Due to the appearance of intensive livestock-rearing systems since the 1970s, a vast amount of liquid manure (slurry) has been produced. The application and utilization are partly regulated for this special substance, which contains urine, excrement, process water, and other chemicals, such as insecticides and disinfectants. Our research was conducted on a slurry management system of a dairy cattle farm, focusing on the investigation of the presence of oestrogenic substances and toxicity of slurry before and after using a separator technology. Yeast oestrogen screen shows in this study that the separation of the liquid and solid phases of slurry contributes to the reduction in oestrogenic substances. Based on the toxicological studies, the growth inhibition of algae was 93%, and the inhibition of the germination of higher plant seeds was 25%, without separation. After separation of the phases, growth and germination were comparable with the negative control; moreover, some stimulation was detected. Consequently, harmful substances were removed with the suspended solid phase. From the present study, we can conclude that stakeholders should support separation technology in intensive livestock-rearing systems, and ecotoxicological investigations obviously help the risk management of slurry utilization. To our best knowledge, this is the first paper presenting detailed and complex toxicological study on slurry samples.
Many waterbirds used to feed mainly on land but spend a considerable amount of time at waterbody for roosting. These waterbirds are known to bring a considerable amount of nutrients from terrestrial to the aquatic ecosystem with their faeces. In small waterbody, large congregations of waterbirds can cause huge nutrient loading to the lake. This sometimes may exceed 70% of the total lake nutrient budget. The present study intends to investigate the importance of waterbirds in terms of nutrient loading with faecal matter. The study was conducted at a shallow, eutrophic lake with high winter avian congregation and negligible anthropogenic nutrient input. Daily dropping production by individual waterbird, elemental concentration in dropping, individual species count and lake use pattern by waterbirds have been taken into consideration for the nutrient loading estimation by waterbird. Waterbirds were found to be the most important nutrient source to the lake, contributing about 89.5% of total nitrogen (N) and 89.9% of total phosphorous (P). Waterbirds contribute 370 kg year−1 (17.68 g m−2 year−1) and 67 kg year−1 (3.21 g m−2 year−1) of N and P, respectively, to the waterbody. Among waterbirds, Dendrocygna javanica was found to contribute the most amount of nutrients to the lake. Apart from waterbirds, precipitation was found to be the second important nutrient source to the lake. It was found that the lake receives most of the nutrients during winter due to high winter avian congregations. The present study concludes that waterbirds are the most important nutrient source for the studied lake. This study highlights the potential of waterbirds as a eutrophicating agent and future research should include it in eutrophication research if present at a high number. After all, this kind of study in the tropical/subtropical region is lacking and this study could put a light on the importance of waterbirds in this kind of system.
The Caatinga is a Brazilian biome, which belongs to the group of dry tropical forests and constitutes one of the largest semiarid areas in the world, with high housing levels of biodiversity. Despite this, the biome has been intensely impacted by anthropic interference, which makes sustainable forest management (SFM) practices an opportunity to associate the conservation of the biome with the generation of income. However, the effects of different SFM practices on the Caatinga balance have not yet been addressed, especially concerning soil and litter. This study aims to answer the following questions: (1) Do forest management practices influence leaf litter’s decomposition and chemical composition? (2) Does the effect of forest management on litter decomposition vary according to its level of intervention in the vegetation? For this, the leaf litter decomposition was evaluated in three forest management conditions and a control condition: clear cutting (CC), selective cutting by minimum diameter (SCD), selective cutting by species (SCS), and unmanaged Caatinga (UC). Decomposition was evaluated using the litterbags method over 260 days. The levels of total nitrogen, polyphenols, lignin, and cellulose in the leaf litter were determined at the beginning and end of the experiment. Our results showed the participation of leaves in the total litter (CC = 15%; SCD = 24%; SCS = 46%; UC = 55%). In all treatments, the leaf material decomposition process occurred with greater intensity after 120 days, reaching losses greater than 33% at 180 days. The management SCS is the practice that most favors the litter decomposition process with the most expressive value of k constant (0.0038 g g−1 dia−1) and half-life of 182 days compared to the others and may have future implications for nutrient cycling. On the other hand, CC and SCD were the practices that most increased the amount and composition of the accumulated litter and the mineralization of chemical compounds of the leaf litter.
