Potential Effects of a Forest Management Plan on Bachman's Sparrows (Aimophila aestivalis): Linking a Spatially Explicit Model with GIS

By combining a spatially explicit, individual-based population simulation model with a geographic information system, we have simulated the potential effects of a U.S. Forest Service management plan on the population dynamics of Bachman's Sparrow ( Aimophila aestivalis ) at the Savannah River Site, a U.S. Department of Energy facility in South Carolina. Although the Forest Service's management plan explicitly sets management goals for many species, most of the prescribed management strategy deals with the endangered Red-cockaded Woodpecker ( Picoides borealis ) because of legal requirements. We explored how a species (the sparrow) that is not the target of specific management strategies but that shares some habitat requirements with the woodpecker, would fare under the management plan. We found that the major components of the proposed management plan may allow the sparrow population to reach and exceed the minimum management goal set for this species, but only after a substantial initial decline in sparrow numbers and a prolonged transition period. In the model, the sparrow population dynamics were most sensitive to demographic variables such as adult and juvenile survivorship and to landscape variables such as the suitability of young clearcuts and mature pine stands. Using various assumptions about habitat suitability, we estimated that the 50-year probability of population extinction is at least 5% or may be much higher if juvenile survivorship is low. We believe, however, that modest changes in the management plan might greatly increase the sparrow population and presumably decrease the probability of extinction. Our results suggest that management plans focusing on one or a few endangered species may potentially threaten other species of management concern. Spatially explicit population models are a useful tool in designing modifications of management plans that can reduce the impact on nontarget species of management concern.     

首钢大石河铁矿采用“内循环方式”回收尾矿金属

针对当前黑色治金矿山企业选矿生产尾矿品位上升、金属流失严重问题,阐述了利用原有设备实施工艺改造,探索采用“内循环方式”回收尾矿金属,以降低尾矿品位,提高经济效益,节约矿石资源。     

An active region model for capturing fractal flow patterns in unsaturated soils: model development

Preferential flow commonly observed in unsaturated soils allows rapid movement of solute from the soil surface or vadose zone to the groundwater, bypassing a significant volume of unsaturated soil and increasing the risk of groundwater contamination. A variety of evidence indicates that complex preferential patterns observed from fields are fractals. In this study, we developed a relatively simple active region model to incorporate the fractal flow pattern into the continuum approach. In the model, the flow domain is divided into active and inactive regions. Flow occurs preferentially in the active region (characterized by fractals), and inactive region is simply bypassed. A new constitutive relationship (the portion of the active region as a function of saturation) was derived. The validity of the proposed model is demonstrated by the consistency between field observations and the new constitutive relationship.     

Degradation of RPA 202248 [U-14C-phenyl]alpha(-(cyclopropylcarbonyl)-2-(methylsulfonyl)-beta-oxo-4-(trifluromethyl)benzenepropanenitrile), the primary degradation product of isoxaflutole, in an outdoor aquatic microcosm system

Isoxaflutole, the active ingredient in BALANCE WDG and BALANCE PRO corn herbicides and a co-formulant with the herbicide flufenacet in the product EPIC, is readily degraded in soil and water to RPA 202248 alpha(-(cyclopropylcarbonyl)-2-(methyvlsulfonyl)-beta-oxo-4-(trifluromethyl)benzenepropanenitrile). Because RPA 202248 is responsible at the molecular level for isoxaflutole's herbicidal activity it is important to understand the environmental behavior of the degradation product. Laboratory studies suggest that RPA 202248 is stable to hydrolysis and photolysis in aqueous systems and hence poses a possible environmental concern. As part of a program of work towards understanding the actual field situation, an outdoor microcosm study was carried out. Over the course of the 29-day study, residues remained predominantly in the aqueous phase. A slow but steady degradation of RPA 202248 was observed leading to the formation of RPA 203328 (2-methylsulfonyl-4-trifluoromethylbenzoic acid), which has no herbicidal activity. The half-life of RPA 202248 was calculated to be 103 days. These findings indicate that aqueous degradation should be considered as a potential route of dissipation when assessing the fate of RPA 202248 in large scale impounded water bodies, such as ponds, lakes, or reservoirs in the Mid-West Corn Belt.     

