Bisphenol A (BPA) is a typical endocrine-disrupting chemical (EDC) used worldwide. Considering its adverse effects, BPA has been banned or strictly restricted in some nations, and many analogs have been introduced to the market. In this study, we selected three representative substitutes, BPS, BPF, and BPAF, along with BPA, to assess the developmental and reproductive effects on Daphnia magna. The F0 generation was exposed to bisphenols (BPs) at an environmentally relevant concentration (100 μg/L) for 21 d; then the embryo spawn at day 21 was collected. Behavior traits, the activity of antioxidant enzymes, and gene transcription were evaluated at three developmental stages (days 7, 14, and 21). Notably, body length, heart rate, and thoracic limb beating were significantly decreased, and D. magna behaved more sluggishly in the exposed group. Moreover, exposure to BPs significantly increased the antioxidant enzymatic activities, which indicated that BPs activated the antioxidant defense system. Additionally, gene expression indicated intergenerational effects in larvae, particularly in the BPAF group. In conclusion, BPA analogs such as BPF and BPAF showed similar or stronger reproductive and developmental toxicity than BPA in D. magna. These findings collectively deepen our understanding of the toxicity of BPA analogs and provide empirical evidence for screening safe alternatives to BPA.

Dramatic changes in lake water conditions may induce sensitive feedback in sediments, such as the release of phosphate and ammonia. There is a lack of the understanding of sediment nutrient release fluxes and their responses to various environmental factors in plateau lakes. In this study, nutrient contents in the water and sediment, sediment nutrient release rates, and their responses to various influential factors in a steppe shallow plateau lake, Lake Hulun, China, were investigated. Sediment is a large store of nutrients, with bioavailable phosphorus of 555 mg kg⁻¹ in surface lake sediments. If water became anoxic, sediments will release appreciable amounts of phosphate (2.1 mg P m⁻² d⁻¹) and ammonia (40.0 mg N m⁻² d⁻¹), three times greater than those in oxic conditions. Raised temperatures greatly increased sediment phosphate release rates, while the highest temperature (23 °C) slightly decreased ammonia release rates due to strong nitrification. Assuming a whole year of internal loading, ammonia and dissolved reactive phosphorus concentrations in water column would increase by an estimated 0.22 mg N L⁻¹ and 0.01 mg P L⁻¹, respectively, which is equal to 2 and 0.5 times of their ambient concentrations. A pH increase from 8.4 to 9.4 significantly decreased internal nitrogen and phosphorus release rates by around three times. Overall, dissolved oxygen (DO) and pH had a greater impact on sediment nutrient release from lake sediments compared to temperature, and further increased the eutrophic status in the overlying water when these three parameters varied within the normal seasonal range (temperature: 1.9–23.1 °C, DO: oxic and anoxic; pH: 7.5–9.4). With the periodic low DO and frequency of drought in the future, lake management strategies that mitigate water eutrophication, such as water diversion, may need to be considered.

Lakes in cold and arid regions are extremely vulnerable to global climate change, and the study of seasonal spatial and temporal fluctuations of lake-groundwater chemistry is of major significance for water resource management and environmental preservation. In this study, we combined hydrogeochemical, multivariate statistical, and spatial interpolation methods to assess spatial and temporal variations of lake and groundwater chemistry in Hulun Lake during the frozen and non-frozen periods. The results show that sodium (Na⁺) is the most abundant cation in the Hulun Lake area. Bicarbonate (HCO₃⁻) and sulfate (SO₄²⁻) are the most predominant anions in the lake, river, and ground water during both seasons. The higher Na⁺ + K⁺ concentrations in the frozen season were related to longer circulation time and lower renewable rate. The water chemistry of the lake was of the HCO₃-SO₄-Cl-Na type and that of groundwater in the east and west regions was of the SO₄-Cl-Na and HCO₃-Na types, respectively. The chemical compositions of groundwater in the non-frozen season were mainly affected by evaporation and concentration, while rock weathering, evaporation, and human activities jointly controlled groundwater chemical component in the frozen period. Based on hierarchical cluster analysis (HCA) and principal component analysis (PCA) methods, Ca²⁺, NO₃⁻, and SO₄²⁻ were identified as the main controlling indicators of the chemical characteristics of groundwater and lake water. The increase of Ca²⁺ concentration in the center of the lake was related to groundwater discharge along the marginal tectonic fracture zone along the lake shores, which was the potential groundwater discharge area. The unconsolidated aquifer provides recharge channels for groundwater on the eastern side, which has a certain influence on the increase of nutrient concentration (NO₃⁻) in the lake on the eastern shore. This research adds to our rough understanding of the lake-groundwater interaction in Hulun Lake, and provides a scientific foundation for the sustainable use of water resources, as well as the eco-logical integrity preservation in cold and arid regions.