Inorganic and organic losses of nitrogen from upland regions of Britain: concentrations and fluxes

The nitrogen (N) composition of streams draining eight upland regions of Britain was compared using monthly samples collected between April 1997 and April 1998. Stream samples were analysed for total N (TN), particulate N (PN), nitrate (NO3), ammonium (NH4), and dissolved organic nitrogen (DON). Concentrations of TN were small, generally less than 1.5 mg N l(-1), were dominated by dissolved forms of N, and varied significantly between regions. NO3 accounted for the majority of variability. Concentrations of DON also varied between regions but to a smaller extent than those of NO3. There were considerable variations in TN fluxes between upland regions, which ranged between 3.8 and 16.1 kg N ha(-1) year(-1). The majority of the variation was due to NO3 fluxes, which were largest in regions receiving largest inputs of atmospheric N deposition and ranged between 1.4 and 13.5 kg N ha(-1) year(-1). Fluxes of DON ranged between 1 and 3.5 kg N ha(-1) year( -1), while fluxes of PN were generally less than 0.5 kg N ha(-1) year(-1) , and NH4 fluxes ranged between 0.1 and 0.4 kg N ha(-1) year(-1). NO3 was the dominant fraction (47-84%) of N exported from all upland regions except the Highlands, where DON accounted for 52% of the TN flux. This study has shown that the DON fraction is an important component of the total N transported by upland streams in Britain.     

The influence of weather on asthma in Nairobi

The frequency of bronchial asthma in Nairobi is related to meteorological parameters such as relative humidity, rainfall, dew point temperature, hours of sunshine and dry bulb temperature. Two seasons were taken for study: one cold season (May–August 1975) and one relatively warm season (December 1975–March 1976). It was found that significant correlations occurred at a lag of 2 or 3 days, but not at a lag of 4 or 5 days. Cold and wet weather during the cold season and heat of the day and dryness of the atmosphere during the warm season aggravate asthma in Nairobi.. The frequency of asthmatic attacks is about the same during the two seasons, but the intensity of suffering of a greater majority of patients is more in cold and wet weather than in warm and dry weather. 20–25% of the patients do not feel any relationship between weather and their asthmatic troubles. Nearly twice as many patients suffer from cough with the production of sputum in the cold season than in the warm season. About three times as many patients suffer from bronchospasm in the cold season than in the warm season. Severe asthmatic attacks occur almost equally in both the seasons.     

上海地区大气氮湿沉降及其对湿地水环境的影响

根据1998～2003年上海地区雨水中NO₃^--N、NH₄⁺-N浓度,采用单因子评估模式评价了降雨对湿地水环境的影响,并结合降雨量数据,研究了大气湿沉降氮通量.结果表明,上海地区雨水中氮浓度较高,6年雨水平均硝态氮浓度为259 mg·L^-1,铵态氮浓度为2.16 mg·L^-1,总无机氮（TIN）浓度474 mg·L^-1,远大于水体富营养水中氮浓度阀值（0.2 mg·L^-1）,依据降水中的氮浓度,降水已达到地表水V类、劣V类水平.6年湿沉降氮通量平均值为58.1 kg·hm^-2·yr^-1,其中NO₃^--N占54%.大气氮沉降对湿地水体富营养化影响值得关注.     

