Cone penetrometer testing,hydropunch®, and borehole geophysics applications for environmental investigations

An effective groundwater monitoring system can be implemented by the combined utilization of cone penetrometer (CPT), HydroPunch^® sampling, and borehole geophysical methods. The combined techniques provide a cost‐effective method for the design of a groundwater monitoring system for geologists or hydrogeologists assessing a site. With the relatively high costs associated with determining groundwater quality for site assessments, coupled with regulatory agency compliance, these combined methods can provide an effective edge in an increasingly competitive environmental industry. CPT combined with HydroPunch sampling can delineate the horizontal and vertical extent and concentration of a contaminant plume, define the extent and thickness of a free product plume, define soil and aquifer characteristics, and aid in the proper selection of well location and screen placement. The use of borehole geophysics further enhances the interpretation provided from the CPT. The interpretation of borehole geophysics provides additional information about the deposition regime of the area of investigation and a more detailed investigation of the stratigraphy. The CPT and HydroPunch can be used in unconsolidated sediments, and HydroPunch sampling can be combined with a hollow‐stem auger system. Borehole geophysics can be run in almost any environment. CPT and borehole geophysics provide information on specific lithologic characteristics necessary to obtain a groundwater sample from vertically separated aquifers. The HydroPunch can obtain a discrete, chemically representative groundwater sample from the targeted aquifer. CPT and borehole geophysics can also be used to determine lithology and for correlation of equivalent stratas from one borehole or well to the next. Borehole geophysical interpretation also provides a means of determining not only the stratigraphy and lithology but also the aquifer parameters and the type of fluids in the aquifer. Hydrogeologic and geologic data obtained from using these three methods can be employed to maximize the cost‐effectiveness and design efficiency of a groundwater monitoring system. Proper location of wells and screened interval placements are determined by a coherent design process rather than by random chance. Two studies demonstrating the combined applications of CPT, HydroPunch, and borehole geophysics for the design and placement of groundwater monitoring wells are presented in the following discussion.     

Stimulus-Secretion Coupling in Isolated Adrenal Chromaffin Cells: Calcium Channel Activation and Possible Role of Cytoskeletal Elements

Abstract: The catecholamine secretory function of a preparation of isolated bovine adrenal chromaffin cells has been further characterized under conditions designed to elucidate the mechanism of calcium channel activation and the possible role of cytoskeletal elements in stimulus-secretion coupling. Three related sets of data were obtained: (1) Differences in kinetics, Ca dependence, strength, and additivity of the secretory response to acetylcholine (ACh) versus excess K; (2) the effects on secretion of the Ca channel-blocking agents, Ni, Mg, and verapamil; and (3) the Ca dependence of vinblastine action on ACh- and K-evoked secretion. The results suggest that a major portion of the Ca influx required for catecholamine release enters the cell via voltage-dependent Ca channels with some additional Ca influx via the ACh receptor channel. Comparison of the present secretion data with corresponding known electrophysiological properties of isolated chromaffin cells provides added evidence for a role of chromaffin cell action potentials in regulation of Ca influx and the secretory response. Elevated Ca concentrations enhanced K-evoked secretion to levels comparable to that of ACh but did not induce a vinblastine block of K-evoked release. This provides further evidence against a role of microtubules in the common exocytosis event per se. However, a role of cytoskeletal elements in directing the movement of secretory granules, or an action of vinblastine at cholinergic receptors, remain distinct possibilities.     

Different temporal trends in vascular plant and bryophyte communities along elevational gradients over four decades

Despite many studies showing biodiversity responses to warming, the generality of such responses across taxonomic groups remains unclear. Very few studies have tested for evidence of bryophyte community responses to warming, even though bryophytes are major contributors to diversity and functioning in many ecosystems. Here, we report an empirical study comparing long‐term change in bryophyte and vascular plant communities in two sites with contrasting long‐term warming trends, using “legacy” botanical records as a baseline for comparison with contemporary resurveys. We hypothesized that ecological changes would be greater in sites with a stronger warming trend and that vascular plant communities, with narrower climatic niches, would be more sensitive than bryophyte communities to climate warming. For each taxonomic group in each site, we quantified the magnitude of changes in species'' distributions along the elevation gradient, species richness, and community composition. We found contrasted temporal changes in bryophyte vs. vascular plant communities, which only partially supported the warming hypothesis. In the area with a stronger warming trend, we found a significant increase in local diversity and dissimilarity (β‐diversity) for vascular plants, but not for bryophytes. Presence–absence data did not provide sufficient power to detect elevational shifts in species distributions. The patterns observed for bryophytes are in accordance with recent literature showing that local diversity can remain unchanged despite strong changes in composition. Regardless of whether one taxon is systematically more or less sensitive to environmental change than another, our results suggest that vascular plants cannot be used as a surrogate for bryophytes in terms of predicting the nature and magnitude of responses to warming. Thus, to assess overall biodiversity responses to global change, abundance data from different taxonomic groups and different community properties need to be synthesized.     

