Solar Disinfection of Water for Inactivation of Enteric Viruses and its Enhancement by Riboflavin

Solar disinfection (SODIS) has been described as a cheap and effective method of treating contaminated water to inactivate pathogenic microorganisms. In this study, SODIS was assessed for its efficacy in inactivating three enteric viruses (coxsackievirus B3, coxsackievirus B5 and poliovirus), either on its own or in the presence of riboflavin as a disinfection enhancer. On its own, SODIS produced a reduction of virus infectivity of 4–6 log₁₀ in 6 h. In the presence of riboflavin, inactivation was more rapid in all viruses studied, and with coxsackievirus B5 and poliovirus an extra 1–2 log₁₀ increase in reduction of infectivity was observed after 6 h exposure. This study provides a practical example of low technology methods which could be utilised to provide safe drinking water in various circumstances.     

Composition of Floating Debris in Harbours of the United States

As part of a programme to characterize floating anthropogenic debris in the aquatic environment, the US Environmental Protection Agency (EPA) conducted 18 field surveys in the harbours of major metropolitan cities of the east, west, and Gulf coasts of the United States and the Mid-Atlantic Bight. the surveys were designed to provide information on the types, relative amounts, and distributions of aquatic debris in different geographic regions of the United States. Neuston nets (0.33 mm mesh) were used to collect surface debris during outgoing tides on two or three consecutive days in selected areas of each city. After each net tow, the debris, which ranged in size from small resin pellets to large plastic sheeting pieces, was identified, categorized, and counted. the data are being used to qualitatively characterize aquatic debris in coastal metropolitan areas, to examine potential regional variations, and to tentatively identify potential sources.     

Inferring extinction of mammals from sighting records, threats, and biological traits

For species with five or more sightings, quantitative techniques exist to test whether a species is extinct on the basis of distribution of sightings. However, 70% of purportedly extinct mammals are known from fewer than five sightings, and such models do not include some important indicators of the likelihood of extinction such as threats, biological traits, search effort, and demography. Previously, we developed a quantitative method that we based on species' traits in which we used Cox proportional hazards regression to calculate the probability of rediscovery of species regarded as extinct. Here, we used two versions of the Cox regression model to determine the probability of extinction in purportedly extinct mammals and compared the results of these two models with those of stationary Poisson, nonparametric, and Weibull sighting-distribution models. For mammals with five or more sightings, the stationary Poisson model categorized all but two critically endangered (flagged as possibly extinct) species in our data set as extinct, and results with this model were consistent with current categories of the International Union for the Conservation of Nature. The scores of probability of rediscovery for individual species in one version of our Cox regression model were correlated with scores assigned by the stationary Poisson model. Thus, we used this Cox regression model to determine the probability of extinction of mammals with sparse records. On the basis of the Cox regression model, the most likely mammals to be rediscovered were the Montane monkey-faced bat (Pteralopex pulchra), Armenian myotis (Myotis hajastanicus), Alcorn's pocket gopher (Pappogeomys alcorni), and Wimmer's shrew (Crocidura wimmeri). The Cox model categorized two species that have recently disappeared as extinct: the baiji (Lipotes vexillifer) and the Christmas Island pipistrelle (Pipistrellus murrayi). Our new method can be used to test whether species with few records or recent last-sighting dates are likely to be extinct.     

An invasive riparian tree reduces stream ecosystem efficiency via a recalcitrant organic matter subsidy

A disturbance, such as species invasion, can alter the exchange of materials and organisms between ecosystems, with potential consequences for the function of both ecosystems. Russian olive (Elaeagnus angustifolia) is an exotic tree invading riparian corridors in the western United States, and may alter stream organic matter budgets by increasing allochthonous litter and by reducing light via shading, in turn decreasing in-stream primary production. We used a before-after invasion comparison spanning 35 years to show that Russian olive invasion increased allochthonous litter nearly 25-fold to an invaded vs. a control reach of a stream, and we found that this litter decayed more slowly than native willow. Despite a mean 50% increase in canopy cover by Russian olive and associated shading, there were no significant changes in gross primary production. Benthic organic matter storage increased fourfold after Russian olive invasion compared to pre-invasion conditions, but there were no associated changes in stream ecosystem respiration or organic matter export. Thus, estimated stream ecosystem efficiency (ratio of ecosystem respiration to organic matter input) decreased 14%. These findings show that invasions of nonnative plant species in terrestrial habitats can alter resource fluxes to streams with consequences for whole-ecosystem functions.     

