Based on the achievement of local ecological geochemical survey,the selenium in surface layer soil of Zhangqiu green Chinese onion within production area is systematically studied in this study.And the ecological geoc...Based on the achievement of local ecological geochemical survey,the selenium in surface layer soil of Zhangqiu green Chinese onion within production area is systematically studied in this study.And the ecological geochemical characters of selenium both in surface layer soil and in green Chinese onions are analyzed,and the relationship between the selenium in plant and soil is discussed.The results show that soil in Zhangqiu is rich in selenium,and it is suitable to develop the selenium-rich green Chinese onion products.展开更多
It is a great concern in international oceanology to mine cobalt-rich crust. At present, spiral mining head is regarded as the best crushing scheme. Based on the dynamic model of spiral mining head, the of cobalt crus...It is a great concern in international oceanology to mine cobalt-rich crust. At present, spiral mining head is regarded as the best crushing scheme. Based on the dynamic model of spiral mining head, the of cobalt crust’s crushing process was simulated with the ANSYS software. The material model of Johnson and Cook Plasticity, maximal princi- pal stress failure criterion, and eroding contact arithmetic were selected. At the same time, the influence of cutting depth, feed speed, rotational speed of mining head on torque and force subjected by mining head was taken into account. At last a computer simulation model of crushing process of cobalt crust was established. By analyzing simulation results, the relationships among these controllable process parameters, torque and force can be obtained, which will provide a technical reference for practical mining system.展开更多
Cloud forests are unusual and fragile habitats, being one of the least studied and least understood ecosystems. The tropical Andean dominion is considered one of the most significant places in the world as regards bio...Cloud forests are unusual and fragile habitats, being one of the least studied and least understood ecosystems. The tropical Andean dominion is considered one of the most significant places in the world as regards biological diversity, with a very high level of endemism. The biodiversity was analysed in an isolated remnant area of a tropical montane cloud forest known as the "Bosque de Neblina de Cuyas", in the North of the Peruvian Andean range. Composition, structure and dead wood were measured or estimated. The values obtained were compared with other cloud forests. The study revealed a high level of forest biodiversity, although the level of biodiversity differs from one area to another: in the inner areas, where human pressure is almost inexistent, the biodiversity values increase. The high species richness and the low dominance among species bear testimony to this montane cloud forest as a real enclave of biodiversity.展开更多
Serious soil erosion has already resulted in degradation of the Loess Plateau of China. Soil erosion is commonly accompanied by extensive soil nutrient loss. Because of enrichment processes,sediment nutrient content i...Serious soil erosion has already resulted in degradation of the Loess Plateau of China. Soil erosion is commonly accompanied by extensive soil nutrient loss. Because of enrichment processes,sediment nutrient content is often higher than that of natural soil. The objective of this study is to determine the enrichments of organic matter and total nitrogen in sediment in hilly and gully loess areas on the Loess Plateau of China. Measurements of enrichment ratios (ER) of organic matter (EROM) and total nitrogen (ERTN) in sediment as affected by rainfall, slope gradient, tillage, and fertilization were made in the field under natural rainfall conditions. The results showed that the enrichment of clay in sediment resulted in the enrichment of organic matter (OM) and total nitrogen (TN) in sediment. The averages of sediment clay ER, EROM and ERTN for the various slope gradients were 1.77, 2.09 and 1.61, respectively. The soil erosive module was negatively correlated with EROM and ERTN. Our results indicate that measures to reduce soil erosion, i.e. reducing rainfall erosivity, decreasing soil slope gradient, decreasing fertilizer use, and using level trenches, may increase EROM and ERTN. Both quantity and quality of sediment yield should be considered when implementing erosion control measures.展开更多
While many harmful algal blooms have been associated with increasing eutrophication, not all species respond similarly and the increasing challenge, especially for resource managers, is to determine which blooms are r...While many harmful algal blooms have been associated with increasing eutrophication, not all species respond similarly and the increasing challenge, especially for resource managers, is to determine which blooms are related to eutrophication and to understand why particular species proliferate under specific nutrient conditions. The overall goal of this brief review is to describe why nutrient loads are not changing in stoichiometric proportion to the "Redfield ratio", and why this has important consequences for algal growth. Many types of harmful algae appear to be able to thrive, and/or increase their production of toxins, when nutrient loads are not in proportion classically identified as Redfield ratios. Here we also describe some of the physiological mechanisms of different species to take up nutrients and to thrive under conditions of nutrient imbalance.展开更多
