Effect of application compost and vermicompost from market waste on soil chemical properties and plant growth

This study was conducted to determine the effect of compost and vermicompost from market organic waste on the soil chemical properties and the growth of maize. The treatments tested were three doses of compost (2.5, 5, and 10 t/ha), three doses of vermicompost (2.5, 5, and 10 t/ha), and one control (without compost or vermicompost). At the time of harvest (10 weeks after planting), maize shoot dry weight, root dry weight, cob length, cob diameter, cob with husk, and cob dry weight, as well as the soil chemical properties organic carbon (C), total nitrogen (N), total phosphorus (P), available P, total potassium (K), and pH were observed. Maize plant height, leaf number, and stem diameter were observed at 2, 4, 6, and 8 weeks after planting. The results showed that the application of compost and vermicompost significantly affected soil chemical properties and the yield of maize. The application of 10 t vermicompost/ha resulted in the highest yield of maize and highest increase of soil organic carbon, total phosphorus available phosphorus, total potassium, and pH by 7.21%, 112.41%, 287.44%, 85.44% and 17.58%, respectively. The application of 10 t compost/ha resulted in the highest increase of soil total N by 44%.

Total Phosphorus and Reactive Phosphate Removal from Aquaculture Wastewater using Calcined Eggshell

Phosphorus is the key nutrient in fish feed, and it has been one of the major soluble nutrients found in aquaculture wastewater (AW). This work aims to evaluate the removal of Total Phosphorus (TP) and Reactive Phosphate (PO4 3-) via adsorption in batch studies using thermally calcined eggshell as adsorbent. The effect of calcination temperature (700 – 1000°C), particle size and holding time were investigated. The screening phase showed that calcined eggshell at 800 °C for 30 minutes was the most suitable condition. Characterization of adsorbents revealed that crystalline structure and functional groups were responsible for the TP and PO4 3- removal using calcined eggshell from AW. Adsorption equilibrium was attained after 15 min with the dosage of 0.2 g of the optimized adsorbent, capable of removing more than 97 % of TP and PO4 3- from AW. This finding has proven the ability of calcined eggshell waste as a potential phosphorus adsorbent from liquid effluents.

Dynamic Microbial Network Structure and Assembly Process in Rhizosphere and Bulk Soils Along a Coniferous Plantation Chronosequence

Aims: During plantation development, microbial composition and diversity are critical for the establishment of plant diversity and multiple ecosystem functions. Here we aimed to evaluate the impacts of chronosequence and soil compartment on the bacterial and fungal community compositions, species co-occurrence, and assembly processes in forest ecosystem.Methods: Soils were collected in rhizosphere and bulk soils along a Pinus tabulaeformis plantation chronosequence (15, 30 and 60 years old). The bacterial and fungal communities were determined using amplicon sequencing.Results: The effect of stand age on the soil properties and microbial community structures was stronger than the effect of the soil compartment. In all soil samples, the dominant bacterial phyla were Proteobacteria, Acidobacteria, Actinobacteria, and Chloroflexi. Basidiomycota, Ascomycota, and Mortierellomycota were the dominant fungal phyla. Higher turnover rates of soil microbial communities were observed in rhizosphere soil than in bulk soil. Dispersal limitation governed the bacterial and fungal community assembly in all soil samples, and the fungal community was more susceptible to dispersal limitation. The bacterial and fungal keystone species compositions in the rhizosphere had significant positive correlations with the soil total phosphorus and nitrite nitrogen and total nitrogen and total phosphorus, respectively, indicating their importance in soil nitrogen and phosphorus cycling. The complexity of bacterial networks increased along the chronosequence. Fungal network complexity did not show a clear age-related trend but increased from bulk soil to the rhizosphere.Conclusions: During Pinus tabulaeformis plantation development, soil microbial assembly was less environmentally constrained due to an increase in resource availability.

Research on water environmental capacity accounting of the Yongzhou Section of Xiangjiang River Basin based on the SWAT-EFDC coupling model

In this paper, a coupling model of SWAT (Soil and Water Assessment Tool) and EFDC (Environmental Fluid Dynamics Code) was established, and the relationship between the pollution source and water quality response was identified. Based on the hydrodynamic water quality simulation results and the one-dimensional WEC (water environmental capacity) theoretical formula, the total nitrogen and total phosphorus WEC and the remaining WEC of the Yongzhou Section of Xiangjiang River Basin under the guaranteed rate of 90% and in 2017 were calculated, respectively. It can be seen from the results that the total nitrogen WEC of the Yongzhou Section of Xiangjiang River Basin in 2017 is 27,673.04 t, the total nitrogen WEC under the guaranteed rate of 90% is 19,497.61 t/a and the total phosphorus WEC of the Yongzhou Section of Xiangjiang River Basin in 2017 is 4,877.22 t. The total phosphorus WEC under the guaranteed rate of 90% is 2,936.64 t/a; in 2017, the remaining WECs of total nitrogen and total phosphorus in the entire basin are 14,646.69 and 3,358.67 t, respectively.

Diagnosis of ecological quality of Dohou Lake on the basis of environmental parameters and phytoplankton community, Western Côte d’Ivoire

The ecological quality of Dohou Lake in Duékoué was determined from the phytoplankton community and physico-chemical parameters. All of the stations in Dohou Lake are dominated by Cyanobacteria and Bacillariophyta individuals, with high monthly proportions observed during the study period. Ecological indicators such as total phosphorus, transparency and chlorophyll made it possible to assess the physico-chemical quality of the environment. Thus, mean total phosphorus values ranged from 970 to 1150 µg/L from station D7 to station D6. Minimum transparency values ranged from 0.1 to 0.5 m from station D7 to D3, and mean values ranged from 0.3 m (station D7) to 0.69 m (station D1). For chlorophyll a, mean values ranged from 3.52 µg/L to 12.98 µg/L from station D7 to station D2, with maximum values for this parameter ranging from 13.4 µg/L (station D7) to 46.73 µg/L (station D2). All of the stations on Dohou lake are therefore in an eutrophic state. The monthly variations in the different proportions of phytoplankton groups observed indicate a clear predominance of Cyanobacteria followed by Bacillariophyta. The values of the Planktonic Index (PI) indicate that the stations are in average ecological condition, except for station D7, which is in poor ecological condition. These ecological qualities are reflected by the spatial and temporal dominance of 4 functional groups which are C, LM, K, and S1.