Sensitivity analysis of North American bird population estimates

The Partners in Flight North American Landbird Conservation Plan provided estimates of population sizes for 448 landbird species using a multiplicative model. Input parameters in this calculation included the area of state × Bird Conservation Region polygons, area-specific mean Breeding Bird Survey counts circa 1995, and adjustment factors for the distance over which species may presumably be correctly counted, the assumed pairing of singing males with non-singing females, and variability in the propensity of birds to sing over the course of the survey day. I assessed the sensitivity of this population calculation to changes in the input parameters. I assessed both local and global sensitivity of the model to changes in the parameters with Monte Carlo one-at-a-time simulations and the Fourier amplitude sensitivity test (FAST). Monte Carlo simulations were an estimate of local model sensitivity whereas FAST estimated global model sensitivity, accommodating the potential shared variance between model parameters. Monte Carlo simulations suggested population estimates were 39% more sensitive to changes in the detection distance adjustment than to the other parameters; the other parameters were nearly equal in their contribution to model sensitivity. Conversely, FAST analysis determined that each of the input variables aside from the pair adjustment provided roughly equal contributions to variability in population estimates. The most efficient means for improving continental population estimates for birds surveyed by the Breeding Bird Survey will be through increased scrutiny of the species-specific distance detection and time-of-day adjustments and improved understanding in the spatial and temporal variability in the mean Breeding Bird Survey count.     

Biofuel development, food security and the use of marginal land in China

With concerns of energy shortages, China, like the United States, European Union, and other countries, is promoting the development of biofuels. However, China also faces high future demand for food and feed, and so its bioenergy program must try to strike a balance between food and fuel. The goals of this paper are to provide an overview of China's current bioethanol program, identify the potential for using marginal lands for feedstock production, and measure the likely impacts of China's bioethanol development on the nation's future food self-sufficiency. Our results indicate that the potential to use marginal land for bioethanol feedstock production is limited. Applying a modeling approach based on highly disaggregated data by region, our analysis shows that the target of 10 million t of bioethanol by 2020 seems to be a prudent target, causing no major disturbances in China's food security. But the expansion of bioethanol may increase environmental pressures due to the higher levels of fertilizer use. This study shows also that if China were able to cultivate 45% of its required bioethanol feedstock on new marginal land, it would further limit negative effects of the bioethanol program on the domestic and international economy, but at the expense of having to apply another 750 thousand t of fertilizer.     

Runoff water quality during drought in a zero-order georgia piedmont pasture: nitrogen and total organic carbon

Approximately 11% of the Southern Piedmont (1.8 million ha) is used for pasture and hay production, mostly under low-input management. Few studies have investigated in the region long-term nitrogen and carbon losses in surface runoff, which can be significant. We present 1999 to 2009 hydrologic and water quality data from a rotationally grazed, 7.8-ha, zero-order pasture (W1) near Watkinsville in the Georgia Piedmont. Annual rainfall was 176 to 463 mm below the long-term average (1240 mm) in 7 of the 11 yr. There were 20 runoff events during 86 mo of below-average rainfall (deficit period), compared with 54 events during 46 mo of nondeficit period. Mean event flow-weighted concentration (in mg L) was 0.96 for nitrate-nitrogen (NO-N), 0.97 for ammonium-nitrogen (NH-N), 3.70 for total nitrogen (TN), and 9.12 for total organic carbon (TOC) ( = 43-47; limited due to instrument problem). Nutrient loads (in kg ha per event) averaged 0.04 for NO-N, 0.03 for NH-N, 0.19 for TN, and 0.54 for TOC. Total loads for N and TOC were 6 to 11 times greater from nondeficit than from deficit periods. The observed N concentrations, while well below maximum drinking water standard limits, could pose risk for eutrophication, which can be stimulated at lower concentrations. However, the ability of headwater streams, such as the one downstream of W1, to reduce nutrient concentrations might partially alleviate this concern. The results of this study point to the need to use a long-term dataset that includes measurements made in drought and wet years when evaluating the efficacy of water quality standards.     

