带状柠条人工林对带间植被特征的影响

本文以察右后旗半干旱地区4m、8m带间距柠条人工林带间植被为研究对象,在典型样地内采取样方法对带间植被特征进行调查。结果表明：与ck比较,营造带状柠条林后带间植被特征明显改善,植物分别增加了4科6属7种（4m）、4科7属7种（8m）,重要值由藜科植物占绝对优势演变为禾本科植物占绝对优势;多年生草本植物分别增加了7种（4m）和5种（8m）,半灌木增加了1种（4m）和2种（8m）;牧草性质改善,优等牧草增加了2种（4m）和3种（8m）,重要值均值较大。     

Pros and cons of eliminating veld burning

Fire has been a factor of the environment in Africa since time immemorial and it is often caused by natural agencies such as lightning. It is maintained that there is much prejudice against veld burning, often ill‐founded. Fire has caused and maintained most of the world's grassland. When fire has been prevented plant succession has resulted in bush encroachment in the savanna and surrounding areas or in fynbos encroachment in others. Fire results in much old grass being wasted but, if this is not removed in some manner, the grazing deteriorates. Old grass can be removed by fire, mowing or grazing, using high protein supplements. The consequences of the different methods of removal, other than mowing, may be equally deleterious.     

Scientifiques Sans Frontières Australia Providing Environmental Science Support to Local Communities in Rehabilitation of Waterways

Water, Air, & Soil Pollution -     

The distribution of pepsinogen within the abomasa of cattle and sheep infected with Ostertagia spp. and sheep infected with Haemonchus contortus.

The effect of nematode infections on the production of pepsinogen by ruminants was investigated immunohistochemically and biochemically. Abomasal tissues were collected from parasite-naive cattle and sheep, from sheep infected with predominantly Ostertagia circumcincta, sheep infected experimentally with Haemonchus contortus and cattle infected with Ostertagia ostertagi. Pepsinogen was also assayed biochemically in homogenates of fundic mucosae from sheep infected with predominantly O. circumcincta. Infection with Ostertagia spp. parasites was associated mainly with nodular hyperplasia, resulting in increased numbers of cells that produce both pepsinogen and mucus. Measured biochemically, nodules contained more pepsinogen than adjacent more normal mucosa (p < 0.05), and this effect was largely attributable to the greater mass of nodules. Infection of sheep with H. contortus was associated with generalised hyperplasia, characterised by increased numbers of mucopeptic cells and in at least one animal with reductions in parietal cell numbers. At the same time, the zymogen granule content of chief cells was reduced. Similar changes were occasionally seen in sheep infected predominantly with O. circumcincta. Generalised hyperplasia is likely to be indicative of the presence of ambulatory parasitic stages as opposed to those confined to nodules. The potential for the enhanced production of pepsinogen by increased numbers of cells with a joint mucous cell and zymogenic cell phenotype may offset decreases in the numbers of chief cells or reductions in chief cell activity.     

Erythema multiforme in dogs and cats: literature review and case material from the Cornell University College of Veterinary Medicine (1988–96)

A review of case material from the Cornell University College of Veterinary Medicine from 1988 to 1996 identified 20 dogs and one cat with definitive or presumed erythema multiforme. An additional 24 dogs and five cats with definitive or presumed erythema multiforme were found in the veterinary literature. Erythema multiforme accounted for only 0.40% and 0.11%, respectively, of all the canine and feline dermatology cases examined over a 9-year period. German Shepherd dogs and Pembroke Welsh Corgis appeared predisposed. The condition was manifested as a vesiculobullous and/or ulcerative dermatosis in the majority of dogs and cats. In dogs, the most commonly affected body sites included the ventrum (especially axillae and groin), mucocutaneous junctions, oral cavity, pinnae, and footpads. Histopathological findings in cutaneous and mucocutaneous biopsy specimens were consistent with previously published criteria. In dogs, erythema multiforme occurred more frequently in patients receiving drug therapy. In cats, all cases of erythema multiforme were presumed to be drug related. Elimination of the associated trigger factor and supportive care usually resulted in resolution of the erythema multiforme within 1–2 weeks. Four dogs with severe idiopathic erythema multiforme were successfully managed with glucocorticoids or azathioprine.     