The purpose of this study was to examine the sedimentary facies characteristics of lower Cambrian Niutitang Formation(∈1n)in South China,to reveal the mechanism of organic matter enrichment,and to guide exploration o...The purpose of this study was to examine the sedimentary facies characteristics of lower Cambrian Niutitang Formation(∈1n)in South China,to reveal the mechanism of organic matter enrichment,and to guide exploration of shale gas.Macro investigation and experimental analyses were used to assess the lithology in detail,total organic matter mass fraction w(TOC),mineral composition,and trace element characteristics of∈1n.The influencing factors of organic matter enrichment were discussed extensively,and a sedimentary facies mode was suggested.In the early stage of∈1n,the locations of Well E’yangye 1,Well Ciye 1,Well Changye 1,and Well Anye 1 respectively develop,platform inner sag,outer shelf,Jiangnan slope belt,and South China detention basin.In the late stage of∈1n,the sedimentary facies evolve with decreasing sea level.The study area presents a complete three-step basin in the Early Cambrian.In the early stage of∈1n,the first step is the Yangtze carbonate platform,the second step is the outer shelf and slope,and the third step is the deep-water basin.From the Yangtze carbonate platform to the deep-water basin,w(TOC)and the mass fraction of quartz gradually increase,the mass fraction of carbonate mineral decreases,and the mass fraction of clay mineral is higher in the second step.The sea level fluctuation results in a higher w(TOC)vertically in the lower∈1n shale,and the paleogeographic(provenance)conditions lead to better horizontal development of organic matter in the outer shelf,slope and detention basin.Trace elements are abundant in the lower∈1n,and w(TOC)is correlated positively with many trace elements.In the outer shelf,slope,and adjacent areas,hydrothermal activity and upwelling current bring nutrient-rich material and promote organic matter enrichment under a strong reducing condition.Deep-shelf,slope and deep-water basin are the best facies for the formation and preservation of organic matter,especially deep-water basin facies.It remains necessary to strengthen the exploration of shale gas in the deep-water basin of∈1n in central Hunan,China.展开更多
The aim of this study is to elaborate a possible missing source of high-throughput organic nitrogen in rainfall.The authors classified the observed flux data of dissolved organic nitrogen in terms of the attributes of...The aim of this study is to elaborate a possible missing source of high-throughput organic nitrogen in rainfall.The authors classified the observed flux data of dissolved organic nitrogen in terms of the attributes of the wet deposition event itself,such as the season,precipitation,air mass backward trajectory,and effect of typhoons.The monitoring results of the ocean eutrophication and the chlorophyll-a map of the surface water were compared with the trajectory of the high-flux deposition events.The results show that approximately one third of the total wet deposition organic nitrogen derived from a confluence of three factors:rain in the wet season,air masses from the ocean,and rainfall over 50 mm.It could be seen that the co-occurrence of intense events such as a typhoon and eutrophic surface sea waters might be an important source of dissolved organic nitrogen in wet deposition.展开更多
We studied the depth distribution of periphyton,growing on inundated dead trees in Kenyir Lake,Malaysia in June 1995.The algal floral composition and structure manifested changes down the depth gradient in terms of sp...We studied the depth distribution of periphyton,growing on inundated dead trees in Kenyir Lake,Malaysia in June 1995.The algal floral composition and structure manifested changes down the depth gradient in terms of species richness,abundance,diversity and cell density.In regression analysis,all these algal attributes were negatively correlated with the depth gradients at P<0.05.In terms of species richness,the bacillariophytes showed dominance over the cyanophytes and chlorophytes;whereas with respect to standing crop,the cyanophytes showed dominance over the bacillariophytes and chlorophytes.The chlorophyll a was higher at the mid and bottom-depths than the surface-depth in both the downstream and upstream sites,which showed that vertical productivity or biomass accumulation was greater in low light irradiance.The product-moment correlation analysis showed that conductivity,turbidity,dissolved oxygen,reactive phosphate and ammonium-nitrogen were highly correlated with the algal assemblage data.However,photosynthetic active radiation(PAR) showed poor correlation with the community data.These observations have cast some light on the autoecological characteristics,habitat preferences and environmental responses of tropical periphytic communities.展开更多
