Phosphorus leaching in sandy outwash soils following potato-processing wastewater application

Land application of wastewater presents potential for ground water pollution if not properly managed. In situ breakthrough tests were conducted using potato (Solanum tuberosum L.)-processing wastewater and a Br tracer to characterize P leaching in seasonally frozen sandy outwash soils. In the first test, P and Br breakthrough were measured in a 7-m deep well following wastewater [2.94 mg L(-1) total P (TP); 280 mg L(-1) Br] application at the site that had 13.1 mg water-extractable P (WEP) kg(-1)and 94.4 mg Bray-1 P kg(-1). Bromide was detected in the well after approximately 0.4 pore volumes, but there was no P break-through after 7 pore volumes. In the second breakthrough test, wastewater containing 3.6 mg L(-1) TP and 259 mg L(-1) Br was applied on 1.5-m deep lysimeters at low (0.8 mg WEP kg(-1); 12.1 mg Bray-1 P kg(-1)) and high soil test P sites (104 mg WEP kg(-1); 585 mg Bray-1 P kg(-1)). Leachate TP concentration during the test remained constant (0.04 mg L(-1)) at the low P sites but increased from approximately 3.5 to 5.6 mg L(-1) at the high P sites. These results indicate no P leaching in low P soils, but leaching in high P soils, thus suggesting that most of the P leached at the high P sites was mainly due to desorption and dissolution of weakly adsorbed P from prior P applications. This was consistent with P transport simulations using the convective-dispersive equation. We conclude that P concentration in land-applied wastewater should be regulated based on soil test-P level plus wastewater P loading.     

Accelerated soil dissipation of tebuconazole following multiple applications to peanut

Repeated application may increase rates of pesticide dissipation in soil and reduce persistence. The potential for this to occur was investigated for the fungicide, tebuconazole (alpha-[2-(4-chlorophenyl)ethyl]-alpha-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol), when used for peanut (Arachis hypogaea L.) production. Soil samples were collected from peanut plots after each of four tebuconazole applications at 2-wk intervals. Soil moisture was adjusted to field capacity as necessary and samples were incubated in the laboratory for 63 d at 30 degrees C. Untreated plot samples spiked with the compound served as controls. Results indicated accelerated dissipation in field-treated samples with the time to fifty percent dissipation (DT50) decreasing from 43 to 5 d after three tebuconazole applications. Corresponding increases in rates of accumulation and decay of degradates were also indicated. Best-fit equations (r2 = 0.84-0.98) to dissipation kinetic data combined with estimates of canopy interception rates were used to predict tebuconazole and degradates concentration in soil after each successive application. Predicted concentrations compared with values measured in surface soil samples were from twofold less to twofold greater. Use of kinetic data will likely enhance assessments of treatment efficacy and human and ecological risks from normal agronomic use of tebuconazole on peanut. However, the study indicated that varying soil conditions (in particular, soil temperature and water content) may have an equal or greater impact on field dissipation rate than development of accelerated dissipation. Results emphasize that extension of laboratory-derived kinetic data to field settings should be done with caution.     

Residues of endosulfan and other selected organochlorine pesticides in farm areas of the Lower Fraser Valley, British Columbia, Canada

Crop soils, ditch sediments, and water flowing from several farm areas to salmon tributary streams of the Fraser River in the Lower Fraser Valley (LFV) of British Columbia, Canada, were sampled in 2002-2003 to quantify for residues of an organochlorine cyclodiene pesticide, endosulfan (END = alpha-endosulfan + beta-endosulfan + endosulfan sulfate). Residues from historical use of other selected organochlorine pesticides, namely, cyclodienes (aldrin, alpha-chlordane, gamma-chlordane, dieldrin, endrin, endrin aldehyde, heptachlor, and heptachlor epoxide), hexachlorocyclohexanes [alpha-benzene-hexachloride (alpha-BHC), beta-BHC, delta-BHC, and gamma-BHC (lindane)], and DDT-related compounds (p,p-DDT, p,p-DDD, p,p-DDE, and methoxychlor) were also determined. Reference and background levels of these pesticides in ditches leading to fish streams were obtained from pristine watershed areas. Varying amounts of END residues were detected in soils (<0.02-5.60 mg kg(-1) dry wt.) and ditch sediments (<0.02-3.33 mg kg(-1) dry wt.) in mainly three of five farm areas sampled. Likewise, residues (excluding END) of other selected organochlorine compounds such as aldrin, BHC, chlordane, endrin, p,p-DDT, methoxychlor, and their respective major transformation products (endosulfan sulfate, dieldrin, endrin aldehyde, heptachlor, heptachlor epoxide, p,p-DDD, and p,p-DDE) were found in crop soils (<0.02-16.2 mg kg(-1) dry wt.) and sediments (<0.02-9.73 mg kg(-1) dry wt.). Most of these pesticides (END: <0.01-1.86 microg L(-1); other selected organochlorine pesticides: <0.0.1-1.50 microg L(-1)) were also found in ditch water leading to salmon streams in several farms. The END levels of crop soils from the same LFV study farms in 1994 and 2003 indicated an estimated decline of 22% to 1.35 mg kg(-1) dry wt. during that period. This reduction was probably due to the increasing use of alternate pesticides (e.g., organophosphorus compounds). Some possible biological implications of these pesticide residues on nontarget organisms in the LFV are discussed.     