Atmospheric deposition of nitrogen and sulphur compounds in the Czech Republic

Estimates of dry and wet deposition of nitrogen and sulphur compounds in the Czech Republic for the years 1994 and 1998 are presented. Deposition has been estimated from monitored and modeled concentrations in the atmosphere and in precipitation, where the most important acidifying compounds are sulphur dioxide, nitrogen oxides, ammonia, and their reaction products. Measured atmospheric concentrations of SO2, NOx, NH3, and aerosol particles (SO4(2-), NO3-, and NH4+), along with measured concentrations of SO4(2-), NO3-, and NH4+ in precipitation, weighted by precipitation amounts, were interpolated with Kriging technique on a 10- x 10-km grid covering the whole Czech Republic. Wet deposition was derived from concentration values for SO4(2-), NO3-, and NH4+ in precipitation and from precipitation amounts. Dry deposition was derived from concentrations of gaseous components and aerosol in the air, and from their deposition velocities. A multiple resistance model was used for calculation of SO2, NOx, and NH3 deposition velocities. Deposition velocities of particles were parameterized. It was estimated that the annual average deposition of SOx in the Czech Republic decreased from 1384 to 1027 mol H + ha(-1) a(-1) between 1994 and 1998. The annual average NOy deposition was estimated to be 972 and 919 mol H + ha(-1) a(-1) in 1994 and 1998, respectively. The annual average NHx deposition was estimated to be 887 mol H+ ha(-1) a(-1) and 779 mol H + ha(-1) a(-1) in 1994 and 1998, respectively. It was estimated that the annual average of the total potential acid deposition decreased from 3243 to 2725 mol H + ha(-1) a(-1) between 1994 and 1998. Sulphur compounds (SOx) contributed about 38%, oxidized nitrogen species (NOy) 34%, and reduced nitrogen species (NHx) 28% to the total potential acid deposition in 1998. The wet deposition contributed 42% to the total potential acid deposition in 1998.     

Temporal changes in nitrogen pollution in northeastern Estonia

During the last 5 decades the northeastern part of Estonia (the region where oil shale and the chemical industry are located) has been subjected to pollution with acidic compounds. In 1981-1988 the yearly mean nitrogen (N) deposition load was up to 11.1 kg ha(-1). This N pollution level combined with the deposition of sulphur (S) could have seriously endangered the environment, but the simultaneous emission of strongly alkaline fly ash restrained acidification processes. After 1989-1991 the situation changed, and in 1994-1996 the N deposition load in northeastern Estonia remained within the range of 2.6 to 6.6 kg ha(-1) year(-1) and that of S within 2 to 50 kg ha(-1) year(-1). Because the fly ash deposition is permanently decreasing, more sensitive lichens and mosses can be subjected to critical N+S loads in the future. The proportion of oil shale industry in total emission of NOx in Estonia from stationary sources equals approximately 65 to 75%. During 1996-2000 the yearly mean concentration of NO2 in the air of towns increased from 9 to 12 to 16 to 29 g m(-3). The emission of N compounds was mainly caused by N oxides in flue gases from power plants, as well as ammonia and carbamide discharges from chemical plants. In 1988-1990 the estimated yearly total emission of NOx (as NO2 equivalent) was about 18 to 18.6 thousand t and in 1994-2000, 9.9 to 11.8 thousand t.     

Nitrogen deposition and leaching from two forested catchments in Southwest China--preliminary data and research needs

Increased nitrogen deposition has resulted in increased nitrogen pools and nitrogen leaching in European and North American forest soils. The development in Asia in general, and China in particular, suggests increased deposition of reduced nitrogen from changes in agricultural practices and of oxidized nitrogen from rapid growth of the transportation sector. Decreased nitrogen retention in forested areas in the future may cause increased NO3- leaching and, thus, acidification and eutrophication in surface waters. The differences in climate, ecosystems, land use, and deposition history make direct application of knowledge from studies in Europe and North America difficult. In Southwest China the potential for nitrogen mobilization from forest soils may be high because of the warm and humid climate, resulting in high decomposition rates of soil organic matter. However, there are very few data available for quantifying the suspected potential for increased nitrogen leaching in forest ecosystems. Here we present data from two forested catchments, dominated by Masson pine (Pinus massoniana), near Guiyang and Chongqing, respectively, in Southwest China. The present nitrogen deposition is moderate, estimated in the range from 10 to 40 kg N ha(-1) year(-1). The C/N ratios of the soils are generally below 15. Nitrate concentrations in soil water are rather variable in space, with highest values of several hundred microequivalents per liter. The turnover rate of nitrogen in the forest ecosystem is quite high compared to the atmospheric deposition rate. At present, nitrate runoff from the catchments is low and intermediate in Guiyang and Chongqing, respectively. More research is needed to improve our ability to predict future nitrogen leaching from subtropical Asian coniferous forests.     

