Analysis of transgenic Indian mustard plants for phytoremediation of metal-contaminated mine tailings

Transgenic Indian mustard [Brassica juncea (L.) Czern.] plants overproducing the enzymes gamma-glutamylcysteine synthetase (ECS) or glutathione synthetase (GS) were shown previously to have increased levels of the metal-binding thiol peptides phytochelatins and glutathione, and enhanced Cd tolerance and accumulation. Furthermore, transgenic Indian mustard plants overexpressing adenosine triphosphate sulfurylase (APS) were shown to have higher levels of glutathione and total thiols. These results were obtained with a solution culture. To better examine the phytoremediation potential of these transgenics, a greenhouse experiment was performed in which the transgenics were grown on metal-contaminated soil collected from a USEPA Superfund site near Leadville, Colorado. A grass mixture used for revegetation of the site was included for comparison. The ECS and GS transgenics accumulated significantly (P < 0.05) more metal in their shoot than wild-type (WT) Indian mustard, while the APS plants did not. Of the six metals tested, the ECS and GS transgenics accumulated 1.5-fold more Cd, and 1.5- to 2-fold more Zn, compared with wild-type Indian mustard. Furthermore, the ECS transgenics accumulated 2.4- to 3-fold more Cr, Cu, and Pb, relative to WT. The grass mixture accumulated significantly less metal than Indian mustard: approximately 2-fold less Cd, Cu, Mn, and Zn, and 5.7-fold less Pb than WT Indian mustard. All transgenics removed significantly more metal from the soil compared with WT Indian mustard or an unplanted control. While WT did not remove more metal than the unplanted control for any of the metals tested, all three types of transgenics significantly reduced the soil metal concentration, and removed between 6% (Zn) and 25% (Cd) of the soil metal. This study is the first to demonstrate enhanced phytoextraction potential of transgenic plants using polluted environmental soil. The results confirm the importance of metal-binding peptides for plant metal accumulation and show that results from hydroponic systems have value as an indicator for phytoremediation potential.     

Impacts of nutrient additions and digging for human waste disposal in natural environments, Tasmania, Australia

Very little research has been undertaken on the impacts of human toilet waste disposal in non-serviced sites in the wild. The objective of the present project was to determine the relative impacts of the mechanical disturbance of digging during the burial of toilet waste (faeces and toilet paper), and urination, on Tasmanian vegetation types that occur in areas used for wild country camping, in order to develop appropriate guidelines. The mechanical disturbance of digging cat-holes 15 cm deep, typical of those used for toilet disposal in the Tasmanian wild, had largely negative effects on the growth of a few native plant species. These effects were of little or no conservation significance. The nutrient additions simulated by the addition of artificial urine to undug ground and dug ground had largely positive effects on nine distinct types of native vegetation, encouraging the growth of many plant species at many sites, while discouraging the growth of moss at one site. No weed species found at any of the sites were significantly affected by the treatments. Thus, it appears that scattered disposal of urine, even combined with digging, is unlikely to present a major conservation problem in the Tasmania's wild country, and that present guidelines are appropriate, where achievable.     

Management and valuation of an environmentally sensitive area: Norfolk Broadland,England, case study

Wetlands, like any other environmentally sensitive resource, require very careful evaluation. While it is accepted that all wetlands may be equally valuable in terms of maintaining global life-support systems, individual areas may be ranked according to their uniqueness or the irreplaceability of the resource should the wetland be developed. The various techniques available for evaluating the wetland resource in the development versus conservation conflict situation are critically assessed. Indirect appraisal via the opportunity cost method can generate valuable data which have contributed to the mitigation of such conflict situations.The Broadland, in Norfolk, England, recently designated an environmentally sensitive area (ESA), provides a case study example of wetland management. The search for an acceptable flood alleviation strategy for the ESA is examined in detail. The economic and environmental asset structure of the study area is examined at two levels. A basic screening system is applied to each of the identified flood protection planning units to enable the rank ordering of the units. A more detailed appraisal is then made of the value of selected units so that the cost-effectiveness of any planned expenditure on flood protection works can be assessed. Specific management issues and their likely effect on the environment, in terms of land use for example, are also addressed. The 1986 Agriculture Act marks a potential watershed in British conservation policy. The ESA policy encompasses a dual management strategy that attempts to stimulate compatible agricultural and conservation practices and activities. Other countries that still retain significant unspoiled wetland resources may find that preemptive regulatory government intervention in favor of conservation would help to avoid the worst aspects of the British experience.     

