The application of wetland plants to purify surface rivers has gradually become an important means to control water pollution. However, there are many species of wetland plants which differ greatly in living conditions, water purification effects and pollutant migration paths. Therefore, it is necessary to select suitable wetland plants and quantitatively analyze the effects of different wetland plants on pollutant transport paths for the protection of water quality. In this research, the Typha orientalis C. Presl (T), Lemna minor L.(L) and Ceratophyllum demersum L.(C) were selected as typical wetland plants to conduct single-factor and multi-factor experiments under different water quality conditions. The results showed that wetland plants had significantly decreased nitrogen (N) and phosphorus (P) concentration in two sewage bodies. The NH₄⁺-N and NO₃⁻-N removal efficiencies ranged from 71 to 96% and from 46% to 76%, and the PO₄³⁻-P removal efficiencies ranged from 79% to 94% . The concentration of nutrient in the sewage decreased rapidly in the early stage and then tended to reach a stable state. The total nitrogen (TN) removal efficiencies under two kinds of sewage ranked as follows: T+L+C>T>C>L. Under high concentration sewage, the TN removal efficiencies by wetland plants mostly attributed to the change in the microbial status of the water body, which ranged from 82% to 95%. Under low concentration sewage, the combination of wetland plants could optimize the purification effect of plant consumption and microbial decomposition, and the TN removal efficiencies ranged from 75% to 95%. The total phosphorus (TP) removal efficiencies of T and T+L+C were better in two concentration sewages. The research demonstrated that P in sewage was mainly accumulated in soil matrix and it was important to select the emergent plants with well-develoed roots and vigorous growth to purify sewage.

A considerable amount of research has been conducted on the impacts of recreational boating activities on fishes but little or no synthesis of the information has been undertaken. This review shows that motor boats impact on the biology and ecology of fishes but the effects vary according to the species and even particular size classes. Direct hits on fishes by propellers are an obvious impact but this aspect has been poorly documented. Alterations in the wave climate and water turbidity may also influence fishes and their habitats, especially submerged and emergent plant beds. Sound generated by boat motors can also influence the communication and behaviour of certain species. Pollution arising from fuel spillages, exhaust emissions and antifouling paints all have detrimental effects on fishes. Finally, the use of recreational boats as vectors of aquatic invasive organisms is very real and has created major problems to the ecology of aquatic systems.

Feeding a growing population requires striking a balance between increasing production and decreasing environmental impacts in agricultural settings. We established 12 experimental mesocosms with silt loam atop a base of sand and examined the ability of three emergent aquatic plants common to the USA to remediate pesticides and nutrients in agricultural runoff. Mesocosms were planted in monocultures of Myriophyllum aquaticum, Polygonum amphibium, and Typha latifolia, or left unvegetated to serve as controls. All mesocosms were amended with target concentrations of 10 mg L⁻¹ (each) nitrate, ammonium, and orthophosphate; 20 μg L⁻¹ (each) of the pesticides propanil and clomazone; and 10 μg L⁻¹ of the pesticide cyfluthrin. After a 6-h-simulated agricultural runoff with amended water, mesocosms sat idle for 48 h before flushing with unamended water for another 6 h. Outflow water samples were collected and analyzed for contaminant concentrations. Most significant differences between vegetated mesocosms and controls occurred when comparing mean contaminant transfer/transformation rates post-amendment. Differences among plant species occurred regarding retention of dissolved nutrients orthophosphate, ammonium, and nitrate. Similarly, all three plant species retained more propanil than controls during post-amendment (8–48 h), but individual plant differences occurred with regard to clomazone and cyfluthrin retention. While variation in mitigation of specific dissolved components of nutrients suggests different mechanisms involved in nutrient cycling within our mesocosms, consistent overall total nutrient and pesticide reduction during the post-amendment period indicate that holding runoff in vegetated ditches may reduce transport of agricultural contaminants to downstream aquatic ecosystems.