Green roof stormwater retention: effects of roof surface, slope, and media depth

Urban areas generate considerably more stormwater runoff than natural areas of the same size due to a greater percentage of impervious surfaces that impede water infiltration. Roof surfaces account for a large portion of this impervious cover. Establishing vegetation on rooftops, known as green roofs, is one method of recovering lost green space that can aid in mitigating stormwater runoff. Two studies were performed using several roof platforms to quantify the effects of various treatments on stormwater retention. The first study used three different roof surface treatments to quantify differences in stormwater retention of a standard commercial roof with gravel ballast, an extensive green roof system without vegetation, and a typical extensive green roof with vegetation. Overall, mean percent rainfall retention ranged from 48.7% (gravel) to 82.8% (vegetated). The second study tested the influence of roof slope (2 and 6.5%) and green roof media depth (2.5, 4.0, and 6.0 cm) on stormwater retention. For all combined rain events, platforms at 2% slope with a 4-cm media depth had the greatest mean retention, 87%, although the difference from the other treatments was minimal. The combination of reduced slope and deeper media clearly reduced the total quantity of runoff. For both studies, vegetated green roof systems not only reduced the amount of stormwater runoff, they also extended its duration over a period of time beyond the actual rain event.     

Rapid manganese removal from mine waters using an aerated packed-bed bioreactor

In the UK, the Environmental Quality Standard for manganese has recently been lowered to 30 microg/L (annual average), which is less than the UK Drinking Water Inspectorate's Maximum Permitted Concentration Value (50 microg/L). Current passive treatment systems for manganese removal operate as open-air gravel-bed filters, designed to maximize either influent light and/or dissolved oxygen. This requires large areas of land. A novel enhanced bioremediation treatment system for manganese removal has been developed that consists of a passively aerated subsurface gravel bed. The provision of air at depth and the use of catalytic substrates help overcome the slow kinetics usually associated with manganese oxidation. With a residence time of only 8 h and an influent manganese concentration of approximately 20 mg/L, >95% of the manganese was removed. The treatment system also operates successfully at temperatures as low as 4 degrees C and in total darkness. These observations have positive implications for manganese treatment using this technique in both colder climates and where large areas of land are unavailable. Furthermore, as the operation of this passive treatment system continually generates fresh manganese oxyhydroxide, which is a powerful sorbent for most pollutant metals, it potentially has major ancillary benefits as a removal process for other metals, such as zinc.     

Nitrogen removal in laboratory model leachfields with organic-rich layers

Septic system leachfields can release dissolved nitrogen in the form of nitrate into ground water, presenting a significant source of pollution. Low cost, passive modifications, which increase N removal in traditional leachfields, could substantially reduce the overall impact on ground water resources. Bench-scale laboratory models were constructed to evaluate the effect of placing an organic layer below the leachfield on total N removal. The organic layer provides a carbon source for denitrification. Column units representing septic leachfields were constructed with sawdust-native soil organic layers placed 0.45 m below the influent line and with thicknesses of 0.0, 0.3, 0.6, and 0.9 m. Using a synthetic septic tank effluent, NO(3)-N concentrations at 3.8 m below the influent line were consistently below 1 mg L(-1) during 10 months of operation compared with a NO(3)-N concentration of nearly 12 mg L(-1) in the control column. The average total N removal increased from 31% without the organic layer to 67% with the organic layer. Total N removal appeared limited by the extent of organic N oxidation and nitrification in the 0.45-m aerobic zone. Design modifications targeted at improving nitrification above the organic layer may further increase total N removal. Increased organic layer thicknesses from 0.3 m to 0.9 m did not significantly improve average total N removal, but caused a shift in residual nitrogen from organic N to ammonia N. Results indicate that addition of a layer of carbon source material at least 0.3 m thick below a standard leachfield substantially improves total N removal.     