Characterization of wet and dry deposition in the downwind of industrial sources in a dry tropical area

An atmospheric deposition study was conducted in the downwind of Shaktinagar Thermal Power Plant (STPP), Renusagar Thermal Power Plant (RTPP), and Anpara Thermal Power Plant (ATPP), at Singrauli region, Uttar Pradesh (UP), India to characterize dry and wet deposition in relation to different pollution loading. During the study period, dry and wet depositions and levels of gaseous pollutants (SO2 and NO2) were estimated across the sites. Dry deposition was collected on a monthly basis and wet deposition on an event basis. Depositions were analyzed for pH, nitrate (NO3-), ammonium (NH4+), and sulphate (SO4(2-)) contents. Dry deposition rate both collected as clearfall and throughfall varied between 0.15 to 2.28 and 0.33 to 3.48 g m(-2) day(-1), respectively, at control and maximally polluted sites. The pH of dry deposition varied from 5.81 to 6.89 during winter and 6.09 to 7.02 during summer across the sites. During the rainy season, the mean pH of clear wet deposition varied from 6.56 to 7.04 and throughfall varied from 6.81 to 7.22. The concentrations of NO2 and SO2 pollutants were highest during the winter season. Mean SO2 concentrations varied from 18 to 75 g m(-3) at control and differently polluted sites during the winter season. The variation in NO2 concentrations did not show a pattern similar to that of SO2. The highest NO2 concentration during the winter season was 50 g m(-3), observed near RTPP. NO2 concentration did not show much variation among different sites, suggesting that the sources of NO2 emission are evenly distributed along the sites. The concentrations of NH4+, NO3-, and SO4(2-) ions in dry deposition were found to be higher in summer as compared to the winter season. In dry deposition (clearfall) the concentrations of NH4+, NO3-, and SO4(2-) varied from 0.13 to 1.0, 0.81 to 1.95, and 0.82 to 3.27 mg l(-1), respectively, during winter. In wet deposition (clearfall), the above varied from 0.14 to 0.74, 0.81 to 1.82, and 0.67 to 2.70 mg l(-1), respectively. The study clearly showed that both dry and wet depositions varied between the sites and season, suggesting significant impact of industrial activities in modifying the atmospheric input. The nonacidic deposition suggests that there is no threat of acidification of the receiving ecosystem at present.     

Nitrogen oxide emissions following wetting of dry soils in forest and pastures in Rondônia, Brazil

Rains at the end of the dry season can trigger increases in emissions of nitric oxide (NO) and nitrous oxide from forest and pasture soils in the Amazon Basin. The relative importance of the rain-stimulated emissions in the seasonal and annual budgets of these nitrogen gases for forests and pastures in the western Amazon is not well established. We measured soil emissions of NO and N₂O from a forest and two pastures, 11 and 26 years old, after a simulated rain event. Wetting the soil resulted in very small pulses of NO or N₂O from forest soils and no significant NO or N₂O pulses from the pastures. We estimated that in the forest, the amounts of each gas emitted from pulses during the dry to wet transition period represented 3.4% of the NO and 1.8% of the N₂O dry-season emissions, but amounted to less than 2% of the annual emissions of either gas. Total N oxide emissions of 5.6 kg N/ha/yr from the forest were nearly evenly divided between NO (42%) and N₂O (58%). The emissions of NO were evenly distributed over the wet and dry seasons, while over 84% N₂O fluxes occurred during the wet season.     

