A methodology for treating missing data applied to daily rainfall data in the Candelaro River Basin (Italy)

Environmental time series are often affected by the “presence” of missing data, but when dealing statistically with data, the need to fill in the gaps estimating the missing values must be considered. At present, a large number of statistical techniques are available to achieve this objective; they range from very simple methods, such as using the sample mean, to very sophisticated ones, such as multiple imputation. A brand new methodology for missing data estimation is proposed, which tries to merge the obvious advantages of the simplest techniques (e.g. their vocation to be easily implemented) with the strength of the newest techniques. The proposed method consists in the application of two consecutive stages: once it has been ascertained that a specific monitoring station is affected by missing data, the “most similar” monitoring stations are identified among neighbouring stations on the basis of a suitable similarity coefficient; in the second stage, a regressive method is applied in order to estimate the missing data. In this paper, four different regressive methods are applied and compared, in order to determine which is the most reliable for filling in the gaps, using rainfall data series measured in the Candelaro River Basin located in South Italy.     

Measuring sustainable urbanization in China: a case study of the coastal Liaoning area

The global urbanization process poses a serious challenge to achieving sustainable development. The significance of sustainable urbanization has been increasingly appreciated, yet, very little empirical evidence has been provided for this prospect. In this paper, we use the Human Development Index and the ecological footprint to measure the sustainability of the coastal Liaoning area. We then use the quadrant map approach to determine the relationship between sustainability and urbanization. The results show that the coastal area has made progress in sustainable urbanization in the social dimension. Improvement in the environmental dimension has been dynamic. Our results indicate that sustainable urbanization is a dynamic, multi-dimensional progress that requires regular monitoring and reevaluation. This paper also highlights the importance of choosing more complete indicators for measuring the sustainability of urbanization, as no single model or measurement is sufficient for quantifying the different dimensions of sustainability.     

Decline in body size and female fraction in the grass snake (Natrix natrix,Linnaeus 1758) population after 40 years (Southern Poland)

Environmental Science and Pollution Research - Depletion of free-living populations is often associated with changes in fitness-related traits, e.g., body size. Ongoing decrease in body size has...     

Microwave pretreatment for enhancement of phosphorus release from dairy manure

Both the advanced oxidation process (AOP) using a combination of hydrogen peroxide addition and microwave heating (H2O2/microwave), and the microwave heating process were used for solubilization of phosphorus from liquid dairy manure. About 80% of total phosphate was released into the solution at a microwave heating time of 5 min at 170 degrees C. With an addition of H2O2, more than 81% of total phosphate could be released over a reaction period of 49 h at ambient temperature. The AOP process could achieve up to 85% of total phosphate release at 120 degrees C. The results indicated that both the microwave, and the AOP processes could effectively release phosphate from liquid dairy manure. These processes could serve as pretreatments for phosphorus recovery from animal wastes, and could be combined with the struvite crystallization process to provide a new approach in treating animal wastes.     

Removal of natural organic matter by cationic hydrogel with magnetic properties

Magnetic cationic hydrogel (MCH) was synthesized, and its removal efficiency and mechanisms in regard to natural organic matter (NOM, represented by humic acid and fulvic acid) from the aqueous environment were studied. The effects of time, adsorbent dosage, initial pH, ionic strength, background ions, and NOM types were also investigated. MCH was characterized and found to have a strong magnetic character, yielding an extra advantage for recycling and reuse. Batch studies showed that the removal of Aldrich humic acid (AHA) by MCH was effective. The main mechanism for the removal of NOM is believed to be due to electrostatic interaction. NOM with larger molecular weight tended to be preferentially removed. Solutions with low pH, high ionic strength, and background electrolytes containing calcium, sulfate and bicarbonate were unfavorable for AHA removal. The adsorption-desorption of MCH was evaluated in three cycles, and demonstrated high regeneration rates.     

Catalytic hydrodechlorination of 1,2-dichloroethane using copper nanoparticles under reduction conditions of sodium borohydride

1,2-Dichloroethane (1,2-DCA) is a raw material used for the manufacture of vinyl chloride monomer (VCM) and therefore has very often been detected in the groundwater nearby the VCM manufacturing plant. Zero-valent iron (ZVI) is capable of degrading a wide array of highly chlorinated contaminants; however, the reactivity of ZVI towards 1,2-DCA is very low. In this study, zero-valent copper nanoparticles have been synthesized for effective dechlorination of 1,2-DCA under reduction conditions of sodium borohydride. Copper nanoparticles consisted of mainly metallic copper (Cu(0)) with small amounts of cuprous oxide (Cu(2)O). They have surface areas of about 19.0 m(2) g(-1) and an average diameter of 15 nm. Batch experiments were conducted to test the effectiveness of copper nanoparticles for 1,2-DCA degradation using sodium borohydride as electron donors where the ORP was measured as -1100 mV. More than 80% of 1,2-DCA (30 mg L(-1)) was rapidly degraded within 2 h in the presence of both copper nanoparticles (2.5 g L(-1)) and borohydride (25 mM). No reduction of 1,2-DCA was observed when the system contained either copper nanoparticles alone or borohydride alone. The degradation intermediates included ethane and ethylene accounting for 79% and ～1.5% of the 1,2-DCA lost, respectively. Potential environmental applications can be achieved by immobilizing copper nanoparticles onto the surface of reducing metals to form a reactive bimetallic structure.     

Performance evaluation of phycocyanin probes for the monitoring of cyanobacteria

The performance of two field probes (YSI 6600 and TriOS), used for the measurement of in vivo phycocyanin fluorescence, was compared and validated in the laboratory in 2008 and 2009 with cultures of Microcystis aeruginosa and field samples. The background noise of the two probes was low and the detection limits were estimated at 1500 cells mL(-1) for the YSI and 0.69 μg PC L(-1) for the TriOS. The linearity and repeatability of both probes have been excellent. Strong relationships were observed between the in vivo fluorescence and the total cyanobacterial biovolume (R(2) = 0.82 YSI; 0.83 TriOS) or the abundance (R(2) = 0.71 YSI; 0.75 TriOS) of cyanobacteria. However, the difference between cell densities determined by microscopy and measured by the YSI can be very large and has been associated to the variability of cell volume among cyanobacteria. This last observation makes the YSI a qualitative tool if a post-calibration is not done. The analysis of filtrated samples showed that dissolved phycocyanin (extracellular) may represent a significant fluorescence signal. No relationship could be established between the abundance, the total cyanobacterial biovolume or the in vivo fluorescence of phycocyanin and the concentrations of cyanotoxins (R(2) ≤ 0.22).