The eutrophication, hypoxia and coastal acidification are attracting more and more attention. In this study, inorganic carbon parameters, including dissolved inorganic carbon (DIC), total alkalinity (TA) and calcu...The eutrophication, hypoxia and coastal acidification are attracting more and more attention. In this study, inorganic carbon parameters, including dissolved inorganic carbon (DIC), total alkalinity (TA) and calculated partial pressure of CO2 (pCO2), obtained from a summer cruise in August, 2009, were used to investigate their integrated response to biological processes accompanying the oxygen depletion in the areas off the Changjiang Estuary. According to the observations, the typical hypoxia occurred in the bottom water just outside the Changjiang Estuary with Dissolved Oxygen (DO) lower than 2.00 mg L^-1. The biological uptake in the surface water and the decomposition of organic matter in the bottom water were fully coupled with each other. The high concentration of Chl_a (Chl_a = 10.9μgL^-1) and DO (9.25 mgL^-1), profoundly decreased DIC concentration 0828 μmolkg^-1) and elevated pH (8.42) was observed in the surface water. The correspondingly increased DIC and depletion of oxygen were observed in the bottom water. The semi-quantitative analysis proved that the locally-produced phytoplankton, determined by primary productivity, was deposited to the bottom and contributed about 76% of total amount of the organic carbon decomposition in the bottom. However, in the bottom hypoxia (DO = 2.05 mgL^-1) area observed in the Southern Zhejiang coastal water, the responding patterns of inorganic carbon parameters deviated from the previous one. The expanding of Changjiang Diluted Water (CDW), the adding of Hangzhou Bay water (with high DIC concentration) and Coastal Current together modify the DIC background value in this area, and the local degeneration and upwelling process may also help to offset the local DIC removed by net biological uptake in surface water. In addition when the mixing occurring in autumn, which may break the summer stratification, the excess release of high DIC in the bottom water to the subsurface water could have an important influence on coastal acidification and the CO2 uptake capacity in this area.展开更多
In this paper, the analysis of the environmental impacts of a biopolymer based on starch is presented. These impacts were calculated from a cradle to gate LCA (Life Cycle Assessment), based on UNEEN ISO 14040:2006 ...In this paper, the analysis of the environmental impacts of a biopolymer based on starch is presented. These impacts were calculated from a cradle to gate LCA (Life Cycle Assessment), based on UNEEN ISO 14040:2006 and UNEEN ISO 14044, using as functional unit 1 kg of produced biomaterial. The impact categories analyzed were global wanning, ozone depletion, acidification and eutrophication. The results indicate that the electricity causes the highest impacts in the global warming and ozone depletion categories, but compared to synthetic polymers, the emissions are low. Finally, in the case of eutrophication, the impacts are similar to other biopolymers but higher in comparison with petroleum-based polymers like HDPE (High Density Polyethylene), LDPE (Low Density Polyethylene), PP (Polypropylene), PS (Polystyrene) and PET (Polyethylene Terephthalate).展开更多
We analyzed the distributional patterns of95 selected species of leptosporangiate ferns inhabiting the Mexican Mountain Component, using grid-cells of one geographical degree as unit areas,applying endemism indices an...We analyzed the distributional patterns of95 selected species of leptosporangiate ferns inhabiting the Mexican Mountain Component, using grid-cells of one geographical degree as unit areas,applying endemism indices and richness and beta diversity analyses.Distributional data were obtained from several herbaria and specialized literature.Five grid-cells appear to be important for fern species richness, as they contain 35 to 49 species.These gridcells are located in the Sierra Madre Oriental(SMO),Trans-Mexican Volcanic Belt(TMVB) and the Sierra Madre del Sur(SMS).Mean richness by latitudinal belts of one degree showed that the belts with highest values are related to the TMVB and SMS.A total of 13grid-cells were recognized as important from theperspective of endemism; most of them are located also in the SMO, TMVB and SMS.The richest gridcells coincided with one of the main centres of endemism for ferns obtained in this study, located in the convergence of the southern part of the SMO, the eastern portion of the TMVB and the northern part of the SMS, reflecting the high humidity existing on the mountain slopes facing the Gulf of Mexico.Some important grid-cells recognized from richness and endemism analyses coincide with Mexican Natural Protected Areas.The beta diversity analysis showed a low degree of similarity among grid-cells, implying a high species replacement, as the result of environmental heterogeneity occurring in the Mexican mountain systems.On the other hand, the spatial analysis suggested a pattern of phytogeographical regionalization comprising twomain areas: the Mexican Transition Zone and the Mexican Central Plateau.Ferns play an important role in the Mexican biodiversity and contributing to the beta diversity of Mexico.展开更多
