Balancing recreation and conservation is an important issue in Canada's parks and protected areas. Increased levels of visitation to parks, especially to backcountry areas, create undue pressure on natural resources, resulting in a variety of ecological impacts. This paper illustrates the issue of visitor-induced changes on the chemical composition of soils in Mt Robson Provincial Park, British Columbia. Soil samples were collected from dish wash stations and fire pits (disturbed sites) at seven campgrounds located along two popular backcountry trails, and were compared to samples obtained from adjacent undisturbed control sites. Analysis of soil samples suggest that the lower amounts of aluminum, potassium, magnesium and sodium in many of the 'disturbed' samples can be related to intense leaching in dish wash stations, and can be attributed to frequent disposal of waste water from washing and cooking activities. Soils in wash stations generally had higher phosphorus, copper and zinc contents as compared to controls. Soils in fire pits were elevated in copper, relative to controls. Results of this study support park regulations that waste water disposal and camp fires be restricted to designated areas. Informing the public of scientific studies helps them understand the consequences of their activities; this may help persuade them to observe park rules and regulations. 相似文献
The geographical limitations of Singapore, its restricted natural resources and voluminous municipal and industrial waste streams, make environmental management a major challenge for the island state. In an attempt to find ways to reduce importation of raw materials and the waste sent to landfill, light weight aggregates were produced from marine clay and a CaF(2)-rich semiconductor industry sludge. Aggregates were produced in a bench-scale rotary kiln with three clay/sludge loadings (90/10, 70/30 and 50/50%). All three mixtures showed good bloating behavior during firing and the ceramic pellets (1-1.5cm diameter) had densities well below that required for light-weight aggregates. In the initial tests, the pore sizes of the aggregates were in general too large resulting in high water absorption. Comparisons between the composition of the two waste products and the aggregates showed a significant loss of fluorine (40-60%) during processing; a problem which may require flue gas treatment. Leach testing showed that the formed aggregates would not pose a human or environmental hazard in terms of fluorine mobilization. 相似文献
Long-term field trials using lignite fly ash (LFA) were carried out in rice crops during the period 1996-2000 at Mine I, Neyveli Lignite Corporation, Tamil Nadu. LFA, being alkaline and endowed with an excellent pozzolanic nature, silt loam texture, and plant nutrients, has the potential to improve the texture, fertility, and crop productivity of mine spoil. The rice crops were the first, third, fifth, and sixth crops in rotation. The other crops, such as green gram (second) and sun hemp (fourth), were grown as green manure. For experimental trials, LFA was applied at various dosages (0, 5, 10, 20, 50, 100, and 200 t/ha), with and without press mud (10 t/ha), before cultivation of the first crop. Repeat applications of LFA were made at the same dosages in treatments of up to 50 t/ha (with and without press mud) before cultivation of the third and fifth crops. Press mud, a lightweight organic waste product from the sugar industry, was used as an organic amendment and source of plant nutrients. Also, a recommended dosage of chemical fertilizer, along with gypsum, humic acid, and biofertilizer as supplementing agents, was applied in all the treatments, including control. With one-time and repeat applications of LFA, from 5 to 20 t/ha (with and without press mud), the crop yield (grain and straw) increased significantly (p < 0.05), in the range from 3.0 to 42.0% over the corresponding control. The maximum yield was obtained with repeat applications of 20 t/ha of LFA with press mud in the third crop. The press mud enhanced the yield in the range of 1.5-10.2% with various dosages of LFA. The optimum dosage of LFA was 20 t/ha for both one-time and repeat applications. Repeat applications of LFA at lower dosages of up to 20 t/ha were more effective in increasing the yield than the corresponding one-time applications of up to 20 t/ha and repeat applications at 50 t/ha. One-time and repeat applications of LFA of up to 20 t/ha (with and without press mud), apart from increasing the yield, evinced improvement in the texture and fertility of mine spoil and the nutrient content of crop produce. Furthermore, some increase in the content of trace and heavy metals and the level of gamma-emitters in the mine spoil and crop produce was observed, but well within the permissible limits. The residual effect of LFA on succeeding crops was also encouraging in terms of eco-friendliness. Beyond 20 t/ha of LFA, the crop yield decreased significantly (p < 0.05), as a result of the formation of hardpan in the mine spoil and possibly the higher concentration of soluble salts in the LFA. However, the adverse effects of soluble salts were annulled progressively during the cultivation of succeeding crops. A plausible mechanism for the improved fertility of mine spoil and the carryover or uptake of toxic trace and heavy metals and gamma-emitters in mine spoil and crop produce is also discussed. 相似文献
Onsite wastewater treatment systems (OWTS) are becoming increasingly important for the treatment and dispersal of effluent
in new urbanised developments that are not serviced by centralised wastewater collection and treatment systems. However, the
current standards and guidelines adopted by many local authorities for assessing suitable site and soil conditions for OWTS
are increasingly coming under scrutiny due to the public health and environmental impacts caused by poorly performing systems,
in particular septic tank-soil adsorption systems. In order to achieve sustainable onsite wastewater treatment with minimal
impacts on the environment and public health, more appropriate means of assessment are required. This paper highlights an
integrated risk based approach for assessing the inherent hazards associated with OWTS in order to manage and mitigate the
environmental and public health risks inherent with onsite wastewater treatment. In developing a sound and cohesive integrated
risk framework for OWTS, several key issues must be recognised. These include the inclusion of relevant stakeholders throughout
framework development, the integration of scientific knowledge, data and analysis with risk assessment and management ideals,
and identification of the appropriate performance goals for successful management and mitigation of associated risks. These
issues were addressed in the development of the risk framework to provide a generic approach to assessing risk from OWTS.
