Effects of antibiotics on nitrogen uptake of four wetland plant species grown under hydroponic culture.

To investigate the effects of antibiotics on nitrogen removal and uptake by wetland plants, four typical macrophyte species, Cyperus alternifolius L., Typha angustifolia L., Lythrum salicaria L., and Acorus calamus L., were grown in hydroponic cultivation systems and fed wastewater polluted with 10 µg L-1 Ofloxacin (OFL) and Tetracycline (TET). Biomass production, nitrogen mass concentration, chlorophyll content, root exudates, and nitrogen removal efficiency of hydroponic cultivation were investigated. The results indicated that in all hydroponic systems, NH4+-N was entirely removed from the hydroponic substrate within 1 day and plant nitrogen accumulation was the main role of the removed NO3-. OFL and TET stimulated the accumulation of biomass and nitrogen of A. calamus but significantly inhibited the NO3--N removal ability of L. salicaria (98.6 to 76.2%) and T. augustifolia (84.3 to 40.2%). This indicates that A. calamus may be a good choice for nitrogen uptake in wetlands contaminated with antibiotics. OFL and TET improved the concentrations of total organic carbon (TOC), total nitrogen (TN), organic acid, and soluble sugars in root exudates, especially for oxalic acid. Considering the significant correlation between TOC of root exudates and nitrogen removal efficiency, the TOC of root exudates may be an important index for choosing macrophytes to maintain nitrogen removal ability in wetlands contaminated with antibiotics.

Influence of vegetation type and temperature on the performance of constructed wetlands for nutrient removal.

In this study, the influence of vegetation type and environmental temperature on performance of constructed wetlands (CWs) was investigated. Results of vegetation types indicated that the removal of most nutrients in polyculture was greater than those in monoculture and unplanted control. The greatest removal percentages of NH4+-N, total nitrogen (TN) and total phosphorus (TP) in polyculture were 98.7%, 98.5%, and 92.6%, respectively. In experiments of different temperatures, the removal percentages of NH4+-N, NO3--N, TN and TP in all CWs tended to decrease with the decline of temperature. Especially, a sharp decline in the removal percentages of NO3--N (decreased by above 13.8%) and TN (decreased by above 7.9%) of all CWs was observed at low temperature (average temperature of 8.9 °C). Overall, the performance of CWs was obviously influenced by temperature, and the polyculture still showed best performance in the removal of nitrogen when the average temperature dropped to 19.8 °C. Additionally, the variations of urease activities in rhizosphere soil tended to decrease with the decreasing temperature. Overall, a substantial enhancement for nitrogen and TP removal in polyculture (Canna indica + Lythrum salicaria) was observed. In conclusion, CW cultivated with polyculture was a good strategy for enhancing nutrient removal when temperature was above 19.8 °C.

A comparative study of anti-Candida activity and phenolic contents of the calluses from Lythrum salicaria L. in different treatments.

In the study, anti-Candida activity and phenol contents of Lythrum salicaria L. calli and wild species have been evaluated. The seeds of L. salicaria (Lythraceae), collected from Lahidjan City in the north of Iran, were cultured in Murashige and Skoog medium (MSM) with a supplement, gibberellin, to germinate. Callus inductions were performed from segments of seedling on MSM containing different concentrations of plant growth regulators, 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzylaminopurine (BAP). The activity of calluses extracts, wild plant, gallic acid, and 3,3',4'-tri-O-methylellagic acid-4-O-ß-D-glucopyranoside (TMEG) as the main phenolic compounds against Candida albicans was assessed using cup plate diffusion method. The total phenols contents of calli and wild plant extracts were analyzed using Folin-Ciocalteu reagent. The callus formation in MSM supplemented with various concentrations of 2,4-D and BAP were 0-100 %. Anti-Candida activity of callus extract which obtained from MSM supplemented with 2,4-D and BAP (1 mgdm(-3)) was similar to the wild plant extract. Minimum inhibitory concentration values of gallic acid and TMEG were obtained as 0.312 and 2.5 mgcm(-3), respectively. Gallic acid equivalent values in all treatments were from 0 to 288 µg GAE mg(-1). Phenolic contents of plant aerial parts (331±3.7 µg GAE mg(-1)) and the callus, which developed in MSM including 1 mgdm(-3) of both 2,4-D and BAP, showed the same phenolic value and exhibited anti-Candida extract activity.

