Saline-alkali land is the main reserve soil resource. The amount of arable farmland soil can be increased through improvement and utilization of saline-alkali land. Bio-organic fertilizer is an effective saline-alkali soil conditioner, but there are few studies on the improvement of saline-alkali soil with traditional Chinese medicine residues (TCMRs). In this study, an organic fertilizer made from Ganoderma lucidum residue (GLR) was mixed with saline-alkali soil at different proportions; physicochemical properties, enzyme activity, and microbial community characteristics of the soil were investigated. The results showed that the soil pH, as well as bulk density and electrical conductivity were significantly reduced, while the soil moisture content and porosity were significantly increased after the GLR organic fertilizer incorporation. Soil invertase and soil amylase activities significantly increased, as well as the diversity and richness of the soil microbial community structure. The abundance of the dominant phyla, Bacteroidota, Actinobacteriota, Chloroflexi, Firmicutes, and Basidiomycota, increased, while the abundance of the dominant Proteobacteria and Ascomycota phyla decreased. The best improvement effect is obtained when the application ratio of GLR organic fertilizer is 25%. The findings showed that TCMRs have positive application prospects in saline-alkali soil improvement.

In order to determine the characteristics of phytoplankton community structure in Nanhai Lake in Baotou City and its relationship with environmental factors, water and phytoplankton samples were collected and composition and biomass were investigated at six sites in the spring, summer, and autumn of 2021. This article used correlation analysis and redundancy analysis (RDA) combined with the community turnover index (BC) to analyze the phytoplankton functional groups. The results showed that 7 phyla and 68 genera of phytoplankton were identified in the water body, of which Chlorophyta, Bacillariophyta, Cyanobacteria, Chrysophyta, Euglenophyta, Cryptophyta, and Pyrrophyta accounted for 34%, 32%, 16%, 6%, 4%, 4%, and 3%, respectively. The phytoplankton in the water body was classified into 23 functional groups, of which MP and D functional groups were the long−term dominant functional groups, indicating that the habitat is a turbid water body. The ecological state index (Q) value ranged from 1.94 to 3.13, with an average value of 2.74. The comprehensive nutritional index (TSIM(∑)) was between 49.32 and 52.11, with an average value of 51.72, indicating that Nanhai Lake was in a mesotrophic state. Correlation analysis and redundancy analysis (RDA) showed that multiple nutrients, transparency (SD), chemical oxygen demand (COD), water temperature (WT), and Chlorophyll a (Chl−a) were the main environmental factors affecting the biomass of dominant functional groups in the water body. The study showed the characteristics of the functional groups of algae in a precious urban lake in arid and semi−arid areas of China and their relationship with environmental factors (physical and chemical indicators, anions and cation ions, and heavy metal ions), and provided a scientific basis for its water quality evaluation.

The emerging Arthrospira industry in Ordos utilizes alkaline resources, the discharge of aquaculture wastewater from which may potentially influence the surrounding aquatic environment. Water quality and phytoplankton communities were systematically monitored at three representative ponds in both the green (H-1) and yellow ponds (H-2) of Lake Hammatai (three sites per pond) during April, June, August, and October of 2017 and 2018. Our results showed that phytoplankton biomass and abundance in Lake Hammatai were relatively low compared to other saline–alkaline lakes. The phytoplankton community was primarily dominated by Arthrospira spp. and Chlamydomonas spp. A low TN/TP ratio, together with elevated organic nitrogen concentrations, appeared to jointly facilitate the dominance of Arthrospira spp. Both lake water and wastewater were characterized by Na⁺ as the dominant cation, along with high concentrations of HCO₃⁻ and CO₃²⁻. Redundancy analysis (RDA) identified Na⁺, K⁺, Cl⁻, and HCO₃⁻ as the key environmental factors shaping algal community structure. These findings reveal the potential effects of aquaculture effluent on phytoplankton communities and water chemistry in alkaline lakes, offering insights into the response of fragile ecosystems to anthropogenic disturbances and informing targeted management strategies.