Modeling Stream Channel Characteristics From Drainage‐Enforced DEMs in Puget Sound,Washington, USA1

Abstract: Mapping stream channels and their geomorphic attributes is an important step in many watershed research and management projects. Often insufficient field data exist to map hydromorphologic attributes across entire drainage basins, necessitating the application of hydrologic modeling tools to digital elevation models (DEMs) via a geographic information system (GIS). In this article, we demonstrate methods for deriving synthetic stream networks via GIS across large and diverse basins using drainage‐enforced DEMs, along with techniques for estimating channel widths and gradient on the reach scale. The two‐step drainage enforcement method we used produced synthetic stream networks that displayed a high degree of positional accuracy relative to the input streams. The accuracies of our estimated channel parameters were assessed with field data, and predictions of bankfull width, wetted width and gradient were strongly correlated with measured values (r² = 0.92, r² = 0.95, r² = 0.88, respectively). Classification accuracies of binned channel attributes were also high. Our methodology allows for the relatively rapid mapping of stream channels and associated morphological attributes across large geographic areas. Although initially developed to provide salmon recovery planners with important salmon habitat information, we suggest these methodologies are relevant to a variety of research and management questions.     

Nuptial feeding of spermless spermatophores in the Hawaiian swordtail cricket, Laupala pacifica (Gryllidae: Triginodiinae)

Crickets in the genus Laupala (subfamily Trigonidiinae) have an elaborate courtship system, defined by a highly ritualized serial transfer of multiple spermatophores. Males produce multiple “micro” spermatophores followed by a final “macro” spermatophore during a single mating bout. Remarkably, the microspermatophores of L. cerasina, the first species whose mating system was studied in detail, were discovered to be spermless. However, in a study of another species, L. pacifica, sperm transfer was reported after every copulation suggesting that L. pacifica microspermatophores contain sperm. The presence or absence of sperm in the microspermatophore has important implications for the evolution of this exaggerated courtship system and the origin of nuptial gifts. In this study, we systematically examined L. pacifica spermatophore contents for sperm using a fluorescent nuclear stain. We detected sperm only in macrospermatophores. This finding suggests that spermless microspermatophores are typical for Laupala; thus, to determine the origin of this highly modified phenotype will require comparative analyses with closely related outgroups that exhibit less exaggerated courtship systems.     

Do the risks of predation and intermale competition affect courtship behavior in the salamander Desmognathus ochrophaeus?

Summary Natural populations of mountain dusky salamanders, Desmognathus ochrophaeus (Amphibia: Caudata: Plethodontidae), may experience two types of risk during courtship encounters: interspecific predation, affecting both sexes, and intraspecific competition for mates, affecting males. We conducted two experiments in the laboratory to determine whether and how these two risks influence the outcome of male-female encounters. In experiment 1, courtship interactions resulting in spermatophore deposition were inhibited in the presence of a restrained species of salamander (Gyrinophilus porphyriticus) known to prey on D. ochrophaeus. Probability of successful courtship was not affected by the presence of a restrained species that is not predatory (Plethodon teyahalee). In experiment 2, courtship interactions resulting in spermatophore deposition were inhibited in the presence of two restrained conspecific males, but were unaffected in the presence of a single restrained male. We conclude that the dual risks of predation and intrasexual competition for mates have been significant selective factors in shaping the evolution of courtship decisions in Desmognathus ochrophaeus. Correspondence to: P. Verrell     

Current uses of the EPA lead model to assess health risk and action levels for soil

