Monitoring of Gin Drinkers' Bay landfill,Hong Kong: II. Gas contents,soil properties,and vegetation performance on the side slope

This second part of the study concerned the plant cover, gas contents, and soil properties of the side slope area of the landfill, which is not protected against gas infiltration. Five different sites on the slope and a control site outside the landfill were chosen, and pipes were installed in the region. Gas contents were tested, and plant cover recorded by quadrat analysis Over 20 species of grasses, herbs, and vines were present on the slope The relative adaptabilities of the species were ranked according to the abundance of the plants Plant cover was found to be negatively correlated with landfill gas contents. The landfill soil had elevated contents of nitrogen, organic carbon, and extractable metals Total nitrogen, ammonia nitrogen, and extractable lead were further identified to be negatively correlated while available phosphate was positively correlated with plant cover     

A first alternative for estimating the physical carrying capacities of natural areas for recreation

Utilizing an adaptation of the Universal Soil Loss Equation, this article discusses a method for approximating the physical carrying capacity of natural areas for outdoor recreation. Classification of forested woodland and field environments is based upon the conversion of ground cover coefficients to the percentage of ground cover required to maintain soil productivity over time. Four canopy types, three canopy densities, and two general types of ground cover are recognized in the equation as well as soil characteristics, topographical variations, and rainfall velocities and intensities. The method requires that the areal distribution of soils occurring within natural areas be mapped. Approximations will vary according to the intensity of the planning desired, and may range from a general classification of large land areas to highly site-specific evaluations. Data generated from over 40 years of cooperative research form the basis for classifying natural areas according to their relative physical capacities to accommodate outdoor recreation.     

A review of major factors influencing plant responses to recreation impacts

This article reviews some of the more important factors found to influence the susceptibility of plants to trampling impacts associated with recreational use of natural areas. A three-way interaction mediates plant responses to impacts: plant x environment x stress level(s). Plant responses vary in part according to the genetic constitution of the plant, life and growth form, the adaptive flexibility of the plant, and anatomical differences inherent to growth habit and morphology. Other factors that influence plant sensitivities to impacts are the habitat environments in which plants grow, since a number of conditions such as moisture excesses or deficiencies, nitrogen or oxygen starvation, late frosts, etc., cause physiological injury and may increase plant sensitivity to impacts. Among the environmental factors that may increase or lessen plant sensitivities to impacts are soil moisture levels, canopy density, elevation, aspect, microclimate, soil drainage, texture, fertility and productivity. Seasonal influences also bear consideration since environmental changes and phonological and physiological events are mediated by time of year. Stresses are caused by both direct and indirect forms of impact and vary according to season of use, frequency and amount of use, and the type of activity. These interactions are further complicated by evidence that inter- and intraspecific competition, antagonism, and commensalism may influence differences in the sensitivity of plant communities to impacts.     

空气—乙炔原子吸收分光光度法测定大气污染源中的镉含量

本文研究了硝酸高氯酸体系消解火焰原子吸收法测定烟尘颗粒物中镉的方法。方法的检测限为３×１０－６ｍｇ／ｍ３（采样体积１０ｍ３）。实际样品测定的相对偏差小于１０％，加标回收率大于８８％     

用几种溶样方法对典型土样中Pb、Cr、Ni、Cd、Mn、Cu、Zn的溶出情况比较

本文采用HNO_3、HCl-HNO_3、HNO_3-H_2SO_4-HClO_4,溶洋方法消解土样,用原子吸收法测定题述中的元素,并与HCl-HNO_3-HF-HClO_4全消解方法进行了比较.发现除用HF以外的其它酸溶法Pb、Cr的溶出较少溶出比分别低于55％和67％,主要原因是Pb、Cr包藏在土壤的矿物晶格中。     

镉的激光时间分辨荧光测定

本文报道了以７－碘－８－羟基喹啉－５－磺酸（Ｆｅｒｏｎ）作荧光增强剂测定镉的激光时间分辨荧光分析方法。在１．５～１０００ｎｇ／ｍｌ的范围内，镉浓度和荧光强度呈良好的线性关系（γ＞０．９９９），方法的检出限为１．５ｎｇ／ｍｌ。可用于水中镉的测定，也可用于其它环境样品的测定。     

Heavy Metals and Selenium in Herring Gulls (LARUS ARGENTATUS) NESTING IN COLONIES FROM EASTERN LONG ISLAND TO VIRGINIA