The spacial distribution characteristics, activity and degradation capability of the biofilm in integrated vertical-flow constructed wetland were investigated. Results showed that the biofilm widely distributed in the...The spacial distribution characteristics, activity and degradation capability of the biofilm in integrated vertical-flow constructed wetland were investigated. Results showed that the biofilm widely distributed in the substrate of integrated vertical-flow constructed wetland and mainly in the 0-10 cm top layer where the activity ofdehydrogenase of the biofilm was also higher than that of other layers. The water quality could also affect the activity of the biofilm, for the TF(1,3,5-Triphenylformazan) amount reduced by the biofim incubated in water of the higher eutrophication was larger, too. The PCP (pentachlorophenol) removal rate by the substrate with biofilm was 1.5 times that without biofilm. In total, the biofilm of the down-flow chamber appeared larger biomass, higher dehydrogenase activity and stronger degradation capability of organic contamination than that in up-flow chamber and it was the major place for removal of the organic matters in waste water.展开更多
Resin adsorption technique with XAD-8 and XAD-4 was used to characterize the raw water from Erlong reservoir in Jilin province of China. The NOM chemical composition sequences of four organic fractions in the raw wate...Resin adsorption technique with XAD-8 and XAD-4 was used to characterize the raw water from Erlong reservoir in Jilin province of China. The NOM chemical composition sequences of four organic fractions in the raw water, from high to low, are fulvic acid (FA) fraction, hydrophilic non-acid (HPINA) fraction, hydrophilic acid (HPIA) fraction, and humic acid (HA) fraction. Experimental results show that FA is the main precursor of THMFP among the four organic fractions. However, HA or hydrophobie acid exhibits the highest chlorination activity in forming THMs. It is also found that the value of FI/DOC or SUVA and the specific THMFP have better positive correlation. It is implied that certain source water has unique nature of NOM and DBPs.展开更多
The existence of nanographene in cluster form is discussed in organic solvents. Theories are developed based on the columnlet, bundlet and droplet models describing the size-distribution functions. Phenomena present a...The existence of nanographene in cluster form is discussed in organic solvents. Theories are developed based on the columnlet, bundlet and droplet models describing the size-distribution functions. Phenomena present a unified explanation in the columnlet model in which free energy of Cgraphene involved in cluster is combined from a volume part proportional to the number of molecules n in cluster and a constant. The columnlet model enables describing distribution function of Cgraphene clusters by size. From purely geometrical considerations the columnlet (Cgraphene), bundlet (single-wall carbon nanotube), CNT (carbon nanotube), SWNT (single-wall C-nanotube), and carbon nanobud, CNB (carbon nanobud)) and droplet (fullerene) models predict dissimilar behaviours. The interaction-energy parameters of Cgraphene are taken from C60. An CNB behaviour or further is expected. The decay of solubility with rising temperature is smaller for Cgraphene than for SWNT and CNB and, furthermore, than for C60, in agreement with lesser numbers of units in Cgraphene clusters. The discrepancy between the experimental data of the heat of solution of fullerenes, CNTs, CNBs and graphenes is ascribed to the sharp concentration dependence of the heat of solution. The diffusion coefficient drops with temperature result greater for Cgraphene than CNB and SWNT than C60 corresponding to lesser number of units in clusters. The aggregates near (C60)13, SWNT/CNB7 and (Cgraphene)3 could be representative of the droplet, bundlet and columnlet models.展开更多
基金Supported by China Geological Survey Bureau Project(1212010310306)~~
文摘Based on the achievement of local ecological geochemical survey,the selenium in surface layer soil of Zhangqiu green Chinese onion within production area is systematically studied in this study.And the ecological geochemical characters of selenium both in surface layer soil and in green Chinese onions are analyzed,and the relationship between the selenium in plant and soil is discussed.The results show that soil in Zhangqiu is rich in selenium,and it is suitable to develop the selenium-rich green Chinese onion products.