Influence of Anthropogenic Load in River Basins on River Water Status: A Case Study in Lithuania

Twenty-four rivers in different parts of Lithuania were selected for the study. The aim of the research was to evaluate the impact of anthropogenic load on the ecological status of rivers. Anthropogenic loads were assessed according to the pollution sources in individual river catchment basins. The total nitrogen (TN) values did not correspond to the “good” and “very good” ecological status classes in 51% of the tested water bodies; 19% had a “bad” to “moderate” BOD7, 50% had “bad” to “moderate” NH4-N, 37% had “bad” to “moderate” NO3-N, and 4% had “bad” to “moderate” PO4-P. The total phosphorus (TP) values did not correspond to the “good” and “very good” ecological status classes in 4% of the tested water bodies. The largest amounts of pollution in river basins were generated from the following sources: transit pollution, with 87,599 t/year of total nitrogen and 5020 t/year of total phosphorus; agricultural pollution, with 56,031 t/year of total nitrogen and 2474 t/year of total phosphorus. The highest total nitrogen load in river basins per year, on average, was from transit pollution, accounting for 53.89%, and agricultural pollution, accounting for 34.47%. The highest total phosphorus load was also from transit pollution, totaling 58.78%, and agricultural pollution, totaling 28.97%. Multiple regression analysis showed the agricultural activity had the biggest negative influence on the ecological status of rivers according to all studied indicators.

Excessive application of chemical fertilizer and organophosphorus pesticides induced total phosphorus loss from planting causing surface water eutrophication

Total phosphorus (TP) loss from planting was one of the resources causing agricultural non-point source pollution. It is significant to clarify the factors influencing TP loss, as well as explore the relationship between TP loss from planting and surface water eutrophication for making recommendations on the reduction of environmental pollution. In this study, the minimum and maximum of average TP loss was appeared in Qinghai and Shandong province with the TP loss of 7.7 × 102 t and 7.5 × 103 t from 2012 to 2014, respectively. The results of structural equation model (SEM) indicating that the effect of anthropogenic drivers on TP loss was more important than natural conditions due to the higher path coefficient of anthropogenic drivers (0.814) than that of natural conditions (0.130). For anthropogenic drivers, the path coefficients of usage of fertilizer and pesticides, which was often excessively applied in China, were 0.921 and 0.909, respectively causing they the two dominant factors affecting TP loss. Annual precipitation and relative humidity, which were belongs to natural conditions, increased TP loss by enhancing leaching and surface runoff. However, light duration could reduce TP loss by promoting crop growth and increasing TP absorption of crops, with a path coefficient of − 0.920. TP loss of each province in per unit area from planting was significantly correlated with TP concentration of its surface water (p < 0.05), suggesting that TP loss from planting was the main factor causing surface water eutrophication. This study targeted presented three proposals to reduce the TP loss from planting, including promotion of scientific fertilization technologies, restriction of organophosphorus pesticides, and popularization of water saving irrigation technologies. These findings as well as suggestions herein would provide direction for the reduction of TP loss from planting.

Temporal changes in nutrients in a deep oligomictic lake: the role of external loads versus internal processes

The impact of climate change on stratification and mixing patterns has important effects on nutrient availability and plankton dynamics in deep lakes. We demonstrate this in a long-term study of Lake Maggiore, a deep oligomictic lake located in the subalpine lake district in Northern Italy. Studies on physical, chemical and biological features of the lake have been performed continuously since the 1980s. The lake recovered from eutrophication in response to a reduction of catchment nutrient loads and reached a stable oligotrophic status by the end of the 1990s, with average total phosphorus concentrations in the water column around 10 µg L-1. However, both reactive and total phosphorus have slightly increased since 2010, leading to a shift in the lake trophic state towards mesotrophy. The increase in phosphorus has been limited to the hypolimnetic layers, concentrations being fairly stable or decreasing in the epilimnion. Reactive silica also progressively increased in the hypolimnion, while nitrate and total nitrogen concentrations have steadily decreased in both deep and surface layers, especially in the summer period. These changes were assessed in relation to catchment loads, atmospheric deposition and climate-related variations in stratification and mixing patterns and in nutrient retention. Long-term changes in primary production, represented by chlorophyll levels, and biovolume of the main algal groups were also considered. During the eutrophication period and until the 1990s, in-lake phosphorus concentrations were tightly related to external loads; successively, phosphorus and its vertical distribution up the water column became more controlled by internal processes, in particular by stratification and mixing regime. An increase of thermal stability and a reduced frequency and intensity of deep mixing events has fostered oxygen depletion and phosphorus and silica accumulation in the hypolimnion. Another consequence of reduced deep mixing events, has been a reduction in nutrient replenishment of the upper layers at spring mixing. External loads are still the main driver of change for nitrogen compounds: the decrease in the atmospheric load of nitrogen that occurred in the Lake Maggiore area over the last decade, as an effect of reduced nitrogen emissions, has caused decreasing concentration of inorganic nitrogen in the lake. However, the phytoplankton community changes observed might also play a role in nitrogen dynamics, particularly in the nitrate minima observed during summer in recent years.