An experiment was conducted under hydroponic culture conditions to determine effects of nutrient deficiencies on cadmium (Cd) accumulation of Tagetes erecta L. and its possible mechanisms. Seedlings of similar size were pre-cultured in either N- or P- deprived nutrient solution for 7 days before exposure to 0.1 mg Cd L-1. The control plants had normal nutrient supply before and during Cd exposure. The plants were harveste after 7 days exposure to Cd. In N-deprived plants, Cd levels in roots, stems and roots were significantly reduced, which was consistent with a decrease of phytochelatins (PCs) in roots. Cd accumulation was the lowest in N-deficient plants, corresponding to substantial decreases in organic acids. In P-deprived plants, the obvious increase of Cd content in the root and stem and decrease of Cd content in the leaf accorded with increases of citric acid in the root and malic acid in the stem, supporting the suggestion that organic acids sequester soluble Cd and reduce Cd transport into the leaf.

Hydroponic experiments were carried out to study the effects of cell division inhibitor (Maleic hydrazide MH) and protein synthesis inhibitor（Cycloheximide CHI）on Cd accumulation in Tagetes erecta L and their possible mechanisms. Seedlings were exposed to 4 mmol L-1 MH or 3 µmol L-1 CHI in 0.1 mg L-1 Cd-containing solution for 3 days. After treatment, the Cd content in leaves was significantly (P<0.05) reduced under MH or CHI treatment, which was consistent with the decreased soluble protein contents in leaves, suggesting that protein synthesis plays a role in Cd accumulation in leaves of Tagetes erecta L. Both of the plant growth inhibitors led to increased Cd contents in roots compared with the control, corresponding with increased GSH, Cys or γEC content under MH or CHI treatment, indicating that those S-containing compounds may be related to the increased Cd content in roots under the plant growth inhibitor treatments. On the other hand, the two inhibitors increased the citric acid content in all the tissues of Tagetes erecta L except for that in leaves under CHI treatment. All the results suggest that protein synthesis may be responsible for Cd accumulation in leaves of Tagetes erecta L, while the S-containing compounds and organic acids are associated with Cd absorption in roots of Tagetes erecta L.

A hydroponic culture experiment was conducted to study the effect of temperature and nutrient level on Cd accumulation inTagetes erectaL.. In the first experiment, shoot Cd accumulation and transpiration rate at different temperature was determined. Cd accumulation was lower with higher transpiration rate at 35°C than that of 25°C or 15°C with lower transpiration rate. In the other experiment, cadmium accumulation of plants varies significantly under the condition of different nutrient supplication. Contents of Cd in roots were not high, but the contents of Cd in shoots were the highest when plants were cultivated in 0.05-fold Hoagland’s solution. Roots Cd accumulation decreased as the concentration of single nutrient element (N, P, S) decrease or absence, and shoots Cd accumulation decrease in the condition of sulfur deficiency and sulfur absence. It was shown that transpiration is not the primary factor affecting Cd accumulation inTagetes erectaL, but growth rate of plants has certain correlation with Cd accumulation; contents of Cd in roots are most affected by the supplication of nutrient elements, yet shoots accumulation is relatively lagging behind; different nutrient element has some different effect on Cd accumulation, and the effects of nitrogen and sulfur on the shoots Cd accumulation are the greatest.

Toxic data of local fishes was very essential in the derivation of local water quality criteria. In this study, two local fishes (S.dabryi and P.parva) of Liao River were chosen to conduct 96-h acute toxic data under ammonia (total ammonia) whose pollution was proved to be serious in Liao River. 96 h LC50s of S.dabryi and P.parva under total ammonia were 35.36 mg/L (pH=7.50, T=20.00°C) and 30.35 mg/L (pH=7.50, T=20.00°C), respectively. These toxic values could be used to supply the local database which was the basement to formulate site-specific water quality criteria accordingly in Liao River.