Smog nitrogen and the rapid acidification of forest soil, San Bernardino Mountains, southern California

We report the rapid acidification of forest soils in the San Bernardino Mountains of southern California. After 30 years, soil to a depth of 25 cm has decreased from a pH (measured in 0.01 M CaCl2) of 4.8 to 3.1. At the 50-cm depth, it has changed from a pH of 4.8 to 4.2. We attribute this rapid change in soil reactivity to very high rates of anthropogenic atmospheric nitrogen (N) added to the soil surface (72 kg ha(-1) year(-1)) from wet, dry, and fog deposition under a Mediterranean climate. Our research suggests that a soil textural discontinuity, related to a buried ancient landsurface, contributes to this rapid acidification by controlling the spatial and temporal movement of precipitation into the landsurface. As a result, the depth to which dissolved anthropogenic N as nitrate (NO3) is leached early in the winter wet season is limited to within the top approximately 130 cm of soil where it accumulates and increases soil acidity.     

Nitrate in polluted mountainous catchments with Mediterranean climates

The mountains of southern California receive some of the highest rates of nitrogen (N) deposition in the world (approximately 40 kg ha(-1) year(-1)). These high rates of deposition have translated into consistently high levels of nitrate (NO3-) in some streams of the San Bernardino Mountains. However, not all streams are exhibiting these high levels of NO3-. Perennial streams have high NO3- concentrations (approximately 200 micromoles l(-1)) while ephemeral streams do not (approximately 20 micromoles l(-1)). This difference points to groundwater as the source of the NO3- observed in streams. Furthermore, the evidence indicates a differential impact of N deposition on terrestrial and aquatic systems in Mediterranean climates, with aquatic systems being impacted more quickly. The primary reason for this difference involves the asynchrony between the time that atmospheric deposition occurs (summer), the time period of maximum soil NO3- availability and leaching (winter), and the time of maximum plant N demand (spring). Our results indicate that semiarid Mediterranean climate systems behave differently from more humid systems in that, because of this asynchrony, aquatic systems may not be indicative of changes in terrestrial ecosystem response. These differences lead us to the conclusion that the extrapolation of impacts from humid to Mediterranean climates is problematic and the concept of N saturation may need to be revisited for semiarid and seasonally dry systems.     

太湖地区氮素湿沉降动态及生态学意义：以常熟生态站为例

在常熟生态站2001年6月至2003年5月连续两年定位收集湿沉降,对太湖地区氮素湿沉降动态进行研究．结果表明,湿沉降氮输入量季节变化显著,夏、春季高,秋、冬季低．在湿沉降输入氮中NH4^+-N、NO3^--N和DON的比例分别为47．6％、35．1％和17．4％．湿沉降中NH4^+-N主要来自当地农田的氨挥发,湿沉降NH4^+-N月输入量随月降雨量增加而增加(R0=0．3178^**)．该地区空气中NO3^--N浓度相对比较稳定,湿沉降中NO3^--N浓度与降雨量呈负相关(R^2=0．4205^***)．湿沉降NO33^--N月输入量与月降雨次数呈直线正相关(R^2=0．6757***),而与月降雨量相关性较差(R^2=0．1985^*)．湿沉降TN年输入量为27．0kg·hm^-2,并在所有降雨中,氮浓度均超过水体富营养化阈值(0．2mg·L^-1)．     

Seasonal environments, episodic density compensation and dynamics of structure of chiropteran frugivore guilds in Paraguayan Atlantic forest

Seasonal environmental variation experienced in the subtropics may contribute substantially to dynamics of community structure. This is particularly true for Neotropical bats because the geographic terminus of most families occurs there. Paraguayan Atlantic forest provides an ideal opportunity to evaluate effects of seasonality on structure of communities; it exhibits notable spatial and seasonal environmental variation and lies near the edge of the geographic distribution of most tropical bat species occurring there. We examined seasonality of bat populations and communities as well as correspondence to seasonal environmental conditions in eastern Paraguay. Most species exhibited lower abundances in the cool than in the warm season. Nonetheless, magnitude of differences was species-specific. Accordingly, highly significant differences between warm and cool seasons existed regarding species composition, evenness and diversity. Moreover, consistent with competition theory, magnitude of positive correlation between morphological distance and abundance and hence degree of structure was greater in the cool than warm season. Across the New World, seasonality assumes various forms (i.e. cold winters, dry and wet seasons) suggesting that better understanding of mechanistic bases of bat community structure in general may come from seasonal perspectives.     