机械镀锌工艺的清洁生产

结合机械镀锌的实际生产过程 ,讨论了机械镀锌实现清洁生产的主要途径 ,并且从工艺过程、经济效益、环境效益 3个方面对机械镀锌进行了综合评价 ,结果表明 ,机械镀锌是切实可行的清洁生产技术     

Human exposure and health risk of alpha-, beta-, gamma- and delta-hexachlorocyclohexane (HCHs) in Tianjin, China

The dynamic exposures to HCHs of individuals born between the years 1913 and 1993 in Tianjin have been simulated by connecting a fugacity model (IV) with a multimedia exposure model. Ingestion is the most important pathway for human beings to take up HCHs, and concentrations in the human body correlate with body weight changes. Accumulations of HCHs were derived assuming that the degradation in human body behaved linearly. The health risk of exposure to HCHs was measured using cancer risk and loss of life expectancy (LLE), and LLE was modified from its original definition to incorporate a dynamic calculation that takes variances in exposure into account. Monte-Carlo simulations were run to analyze the uncertainties of the model.     

Incineration of paper sludge in a prototype vortexing fluidized bed combustor

All experiments were carried out in a prototype vortexing fluidized bed combustor (VFBC). The dimension of the combustion chamber is 0.7 x 1.4 x 2 m, and the freeboard section is 1 m i.d. and 4 m in height. Paper sludge was used as the feeding material. Two types of coal particles were employed as the supplementary fuel. In order to understand the characteristics of the VFBC system for paper sludge incineration, the effect of various operating parameters, such as the primary airflow, excess air ratio, and secondary airflow rates, on temperature distribution, ash elutriation, combustion efficiency, and pollutant emissions were investigated.     

Mechanism of PCBs formation from the pyrolysis of chlorobenzenes

Polychlorinated biphenyls (PCBs) were formed by pyrolysis of chlorobenzenes in a HCl atmosphere. Varieties of substituted chlorobenzenes were used as model compounds to optimize the condensation reaction. Lower chlorinated benzenes produce more PCBs than that of higher ones. Up to 0.7 microg PCBs/mg 1,2,3-trichlorobenzene was produced through the condensation reaction.     

Effects of metabolites of benzo(a)pyrene on unschedule DNA synthesis in BALB/3T3 cell line

In order to explore the damage from metabolites of benzo(a)pyrene on DNA of mammalian cells, the effects of four metabolites of benzo(a)pyrene (anti-BPDE, syn-BPDE, 3-OH-BP and 9-OH-BP) on synthesis of DNA and unschedule DNA synthesis (UDS) in BALB/3T3 cells were assayed, by methods of single-labeling and double-labeling. The results showed that all of the four agents were able to increase the synthesis of DNA, but only three of them (apart from syn-BPDE) induced UDS in BALB/3T3 cells. The above indicates that the metabolites of benzo(a)pyrene are able to damage DNA in BALB/3T3 cells, and that this effect may be relative to the sterical structure of metabolites of benzo(a)pyrene.     

A triple-continuum approach for modeling flow and transport processes in fractured rock

This paper presents a triple-continuum conceptual model for simulating flow and transport processes in fractured rock. Field data collected from the unsaturated zone of Yucca Mountain, a repository site of high-level nuclear waste, show a large number of small-scale fractures. The effect of these small fractures has not been considered in previous modeling investigations within the context of a continuum approach. A new triple-continuum model (consisting of matrix, small-fracture, and large-fracture continua) has been developed to investigate the effect of these small fractures. This paper derives the model formulation and discusses the basic triple-continuum behavior of flow and transport processes under different conditions, using both analytical solutions and numerical approaches. The simulation results from the site-scale model of the unsaturated zone of Yucca Mountain indicate that these small fractures may have an important effect on radionuclide transport within the mountain.