The Response of Hydrophytes to Environmental Pollution with Heavy Metals

The effects of Cu²⁺, Cd²⁺, and Ni²⁺ at low and high concentrations (0.025 and 0.25 mg/ml) on the accumulation capacity, the state of the pigment complex, and photosynthesis rate have been studied in model experiments with three floating hydrophytes (Hydrocharis morsus-ranae L., Lemna gibba L., and Potamogeton natans L.) and four submerged hydrophytes (Elodea canadensis Michx., Lemna trisulka L., Ceratophyllum demersum L., and Potamogeton lucens L.). Copper and cadmium are especially toxic at the concentrations studied. The effect of Cu²⁺ was the strongest in hydatophytes, and the effect of Cd²⁺, in pleustophytes. It is hypothesized that the differences between hydrophytes with respect to accumulation of metals and decrease in photosynthesis rate may cause predominant elimination of submerged species. Therefore, changes in the species structure of hydrophyte communities may be expected in waters polluted with metals.     

长江上游重庆段近20 a降水时空变化特征

全球气候变暖背景下,中国的降水分布日趋复杂,气象灾害造成的损失巨大。为满足防灾减灾与水资源管理的数据支撑需求,基于长江上游重庆段近20 a降水数据,利用线性回归、M-K非参数检验等方法,探究降水的时间变化趋势与空间分异特征。结果表明：近20 a重庆市年降水量在875.6—1348.2 mm。时间上,春、秋两季呈明显增多的趋势,其中3月最显著。降水在14 a时间尺度的周期过程线中波动最强,是第一主周期。空间分布上,呈西低东高的特点,在渝西和长江河谷地区降水相对偏少,主要受重庆地形的影响;渝西和渝东北地区秋季降水显著增多。研究结果可为长江流域旱涝灾害防治、水资源开发利用及经济社会可持续发展提供数据支撑,同时可为植被修复与生态廊道保障提供参考。     

La_(2-x)Sr_xCuO_(4±λ)系列催化剂的合成、表征及NO分解催化性能的研究

合成了x值不同的 La_2.x_Sr_xCuO_(4±λ)(x=0.0—1.0)系列复合氧化物催化剂.用XRD、IR,XPS和化学分析等方法对催化剂的组成、结构进行了表征,并对NO分解的催化性能和作用机理进行了研究.结果表明:在x=0.0—1.0范围内.所有样品都具有A_2BO_4结构.发现NO分解活性与氧空位(缺陷)的浓度有关,与不同价态的Cu离子含量之间无直接关系.     

HYDROLOGIC EFFECTS OF TWO METHODS OF HARVESTING MATURE SOUTHERN PINE1

ABSTRACT: Hydrologic responses to logging with skidders and responses to logging with a cable yarder are compared. After a 23-year calibration with an undisturbed control catchment, mixed stands of shortleaf pine (Pinus echinata Mill.) and hardwoods were clearfelled on two small catchments in the hilly Coastal Plain of north Mississippi and observed for five years. Runoff increased 370 mm (skidded) and 116 mm (yarded) during the first year with 1876 mm of rainfall, and 234 mm (skidded) and 228 mm (yarded) during the second year when 1388 mm of precipitation equaled the calibration mean. Sediment concentrations for the yarded catchment during the first two years averaged 641 and 1,629 mg L^?1, respectively, and yields were 6,502 and 12,086 kg ha^?1. Compared to calibration means of 74 mg L^?1 and 142 kg ha^?1, these extreme values can be attributed largely to transport of sediment stored in the channel and to erosion of subsurface flow paths, which was exacerbated by high flow volumes. During the first year, the concentration (231 mg L^?1) and yield (2,827 kg ha^?1) for the control catchment also exceeded the calibration means. However, concentrations (134 mg L^?1) and yields (1,806 kg ha^?1) for the skidded catchment were about 40 percent lower than for the control catchment during the first year, and were higher than those for the control only during the second year. Because deep percolation was limited and because rainfall was unusually high, increases in flows and sediment concentrations and yields probably approximate maximum responses to clearcut harvesting in the uplands of the southern Coastal Plain.     

Potential coastal impacts of contemporary changing climate on South Asian seas states

The threat of man-induced global change on the nations of the South Asian seas region varies from place to place because of differences in exposure to monsoons and stoms, differences in local tectonics and subsidence, and variations in air and sea climates. Because several nations are involved, some having subsistence budgets, and given the cost of deriving independently a comprehensive response to global change, the similarities and differences between national settings must be identified soon. These comparisons will form the basis for local response strategies: the similarities provide a basis for responses similar to that of other nations and the differences provide for local adaptation. That climate change on the South Asian coastal region will have an impact is certain: its economics, environment, and coastal land uses are dominated to a certain extent by this marine influence. The extent of these impacts, however, is uncertain. Accompanying global change will be changes in sea level, differences in storm climate, and altered precipitation patterns; science cannot define today what pattern these changes will take. Because global change is inevitable—although its magnitude, timing, and geographic distribution are unknown—the South Asian seas region should begin the appropriate research and planning studies to set forth a reasoned response to global change, for implementation when scientific evidence for global change is more quantitative.     