Field metabolic rate of lactating female Galápagos fur seals (Arctocephalus galapagoensis): the influence of offspring age and environment.

Galápagos fur seals, Arctocephalus galapagoensis, live in a seasonal environment which varies strongly in productivity from year to year. We measured how the field metabolic rates (FMR) of lactating females varied with season, pup age and year. Energy expenditure was measured using doubly labeled water (DLW) during the cold seasons of 1984 and 1985 in 9 mothers of 1-3-month-old pups and 5 mothers of yearlings, and during the 1986 warm season in 8 mothers of 6-month-old pups. Young pups gained 0.84% mass/day during the cold season, but larger pups during the warm season lost 1.25% mass/day. During the warm season, females had lower relative total body water than during the cold season suggesting higher fat content during the warm, less productive season, but the effect was even more marked when comparing different years of the study: fat content was high in 1984 and 1986 and low in 1985. The FMR of mothers varied from 134 to 167 W but did not show significant differences between any of the pup age-groups. Among the years of the study, FMR showed only a trend towards low energy expenditure of mothers of young pups in 1984. The mean FMR was lower than for other otariids. Mothers may limit energy expenditure independent of pup age and season to minimize their own risk of starvation in an environment of comparatively low productivity, varying unpredictably due to frequent El Ni?o events.     

丹江口水库淅川库区大气氮湿沉降特征

大气氮沉降是除河流输入外水库水体重要的外源氮输入途径。以丹江口水库淅川库区为研究区,于2018年11月至2019年10月在库区周边设置了6个采样点,采集并分析了库区大气氮湿沉降样品,探讨氮湿沉降的时空分布特征以及对水库水体外源氮输入的贡献。研究结果表明,研究区大气氮湿沉降量为24.21 kg hm^-2 a^-1,其中氨氮占比（47.45％）为最大,有机氮占比（36.34％）次之,硝氮占比（16.21％）最小。硝氮湿沉降量在空间上表现出显著差异性。氨氮、有机氮湿沉降量的季节差异显著,氨氮是以夏季最高,秋季次之,冬季最低,而有机氮是以秋季最高,夏季次之,冬季最低。氨氮、硝氮、有机氮湿沉降量之间存在显著相关性,氨氮、有机氮湿沉降量与降水量之间存在显著相关性。总氮、氨氮湿沉降量分别为1321.98 t/a和627.34 t/a,分别占河流总氮、氨氮入库量的10.82％、34.85％。研究结果可为探索有针对性的库区水体氮污染控制途径提供重要理论基础。     

青藏高原异地半圈养藏羚警戒行为的适应性研究

行为是反映动物应对环境变化的最直接形式。动物可以根据周围环境条件的变化以及自身的生理状况来调整行为,异地放养是保护珍稀动物的有效方法,但必然会对其行为产生影响。为了探讨藏羚(Pantholops hodgsonii)对异地环境的行为学适应,对异地圈养藏羚的警戒行为进行了不同季节间的比较研究,采用全事件记录法和焦点动物取样法,记录和统计了异地圈养藏羚在冷季和暖季的警戒行为,进而推测其对人类干扰的行为适应性。研究结果表明,雌性和雄性藏羚的警戒时间及警戒比例(警戒时间占全天活动时间的比例)在暖季存在显著差异(警戒时间:Z=4.36,P<0.05;警戒比例:Z=4.559,P<0.05),而在冷季则无差异(警戒时间:Z=0.001,P>0.05;警戒比例:Z=0.0014,P>0.05);而季节差异对雌、雄性藏羚的警戒时间、警戒比例均具有极显著的影响(雄性-警戒时间:F=31.758,P<0.01;警戒比例:F=21.768,P<0.01;雌性-警戒时间:F=14.98,P<0.01;警戒比例:F=11.05,P<0.01);但是季节和性别对藏羚警戒行为的影响没有交互作用(Z=?0.576,P>0.05)。这些结果提示异地圈养藏羚警戒行为的变化可能是对陌生环境适应的结果。     