Can forest management be used to sustain water-based ecosystem services in the face of climate change?

Forested watersheds, an important provider of ecosystems services related to water supply, can have their structure, function, and resulting streamflow substantially altered by land use and land cover. Using a retrospective analysis and synthesis of long-term climate and streamfiow data (75 years) from six watersheds differing in management histories we explored whether streamflow responded differently to variation in annual temperature and extreme precipitation than unmanaged watersheds. We show significant increases in temperature and the frequency of extreme wet and dry years since the 1980s. Response models explained almost all streamflow variability (adjusted R2 > 0.99). In all cases, changing land use altered streamflow. Observed watershed responses differed significantly in wet and dry extreme years in all but a stand managed as a coppice forest. Converting deciduous stands to pine altered the streamflow response to extreme annual precipitation the most; the apparent frequency of observed extreme wet years decreased on average by sevenfold. This increased soil water storage may reduce flood risk in wet years, but create conditions that could exacerbate drought. Forest management can potentially mitigate extreme annual precipitation associated with climate change; however, offsetting effects suggest the need for spatially explicit analyses of risk and vulnerability.     

Cloning of urea transporters from the kidneys of two batoid elasmobranchs: evidence for a common elasmobranch urea transporter isoform

One of the two phloretin-sensitive, facilitated urea transporters identified from the kidneys of the myliobatiform, euryhaline elasmobranch, Dasyatis sabina, a 379 amino acid protein ([D. sabina]strUT-2), was very similar to the 380 amino acid isoform (shUT) present in the kidney of the squaliform, dogfish shark, Squalus acanthias (a species that can be considered marginally euryhaline since it utilizes upper estuarine, as well as ocean habitats). To test the proposal that this isoform is a conserved urea transporter (UT) expressed in the kidneys of diverse elasmobranchs, UTs were cloned from the kidneys of a rajiform elasmobranch, the stenohaline skate, Leucoraja ocellata and another dasyatid stingray, the marginally euryhaline, Dasyatis say. Utilizing 5′/3′ RACE, a 2,060 nt cDNA that encoded a phloretin-sensitive, 378 amino acid skate urea transporter ([L. ocellata]skUT-2) and a 1,683 nt cDNA that encoded a stingray 379 amino acid UT ([D. say]strUT-2) were obtained. These deduced UTs have a very high sequence identity with the known elasmobranch Uts. [L. ocellata]skUT-2 was 86% identical to [D. sabina]strUT-2 and 84% identical to [S. acanthias]shUT. [D. say]strUT-2 was 97% identical to the [D. sabina]strUT-2. These findings support the hypothesis that a conserved UT isoform is present in the kidneys of marine elasmobranchs, and is an important pathway for facilitated urea transport in the kidneys of marine elasmobranchs. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. H.A. Gefroh and E.E. Cwengros contributed equally to this study.     

种植密度和降水对冬小麦田N2O排放的影响

为研究种植密度对农田N2O排放的影响和探讨N₂O排放季节性波动的原因,于1999～2000年小麦生长季在南京市郊江宁县进行了不同播种量(0、90、180和270kg/hm²)的大田试验.观测分析结果表明:在相同的气象条件和田间管理下,播种～越冬阶段的N₂O排放不受播种量的影响,返青～成熟阶段的N₂O排放通量与播种量成正比.裸地条件下的N₂O排放与播量为90kg/hm²下的排放无明显差异.造成该生长季内N₂O排放季节性波动的主要原因是降水,返青～成熟阶段的N₂O排放通量随观测日前6d的加权平均降水量呈指数增加.