Solar radiation synthetic series for power purchase agreements

The present paper proposes a methodology based on the implementation and assessment of autoregressive (AR) solar radiation models for generating synthetic series and providing guidance on bidding strategies for power purchase agreements. The work considered conventional and periodic AR models with different lag orders, assessing the models against real solar radiation measurements. The synthetic series generation process developed 1000 1-year monthly solar radiation scenarios that were later employed for simulating electric energy production and power purchase agreement models. This application allowed one to evaluate the risk associated with the energy supply security, supporting bidding strategies in energy auctions. A real study case is also illustrated in detail, referring to a spot in the Brazilian best irradiance area.

     

Underestimation of phosphorus fraction change in the supernatant after phosphorus adsorption onto iron oxides and iron oxide–natural organic matter complexes

The phosphorus(P) fraction distribution and formation mechanism in the supernatant after P adsorption onto iron oxides and iron oxide-humic acid(HA) complexes were analyzed using the ultrafiltration method in this study.With an initial P concentration of 20 mg/L(I =0.01 mol/L and pH = 7),it was shown that the colloid(1 kDa-0.45 μm) component of P accounted for 10.6%,11.6%,6.5%,and 4.0%of remaining total P concentration in the supernatant after P adsorption onto ferrihydrite(FH),goethite(GE),ferrihydrite-humic acid complex(FH-HA),goethite-humic acid complex(GE-HA),respectively.The 1 kDa component of P was still the predominant fraction in the supernatant,and underestimated colloidal P accounted for 2.2%,55.1%,45.5%,and 38.7%of P adsorption onto the solid surface of FH,FH-HA,GE and GE-HA,respectively.Thus,the colloid P could not be neglected.Notably,it could be interpreted that Fe~(3+) hydrolysis from the adsorbents followed by the formation of colloidal hydrous ferric oxide aggregates was the main mechanism for the formation of the colloid P in the supernatant.And colloidal adsorbent particles co-existing in the supernatant were another important reason for it.Additionally,dissolve organic matter dissolved from iron oxide-HA complexes could occupy large adsorption sites of colloidal iron causing less colloid P in the supernatant.Ultimately,we believe that the findings can provide a new way to deeply interpret the geochemical cycling of P,even when considering other contaminants such as organic pollutants,heavy metal ions,and arsenate at the sediment/soil-water interface in the real environment.     

Influence of pyrolysis temperature on production and nutrient properties of wastewater sludge biochar

The important challenge for effective management of wastewater sludge materials in an environmentally and economically acceptable way can be addressed through pyrolytic conversion of the sludge to biochar and agricultural applications of the biochar. The aim of this work is to investigate the influence of pyrolysis temperature on production of wastewater sludge biochar and evaluate the properties required for agronomic applications. Wastewater sludge collected from an urban wastewater treatment plant was pyrolysed in a laboratory scale reactor. It was found that by increasing the pyrolysis temperature (over the range from 300 °C to 700 °C) the yield of biochar decreased. Biochar produced at low temperature was acidic whereas at high temperature it was alkaline in nature. The concentration of nitrogen was found to decrease while micronutrients increased with increasing temperature. Concentrations of trace metals present in wastewater sludge varied with temperature and were found to primarily enriched in the biochar.     

Stochastic growth reduces population fluctuations in Daphnia-algal systems

Deterministic, size-structured models are widely used to describe consumer-resource interactions. Such models typically ignore potentially large random variability in juvenile development rates. We present simple representations of this variability and show five approaches to calculating the model parameters for Daphnia pulex interacting with its algal food. Using our parameterized models of growth variability, we investigate the robustness of a recently proposed stabilizing mechanism for Daphnia populations. Growth rate variability increases the range of enrichments over which small-amplitude cycles or quasi-cycles occur, thus increasing the plausibility that the underlying mechanism contributes to the prevalence of small-amplitude cycles in the field and in experiments. More generally, our approach allows us to relate commonly available information on variance of development times to population stability.     

Comparison of statistical and theoretical habitat models for conservation planning: the benefit of ensemble prediction