With increasing interest in assessing the health or well-being ofcommunities and ecosystems, birds are being used asbioindicators. Coloniallynesting species breed mainly in coastal areas that are alsopreferred for humandevelopment, exposing the birds to various pollutants. Inthis paper concentrations of heavy metal and selenium in the feathers ofHerring Gulls(Larus argentatus) nesting in several colonies fromMassachusetts toDelaware are reported. There were significant differencesamong colonies forall metals, with metal concentrations being two to nearly fivetimes higher atsome colonies than others. Selenium showed the leastdifference, and cadmium showed the greatest difference among sites. Concentrations of lead werehighest at Pralls Island; mercury was highest at Shinnecock,Huckleberry andHarvey, and manganese was highest at Captree.     

加压流体萃取-气相色谱质谱法测定土壤和沉积物中27种拟除虫菊酯类农药

建立了加压流体萃取-气相色谱质谱法测定土壤和沉积物中27种拟除虫菊酯类农药的方法。以丙酮/正己烷(V∶V=1∶1)为萃取溶剂,在120℃和10. 3 MPa条件下静态萃取7 min,循环3次,石墨化炭黑串接氨丙基键合硅胶固相萃取柱净化,HP-5MS UI色谱柱分离,优化了提取和分析过程的重要条件。方法检出限为0. 001~0. 012 mg/kg,土壤中低、高浓度的加标回收率范围分别为68. 3%~123%和75. 3%~115%,沉积物中低、高浓度的加标回收率范围分别为67. 1%~120%和78. 6%~110%,单一目标物的相对标准偏差(RSD)均<20%(n=6)。实验结果表明,该方法消耗溶剂少、效率高、检出限低、精密度和准确度好,适用于土壤和沉积物中拟除虫菊酯类农药残留的测定。     

新疆和田地区土壤中天然放射性核素含量水平的调查研究

和田地区土壤中天然放射性核素铀－２３８、钍－２３２、镭－２２６和钾－４０按面积加权的均值（Ｂｑ·ｋｇ－１）依次是３７．５２±８．７３、４０．１５±５．３０、３０．０１±４．６０和５３１．１４±４０．７７，属正常本底辐射水平．铀镭平衡状况富铀。     

HEAVY METALS AND SELENIUM IN GREBE EGGS FROM AGASSIZ NATIONAL WILDLIFE REFUGE IN NORTHERN MINNESOTA

Metal levels in eggs can often be used as an indicator of exposure and of potential effects. In previous work at Agassiz National Wildlife Refuge, northwestern Minnesota, the levels of several heavy metals were shown to be significantly higher in the eggs of eared grebes (Podiceps nigricollis) compared to those in the eggs of Franklin’s gulls (Larus pipixcan), black-crowned nightherons (Nycticorax nycticorax) and double-crested cormorants (Phalacrocorax auritus, except for mercury). In the present study we test the hypothesis that there are no differences in the levels of heavy metals in eggs of three species of grebes nesting at Agassiz National Wildlife Refuge (1997, 1999). There were significant differences in levels of selenium, manganese and mercury in the eggs of the grebes collected in 1997, with pied-billed grebe (Podilymbus podiceps) having significantly higher levels of manganese and mercury, and significantly lower levels of selenium, than eared or red-necked grebes (Podiceps grisegena). In 1999, pied-billed grebes had significantly higher levels of mercury, but lower levels of selenium and tin than the other species. The only pattern that was significant and consistent among yearswas selenium; in both years pied-billed grebes had lower levels than the other species. For eared grebes, there was a decline from 1997 to 1998, and again to 1999 for arsenic, cadmium, and selenium. Levels of mercury in the eggs of grebes were not as high, however, as those found in cormorants or night-herons sampled in 1994 at Agassiz National Wildlife Refuge. There were few consistent patterns in the relationships among metals in eared grebe eggs (with the largest sample sizes). The possible reasons for the high levels of some metals in eggs of grebes are unknown, but presumably egg levels represent exposure on the wintering grounds or migratory routes. In comparison to eggs of other birds: 1) the mean levels for manganese were at the high end of the range, and the mean was an order of magnitude higher than the median for the studies examined, 2) mean levels were above the median in the eggs of other birds for lead (red-necked grebe), mercury (pied-billed grebe) and selenium (eared and red-necked grebe).