’s most extensive terrestrial ecosystem,and are a major feed source for livestock.Meeting increasing demand for meat and other dairy products in a sustainable manner is a big challenge.At a field scale,Global Positioning System and ground-based sensor technologies provide promising tools for grassland and herd management with high precision.With the growth in availability of spaceborne remote sensing data,it is therefore important to revisit the relevant methods and applications that can exploit this imagery.In this article,we have reviewed the(i)current status of grassland monitoring/observation methods and applications based on satellite remote sensing data,(ii)the technological and methodological developments to retrieve different grassland biophysical parameters and management characteristics(i.e.degradation,grazing intensity)and(iii)identified the key remaining challenges and some new upcoming trends for future development.Important Findings The retrieval of grassland biophysical parameters have evolved in recent years from classical regression analysis to more complex,efficient and robust modeling approaches,driven by satellite data,and are likely to continue to be the most robust method for deriving grassland information,however these require more high quality calibration and validation data.We found that the hypertemporal satellite data are widely used for time series generation,and particularly to overcome cloud contamination issues,but the current low spatial resolution of these instruments precludes their use for field-scale application in many countries.This trend may change with the current rise in launch of satellite constellations,such as RapidEye,Sentinel-2 and even the microsatellites such as those operated by Skybox Imaging.Microwave imagery has not been widely used for grassland applications,and a better understanding of the backscatter behaviour from different phenological stages is needed for more reliable products in cloudy regions.The development of hyperspectral satellite instrumentation and analytical methods will help for more detailed discrimination of habitat types,and the development of tools for greater end-user operation.
基金financially supported by the National Natural Science Foundation of China(Grant No.42171159)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(No.2019QZKK0601).
文摘Long-chain n-alkanes are one of the most common organic compounds in terrestrial plants and they are well-preserved in various geological archives.n-alkanes are relatively resistant to degradation and thus they can provide high-fidelity records of past vegetation and climate changes.Nevertheless,previous studies have shown that the interpretation of n-alkane proxies,such as the average chain length(ACL),is often ambiguous since this proxy depends on more than one variable.Both vegetation and climate could exert controls on the n-alkane ACL,and hence its interpretation requires careful consideration,especially in regions like the Qinghai-Tibet Plateau(QTP)where topography,biome type and moisture source are highly variable.To further evaluate the influences of vegetation and climate on the ACL in high-elevation lakes,we examined the n-alkane distributions of the surface sediments of 55 lakes across the QTP.Our results show that the ACL across a climatic gradient is significantly affected by precipitation,rather than by temperature.The positive correlation between ACL and precipitation may be because of the effect of microbial degradation during deposition.Finally,we suggest that more caution is needed in the interpretation of ACL data in different regions.
文摘The structure of upper crustal magma plumbing systems controls the distribution of volcanism and influences tectonic processes.Delineating the structure and volume of plumbing systems is,however,difficult because:(1)active
基金funding from NERC Independent Research Fellowship[NE/N01409X/1].
文摘Increased anthropogenic CO_(2) emissions are leading to an increase in CO_(2) uptake by the world's oceans and seas,resulting in ocean acidification with a decrease in global ocean water pH by as much as 0.3–0.4 units by the year 2100.The direct effects of changing pCO_(2) on important microalgal feedstocks are not as well understood.Few studies have focused on lipid composition changes in specific algal species in response to ocean acidification and yet microalgae are an indispensable food source for various marine species,including juvenile shellfish.Isochrysis galbana and Tetraselmis suecica are widely used in aquaculture as feeds for mussels and other shellfish.The total lipid contents and concentrations of I.galbana and T.suecica were investigated when grown under present day(400 ppm)and ocean acidification conditions(1000 ppm)to elucidate the impact of increasing pCO_(2) on an important algae feedstock.Total lipids,long-chain alkenones(LCAs)and alkenoates decreased at 1000 ppm in I.galbana.I.galbana produces higher lipids than T.suecica,and is perhaps as a result more impacted by the change in carbon available for lipid production under higher pCO_(2).I.galbana is an important feedstock,more easily assimilated for growth in juvenile shellfish and reductions in lipid composition may prove problematic for the growth of future shellfish aquaculture.Our findings suggest that higher pCO_(2) impacts on algal lipid growth are species specific and warrant further study.It is therefore vital to examine the impact of high CO_(2) on algal lipid production,especially those commercial shellfish feed varieties to predict future impacts on commercial aquaculture.