Sustainable pattern analysis of a publicly owned Material Recovery Facility in a fast-growing urban setting under uncertainty

Sustainable development goals are achievable through the installation of Material Recovery Facilities (MRFs) in certain solid waste management systems, especially those in rapidly expanding multi-district urban areas. MRFs are a cost-effective alternative when curbside recycling does not demonstrate long-term success. Previous capacity planning uses mixed integer programming optimization for the urban center of the city of San Antonio, Texas to establish that a publicly owned material recovery facility is preferable to a privatized facility. As a companion study, this analysis demonstrates that a MRF alleviates economic, political, and social pressures facing solid waste management under uncertainty. It explores the impact of uncertainty in decision alternatives in an urban environmental system. From this unique angle, waste generation, incidence of recyclables in the waste stream, routing distances, recycling participation, and other planning components are taken as intervals to expand upon previous deterministic integer-programming models. The information incorporated into the optimization objectives includes economic impacts for recycling income and cost components in waste management. The constraint set consists of mass balance, capacity limitation, recycling limitation, scale economy, conditionality, and relevant screening restrictions. Due to the fragmented data set, a grey integer programming modeling approach quantifies the consequences of inexact information as it propagates through the final solutions in the optimization process. The grey algorithm screens optimal shipping patterns and an ideal MRF location and capacity. Two case settings compare MRF selection policies where optimal solutions exemplify the value of grey programming in the context of integrated solid waste management.     

Science in the public process of ecosystem management: lessons from Hawaii, Southeast Asia, Africa and the US Mainland

Partnerships and co-operative environmental management are increasing worldwide as is the call for scientific input in the public process of ecosystem management. In Hawaii, private landowners, non-governmental organizations, and state and federal agencies have formed watershed partnerships to conserve and better manage upland forested watersheds. In this paper, findings of an international workshop convened in Hawaii to explore the strengths of approaches used to assess stakeholder values of environmental resources and foster consensus in the public process of ecosystem management are presented. Authors draw upon field experience in projects throughout Hawaii, Southeast Asia, Africa and the US mainland to derive a set of lessons learned that can be applied to Hawaiian and other watershed partnerships in an effort to promote consensus and sustainable ecosystem management. Interdisciplinary science-based models can serve as effective tools to identify areas of potential consensus in the process of ecosystem management. Effective integration of scientific input in co-operative ecosystem management depends on the role of science, the stakeholders and decision-makers involved, and the common language utilized to compare tradeoffs. Trust is essential to consensus building and the integration of scientific input must be transparent and inclusive of public feedback. Consideration of all relevant stakeholders and the actual benefits and costs of management activities to each stakeholder is essential. Perceptions and intuitive responses of people can be as influential as analytical processes in decision-making and must be addressed. Deliberative, dynamic and iterative decision-making processes all influence the level of stakeholder achievement of consensus. In Hawaii, application of lessons learned can promote more informed and democratic decision processes, quality scientific analysis that is relevant, and legitimacy and public acceptance of ecosystem management.     

应对复杂道路环境的新型清障救援车

<正>交通运输部公路科学研究院最新研制出了一款面向作业空间受限的复杂道路环境的综合清障救援车,在整车结构设计与布局优化、电控系统开发及完备功能集成、多装备协同救援等方面填补了国内空白。近年来,对突发性公共安全事件的应急处置引起了社会各界和政府的高度重视和关注。在突发性公共安全事件中,道路交通事故占比最高,2011年度道路交通事故占我国各类安全事故总数的71.7%,死亡人数     

三江源国家公园生态保护路径研究

建立国家公园体制是我国生态文明体制改革的重点任务.三江源国家公园是中国第一个国家公园体制试点,以探索实现最严格的空间管控和最有效的生态系统保护为目标,以生态保护管理体制机制创新为突破口,科学划定空间布局,明确功能分区管控目标、管控措施,探索生态保护新路径和新模式.通过阐述三江源国家公园体制试点的重要意义,研究总结了4个...