Performance of hybrid vertical up- and downflow subsurface flow constructed wetlands in treating synthetic high-strength wastewater.

The performance and temporal variation of hybrid vertical-subsurface flow constructed wetlands (VFCWs) in response to two-stage combinations of vertical upflow (VUF) and vertical downflow (VDF) were analyzed in this research. The results of high carbon (C) treatment and high nitrogen (N) treatment were similar. The Lythrum salicaria treatment showed higher removal efficiency than CWs planted with Acorus calamus. Under high C- and N-loading treatments, the optimum two-stage combination was VDF-VUF VFCWs planted with A. calamus. Furthermore, the highest nutrient removal efficiencies were achieved in late summer (July and August) and early autumn (September). The chemical oxygen demand and total nitrogen removal efficiencies were significantly affected (P < 0.05) by season, system, and wetland plant.

Suspected Lythrum hyssopifolia (lesser loosestrife) poisoning of cattle.

CASE REPORT: Morbidity and mortality in two herds of cattle in southern New South Wales were associated with ingestion of lesser or hyssop loosestrife (Lythrum hyssopifolia). Clinical signs in adult cows included depression, listlessness, inappetence, anorexia and recumbency. Deaths occurred in 16/48 (33.3%) and 4/60 (6.7%) adult cows, but calves in both herds were unaffected. Elevated concentrations of urea and creatinine were present in the serum of one clinically affected cow and an elevated concentration of urea was detected in the aqueous humour of one cow that died. On histopathological examination, there was severe, acute necrosis of the proximal convoluted tubular epithelial cells in the kidneys of both affected cattle examined. CONCLUSION: There is strong evidence that lesser loosestrife is nephrotoxic for cattle.

Phytoremediation of atrazine by three emergent hydrophytes in a hydroponic system.

A hydroponic system was used to evaluate atrazine (ATZ) removal and uptake by three emergent hydrophytes, Iris pseudacorus, Lythrum salicaria and Acorus calamus, determining their potential as phytoremediation agents for ATZ-contaminated water. After 20 days of exposure, the relative growth rate of plants in sterile conditions was less than in natural conditions. ATZ amount in a culture solution planted with emergent plants decreased significantly compared with an unplanted solution, and the removal rate of ATZ in natural conditions was greater than in sterile conditions (p < 0.05). The degradation contributions of I. pseudacorus, L. salicaria and A. calamus were 75.6, 65.5 and 61.8%, respectively. Those of the corresponding microbial population in the solution were 5.4, 11.4 and 17.4%, respectively. Emergent plants play a dominant role in reducing the ATZ level in the water body and could be used as phytoremediation agents.

[Study on the nitrogen and phosphorus uptake ability of four plants cultivated on floating-bed].

Plant floating-bed tested engineering was constructed for eutrophication control in Dian-shan Lake, the characteristics and nutrient uptake abilities of Canna indica, Iris pseudacorus, Thalia dealbata and Lythrum salicaria were compared. It shows that using upper and lower nylon nets to fix the plants on the floating-bed is beneficial for them to grow and reproduce rapidly. Survival rates of Canna indica, lris pseudacorus, Thalia dealbata and Lythrum salicaria are 83.33%, 83.33%, 76.67% and 53.33% respectively. Ramets of Canna indica and Thalia dealbata are 64 and 78 respectively in November, and the biomass (fresh weight) of these two plants are 32.0 and 38.6 kg per individual plant. Nitrogen (N) and phosphorus (P) content in stems/leaves of Canna indica and Thalia dealbata are greater than those in roots. The ratio between stems/leaves and roots of N, P content in Canna indica are 1.40 and 1.21 respectively, while 1.59 and 1.08 in Thalia dealbata. The difference of cumulative N, P content in plants is mostly on account of different plant biomass. N uptake ability of Thalia dealbata is the highest, which is 457.11 g per square; Canna indica has the highest P uptake ability, which is 41.29 g per square. N, P uptake ability of stems/leaves in Canna indica are 2.17 and 1.86 times higher than that of roots, while 1.73 and 1.17 times higher respectively in Thalia dealbata. Thus, Canna indica and Thalia dealbata are recommended as the floating-bed plants to control the eutrophication in Dian-shan Lake.