基金Project DY105-03-02-1 supported by COMRA project 50474052 supported by National Natural Science Foundation of China
文摘It is a great concern in international oceanology to mine cobalt-rich crust. At present, spiral mining head is regarded as the best crushing scheme. Based on the dynamic model of spiral mining head, the of cobalt crust’s crushing process was simulated with the ANSYS software. The material model of Johnson and Cook Plasticity, maximal princi- pal stress failure criterion, and eroding contact arithmetic were selected. At the same time, the influence of cutting depth, feed speed, rotational speed of mining head on torque and force subjected by mining head was taken into account. At last a computer simulation model of crushing process of cobalt crust was established. By analyzing simulation results, the relationships among these controllable process parameters, torque and force can be obtained, which will provide a technical reference for practical mining system.
基金supported by Nature and Culture International (NCI-Perú) and partially funded through a Grant from the Universidad Politécnica de Madrid
文摘Cloud forests are unusual and fragile habitats, being one of the least studied and least understood ecosystems. The tropical Andean dominion is considered one of the most significant places in the world as regards biological diversity, with a very high level of endemism. The biodiversity was analysed in an isolated remnant area of a tropical montane cloud forest known as the "Bosque de Neblina de Cuyas", in the North of the Peruvian Andean range. Composition, structure and dead wood were measured or estimated. The values obtained were compared with other cloud forests. The study revealed a high level of forest biodiversity, although the level of biodiversity differs from one area to another: in the inner areas, where human pressure is almost inexistent, the biodiversity values increase. The high species richness and the low dominance among species bear testimony to this montane cloud forest as a real enclave of biodiversity.
基金国家重点基础研究发展计划(973计划),国家自然科学基金,The Science Foundation of the State Key Laboratory of Soil Erosion and Dry Farming, CAS
文摘Serious soil erosion has already resulted in degradation of the Loess Plateau of China. Soil erosion is commonly accompanied by extensive soil nutrient loss. Because of enrichment processes,sediment nutrient content is often higher than that of natural soil. The objective of this study is to determine the enrichments of organic matter and total nitrogen in sediment in hilly and gully loess areas on the Loess Plateau of China. Measurements of enrichment ratios (ER) of organic matter (EROM) and total nitrogen (ERTN) in sediment as affected by rainfall, slope gradient, tillage, and fertilization were made in the field under natural rainfall conditions. The results showed that the enrichment of clay in sediment resulted in the enrichment of organic matter (OM) and total nitrogen (TN) in sediment. The averages of sediment clay ER, EROM and ERTN for the various slope gradients were 1.77, 2.09 and 1.61, respectively. The soil erosive module was negatively correlated with EROM and ERTN. Our results indicate that measures to reduce soil erosion, i.e. reducing rainfall erosivity, decreasing soil slope gradient, decreasing fertilizer use, and using level trenches, may increase EROM and ERTN. Both quantity and quality of sediment yield should be considered when implementing erosion control measures.
