Sediment transport in an inland river in North Queensland

Rivers in northern Queensland are ephemeral and carry water mainly as a direct response to heavy rainfall. Sediment is transported downstream with the runoff and sediment deposition may be a major problem in many proposed reservoirs. Hence information about sediment transport, particularly under high flow conditions, is required for planning and design of water storage reservoirs. In this region, bed material samples can be obtained during low flow periods and suspended sediment sampling during floods is possible but only with difficulty. Little reliable data is available.This paper outlines a possible approach to predicting sediment loads in such rivers. Suspended sediment samples have been analysed to give both particulate concentrations and their grain size distributions. The latter have been compared with bed material size distributions, and the concentrations of suspended bed material and wash load components have been estimated.After investigations of a number of methods for predicting bed material transport, those which treat bed load and suspended load independently have been selected. Field data have been used to determine the wash load and the suspended bed material load. The bed load was then computed so that the total sediment load could be determined.This approach has been applied to the Flinders River at Glendower, based on field data obtained by the Queensland Water Resources Commission in 1982/83.     

The particle size characteristics of fluvial suspended sediment: an overview

The particle size characteristics of suspended sediment are of fundamental importance in understanding its role in a variety of environmental processes. Existing knowledge concerning the spatial and temporal variability of the grain size composition of suspended sediment is, however, relatively limited. At the global scale, major contrasts may exist between individual rivers in the calibre of their suspended load and this may be related to a number of controls including climate, catchment geology and basin scale. Any attempt to understand the precise relationship between the grain size characteristics of suspended sediment and those of its source material must also take account of the selectivity of erosion and delivery processes. A local case study undertaken by the authors in the 1500 km² basin of the River Exe in Devon, UK is used to illustrate the considerable spatial variability that may occur within a relatively small area and the complexity of the associated controls.Available evidence concerning the temporal variability of the grain size characteristics of suspended sediment emphasises the diverse patterns of behaviour that may exist and the complexity of the controls involved. In some rivers the sediment may become coarser as flow increases, in others it may become finer, whilst in others it may exhibit a relatively constant grain size composition. Data from the local case study in the Exe basin are again used to highlight the considerable diversity in response to changing discharge that may occur within a relatively small area.Any attempt to understand the dynamics of sediment movement through a river system must also take account of the potential contrast between the ultimate and effective particle size distribution of suspended sediment in response to aggregation. Results from the Exe basin study indicate that even in rivers with relatively low solute concentrations, almost an order of magnitude difference may exist between the median particle size associated with the ultimate and effective grain size distributions.     

A simulation of the process of sedimentation of suspended solids in the Yoshii River estuary

A vertical plane 2D model has been applied to the Yoshii River estuary, Japan, as a means of simulating the process of sedimentation. The current velocity and isohaline distributions were well reproduced in the estuary and the model simulated the concentration distribution of suspended solids for 8 particle size classes by using a transport equation based only on physical processes. The changes of the particle size distribution in surface water were well reproduced by the model. The vertical velocity component plays an important role in the behaviour of suspended solids.     

Assessing toxicity of Lake Diefenbaker (Saskatchewan,Canada) sediments using algal and nematode bioassays

Lake Diefenbaker, on the South Saskatchewan River, Saskatchewan, Canada, receives, on average, 90% of its inflow from snowmelt and rainfall in the Rocky Mountains. The inflowing rivers also receive irrigation return flows and municipal and industrial effluents which may result in the contamination of lake sediments. The sediments were assessed by nematode and algal bioassays.The toxicity of five chemical fractions of the sediment was determined using the nematode Panagrellus redivivus as the test organisms. The results suggest that the sediment chemical fractions frequently inhibit growth and maturation, while lethality was observed at 4 of 12 sites.Samples from 3 of these sites were further evaluated using conventional elutriate Algal Fractionation Bioassays (AFB) with both natural Lake Diefenbaker phytoplankton and a mixed laboratory grown algal culture. The natural phytoplankton showed inhibition at sediment: water ratios of 10: 1; whereas the algal cultures showed both enhancement and inhibition. Evidently, the sediments are frequently toxic to the species tested except for the algal culture. The AFB assesses the mitigative and synergistic effects of contaminants and nutrients and being a conventional elutriate, is more realistic and potentially more acceptable than the chemical fractionation/nematode bioassay technique which essentially considers potential trace organic contaminant effects.     

