Effects of plant diversity on greenhouse gas emissions in microcosms simulating vertical constructed wetlands with high ammonium loading

Wastewater with relatively high nitrogen concentrations is a major source of nitrous oxide (N₂O) and methane (CH₄) emissions and exerts multiple stresses on the environment. Studies have shown that plant diversity plays an important role in ecosystem functioning. However, the effects of plant species diversity on CH₄ and N₂O emissions under high ammonium (NH₄⁺-N) loading rates remain unclear. In this study, a microcosm experiment simulating vertical constructed wetlands supplied with high NH₄⁺-N water levels was established. The treatments included four species richness levels (1, 2, 3, 4) and 15 species compositions. There was no significant relationship between species richness and N₂O emissions. However, N₂O emissions were significantly reduced by specific plant species composition. Notably, the communities with the presence of Rumex japonicus L. reduced N₂O emissions by 62% compared to communities without this species. This reduction in N₂O emissions may have been a result of decreased N concentrations and increased plant biomass. CH₄ emissions did not respond to plant species richness or species identity. Overall, plant species identity surpassed species richness in lowering N₂O emissions from constructed wetlands with high NH₄⁺-N water. The results also suggest that communities with R. japonicus could achieve higher N removal and lower greenhouse gas emissions than other wetland species.     

A salt-free pickling regime for hides and skins using oxazolidine

During the last few decades new materials and technologies have being studied and applied in order to reduce the ecological impact of leather production. Severe restrictions imposed by the pollution control authorities on the disposal of chromium, total dissolved solids and chlorides in tannery effluents have forced the tanners and researchers to look for eco-benign pickling and tanning processes. In this study, we would focus on the novel process development of pickling with the presence of oxazolidine based product. Investigations indicated that oxazolidine is a potential material to replace neutral salts in pickling and, realize high chrome exhaustion in the subsequential chrome tanning.     

Elemental Uptake by Seaweed,Plocamium corallorhirza Along the KwaZulu-Natal Coast of Indian Ocean,South Africa

This study reports the elemental uptake by Plocamium corallorhiza, a Rhodophyta class of coralline alga grown richly along KwaZulu-Natal coastline. The uptake of seven important elements, namely Fe, Mn, As, B, Ti, Zn and Hg, selected based on their abundance in the samples, were investigated for a one-year cycle, from June 2002 to May 2003, at four chosen sites located along the KwaZulu-Natal coastline. The sites spread over 150 km from North to South Coast are Zinkwasi, Ballito, Treasure Beach and Park Rynie. P. corallorhiza possess good manganese and arsenic-accumulating ability and has potential to be an excellent indicator for most of the metals studied. A typical P. corallorhiza sample at Park Rynie (winter) recorded Mn (14 ppm), Fe (6.02 ppm), As (8.4 ppm), B (1580 ppb), Zn (234 ppb), Ti (751 ppb) and Hg (15.8 ppb). The general trend found at all sites was a large decrease in iron concentration in spring and summer and increase in winter. Mercury uptake was lowest in winter and autumn at all sites. The highest mercury levels in the seaweeds were recorded during spring or summer.     

Arsenic Uptake and Accumulation in Curly Endives (Cichorium endivia L.) Irrigated with Contaminated Water

Arsenic accumulation in vegetables for direct human consumption represents a concern for food safety purposes. This potential problem can be of economic importance particularly in much appreciated, high-quality horticultural products. In this work, a greenhouse set of experiments were conducted to evaluate possible phytotoxic effects and arsenic accumulation in the production of curly endives with arsenic contaminated water.

Two concentration levels (0.5 mg/L and 1.0 mg/L) and two arsenic species (As⁺³ and As⁺⁵) were considered. Dry mass production tended to be reduced as As⁺³ concentration increased in irrigation water. However, As⁺⁵ treatments did not show significant dry mass production differences with a blank (control experiment). As accumulation in plant increased with As concentration in irrigation waters, following a linear trend. Nevertheless, the increase of accumulated As was not statistically significant for As⁺⁵ at 0.5 mg/L. Calculated biological absorption coefficients resulted in higher than previous values reported in the literature, which was attributed here to the source of arsenic (irrigation water). Considering field values for As⁺⁵/As⁺³ ratio and averaged concentrations in water, the obtained results support that there is not a short-or medium-term risk to food safety in the curly endive crop in the region of Castilla y León (Spain).     

Metal availability and uptake by sorghum plants grown in soils amended with sludge from different treatments

Several factors depending on the sludge, the soil, or the combination of both substrates, may affect element availability to plants. In this study, an assessment was done of the effect of two sludges obtained by different processes (activated sludge and facultative stabilization pond) on heavy-metal availability and uptake by sorghum plants in soils with high and low copper contents. Results obtained for DTPA-extractable metal indicated higher metal availability in sludge-amended soils. In addition, sludges caused changes in copper and zinc distribution in soil, indicating in most cases a discrete increase in the more labile metal forms. However, observed changes did not increase heavy metal concentration in plant leaves, indicating that assessment of metal availability by a chemical procedure (single extraction or metal fractionation) would not permit a good prediction of metal bioavailability. On the other hand, sludge application at a rate of 100 t ha⁻¹ to high-copper agricultural soils would not imply greater mobility of this metal on account of a greater sorbing capacity provided by the sludges. Such results would indicate that sludges from wastewater treatment plants, meeting the standards of heavy metal contents, regardless of the process by which they were obtained, may be applied to several kinds of soil, even to high-copper soils, with no risk of increasing heavy metal bioavailability to phytotoxic levels in the short range.     