文摘While many harmful algal blooms have been associated with increasing eutrophication, not all species respond similarly and the increasing challenge, especially for resource managers, is to determine which blooms are related to eutrophication and to understand why particular species proliferate under specific nutrient conditions. The overall goal of this brief review is to describe why nutrient loads are not changing in stoichiometric proportion to the "Redfield ratio", and why this has important consequences for algal growth. Many types of harmful algae appear to be able to thrive, and/or increase their production of toxins, when nutrient loads are not in proportion classically identified as Redfield ratios. Here we also describe some of the physiological mechanisms of different species to take up nutrients and to thrive under conditions of nutrient imbalance.
基金Project(2017GK2233)supported by the Science and Technology Innovation Program of Hunan Provine,ChinaProject(2017JJ1034)supported by the Natural Science Foundation of Hunan Province,China。
文摘The purpose of this study was to examine the sedimentary facies characteristics of lower Cambrian Niutitang Formation(∈1n)in South China,to reveal the mechanism of organic matter enrichment,and to guide exploration of shale gas.Macro investigation and experimental analyses were used to assess the lithology in detail,total organic matter mass fraction w(TOC),mineral composition,and trace element characteristics of∈1n.The influencing factors of organic matter enrichment were discussed extensively,and a sedimentary facies mode was suggested.In the early stage of∈1n,the locations of Well E’yangye 1,Well Ciye 1,Well Changye 1,and Well Anye 1 respectively develop,platform inner sag,outer shelf,Jiangnan slope belt,and South China detention basin.In the late stage of∈1n,the sedimentary facies evolve with decreasing sea level.The study area presents a complete three-step basin in the Early Cambrian.In the early stage of∈1n,the first step is the Yangtze carbonate platform,the second step is the outer shelf and slope,and the third step is the deep-water basin.From the Yangtze carbonate platform to the deep-water basin,w(TOC)and the mass fraction of quartz gradually increase,the mass fraction of carbonate mineral decreases,and the mass fraction of clay mineral is higher in the second step.The sea level fluctuation results in a higher w(TOC)vertically in the lower∈1n shale,and the paleogeographic(provenance)conditions lead to better horizontal development of organic matter in the outer shelf,slope and detention basin.Trace elements are abundant in the lower∈1n,and w(TOC)is correlated positively with many trace elements.In the outer shelf,slope,and adjacent areas,hydrothermal activity and upwelling current bring nutrient-rich material and promote organic matter enrichment under a strong reducing condition.Deep-shelf,slope and deep-water basin are the best facies for the formation and preservation of organic matter,especially deep-water basin facies.It remains necessary to strengthen the exploration of shale gas in the deep-water basin of∈1n in central Hunan,China.
基金This research was supported by the National Key R&D Program of China[grant number 2017YFC0210100]the National Natural Science Funds for Distinguished Young Scholars[grant number 41425020]the National Natural Science Foundation[grant numbers 41705123 and 41530641].This work was also supported by the Dinghushan Forest Ecosystem Research Station.
文摘The aim of this study is to elaborate a possible missing source of high-throughput organic nitrogen in rainfall.The authors classified the observed flux data of dissolved organic nitrogen in terms of the attributes of the wet deposition event itself,such as the season,precipitation,air mass backward trajectory,and effect of typhoons.The monitoring results of the ocean eutrophication and the chlorophyll-a map of the surface water were compared with the trajectory of the high-flux deposition events.The results show that approximately one third of the total wet deposition organic nitrogen derived from a confluence of three factors:rain in the wet season,air masses from the ocean,and rainfall over 50 mm.It could be seen that the co-occurrence of intense events such as a typhoon and eutrophic surface sea waters might be an important source of dissolved organic nitrogen in wet deposition.