The selection of emergent plants is of primary importance during the construction of floating treatment wetlands (FTWs). Focusing on the comparison of the nitrogen removal, pot-culture experiments were carried out in floating treatment wetlands constructed with Phragmites australis and Acorus calamus in northeast China, a cold temperate zone. Nitrogen removal and transformation processes were investigated to explore the pathways and factors that influence the nitrogen removal. FTWs showed a high capacity for nitrogen removal. In water with TN concentrations of 9.63 and 4.58 mg L⁻¹, the average TN removal efficiencies of the FTWs constructed with P. australis were 91.5 and 84.2%, respectively, and those of FTWs constructed with A. calamus were 84.2 and 82.8%, respectively. Plant uptake accounted for 36.4 to 77.1% of total N removal. The average TN removal rates of P. australis systems in the first 2 days were 4.20 and 1.77 mg L⁻¹ day⁻¹ for treatments with TN concentrations of 9.36 and 4.58 mg L⁻¹, respectively, significantly higher than those of the A. calamus system, which were 1.75 and 1.04 mg L⁻¹ day⁻¹, respectively. Our results suggested that plant uptake was the main pathway for nitrogen removal in FTWs, and P. australis was a suitable emergent plant species for use in FTW construction in a cold temperate zone.

The growth behavior of canary grass (Phalaris canariensis L) when cultivated in presence of farming fuels is reported in this work. P. canariensis L. is relevant in several countries. It is an emergent plant for phytoremediation and biofuel activities. The following variables: root length, stem length, total plant weight, green tissue weight (tiller, leaf), and total chlorophyll and chlorophyll a/b ratio, were monitored during the growth in presence of commercial fuels (premium grade, regular grade, diesel, and kerosene) at different concentrations. We applied a comprehensive statistical analysis to understand the results: Univariate analysis, factorial analysis of variance, and subsequent Tukey test were applied to the variables to assess the significance of the differences found. The normality of these variables was analyzed with the Shapiro Wilk test. All parameters were affected by all type and concentrations of fuels and its interaction. This is one of the first reported cases which describe the growth parameters responses from canary grass when cultivated in presence of an essentially constant concentration of farming fuels.

Emergent wetland plant species may exhibit different capacity for phytoremediation when used in constructed wetlands. To evaluate cadmium (Cd) remediation capacity of four emergent wetland species [Baumea juncea (R.Br.) Palla, Baumea articulata (R.Br.) S.T. Blake, Schoenoplectus validus (M.Vahl) A. & D.Löve, and Juncus subsecundus N.A. Wakef.], a glasshouse experiment was conducted in hydroponics to investigate the effects of Cd (0, 5, 10, and 20 mg L⁻¹) on plant growth and Cd uptake and translocation as well as uptake of other nutrients after 14 days. The relative growth rates of the three species changed little in various Cd treatments, but was severely inhibited for B. juncea at 20 mg Cd per liter treatment. Hence, the Cd tolerance index (root length in Cd treatment vs. control) was significantly lower in B. juncea compared to other species. Among the species, the highest concentration of Cd was in the roots of J. subsecundus, followed by S. validus, B. articulata, and B. juncea, while the lowest concentration of Cd was in the S. validus shoots. Of all the species, J. subsecundus had the highest bioconcentration factor (BCF) in shoots, whereas S. validus and B. juncea had the lowest BCF in rhizomes and roots, respectively. The translocation factor was significantly lower in S. validus compared to the other species. J. subsecundus had a higher Cd accumulation rate than the other species regardless of the Cd supply. The lowest allocation of Cd in shoots was recorded for S. validus and in roots for B. juncea. The concentrations of other elements (P, S, Ca, Fe, Cu, and Zn) in shoots decreased with Cd additions, but the interactions between Cd and other elements in roots varied with the different species. These results indicate that the four wetland species have good tolerance to Cd stress (except B. juncea at high Cd exposure), varying in Cd accumulation and translocation in tissues. These properties need to be taken into account when selecting species for wetlands constructed for phytoremediation.

The combined pollution, instead of single pollution, has become a widespread contamination phenomenon in aquatic environment. However, little information is now available about the joint effects of the combined pollution, especially co-existed pesticides and heavy metals, on aquatic plants. In the present study, using continuous excitation chlorophyll fluorescence parameters and the OJIP transient, comparisons of herbicide atrazine (ATZ) phytotoxicity on Iris pseudacorus between in the presence and absence of cadmium (Cd) were evaluated over an exposure period of three weeks under laboratory conditions. Results showed that both ATZ and Cd were toxic to I. pseudacorus. The ratio Fᵥ/Fₒ, specific electron transport energy (ET₀/RC), and photochemistry efficiency (PIₐbₛ and PIₜₒₜₐₗ) of this emergent plant species at individual ATZ and Cd concentrations were significantly lower than those of the control. ATZ mainly inhibited electron transport beyond QA at PSII acceptor side as indicated by the sharp rise of the J-step level of fluorescence rise kinetics. A pronounced K-step and the loss of I-step due to the damage on the OEC and PSI also occurred when ATZ was at or above 1.0 mg·L⁻¹. In comparison to ATZ alone, ATZ combined with Cd resulted in a lower amplitude rise in J-step with apparent J-I and I-P phases; and significantly lower Fₒ with higher Fᵥ/Fₒ, as well as greater ET₀/RC with higher values of PIₐbₛ and PIₜₒₜₐₗ. However, the adverse influences of ATZ combined with Cd on the above indicators were still significant as compared with the control. Therefore, the coexistence of Cd alleviated the individual phytotoxicities of ATZ, whereas combined pollution of ATZ and Cd still induced the decline in photosynthetic performance of I. pseudacorus, and its potential ecological impacts on the aquatic vegetation cannot be ignored. Our findings offer a better understanding of the joint effects of the pesticide and heavy metal on non-target aquatic plants, and provided valuable insights into the interaction of these pollutants in aquatic environment.