An inventory of wetland impoundments in the coastal zone of Louisiana,USA: Historical trends

We inventoried wetland impoundments in the Louisiana, USA, coastal zone from the late 1900s to 1985. Historically, impoundment of wetlands for reclamation resulted in direct wetland loss after levees (dikes) failed and the impounded area was permanently flooded, reverting not to wetland, but to open-water habitat. A current management approach is to surround wetlands by levees and water control structures, a practice termed semi-impoundment marsh management. The purpose of this semi-impoundment is to retard saltwater intrusion and reduce water level fluctuations in an attempt to reduce wetland loss, which is a serious problem in coastal Louisiana. In order to quantify the total impounded area, we used historic data and high-altitude infrared photography to map coastal impoundments. Our goal was to produce a documented inventory of wetlands intentionally impounded by levees in the coastal zone of Louisiana in order to provide a benchmark for further research. We inventoried 370,658 ha within the coastal zone that had been intentionally impounded before 1985. This area is equal to about 30% of the total wetland area in the coastal zone. Of that total area, approximately 12% (43,000 ha) is no longer impounded (i.e., failed impoundments; levees no longer exist or only remnants remain). Of the 328,000 ha still impounded, about 65% (214,000 ha) is developed (agriculture, aquaculture, urban and industrial development, and contained spoil). The remaining 35% (114,000 ha) of impoundments are in an undeveloped state (wetland or openwater habitat). In December 1985, approximately 50% (78,000 ha) of the undeveloped and failed impoundments were open-water habitat. This inventory will allow researchers to monitor future change in land-water ratios that occur within impounded wetlands and thus to assess the utility of coastal wetland management using impoundments.     

OEIS complex (cloacal exstrophy): Prenatal diagnosis in the second trimester

OEIS complex (exstrophy of the cloaca) is an association of fetal malformations that includes omphalocele, exstrophy of the bladder, imperforate anus, and spinal defects. Most cases should be prenatally detectable by maternal serum alpha-fetoprotein screening, but an accurate diagnosis is essential for appropriate counselling of the family.     

新农药环境化学行为研究（V）─—三氟羧草醚（Acifluorfen）在土壤和水环境中的滞留、转化

从如下几方面研究了三氟羧草醚在土壤－水环境中的化学行为：一是土壤对该药的吸附，结果表明，吸附强度与土壤理化特性密切相关，Ｆｒｅｕｎｄｌｉｃｈ常数ｋ＿ｆ＝０．９４Ｗ＿（ＯＭ）＋０．６５Ｗ＿（ＣＬＡＹ）－９．５９ｐＨ（ｒ￣２＝０．９４）；二是吸附机理研究，发现三氟羧草醚能与碱金属以外的许多金属离子形成配合物，并证实了与Ｃｕ￣（２＋）形成的双核桥联配合物的可能性；三是实验指出它在水中避光有一定的稳定性，不易水解；四是它在＜３５０ｎｍ的光辐照下，易脱羧转化，速度较快，光解产物有较好的稳定性。     

O_2BG复叶式节能曝气机的性能及其应用

介绍了复叶式节能曝气机的结构,工作原理,性能参数及实际应用情况。     

Turbulence Perturbations in the Neutrally Stratified Surface Layer due to the Interaction of a Katabatic Flow with a Steep Ridge

Turbulence measurements were performed in Antarctica, on the Nansen Ice Sheet, dominated by westerly katabatic winds. The measurements were taken at two sites aligned with the katabatic wind fall-line. The measuring stations were located in the middle of a wide, flat iced area at a distance of 14 km from the base of a sloping surface and at the top of a steep ridge (Inexpressible Island). The aim was to investigate the perturbation of turbulence close to the ground generated by the interaction of the flow with the ridge. We present an analysis comparing the data measured at the upstream unperturbed station with those at the top of the obstacle. Moments and spectra of velocity components have been calculated for almost steady periods. The topography and roughness change produce a combined effect on the flow acceleration (of the opposite sign) and on the turbulent stresses (of the same sign). Spectra of velocity components measured at the top of the ridge and scaled by unperturbed quantities evidence an increment of energy in the high frequency subrange with respect to the up-stream flow. Moreover, the horizontal velocity components display a shift in turbulence maximum towards higher frequencies. The vertical velocity spectrum exhibits an energy increment at low frequencies with respect to the upstream spectrum.