抗马拉硫磷淡色库蚊不同基因型的自然内禀增长率及其对抗性演化的影响

本文涉及淡色库蚊(Culex pipiens pallens)抗马拉硫磷纯合子(RR)、杂合子(RS)和敏感纯合子(SS)的自然内禀增长率及其对马拉硫磷抗性演化的影响。RR、RS和SS的内禀增长率分别为0.1118、0.1171和0.1339。RR和RS基因型在无杀虫剂时呈现出繁殖不利性,RR和RS的相对适合度分别是SS的0.65和0.68。 影响淡色库蚊对马拉硫磷进化的某些因子在计算机上进行了模拟。模拟的因子包括R等位基因的起始频率(P_o)、所用马拉硫磷的剂量和迁入率(m)。模拟结果表明(I)不用药时R等位基因衰减是由于RR和RS基因型的繁殖不利性;(2)在起始种群N_o=200,P_o=0.1,使用杀死全部SS和RS的剂量(8ppm)处理,使R等位基因为有效隐性,并且m≥0.15时可阻止马拉硫磷抗性的发生。     

Functional and phenotypic analyses of interleukin 2-activated tumor-infiltrating lymphocytes

The tumor-infiltrating lymphocytes (TILs) were cultured with interleukin 2 (IL-2) to induce the activated killer cells possessing autologous tumor-killing activity, and analysed their cell surface phenotypes and assessed anti-tumor killing activity. Furthermore, the activated TILs were transferred into 7 patients adoptively resulting in complete remission in a patient with pancreatic cancer and partial remission in another patient with gastric cancer.The cytotoxic activities of activated TILs at 3 weeks-incubation was 72 ± 15, 42 ± 26, 27 ± 21 and 25 ± 15% against K562, Daudi, KATO-III and autologous tumor, respectively. The negative selection method, indicated that the killer cells recognizing autologous tumor cells consisted of CD4- or CD8-positive T lymphocytes and CD16- or CD56-positive natural killer cells. The activated TILs could not only lyse cultured tumor cell lines, but also autologous tumor cells.     

The tellurium content of vegetation

Vegetation growing in the Ely mining district of White Pine County, NV has been analyzed for tellurium to discover whether Te accumulator plants existed similar to those that take up Se in great quantities. In addition, the variation in Te content among species growing in different geological settings was studied. Another objective of this study was to determine the range of Te concentration in vegetation in regions where the Te content of surface materials was high, as in the Ely mining district, and low as in various areas of western CO. Trees and shrubs (480 samples) as well as flowering plants (505 samples) and their associated edaphic materials were collected from six sites in the Ely region and all plant parts were analyzed for Te, Se, Fe, S, Zn, Cu, and Pb. One hundred and five plants were collected from three areas in western CO. There is a highly significant difference between Te uptake by trees and that of perennial flowering plants. Flowers contain significantly more Te on the average than other plant parts. An examination of the Te content of tree parts reveals that leaves sorb the most and branches the least. When the Te content of edaphic materials is high, there is a corresponding increase in the Te content of plants. Shallow perennial plants were not found growing in areas where soils contained more than 10 mg kg⁻¹ Te. Seleniferous species ofAstragalus contain larger quantities of Te than plants in the Ely area, whereas nonseleniferous members of this genus contain much less. The nitrotoxin producing Astragali contain concentrations of Te greater than that encountered in nonseleniferous species but less than that in seleniferous ones. No plants contained more than 1 mg kg⁻¹ Te. Iron, Te, Se, and S are coherent in all plants and in most soils and rocks examined.     