Increasing environmental concentrations of platinum group metals (PGMs), in particular platinum (Pt), rhodium (Rh) and palladium (Pd), from catalytic converters has been reported worldwide. The impact of these three metals on the uptake and use of essential mineral nutrients was examined using two plant models: the submerged aquatic plant, Elodea canadensis, and the terrestrial emergent plant, Peltandra virginica. Plants were grown for 2 weeks in nutrient solutions with either Pt⁴⁺ at concentrations between 0.05 and 5 mg/L, or a 0.1 mg/L Pt⁴⁺, Rh³⁺, Pd²⁺ mixture. Some treatments received additional Ca²⁺, Zn²⁺, or humic acid (with varying pH) to study how these conditions affected PGM uptake. Metal concentration analyses were conducted using a graphite furnace atomic absorption spectrometer (GFAAS) or an inductively coupled plasma emission spectrometer (ICP). Growth response was assessed through total chlorophyll content. There was significant Pt accumulation in plant tissues, from 55 to 326 times the concentration in nutrient solution. At pH 8, the addition of humic acid doubled Pt accumulation in comparison to the control. Additional exogenous minerals did not significantly affect PGM uptake, nor did the uptake of PGMs interfere with the uptake of Ca, Fe or Cu. Synthesis of chlorophyll in new shoots was not affected by Pt accumulation; however, visible chlorosis was observed in older shoots at 5 ppm Pt. Roadside Daucus carota samples from four heavy traffic locations in Dutchess County (New York) were also assessed for PGM content. Pt, Pd and Rh concentrations averaged 14.6, 10.2, and 0.7 μg/g, respectively.

The water of urban landscape park is often confronted with microalgal blooms due to its stagnancy. Bioremediation using the combined emergent and submerged plants to control the microalgae growth was investigated in the present study. Two water bodies (Bei and Xin) of Yuyuantan Park in Beijing were selected for the field experiments, and the other lakes with different vegetation of macrophytes were selected as the comparison. The concentrations of chlorophyll a (chl a), chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP), and water temperature and transparency were monitored before and after bioremediation from 2015 to 2017. Results showed that the effects of microalgal inhibition were more significant 2 years after bioremediation. Specifically, the chl a of Dong Lake without any vegetation of macrophytes was up to 65.1 μg/L in summer of 2017, while the Bei and Xin Lakes was only 6.2 and 11.3 μg/L, respectively. In addition, the water quality and transparency also improved, with water bodies being crystal clear. Submerged plants played major roles in microalgal control and water quality improvement, compared to the lakes with only emergent plants. The intensity of humic acid-like substances in three-dimensional fluorescent spectra was stronger for the lakes with submerged plants.

Combination of emergent and submerged plants has been proved to be able to enhance pollutant removal efficiency of surface flow-constructed wetland (SFCW) during winter. However, intensive photosynthesis of submerged plants during summer would cause pH increase, which may have adverse effects on emergent plants. In this study, nitrogen transformation of lab-scale SFCW under pH gradient of 7.5, 8.5, 9.5 and 10.5 was systematically investigated. The results showed that total nitrogen (TN) removal efficiency decreased from 76.3 ± 0.04 to 51.8 ± 0.04 % when pH increased from 7.5 to 10.5, which was mainly attributed to plant assimilation decay and inhibition of microbe activities (i.e., nitrite-oxidizing bacteria and denitrifiers). Besides, the highest sediment adsorption in SFCW was observed at pH of 8.5. In general, the combination of submerged and emergent plants is feasible for most of the year, but precaution should be taken to mitigate the negative effect of high alkaline conditions when pH rises to above 8.5 in midsummer.