Process requirements for achieving full-flow disinfection of recirculating water using ozonation and UV irradiation

A continuous water disinfection process can be used to prevent the introduction and accumulation of obligate and opportunistic fish pathogens in recirculating aquaculture systems (RAS), especially during a disease outbreak when the causative agent would otherwise proliferate within the system. To proactively prevent the accumulation of fish pathogens, ozonation and ultraviolet (UV) irradiation processes have been used separately or in combination to treat water in RAS before it returns to the fish culture tanks. The objective of the present study was to determine the process requirements necessary to disinfect the full RAS flow, using ozonation followed by UV irradiation, just before the flow was returned to the fish culture tank(s). We found that a proportional-integral (PI) feed-back control loop was able to automatically adjust the concentration of ozone (O₃) generated in the oxygen feed gas (and thus added in the low head oxygenator) in order to maintain the dissolved O₃ residual or ORP at a pre-selected set-point. We determined that it was easier and effective to continuously monitor and automatically control O₃ dose using an oxidative reduction potential (ORP) probe (in comparison to a dissolved ozone probe) that was located at the outlet of the O₃ contact chamber and immediately before water entered the UV irradiation unit. PI control at an ORP set-point of 450 and 525 mv and a dissolved O₃ set-point of 20 ppb provided almost complete full-flow inactivation of heterotrophic bacteria plate counts (i.e., producing <1 cfu/mL) and improved water quality (especially color and %UVT) in a full-scale recirculating system. Achieving this level of treatment required adding a mean dose of approximately 29 ± 3 g O₃ per kg feed. However, because water is treated and reused repeatedly in a water reuse system, the mean daily O₃ demand required to maintain an ORP of 375–525 mV (or at 20 ppb dissolved O₃) was 0.34–0.39 mg/L, which is nearly 10 times lower than what is typically required to disinfect surface water in a single pass treatment. These findings can be used to improve biosecurity and product quality planning by providing a means for continuous water disinfection in controlled intensive RAS.     

Developing a typology of daily travelers based on transportation attitudes: Application of latent class analysis using a survey of millennials and older adults in Hamilton,Ontario

Using survey data of millennials and older adults in Hamilton, Ontario, this exploratory study sought to identify daily travelers based on their attitudes and perceptions toward transportation modes using latent class analysis. Four daily traveler types are identified—“walk and transit-oriented travelers,” “car-oriented commuters,” “multimodal travelers,” and “car-oriented travelers.” The study also examined the association of different sociodemographic characteristics and trip attributes with the four traveler types. Findings suggest that heterogeneity exists within travel-related attitudes among different traveler types. Further, heterogeneous traveler types exist among individuals belonging to the same generation, with the same living arrangements and possession of a driver's license.     

Surface application of ammonium thiosulfate fertilizer to reduce volatilization of 1,3‐dichloropropene from soil

Atmospheric emission of the soil fumigant 1,3‐dichloropropene (1,3‐D) is of environmental concern because of its toxicity and carcinogenicity. Thiosulfate fertilizers have been found to rapidly transform 1,3‐D in soil to non‐volatile ions which are less toxic. We investigated the use of surface application of ammonium thiosulfate (ATS) for reducing 1,3‐D volatilization. In packed soil columns, emission of 1,3‐D applied by sub‐surface injection decreased with increasing ATS application rate and the amount of water used for delivering ATS. When ATS was applied in 9 mm water at 64 g m⁻², total 1,3‐D emission was reduced by 61%. The reduction was 89% when ATS was applied at 193 g m⁻². Bioassays showed that ATS application did not affect the effectiveness of 1,3‐D for controlling citrus nematodes. In field plots where a 1,3‐D emulsified formulation was applied via sub‐surface drip, surface spray of ATS reduced 1,3‐D emissions by 50%, and by 71% when the surface was also covered with polyethylene film. ATS application had no effect on the efficacy of root‐knot nematode control or tomato yields. These results suggest that surface application of thiosulfate fertilizers may be a feasible and effective strategy for minimizing 1,3‐D emissions. © 2000 Society of Chemical Industry     

The role of temperature in the capture and release of fish

We searched major electronic databases to identify peer‐reviewed literature investigating the role of temperature on the stress response and mortality of captured and released fish. We identified 83 studies that fit these criteria, the majority of which were conducted in North America (81%) on freshwater fish (76%) in the orders Perciformes (52%) and Salmoniformes (28%). We found that hook‐and‐line fisheries (65% of all studies) were more commonly studied than all net fisheries combined (24%). Despite the wide recognition for many species that high water temperatures exacerbate the effects of capture on released fish, this review is the first to quantitatively investigate this problem, finding that warming contributed to both mortality and indices of stress in 70% of articles that measured each of those endpoints. However, more than half (58%) of the articles failed to place the experimental temperatures into a biological context, therefore limiting their broad applicability to management. Integration of survival and sublethal effects to investigate mechanisms of fish mortality was relatively rare (28%). Collectively, the results suggest that capture–release mortality increases at temperatures within, rather than above, species‐specific thermal preferenda. We illustrate how knowledge of ecologically relevant high temperatures in the capture and release of fish can be incorporated into management, which will become increasingly important as climate change exerts additional pressure on fish and fisheries.