Yields and nitrogen nutrition of intercropped maize and ricebean (Vigna umbellata [Thumb.] Ohwi and Ohashi)

Maize (Zea mays L.) and ricebean (Vigna umbellata [Thumb.] Ohwi and Ohashi) were grown in intercrop and monoculture on Tropaqualf soils under rainfed conditions in Northern Thailand yearly from 1983 to 1986. De Wit's replacement design was used to compare intercrops and monocultures with a constant plant density equivalent to 80 000 maize or 160 000 ricebean plants ha⁻¹. Combined nitrogen was applied at varying levels to 200 kg N ha⁻¹. In the final two seasons the intercrop ratio of maize: ricebean was also varied. At the time of maize maturity intercrops yielded upt 49 kg ha⁻¹ more N in the above ground plant parts than the best monoculture. Dry matter, grain and nitrogen yield of maize and ricebean in intercrop relative to their monoculture yields (RY, relative yield) were significantly greater than their respective share of the plant population. Relative yield totals (RYT) for grain, dry matter and nitrogen were always greater than 1. Nitrogen uptake per maize plant increased with progressive replacement of maize by ricebean plants. This increase was similar to that obtained by applying combined N. Available soil nitrogen tended to decrease with increasing maize:ricebean ratio. Increasing the maize:ricebean ratio increased the % of nitrogen derived from fixation in ricebean, the increase being equivalent to that obtained by decreasing combined nitrogen application. Approximately the same amount of fertilizer and soil nitrogen was taken up by maize plus ricebean in intercrop as the maize monoculture. The results suggest that the improved nitrogen economy of the intercrop resulted from the strong competitiveness of maize in the use of mineral nitrogen and the enhancement of nitrogen fixation in intercropped ricebean which made it less dependent on the depleted pool of soil nitrogen.     

Lake Erie water snakes revisited: Morph- and age-specific variation in relative crypsis

Summary Populations of water snakes (Nerodia sipedon insularum) on islands in western Lake Erie are variable in colour pattern, consisting of unbanded, intermediate, and banded morphs. In contrast, mainland populations (N. s. sipedon) consist solely of banded morphs. Previous investigators hypothesized that natural selection favoured unbanded morphs on exposed island shorelines and banded morphs in overgrown mainland habitats and that gene flow from mainland populations was responsible for the persistence of banded morphs on islands. To clarify the potential role of natural selection, I quantified relative crypsis among morphs and age classes of water snakes by comparing the size of patches making up their colour patterns with the size of patches in island and mainland backgrounds. This analysis reveals that if unbanded morphs are more cryptic than intermediate and banded morphs on islands, it is only in the young-of-the-year age class. For older snakes on islands and for all snakes on the mainland, unbanded morphs are consistently less cryptic than intermediate and banded morphs. Given these results, the net direction of selection in island populations should depend on the intensity of predation on different age classes of snakes. Overall, selection may favour unbanded morphs (e.g. if predation occurs primarily on young-of-the-year), intermediate and banded morphs (e.g. if predation occurs primarily on older snakes), or be weak or absent (e.g. certain combinations of predation on young-of-the-year and older snakes). Using estimates of relative crypsis to guide reanalysis of morph frequency data, I find support for the hypothesis that unbanded morphs are favoured by natural selection in island populations.     

DNA extraction for 16S rRNA gene analysis to determine genetic diversity in deep sediment communities

A protocol was devised which permitted the extraction of DNA from deep marine sediments up to 503 m below the sea floor. These sediments have been laid down over the last 3 million years. 16S rRNA gene sequences were amplified from the DNA by the polymerase chain reaction. The details of the successful extraction and polymerase chain reaction methodology varied between samples from different depths. This emphasizes the attention to detail required to allow the diversity of bacteria in these deep sediments to be studied.