The utilisation of the developed risk framework for achieving more appropriate assessment and management techniques for OWTS
is presented in a case study for the Gold Coast region, Queensland State, Australia. 相似文献
The regional-scale importance of an aquatic stressor depends both on its regional extent (i.e., how widespread it is) and
on the severity of its effects in ecosystems where it is found. Sample surveys, such as those developed by the U.S. Environmental
Protection Agency’s Environmental Monitoring and Assessment Program (EMAP), are designed to estimate and compare the extents,
throughout a large region, of elevated conditions for various aquatic stressors. In this article, we propose relative risk
as a complementary measure of the severity of each stressor’s effect on a response variable that characterizes aquatic ecological
condition. Specifically, relative risk measures the strength of association between stressor and response variables that can
be classified as either “good” (i.e., reference) or “poor” (i.e., different from reference). We present formulae for estimating
relative risk and its confidence interval, adapted for the unequal sample inclusion probabilities employed in EMAP surveys.
For a recent EMAP survey of streams in five Mid-Atlantic states, we estimated the relative extents of eight stressors as well
as their relative risks to aquatic macroinvertebrate assemblages, with assemblage condition measured by an index of biotic
integrity (IBI). For example, a measure of excess sedimentation had a relative risk of 1.60 for macroinvertebrate IBI, with
the meaning that poor IBI conditions were 1.6 times more likely to be found in streams having poor conditions of sedimentation
than in streams having good sedimentation conditions. We show how stressor extent and relative risk estimates, viewed together,
offer a compact and comprehensive assessment of the relative importances of multiple stressors. 相似文献
Nutrient inputs generally are increased by human-induced land use changes and can lead to eutrophication and impairment of
surface waters. Understanding the scale at which land use influences nutrient loading is necessary for the development of
management practices and policies that improve water quality. The authors assessed the relationships between land use and
stream nutrients in a prairie watershed dominated by intermittent stream flow in the first-order higher elevation reaches.
Total nitrogen, nitrate, and phosphorus concentrations were greater in tributaries occupying the lower portions of the watershed,
closely mirroring the increased density of row crop agriculture from headwaters to lower-elevation alluvial areas. Land cover
classified at three spatial scales in each sub-basin above sampling sites (riparian in the entire catchment, catchment land
cover, and riparian across the 2 km upstream) was highly correlated with variation in both total nitrogen (r2 = 53%, 52%, and 49%, respectively) and nitrate (r2 = 69%, 65%, and 56%, respectively) concentrations among sites. However, phosphorus concentrations were not significantly
associated with riparian or catchment land cover classes at any spatial scale. Separating land use from riparian cover in
the entire watershed was difficult, but riparian cover was most closely correlated with in-stream nutrient concentrations.
By controlling for land cover, a significant correlation of riparian cover for the 2 km above the sampling site with in-stream
nutrient concentrations could be established. Surprisingly, land use in the entire watershed, including small intermittent
streams, had a large influence on average downstream water quality although the headwater streams were not flowing for a substantial
portion of the year. This suggests that nutrient criteria may not be met only by managing permanently flowing streams. 相似文献
Biodiversity conservation in developing countries has been a challenge because of the combination of rising human populations,
rapid technological advances, severe social hardships, and extreme poverty. To address the social, economic, and ecological
limitations of people-free parks and reserves, incentives have been incorporated into conservation programs in the hopes of
making conservation meaningful to local people. However, such incentive-based programs have been implemented with little consideration
for their ability to fulfill promises of greater protection of biodiversity. Evaluations of incentive-based conservation programs
indicate that the approach continually falls short of the rhetoric. This article provides an overview of the problems associated
with incentive-based conservation approaches in developing countries. It argues that existing incentive-based programs (IBPs)
have yet to realize that benefits vary greatly at different “community” scales and that a holistic conceptualization of a
community is essential to incorporate the complexities of a heterogeneous community when designing and implementing the IBPs.