基金Supported by the Goverment of Malaysia,Intensified Research in Priority Areas(IRPA Project)(No.50258-J3)
文摘We studied the depth distribution of periphyton,growing on inundated dead trees in Kenyir Lake,Malaysia in June 1995.The algal floral composition and structure manifested changes down the depth gradient in terms of species richness,abundance,diversity and cell density.In regression analysis,all these algal attributes were negatively correlated with the depth gradients at P<0.05.In terms of species richness,the bacillariophytes showed dominance over the cyanophytes and chlorophytes;whereas with respect to standing crop,the cyanophytes showed dominance over the bacillariophytes and chlorophytes.The chlorophyll a was higher at the mid and bottom-depths than the surface-depth in both the downstream and upstream sites,which showed that vertical productivity or biomass accumulation was greater in low light irradiance.The product-moment correlation analysis showed that conductivity,turbidity,dissolved oxygen,reactive phosphate and ammonium-nitrogen were highly correlated with the algal assemblage data.However,photosynthetic active radiation(PAR) showed poor correlation with the community data.These observations have cast some light on the autoecological characteristics,habitat preferences and environmental responses of tropical periphytic communities.
基金supported by the National Basic Research Program of China(973 program,No.2010CB428903)Public Science and Technology Research Funds the Projects of Ocean(No.201105014)+1 种基金National Natural Science Foundation of China(No.41203085)the Fundamental Research Funds for the Second Institute of Oceanography,SOA(JT0906)
文摘The eutrophication, hypoxia and coastal acidification are attracting more and more attention. In this study, inorganic carbon parameters, including dissolved inorganic carbon (DIC), total alkalinity (TA) and calculated partial pressure of CO2 (pCO2), obtained from a summer cruise in August, 2009, were used to investigate their integrated response to biological processes accompanying the oxygen depletion in the areas off the Changjiang Estuary. According to the observations, the typical hypoxia occurred in the bottom water just outside the Changjiang Estuary with Dissolved Oxygen (DO) lower than 2.00 mg L^-1. The biological uptake in the surface water and the decomposition of organic matter in the bottom water were fully coupled with each other. The high concentration of Chl_a (Chl_a = 10.9μgL^-1) and DO (9.25 mgL^-1), profoundly decreased DIC concentration 0828 μmolkg^-1) and elevated pH (8.42) was observed in the surface water. The correspondingly increased DIC and depletion of oxygen were observed in the bottom water. The semi-quantitative analysis proved that the locally-produced phytoplankton, determined by primary productivity, was deposited to the bottom and contributed about 76% of total amount of the organic carbon decomposition in the bottom. However, in the bottom hypoxia (DO = 2.05 mgL^-1) area observed in the Southern Zhejiang coastal water, the responding patterns of inorganic carbon parameters deviated from the previous one. The expanding of Changjiang Diluted Water (CDW), the adding of Hangzhou Bay water (with high DIC concentration) and Coastal Current together modify the DIC background value in this area, and the local degeneration and upwelling process may also help to offset the local DIC removed by net biological uptake in surface water. In addition when the mixing occurring in autumn, which may break the summer stratification, the excess release of high DIC in the bottom water to the subsurface water could have an important influence on coastal acidification and the CO2 uptake capacity in this area.
文摘In this paper, the analysis of the environmental impacts of a biopolymer based on starch is presented. These impacts were calculated from a cradle to gate LCA (Life Cycle Assessment), based on UNEEN ISO 14040:2006 and UNEEN ISO 14044, using as functional unit 1 kg of produced biomaterial. The impact categories analyzed were global wanning, ozone depletion, acidification and eutrophication. The results indicate that the electricity causes the highest impacts in the global warming and ozone depletion categories, but compared to synthetic polymers, the emissions are low. Finally, in the case of eutrophication, the impacts are similar to other biopolymers but higher in comparison with petroleum-based polymers like HDPE (High Density Polyethylene), LDPE (Low Density Polyethylene), PP (Polypropylene), PS (Polystyrene) and PET (Polyethylene Terephthalate).
