Objectives. To characterize the total content of heavy metals (Cd, Cr, Cu, Hg, Mo, Ni, Pb, and Zn) and trace elements (As and Se) of interest, their bioavailability and solubility during the composting of cow manure and tree litter in piles inoculated with beneficial microorganism (IBM), or not inoculated (NBM), on the university campus of the Universidad Nacional Agraria La Molina (UNALM). Methods. The investigation evaluated composting in six piles, three IBM piles and three NBM piles, for 120 days. Every 30 days, a composite sample was taken from each pile. The raw materials used were cattle manure and tree litter. The variables analyzed were the total concentrations (content) of metals and trace elements of interest, extracted with diethylenetriaminepentaacetic acid/pentatetic acid (DTPA) (for the bioavailability study) and extracted with deionized water (for the solubility study). Results. The average values (n = 3) of the total content (mg.kg(-1)) on day 120 in IBM were in the following order: Zn (404.33) > Cu (86.33) > Pb (71.2) > Cr (34.33) > As (28.0) > Ni (13.83) > Mo (2.86) > Se (1.38) > Cd (1.32) > Hg (0.39) and in NBM: Zn (466.0) > Cu (112.23) > Pb (73.23) > Cr (35.33) > As (29.67) > Ni (14.37) > Mo (3.23) > Se (1.55) > Cd (1.38) > Hg (0.38). The values complied with the Austrian Compost Standard for Landscaping and Land Rehabilitation and the Peruvian Standard for Nonorganic Agriculture. Significant differences were observed in some elements (p < 0.05) between 0 and 120 days in both types of pile (IBM and NBM). Conclusions. For nonorganic agriculture in Peru, urban compost is recommended, whereby raw organic materials are inoculated with beneficial microorganisms during the composting process to reduce the bioavailability of Cu and Zn, as these elements showed less bioavailability than noninoculated piles. The composting process for both piles (IBM and NBM) reduced the solubility in Cu, Pb, and Zn.

Industrial Manufacturing of Aqueous Solutions of Sodium Sulfhydrate (NaHS 43%) in a Multi-Phase Reactor

This research focused on analyzing the behavior of the hourly average concentrations of PM10 and PM2.5 in relation to vehicular traffic, as well as the effect of relative humidity on these concentrations. Measurements of hourly particulate matter concentrations were recorded by the National Meteorology and Hydrology Service of Peru (SENAMHI) at five surface air quality stations. The profiles of PM10 concentrations are related to traffic behavior, showing high levels of concentrations at peak hours, while the PM2.5 profiles are flatter and better related to traffic in February (summer). The decrease in relative humidity between 80 to 65% in the mornings has a greater effect on the increase in PM10 and PM2.5 concentrations in February than in July (winter), and the increase in relative humidity between 65 to 80 % in the afternoon, it has a greater effect on the decrease in the concentration of PM2.5 in February than in July. The air quality in the north (PPD and CRB stations) and east (SJL station) of the Metropolitan Area of Lima (MAL) are the most polluted. The factors that relate PM10 concentrations with the Peruvian standard in February at these stations were 2.79, 1.78 and 1.26, and in July 2.74, 1.28 and 1.36 respectively. The highest and lowest variability of PM10 and PM2.5 in February and July occurred in the northern area (PPD and SMP stations).

The present study is intended to get to know the levels of perimeter diurnal environmental noise of four hospitals in the city of Lima. The measurement mode used at each hospital was A-weighting, with an integration time of five minutes per recording. It was measured in the FAST mode with calibrations made at the beginning and end of the measurement day. Statistical analysis consisted of the mean comparison T test which was applied at all the hospitals considered in the study. At the four hospitals, at all the hours of measurement and both on working days and non-working days (Sunday), LAeq mean values are higher than 83 dBA. On working days, two periods of maximum noise from 08:00 to 10:00 in the morning and from 17:00 to 19:00 in the afternoon coincide with the start and end of working hours. The perimeter diurnal environmental noise levels determined at the vicinity of four hospitals show higher values in all cases to those established by the Peruvian National Environmental Standards for Noise for special protection areas both for working days and for non-working days. Noise that comes from the dense and disorganized traffic of Lima plays a fundamental role in this behaviour.

The current study aims to discover the chemical-morphological characteristics of PM10 through the analysis of Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and Scanning Electron Microscopy (SEM), respectively, in the Metropolitan Area of Lima (MEAL) in the period from January 04 to 18, 2019. The study also aims to analyze the aerosol optical depth (AOD) in the period from January 1, 2014 to October 15, 2020. The effect of the PM2.5 concentrations on health in 2016 has also been quantified. The results indicate that the daily PM10 value of 50 μg/m3 recommended by the World Health Organization was exceeded on 75% of the monitored days. The morphological analysis of PM10 demonstrated the presence of particles of anthropogenic and geogenic origin. Particles from building activities and secondary aerosol formation were found, as well as particles associated with the resuspension of soil and marine aerosols. In 2016, 718, 1426, and 4295 cases of all-cause mortality, on average, could have been avoided in the MEAL if the annual average of PM2.5 would have decreased from 26.53 μg/m3 to 23.88 μg/m3, 21.22 μg/m3, or 10 μg/m3, respectively. In 2016, 1.58%, 3.14% and 9.47% of all causes are respectively attributed to fine aerosol (PM2.5) over 23.88 μg/m3, 21.22 μg/m3, and 10 μg/m3. Policy makers to legally reduce the PM2.5 concentrations in the MEAL could use this result.

Objectives: The Pb non-biodegradability results in bioaccumulation in living organisms causing serious health disorders. The present study aimed to investigate the capacity of Pb (II) adsorption in aqueous solutions using the Brassica nigra species as biosorbent. Methods: The present study was conducted using a synthetic solution with three Pb (II) concentrations (5, 15, and 30 ppm). The B. nigra was suitably treated until it became dry particles. After sifting it, three ranges of grain sizes were obtained. Samples of dry particles were analyzed before and after the biosorption to analyze their topography (SEM), as well as the elements on their surface (EDS). The influence of different operating variables on the biosorption of Pb (II) were analyzed. Kinetics of Pb (II) biosorption was analyzed with pseudo first and second order models. The biosorption in the equilibrium was studied with the Langmuir isotherm and Freundlich isotherm models. Results: The biosorbent B. nigra showed to be efficient for the adsorption of Pb (II). The most influential variables in the adsorption were pH, particle size, and biosorbent/solution ratio. The optimum pH for the adsorption of lead was 5 and removed 82.10% of lead from solution at 5 ppm, 82.24% at 15 ppm and 57.95% at 30 ppm. The results for the particle size between 177 and 297 μm were 82.65% for 5 ppm, 73.71% for 15 ppm, and 53.54% for 30 ppm. The biosorbent/solution ratio of 0.6 mg/mL or the 30 mg dose of biosorbent removed 80.26% for 5 ppm, 79.32% for 15 ppm, and 59.87% for 30 ppm. Biosorption isothermal data could be well interpreted by the Langmuir model with a maximum adsorption capacity of 53.476 mg/g of lead ion on B. nigra stem and roots biomass. The kinetic experimental data was properly correlated with the second-order kinetic model (R 2 = 0.9997). Thus, the best desorbing agent was HNO 3 (0.1N) for Pb (II) desorption. Conclusion: Our study showed that the herb B. nigra, without any chemical treatment, can be used to remove heavy metals such as Pb (II) from water and aqueous solution.