升温突变对川西不同坡向和海拔岷江冷杉径向生长的影响

坡向和海拔作为重要的地形因子决定着林木立地条件的水热分配,为揭示川西地区升温突变前后制约岷江冷杉(Abies fargesii var.faxoniana)径向生长的气候因子变化及其在坡向和海拔上的响应格局,通过树木年轮学方法构建了4个坡向(NE、N、NW和W)的3个海拔梯度(≥3650 m)共12个岷江冷杉的标准年表,采用皮尔逊相关分析和回归分析的方法分析了升温突变前后(1980年)限制岷江冷杉径向生长主要气候因子的变化及径向生长的变化趋势。结果表明：升温前,生长季(7月)低温和降水、前一年冬季(10—11月)最高温和平均温制约岷江冷杉的生长,而当年春季(3月)温度的升高和生长季前(5月)较多的降水不利于其生长。升温后,4个坡向的林线、东北坡中海拔,西坡中、低海拔岷江冷杉的径向生长与大部分月温度表现为正相关关系,且上述样点树木径向生长明显加速。1980年升温前,制约不同样点岷江冷杉径向生长的气候因子具有一致性——坡向和海拔对其径向生长与温度相关关系的干扰和影响较小。增温促进了各坡向林线岷江冷杉的径向生长,且偏阳坡在更大的海拔范围内对增温表现出正反馈。研究对未来气候变化背景下川西不同坡...     

长白山亚高山针叶林沼泽湿地碳源/汇沿水分环境梯度变化规律

高纬度和高海拔区为气候变化敏感区,该区域湿地碳循环与气候反馈关系倍受关注。为探究在全球变暖背景下高海拔区沼泽湿地碳源/汇功能是否发生了转化,以长白山高海拔区沿水分环境梯度分布的5种沼泽类型(草丛沼泽-C、灌丛沼泽-G、落叶松泥炭藓沼泽-LN、落叶松藓类沼泽-LX、落叶松苔草沼泽-LT)为对象,采用静态箱-气相色谱法和相对生长方程法,同步测定各沼泽类型全年尺度上的土壤异养呼吸碳排放量(CO₂和CH₄)、植被年净固碳量及相关环境因子(温度、水位和土壤有机碳等),并依据生态系统净碳收支平衡,量化各沼泽类型的碳源/汇作用,揭示其沿水分环境梯度变化规律及形成机制。结果表明：(1)5种沼泽类型土壤CO₂年均通量((97.68±8.64)—(291.01±18.31)mg m^-2 h^-1)沿水分环境梯度呈阶梯式递增规律性(环境梯度上部生境地段的落叶松苔草沼泽和落叶松藓类沼泽最高,中部生境地段的落叶松泥炭藓沼泽和灌丛沼泽居中,草丛沼泽最低);(2)CH₄年均通量((-0....     

增温和外源碳输入对泥炭地土壤碳氮循环关键微生物功能基因丰度的影响

为探讨温度升高和外源碳输入对泥炭地土壤碳氮循环关键微生物的影响,于2017年7月采集多年冻土区泥炭地表层(0—10 cm和10—20 cm)土壤样品,在10、15℃两个温度下开展为期42d的增温模拟试验,同时设置葡萄糖添加处理,利用荧光定量PCR技术分析泥炭地土壤碳氮循环关键微生物丰度变化,同时分析增温和外源碳输入对泥炭地土壤活性碳组分和无机氮含量的影响。结果表明:温度升高可导致北方泥炭地表层土壤微生物丰度以及群落结构变化,0—10 cm土壤微生物比10—20 cm土壤微生物更加敏感。增温条件下微生物首先快速分解活性有机碳,同时温度升高加快土壤氮周转速率,增加有效氮含量。外源碳输入整体提高了深层土壤微生物丰度,使得10—20 cm土壤细菌、产甲烷菌、甲烷氧化菌、氨氧化细菌以及反硝化细菌丰度显著增加,说明外源碳输入可能会促进10—20 cm土壤甲烷氧化过程、氨氧化过程和反硝化过程。温度和葡萄糖的交互作用对泥炭地表层土壤碳氮循环关键微生物丰度均有显著影响。在增温和外源碳输入条件下,北方泥炭地表层土壤微生物丰度受土壤碳氮活性基质的影响。     