Manganese oxides loaded cellulose, lignin, and rice husk catalysts were prepared by in situ reduction of permanganate. CV, FT-IR, SEM–EDS, TGA, XPS, and XRD analyses were applied to characterize the obtained catalysts. Mn 2p band deconvolution revealed Mn2O3 and MnO2 phases for modified rice husk and cellulose, while amorphous Mn3O4 and MnO2 phases were found for modified lignin. The morphology of MnO2/Mn3O4@KL presents micro/nanospherical particles with aggregation, giving rise to large agglomerations. The relative atomic concentrations of total manganese oxides in fresh catalysts are about 2%, 2.6%, and 6.3% for modified lignin, cellulose, and rice husk, respectively. The photocatalytic degradation of methylene blue on the modified lignin catalyst (60%) was higher than those of modified rice husk (40%) and cellulose (26%), due to the surface charge state and the strong adsorption affinity of lignin-based catalysts with dye. At the optimal contact time of 10 min, the decoloration rate of the modified lignin was higher than 98% for 10 mg/L dye concentration with a catalyst dose of 1 g/L. However, an increase in the initial concentration of dye affects the decoloration rate constants of the modified lignin. The pseudo-first-order rate equation described the kinetic decoloration of methylene blue dye with good correlation coefficients. MnO2/Mn3O4@KL as a low-cost and effective material for the removal of methylene blue may become an alternative catalyst to reduce wastewater pollution.
Concerns about the growing trend of population and limited resources resulted in valuing sustainability and enhancing production. Discussion about new developments, environment, and productions cannot be complete without the sustainability model. Emergy analysis is one of the main tools to measure the sustainability of ecosystems by analyzing inputs, services, and energies with a nature-oriented approach. Accordingly, the present study strived for assessing ecological sustainability from emergy, greenhouse gas (GHG) emissions, and economic viewpoints in rice and wheat production in the province of Mazandaran, Iran. It was concluded that fuel contributes more to GHG emissions with shares equal to 53.89% and 50.6% in the production of rice and wheat, respectively. The average total GHG emissions in rice and wheat production in the region were also 1493.8 kgCO2eq/ha and 837.3 kgCO2eq/ha, respectively. Besides, the average total energy supporting rice and wheat production was estimated at 5.36E + 16 and 5.95E + 16 seJ/ha, respectively. The average modified environmental loading index for wheat and rice was 9.75 and 32.9, respectively. These values were larger than the results reported in the relevant studies, which reflect that there is heavy pressure on the environment due to such agricultural practices. The average environmental sustainability index was also 0.11 and 0.05 for rice and wheat, respectively. The smaller environmental sustainability index as compared to similar studies reflected the lower sustainability of these systems. Economic analyses revealed that the average total net returns of rice and wheat production were 16,980.51 and 1151.34 US$/ha, respectively. Therefore, rice production is more sustainable than wheat production. It is recommended to produce rice and wheat with more caution in this region, especially concerning chemical-based fertilizers and fuel consumption.
The production with increasing demands maintaining the balance of nature and natural diversity is the most challenging part of the agricultural system. However, pests and other insect populations are significant obstacles to the continuous food supply. This study proposes a crop pest management mathematical model using the predator (pests’ natural enemy) and viral infection through bio-pesticides. Impulsive differential equations have been implemented to study the dynamics between all populations, considering the repetitive release of virus micro-pesticides and predator insects in the crop field. The hypothesized model gives the outlook of complex natural dynamics. Two types of scenarios have been analyzed here using the model: One deals with the complete eradication of the field’s pest population, and another is sounder from a biodiversity conservation perspective, that defines the minimum pest population below the economic injury level, which is, nowadays, the major challenge in the agricultural field. Numerical examples show that pest management is successful when considering the minimum pest level that keeps the economic threshold by optimizing predator and virus levels cost-effectively.
Wastewater treatment in the textile factory produces sludge classified as toxic and hazardous waste, which is harmful if left untreated. This study assessed the potential of utilizing sludge from a textile factory in Bandung Regency, Indonesia, as a co-firing fuel in coal boiler furnaces employed in the factory. The study aimed to improve the performance of sludge to meet the required standards for fuel substitution. The analysis involved proximate, ultimate, and ash element tests with correlation of the results with calorific values. The sludge was mixed with coal bottom ash produced by the textile factory and biomass (local refuse-derived fuel) at different ratios. An environmental impact analysis was also carried out with the toxicity characteristic leaching procedure (TCLP) and air emission testing. The results showed that the sludge did not meet the fuel substitution requirements if it was used as a single material. However, the sludge could be used as a substitute for coal by mixing it with bottom ash and biomass; the optimum composition was a ratio of 20% sludge, 40% bottom ash, and 40% biomass by weight. TCLP and air emission test results showed that this mixture was safe for human health and the environment and met the fuel substitution requirements. This study provides a practical solution to the problem of reducing toxic and hazardous waste.