The EPA lead model predicts mean blood lead levels and risk of elevated blood lead levels in children based on lead uptake from multiple sources. In the latest model versions, environmental data from individual homes within a community can be used to predict the overall blood lead distribution and percent risk of exceeding a specific blood lead level (i.e. 10 g dl^–1). Recent criteria used by the EPA to evaluate this information include no more than 5% of houses with a greater than 5% lead risk, and a community weighted-average risk below 5%. Environmental (primarily soil) and blood lead data from a residential community near a smelter were used to illustrate recent uses of the model. Scheduled remediation in the community will remove soil for approximately 60% of the houses (i.e. those with lead levels > 1000 mg kg^–1). After remediation, the model results indicate a relatively low community risk (0.5–1.9%), although the percentage of houses with lead risks above 5% ranged from 3 to as high as 13%, depending on the variation in blood lead and assuming the model's 7 g dl^–1 increase in blood lead with each 1000 mg kg^–1 increase in soil lead level. A comparison of the limited blood lead data with soil lead levels below 1000 mg kg^–1, however, indicated no apparent relationship. Given these uncertainties, less invasive actions than additional soil removal (e.g. exposure intervention, monitoring conditions, and follow-up as necessary) may be appropriate under the new EPA guidance for lead in soil.     

Evolution of clog formation with time in columns permeated with synthetic landfill leachate

Laboratory column tests conducted to gain insight regarding the biological and chemical clogging mechanisms in a porous medium are presented. To seed the porous medium with landfill bacteria, a mixture of Keele Valley Landfill and synthetic leachate permeated through the column under anaerobic conditions for the first 9 days of operation. After this, 100% synthetic leachate was used. The synthetic leachate approximated Keele Valley Landfill leachate in chemical composition but contained negligible suspended solids and bacteria compared with real leachate. The removal of volatile fatty acids (VFAs), primarily acetate, in leachate as it passed through the medium was highly correlated with the precipitation of calcium carbonate (CaCO(3(s))) from solution. The columns experienced a decrease in drainable porosity from an initial value of about 0.38 to less than 0.1 after steady state chemical oxygen demand (COD) removal, resulting in a five-order magnitude decrease in hydraulic conductivity. The decrease in drainable porosity prior to steady state COD removal was primarily due to the growth of a biofilm on the medium surface. After steady state COD removal, calcium precipitation was at least equally responsible for the decrease in drainable porosity as biofilm growth. Clog composition analyses showed that CaCO(3(s)) was the dominant clog constituent and that 99% of the carbonate in the clog material was bound to calcium.     

Shade and flow effects on ammonia retention in macrophyte-rich streams: implications for water quality

Controlled releases of NH4-N and conservative tracers (Br- and Cl-) to five reaches of four streams with contrasting macrophyte communities have shown differing retentions, largely as a result of the way plants interact with stream flow and velocity. First-order constants (k) were 1.0-4.8 d(-1) and retention of NH4-N was 6-71% of amounts added to each reach. Distance travelled before a 50% reduction in concentration was achieved were 40-450 m in three streams under low-flow conditions, and 2400-3800 m at higher flows. Retention (%) of NH4-N can be approximated by a simple function of travel time and k, highlighting the importance of the relationship between macrophytes and stream velocity on nutrient processing. This finding has significant management implications, particularly with respect to restoration of riparian shade. Small streams with predominantly marginal emergent plants are likely to have improved retention of NH4-N as a result of shading or other means of reducing plant biomass. Streams dominated by submerged macrophytes will have impaired NH4-N retention if plant biomass is reduced because of reduced contact times between NH4-N molecules and reactive sites. In these conditions water resource managers should utilise riparian shading in concert with unshaded vegetated reaches to achieve a balance between enhanced in-stream habitat and nutrient processing capacity.     

Comparison of beach bacterial water quality indicator measurement methods

Three methods (membrane filtration, multiple tube fermentation, and chromogenic substrate technology kits manufactured by IDEXX Laboratories, Inc.) are routinely used to measure indicator bacteria for beach water quality. To assess comparability of these methods, quantify within-laboratory variability for each method, and place that variability into context of variability among laboratories using the same method, 22 southern California laboratories participated in a series of intercalibration exercises. Each laboratory processed three to five replicates from thirteen samples, with total coliforms, fecal coliforms or enterococci measured depending on the sample. Results were generally comparable among methods, though membrane filtration appeared to underestimate the other two methods for fecal coliforms, possibly due to clumping. Variability was greatest for the multiple tube fermentation method. For all three methods, within laboratory variability was greater than among laboratories variability.