山西北部农村区域大气活性氮沉降特征

利用DELTA系统、被动采样器和雨量器在山西省北部生态脆弱区朔州的一个监测点通过一整年的监测试验,研究了该地区农村区域大气氮素干湿沉降的月际变化。结果表明:2011年该地区大气氮素湿沉降为12.43kgN hm~(-2)a~(-1),远低于华北平原大气氮素混合沉降的平均值28.0kg N hm~(-2)a~(-1),降水中铵态氮、硝态氮和有机氮平均分别为1.24 mg N/L、1.27 mg N/L、1.26mg N/L。大气氮素湿沉降的年内分布不均,60%的沉降集中在降水较丰沛的4-10月份。试验区干沉降以氧化态氮(HNO_3NO_2和pNO_3~-)的沉降为主,氧化态氮的干沉降量是还原态氮(NH_3和pNH_4~+)的1.37倍,大气氮素干沉降总量为35.43 kg N hm~(-2)a~(-1)。总体来看,作为典型的干旱区,该地区氮的干沉降是湿沉降的3倍,氮素干湿沉降总量达到47.86kg N hm~(-2)a~(-1)。此外,硝态氮和铵态氮在雨水中呈线性相关,而在PM_(10)颗粒物中乘幂正相关;雨水中总碳和总氮呈线性正相关,而PM_(10)颗粒物中二者呈二次多项式关系。鉴于朔州地区古城镇较高的氮沉降数量,应该对该地区输入农田的氮素环境养分引起足够重视。     

Short rotation coppice as alternative land use for Chernobyl-contaminated areas of Belarus

Field experiments were conducted in the Chernobyl-affected area to assess if short rotation coppice (SRC) for energy production is a feasible alternative for contaminated land. Four willow clones were planted on sandy and peaty soil and the radiocaesium (137Cs) and radiostrontium (90Sr) transfer factors (TF) and yield relevant parameters were recorded during four growing seasons. The 137Cs and 90Sr soil-to-willow wood TF on sandy soil (second growing season) were on average 1.40+/-1.06 x 10(-3) m2 kg(-1) and 130+/-74 x 10(-3) m2 kg(-1), respectively. The 137Cs TF recorded for the peaty soil (fourth growing season or end of the first rotation cycle) was on average 5.17+/-1.59 x 10(-3) m2 kg(-1). The 90Sr-TF was on average 2.61+/-0.44 x 10(-3) m2 kg(-1). No significant differences between clones for the 137Cs and 90Sr-TF were observed. Given the high TFs and the high deposition levels, Belarus exemption levels for fuel wood were highly exceeded. The annual average biomass production for one rotation cycle on the peaty soil ranged from 7.8 to 16.0 t ha(-1) y(-1) for one of the clones, comparable with average annual yield figures obtained for western Europe. On the sandy soils, first-year yields were 0.25 t ha(-1) y(-1). These soils are not suitable for SRC production and should better be dedicated to pine forests or drought-resistant grasses.     

Low-temperature resistance in Polylepis tarapacana, a tree growing at the highest altitudes in the world

The Polylepis tarapacana forests found in Bolivia are unique with respect to their altitudinal distribution (4200–5200 m). Given the extreme environmental conditions that characterize these altitudes, this species has to rely on distinct mechanisms to survive stressful temperatures. The purpose of this study was to determine low‐temperature resistance mechanisms in P. tarapacana. Tissue was sampled for carbohydrate and proline contents and micro‐climatic measurements were made at two altitudes, 4300 and 4850 m, during both the dry cold and wet warm seasons. Supercooling capacity (?3 to ?6 °C for the cold dry and ?7 to ?9 °C for the wet warm season) and injury temperatures (?18 to ?23 °C for both seasons), determined in the laboratory, indicate that P. tarapacana is a frost‐tolerant species. On the other hand, an increase in supercooling capacity, as the result of significant increase in total soluble sugar and proline contents, occurs during the wet warm season as a consequence of higher metabolic activity. Hence, P. tarapacana, a frost‐tolerant species during the colder unfavourable season, is able to avoid freezing during the more favourable season when minimum night‐time temperatures are not as extreme.     