基金Support from projects PAPIIT IN215914 and IV201015
文摘We analyzed the distributional patterns of95 selected species of leptosporangiate ferns inhabiting the Mexican Mountain Component, using grid-cells of one geographical degree as unit areas,applying endemism indices and richness and beta diversity analyses.Distributional data were obtained from several herbaria and specialized literature.Five grid-cells appear to be important for fern species richness, as they contain 35 to 49 species.These gridcells are located in the Sierra Madre Oriental(SMO),Trans-Mexican Volcanic Belt(TMVB) and the Sierra Madre del Sur(SMS).Mean richness by latitudinal belts of one degree showed that the belts with highest values are related to the TMVB and SMS.A total of 13grid-cells were recognized as important from theperspective of endemism; most of them are located also in the SMO, TMVB and SMS.The richest gridcells coincided with one of the main centres of endemism for ferns obtained in this study, located in the convergence of the southern part of the SMO, the eastern portion of the TMVB and the northern part of the SMS, reflecting the high humidity existing on the mountain slopes facing the Gulf of Mexico.Some important grid-cells recognized from richness and endemism analyses coincide with Mexican Natural Protected Areas.The beta diversity analysis showed a low degree of similarity among grid-cells, implying a high species replacement, as the result of environmental heterogeneity occurring in the Mexican mountain systems.On the other hand, the spatial analysis suggested a pattern of phytogeographical regionalization comprising twomain areas: the Mexican Transition Zone and the Mexican Central Plateau.Ferns play an important role in the Mexican biodiversity and contributing to the beta diversity of Mexico.
文摘The spacial distribution characteristics, activity and degradation capability of the biofilm in integrated vertical-flow constructed wetland were investigated. Results showed that the biofilm widely distributed in the substrate of integrated vertical-flow constructed wetland and mainly in the 0-10 cm top layer where the activity ofdehydrogenase of the biofilm was also higher than that of other layers. The water quality could also affect the activity of the biofilm, for the TF(1,3,5-Triphenylformazan) amount reduced by the biofim incubated in water of the higher eutrophication was larger, too. The PCP (pentachlorophenol) removal rate by the substrate with biofilm was 1.5 times that without biofilm. In total, the biofilm of the down-flow chamber appeared larger biomass, higher dehydrogenase activity and stronger degradation capability of organic contamination than that in up-flow chamber and it was the major place for removal of the organic matters in waste water.
基金Sponsored by the Key Project of Jilin Provincial Science &Technology Program (Grant No.20070409)
文摘Resin adsorption technique with XAD-8 and XAD-4 was used to characterize the raw water from Erlong reservoir in Jilin province of China. The NOM chemical composition sequences of four organic fractions in the raw water, from high to low, are fulvic acid (FA) fraction, hydrophilic non-acid (HPINA) fraction, hydrophilic acid (HPIA) fraction, and humic acid (HA) fraction. Experimental results show that FA is the main precursor of THMFP among the four organic fractions. However, HA or hydrophobie acid exhibits the highest chlorination activity in forming THMs. It is also found that the value of FI/DOC or SUVA and the specific THMFP have better positive correlation. It is implied that certain source water has unique nature of NOM and DBPs.
文摘The existence of nanographene in cluster form is discussed in organic solvents. Theories are developed based on the columnlet, bundlet and droplet models describing the size-distribution functions. Phenomena present a unified explanation in the columnlet model in which free energy of Cgraphene involved in cluster is combined from a volume part proportional to the number of molecules n in cluster and a constant. The columnlet model enables describing distribution function of Cgraphene clusters by size. From purely geometrical considerations the columnlet (Cgraphene), bundlet (single-wall carbon nanotube), CNT (carbon nanotube), SWNT (single-wall C-nanotube), and carbon nanobud, CNB (carbon nanobud)) and droplet (fullerene) models predict dissimilar behaviours. The interaction-energy parameters of Cgraphene are taken from C60. An CNB behaviour or further is expected. The decay of solubility with rising temperature is smaller for Cgraphene than for SWNT and CNB and, furthermore, than for C60, in agreement with lesser numbers of units in Cgraphene clusters. The discrepancy between the experimental data of the heat of solution of fullerenes, CNTs, CNBs and graphenes is ascribed to the sharp concentration dependence of the heat of solution. The diffusion coefficient drops with temperature result greater for Cgraphene than CNB and SWNT than C60 corresponding to lesser number of units in clusters. The aggregates near (C60)13, SWNT/CNB7 and (Cgraphene)3 could be representative of the droplet, bundlet and columnlet models.