Research progress on CRISPR/Cas9-mediated genome editing technique in plants北大核心CSCD

Many physical, chemical, and biotic stresses always threaten plants during their growth and development. Using the genome editing technique is a good strategy to improve plant characteristics. CRISPR/Cas (clustered regulatory interspaced short palindromic repeats / CRISPR-associated protein), the adaptive and heritable immune system of prokaryotes, is a genome editing technique newly developed during recent years. At present, the type II CRISPR / Cas9 system is most widely used. Many plants, such as Arabidopsis thaliana, tobacco, soybean, tomato, potato, rice, wheat, maize, sorghum, petunia, banana, sweet orange, apple, poplar, and Marchantia polymorpha, have been edited successfully for stress tolerance, delay of fruit ripening, herbicide resistance, and disease resistance, etc. This system is achieved by the formation of nuclease Cas9 and crRNA: tracrRNA (CRISPR-derived RNA:trans-activating RNA) complex. Further studies about the effect of the promoters of Cas9 and gRNA and the number of gRNA targets on gene editing efficiency have been discussed. © 2018 Science Press. All rights reserved.     

Relationship between near-surface morphological traits of familiar plants and their ability for sediment retention in a dry-hot valley北大核心CSCD

To explore the sediment interception capacity of plants and its relationship with the surface morphological traits of plants, we used laboratory simulations and off-site flume experiments to study the ability for sediment retention of six familiar species: Leucaena leucocephala (LL), Melia azedarach (MA), Dodonaea viscosa (DV), Coriaria sinica (CS), Heteropogon contortus (HC), and Eulaliopsis binata (EB) aver two growth periods in the dry-hot river valley of the Jinsha River. We analyzed the relationship between near-surface morphological traits of individuals of six species and their ability for sediment retention. Our study resulted in three main observations. (1) In the flume experiment, three-month seedlings and one-year old seedlings of the six species showed different abilities for sediment retention. In the three-month seedlings, the ability for sediment retention of CS was the highest, followed by MA and LL, whereas it was the lowest in HC and EB. However, in one-year old seedlings, the ability for sediment retention of CS was the highest, but the ability for sediment retention of HC and EB was better than those of MA and LL. Hence, the ability for sediment retention of the six species fluctuated between different growth periods. (2) The three-month old and one-year old seedlings of all six species showed different near-surface morphological traits. (3) The sediment mass was significantly and positively correlated with near-surface leaf areas, crown lengths, crown widths, stem dry matter densities at the intersection volume, and above-ground biomass, but significantly and negatively correlated with the angle between stem and ground, indicating that these latter are the main near-surface morphological traits able to affect sediment retention. In addition, the sediment mass was also correlated (positively and negatively) with the stem epidermal crack number, stem dry matter content, leaf dry matter content at the intersection volume, and dry mass per unit volume of the intersection volume, which could also reflect the ability of sediment retention. We conclude that in the areas where plant measures are used to control soil erosion and intercept sediment, the key, above-mentioned plant morphological factors should be taken into account in order to select the optimal plant species. © 2018 Science Press. All rights reserved.     

Effects of early management of Pinus massoniana plantation target trees on soil physicochemical properties and plant diversity北大核心CSCD

In order to provide a theoretical reference for the early management of target trees in the low mountain region of eastern Sichuan, and a theoretical basis for the sustainable management of masson pine (Pinus massoniana) plantations, we chose three different kinds of densities (100 target trees per hectare, 150 target trees per hectare, and 200 target trees per hectare) in a 33-year-old masson pine plantation in the low mountain region of eastern Sichuan. We investigated the change patterns of soil physicochemical properties and plant diversity during the early stage of the management of the target trees. The results showed that compared to the control (CK), the early stage of management of P. massoniana plantation target trees dramatically improved the soil physical properties, the pH value, contents of organic matter, and total phosphorus (P < 0.05); however, the available phosphorus and the available nitrogen varied slightly (P > 0.05). Compared to the control (CK), significant (P < 0.05) differences in the richness index were observed between shrubs and herbs (P < 0.05), and in the shrub layer, the dominant position was replaced by others. Simpson, Shannon, and Pielou indexes of shrubs showed no significant difference in the study (P > 0.05). On the contrary, Simpson, Shannon, and Pielou i ndexes of herbs were significantly lower than those for CK (P < 0.05). There were significant correlations between plant species diversity and soil physicochemical properties such as soil pH, contents of total phosphorus, and the available nitrogen. The early stage of management of P. massoniana plantation target trees significantly improved the plant diversity and soil physicochemical properties. Among all the three different treatments, the density of 150 target trees per hectare had the best effect on the soil physicochemical properties and plant diversity. © 2018 Science Press. All rights reserved.     

Export inherent safety NOT risk

The author presents a personal view that production of bulk chemicals and the attendant risks are being transferred from developed to developing nations. Some evidence is presented on the transfer of production. The transferred risk is increased because of the larger scale plants that are now built in locales that are less able to cope with the increased hazards. Bhopal was an example of an inherently unsafe plant, with major hazards that could have been avoided or drastically reduced by design. It behoves the industry to adopt the inherently safer philosophy and practice in the new plants that it builds, in order to minimise the opportunity for another accident like Bhopal and the threat to our industry that such an accident would pose.