Vegetation responses to past volcanic disturbances at the Araucaria araucana forest‐steppe ecotone in northern Patagonia

Volcanic eruptions play an important role in vegetation dynamics and its historical range of variability. However, large events are infrequent and eruptions with a significant imprint in today''s vegetation occurred far in the past, limiting our understanding of ecological processes. Volcanoes in southern Andes have been active during the last 10 ka and support unique ecosystems such as the Araucaria–Nothofagus forest. Araucaria is an endangered species, with a fragmented distribution and well‐adapted to fire and volcanic disturbances. Yet, it was suggested that volcanism might have increased the fragmentation. Through the use of pollen and tephra analysis from a sedimentary record, this paleoecological study aims to provide an insight into the vegetation responses to past volcanic disturbances, to assess the role of volcanic disturbance on the vegetation dynamics and to determine if the current fragmentation has been caused by volcanism. Results show that during the last 9 kyr, 39 tephra falls buried the vegetation around Lake Relem, more frequently between 4 and 2 ka. The pollen percentage indicates that the vegetation changed after small tephra fall but seldom caused significant changes. However, the large eruption of Sollipulli volcano (~3 ka) changed the environmental conditions affecting severely the vegetation. Ephedra dominated the early successional stage, perhaps facilitating Nothofagus recovering after ~500 years. Slight increase of Araucaria and Nothofagus obliqua‐type pollen percentages suggests that forest resisted without permanent changes and recovered relatively fast after the large eruption, perhaps because of sparse biological legacies distributed in the landscape. In the study area, the relative stability of Araucaria pollen after several tephra fall suggests no change in its past distribution at the current forest‐steppe ecotone, thus not affecting its current conservation status. Perhaps, random factors, the colonization patterns of the high elevations in the Andes after deglaciation and topography might play a more important role than previously thought.     

夜间变暖提高荫香叶片的光合能力

研究了不同氮供应的条件下夜间变暖对荫香叶片光合能力的影响。当植株生长在相同的日间温度(25℃),而夜间温度从18℃增至20℃时,叶片的光合速率增高(p<0.05)。高氮供应的植株,夜间变暖下其叶片光合速率较低氮供应的高,氮供应增高能促进夜间变暖提高叶片光合速率的效应。在低氮供给和夜间变暖下,植株叶片的光下呼吸和暗呼吸的增高显著(p<0.05)。无论在高氮或低氮供应下,生长在夜间变暖下的植物,其叶片的R ub isco最大羧化速率(Vcm ax)和光合电子传递最大速率(Jm ax)增高(p<0.05),氮供应能增强夜间变暖对Vcm ax和Jm ax的正向效应。夜间变暖降低植株叶片的比叶重,而增加单位叶干重的氮含量(Nm),单位叶面积的氮含量(Na)没发生明显变化。随着全球气候变化,夜间趋暖将有利于树木叶片光合能力的提高,结合高氮供给将会明显地增高植物的碳固定。     

Flux balance analysis in the production of clavulanic acid by Streptomyces clavuligerus

In this work, in silico flux balance analysis is used for predicting the metabolic behavior of Streptomyces clavuligerus during clavulanic acid production. To choose the best objective function for use in the analysis, three different optimization problems are evaluated inside the flux balance analysis formulation: (i) maximization of the specific growth rate, (ii) maximization of the ATP yield, and (iii) maximization of clavulanic acid production. Maximization of ATP yield showed the best predictions for the cellular behavior. Therefore, flux balance analysis using ATP as objective function was used for analyzing different scenarios of nutrient limitations toward establishing the effect of limiting the carbon, nitrogen, phosphorous, and oxygen sources on the growth and clavulanic acid production rates. Obtained results showed that ammonia and phosphate limitations are the ones most strongly affecting clavulanic acid biosynthesis. Furthermore, it was possible to identify the ornithine flux from the urea cycle and the α‐ketoglutarate flux from the TCA cycle as the most determinant internal fluxes for promoting clavulanic acid production. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1226–1236, 2015