Cadmium (Cd) contamination poses a significant threat to ecosystems and human health. Cd stable isotope analysis is increasingly used to identify contaminant sources and track Cd redistribution, but its environmental interpretation remains challenging because source signatures can be modified by isotope fractionation during transport. This review synthesizes recent progress in Cd isotope methods, fractionation mechanisms, environmental reservoirs, source tracing, and cross-media transfer. We organize published evidence around a mechanistic pathway from analytical expression and mass-bias correction to isotope fractionation during evaporation-condensation, biological uptake, adsorption, precipitation, leaching, and soil-plant transport. We further compare isotope behavior in ores, soils, sediments, waters, and biota, and evaluate how isotope signals are preserved or overprinted across rock-soil, water-soil, and soil-plant interfaces. The synthesis shows that Cd isotopes are most reliable for source apportionment when endmembers are isotopically distinct, concentration-isotope mass balances are constrained, and post-source fractionation is explicitly considered. Conversely, overlapping source signatures, limited endmember databases, and incomplete process-specific isotope fractionation offsets (Δ^114/110Cd) remain major obstacles.

The determination of chlorine (Cl) in fertilizers is crucial for plant growth and soil health. Traditional methods such as chemical titration and ion chromatography have limitations including complex sample preparation, time consumption, and high costs. This study proposes a rapid determination method using pressed pellet-wavelength dispersive X-ray fluorescence spectrometry (WDXRF). By optimizing sample preparation conditions (including sample particle size, pressure, and holding time), the optimal measurement time was determined to be 50 s. The method has a detection range of 0.0055–46.51%, with a detection limit of 0.0018%. Sample recovery rates ranged from 90 to 103%. Due to the lack of standard reference materials for fertilizers, the accuracy of the method was verified by spiking solid samples. Compared with traditional methods, this method offers advantages such as high precision, high accuracy, low chemical reagent consumption, and rapid determination, making it suitable for routine analysis of chlorine in fertilizers.