Selection of a modeling approach is an important step in the conservation planning process, but little guidance is available. We compared two statistical and three theoretical habitat modeling approaches representing those currently being used for avian conservation planning at landscape and regional scales: hierarchical spatial count (HSC), classification and regression tree (CRT), habitat suitability index (HSI), forest structure database (FS), and habitat association database (HA). We focused our comparison on models for five priority forest-breeding species in the Central Hardwoods Bird Conservation Region: Acadian Flycatcher, Cerulean Warbler, Prairie Warbler, Red-headed Woodpecker, and Worm-eating Warbler. Lacking complete knowledge on the distribution and abundance of each species with which we could illuminate differences between approaches and provide strong grounds for recommending one approach over another, we used two approaches to compare models: rank correlations among model outputs and comparison of spatial correspondence. In general, rank correlations were significantly positive among models for each species, indicating general agreement among the models. Worm-eating Warblers had the highest pairwise correlations, all of which were significant (P < 0.05). Red-headed Woodpeckers had the lowest agreement among models, suggesting greater uncertainty in the relative conservation value of areas within the region. We assessed model uncertainty by mapping the spatial congruence in priorities (i.e., top ranks) resulting from each model for each species and calculating the coefficient of variation across model ranks for each location. This allowed identification of areas more likely to be good targets of conservation effort for a species, those areas that were least likely, and those in between where uncertainty is higher and thus conservation action incorporates more risk. Based on our results, models developed independently for the same purpose (conservation planning for a particular species in a particular geography) yield different answers and thus different conservation strategies. We assert that using only one habitat model (even if validated) as the foundation of a conservation plan is risky. Using multiple models (i.e., ensemble prediction) can reduce uncertainty and increase efficacy of conservation action when models corroborate one another and increase understanding of the system when they do not.     

Avoidance of death and injury through mionitoring of dams and flood evacuation in Essex, Connecticut, June 1982

During a period of heavy ranfall in Essex, Connecticut, on 4th and 5th June 1982, dams in the town along the Fall River were monitored for signs of braks. The observation of water spilling over one of teh dams at 10 p.m. in 5th June ld to the decision to evacuate community rsidents. The notification and avacuation process was conducted by the cvolunteer fire department over a two-hour periopd. At 12.30 a.m 6th June, the upper dam on the Fall River gave way, rsulting in a rapidly moving floodwave which sequentially destroyed four additional dams along the river. Although there was extensive property damage, gthere were no serious injuries and no deaths. The responsible actons of the town officials in monitoring the dams during the period of heavy rainfall permitted the evacuation order to be given in sufficient time to evacuate the residnts. The success of the evacuation was the result of good communication, trust, and co-operation between town officials and the community.     

Lithium bioaccumulation in Lentinus crinitus mycelia grown in media with different lithium sources and pH values

Environmental Science and Pollution Research - Lentinus crinitus bioaccumulates lithium in mycelia, but bioaccumulation may be affected by pH of the culture medium. Lithium is used in clinical...     

Assessment and Prediction of Soil Erosion and its Impact on the Storage Capacity of Reservoirs in the Bharathapuzha River Basin,India

Environmental Modeling & Assessment - Soil, one of the non-renewable resources on this planet, is being depleted at an alarming rate due to various anthropogenic activities. The effect of soil...     

Phytotoxic effects of phenolic acids from <Emphasis Type="Italic">Merostachys riedeliana,</Emphasis> a native and overabundant Brazilian bamboo

Merostachys riedeliana Rupr. is a native and overabundant bamboo species in the Brazilian Atlantic Forest. Moderate to strong allelopathic activity may be one mechanism that explains this super-dominance and the changes in structure and composition of forest areas occupied by bamboo. This study evaluated the phytotoxic effect of M. riedeliana extracts and fractions and identified their putative allelochemicals. We investigated the presence of allelochemicals in soil collected from stands occupied by M. riedeliana. Furthermore, we evaluated the putative effect of tree allelochemicals, individually and combined, on germination and growth. The aqueous extract of leaves and its ethyl acetate fraction presented the highest inhibitory effects on seed germination and seedling growth. The effect of the extracts and fractions on the target species was species-specific. Neither the individual nor the combined phenolic acids significantly inhibited seed germination; however, a pronounced growth inhibition was observed in M. bimucronata seedlings treated with vanillic acid and in E. verna and M. bimucronata seedlings treated with combined phenolic acids. Isovitexin, vitexin, isoorientin, orientin, and their O-glycoside derivatives, the lactonic dimer of the p-hydroxybenzoic acid and 3,4-methylenedioxymandelic acid were identified in the aqueous extracts and ethyl acetate fraction by Liquid Chromatography-Diode Array Dectector/Electrospray Ionization/Mass Spectrometry (LC-DAD/ESI–MS/MS). The Gas Chromatography-Mass Spectrometer (GC–MS) profile of the same extract and fraction showed the presence of benzoic, benzeneacetic, salicylic, p-hydroxybenzoic, p-hydroxyphenylacetic, vanillic, p-coumaric, protocatechuic, syringic, gallic, m-coumaric vanillylmandelic, 4-methylmandelic, 3,4-methylenedioxymandelic and trans-ferulic acids. The p-benzoic acid and the apigenin 6-C-glucoside (isovitexin) were identified in the soil extract collected from under bamboo-growing areas. Even though laboratory bioassays are not completely predictive of the allelopathic effects that occur in nature, the results of this study provide preliminary evidence of allelopathy as a possible species-specific inhibition mechanism of native species that explain the impoverishment of floristic richness and the functional groups in areas where M. riedeliana is overabundant.