The spatial complexities involved in correctly identifying the beneficiaries in a community and the short-term focus of IBPs
are two major challenges for sustaining conservation efforts. The article suggests improvements in three key areas: accurate
identification of “target” beneficiaries, greater inclusion of marginal communities, and efforts to enhance community aptitudes. 相似文献
River channel migration and cutoff events within large river riparian corridors create heterogeneous and biologically diverse
landscapes. However, channel stabilization (riprap and levees) impede the formation and maintenance of riparian areas. These
impacts can be mitigated by setting channel constraints away from the channel. Using a meander migration model to measure
land affected, we examined the relationship between setback distance and riparian and off-channel aquatic habitat formation
on a 28-km reach of the Sacramento River, California, USA. We simulated 100 years of channel migration and cutoff events
using 11 setback scenarios: 1 with existing riprap and 10 assuming setback constraints from about 0.5 to 4 bankfull channel
widths (bankfull width: 235 m) from the channel. The percentage of land reworked by the river in 100 years relative to current
(riprap) conditions ranged from 172% for the 100-m constraint setback scenario to 790% for the 800-m scenario. Three basic
patterns occur as the setback distance increases due to different migration and cutoff dynamics: complete restriction of cutoffs,
partial restriction of cutoffs, and no restriction of cutoffs. Complete cutoff restriction occurred at distances less than
about one bankfull channel width (235 m), and no cutoff restriction occurred at distances greater than about three bankfull
widths (∼700 m). Managing for point bars alone allows the setbacks to be narrower than managing for cutoffs and aquatic habitat.
Results suggest that site-specific “restriction of cutoff” thresholds can be identified to optimize habitat benefits versus
cost of acquired land along rivers affected by migration processes. 相似文献
Boro rice, an emerging low-risk crop variety of rice, cultivated using residual or stored water after Kharif season. To enhance the quality and production of rice, potassium (K) and phosphorus (P) are the common constituents of agricultural fertilizers. However, excess application of fertilizers causes leaching of nutrients and contaminates the groundwater system. Therefore, assessment and optimization of fertilizer dose are needed for better management of fertilizers. Towards this, the present study determines the path, persistence, and mobility of K and P under the Boro rice cropping system. The experimental site consisted of four plots having Boro rice with four different fertilizer doses of nitrogen (N), P, K viz. 100%, 75%, 50%, and 25% of the recommended dose. Disturbed soil samples were analysed for K and P from pre-sown land to tillering stage at 0–5, 5–10, 10–15, 15–30, 30–45, and 45–60 cm depths. Simultaneously, K and available P were also simulated in the subsurface soil layers through the HYDRUS-1D model. The statistical comparisons were made with RMSER, E, and PBIAS between the modelled values and laboratory-measured values. Although, the results showed that all the treatments considered had agreeable simulations for both K and P, the K simulations were found to be better as compared to P simulations except for 25% where P simulations outperformed K. The simulated concentration at all doses was found most appropriate when measured for the subsurface layers (up to 45 cm), while showed an underestimation in the bottom layers (45–60 cm) of soil.
Working rangelands and natural areas span diverse ecosystems and face both ecological and economic threats from weed invasion. Restoration practitioners and land managers hold a voluminous cache of place-based weed management experience and knowledge that has largely been untapped by the research community. We surveyed 260 California rangeland managers and restoration practitioners to investigate invasive and weedy species of concern, land management goals, perceived effectiveness of existing practices (i.e., prescribed fire, grazing, herbicide use, and seeding), and barriers to practice implementation. Respondents identified 196 problematic plants, with yellow starthistle (Centaurea solstitialis L.) and medusahead (Elymus caput-medusae L.) most commonly listed. Reported adoption and effectiveness of weed management practices varied regionally, but the most highly rated practice in general was herbicide use; however, respondents identified considerable challenges including nontarget effects, cost, and public perception. Livestock forage production was the most commonly reported management goals (64% of respondents), and 25% of respondents were interested in additional information on using grazing to manage invasive and weedy species; however, 19% of respondents who had used grazing for weed management did not perceive it to be an effective tool. Across management practices, we also found common barriers to implementation, including operational barriers (e.g., permitting, water availability), potential adverse impacts, actual effectiveness, and public perception. Land manager and practitioner identified commonalities of primary weeds, management goals, perceived practice effectiveness, and implementation barriers across diverse bioregions highlight major needs that could be immediately addressed through management–science partnerships across the state’s expansive rangelands and natural areas. 相似文献