Warm blood cardioplegia reduces the fall in the intracellular concentration of taurine in the ischaemic/reperfused heart of patients undergoing aortic valve surgery

Summary The effect of cold and warm intermittent antegrade blood cardioplegia, on the intracellular concentration of taurine in the ischaemic/ reperfused heart of patients undergoing aortic valve surgery, was investigated. Intracellular taurine was measured in ventricular biopsies taken before institution of cardiopulmonary bypass, at the end of 30 min of ischaemic arrest and 20 min after reperfusion. There was no significant change in the intracellular concentration of taurine in ventricular biopsies taken after the period of myocardial ischaemia in the two groups of patients (from 10.1 ± 1.0 to 9.6 ±0.9mol/g wet weight for cold and from 9.3 ± 1.3 to 10.0 ± 1.3mol/g wet weight for warm cardioplegia, respectively). Upon reperfusion however, there was a fall in taurine in both groups but was only significant (P 0.05) in the group receiving cold blood cardioplegia (6.9 ± 0.8mol/g wet weight after cold blood cardioplegia versus 8.0± 0.8mol/g wet weight following warm blood cardioplegia). Like taurine, there were no significant changes in the intracellular concentration of ATP after ischaemia in the two groups of patients (from 3.2 ± 0.32 to 2.95 ± 0.43mol/g wet weight for cold and from 2.75 ± 0.17 to 2.62 ± 0.21mol/g wet weight for warm cardioplegia, respectively). However upon reperfusion there was a significant fall in ATP in both groups with the extent of the fall being less in the group receiving warm cardioplegia (1.79 ± 0.19mol/g wet weight for cold and 1.98 ± 0.27mol/g wet weight for warm cardioplegia, respectively). This work shows that reperfusion following ischaemic arrest with warm cardioplegia reduces the fall in tissue taurine seen after arrest with cold cardioplegia. Accumulation of intracellular sodium provoked by hypothermia and a fall in ATP, may be responsible for the fall in taurine by way of activating the sodium/taurine symport to efflux taurine.     

Carbon pools and fluxes in Bruguiera parviflora dominated naturally growing mangrove forest of Peninsular Malaysia

Estimation of carbon pools and fluxes were conducted in Bruguiera parviflora dominated naturally growing protected mangrove forest in Kuala Selangor Nature Park of Peninsular Malaysia. Above and below-ground carbon pools in seedlings were estimated from destructive methods. While, carbon pools and fluxes in saplings and trees were estimated from the derived allometric biomass equations. Carbon concentrations in different parts of seedlings, saplings and trees; and litter were measured during the dry, wet and intermediate seasons. Soil cores up to 1 m were analyzed to measure carbon concentrations and bulk densities at different depths. Litter standing crop of the study area was measured at the dry, wet and intermediate seasons and the range of total amount of litter standing crop was from 0.66 to 0.88 Mg/ha. Carbon concentration found to vary with the plant and litter parts; and also with the seasons and the range of mean weighted carbon concentration was 40.19 ± 0.87–56.52 ± 1.01 %. The carbon pools in seedling, sapling, tree and litter were 0.69, 0.51, 82.62 and 0.41 Mg C/ha respectively. However, 13.95 Mg C/ha/year of carbon flux was associated with saplings, trees and litter. The estimated carbon pool in the soil (up to 1 m) of the study area was 488.04 Mg C/ha. The findings of this study are the first estimation of carbon pools and fluxes in B. parviflora dominated sites and suggests the potential of this site as a carbon pool.