PURPOSE OF THE REVIEW: Freshwater wetlands are found in various climatic zones ranging from tropics to tundra, and their roles from groundwater recharge and flood control to water quality management and biodiversity protection are well recognized. Phosphorus (P) is a limiting nutrient for algal growth in freshwater systems, including wetlands. Various physico-chemical and biological characteristics of wetlands regulate cycles of nutrients such as P. Thus, estimating internal loading of P in wetlands would be crucial in the formulation of effective P management strategies in the wetland systems. This review and limnological data presented may offer needed knowledge/evidence for the effective control of P inputs in wetlands and provide insights on possible ways for interventions in controlling eutrophication and saving the ecosystem from collapse. RECENT FINDINGS: Various ways of P losses such as agriculture, urbanization, etc., to the water bodies have severely impacted water quality of wetlands by altering physical and chemical nature of the P compounds and release bound P to the water columns. Studies indicate that P sorption–desorption dynamic, mineralization, and enzymatic hydrolysis of P in freshwater wetlands’ soils/sediments are crucial in causing internal loading or sink of P in wetland systems. Thus, extensive studies on abovementioned arenas are crucial to restore natural freshwater wetlands or to increase the efficiency of constructed wetlands in retaining P. In general, researchers have elucidated significant amounts of limnological data to understand eutrophication processes in freshwater wetlands; however, studies on the interactions of P stability and hydro-climatic changes are not well understood. Such changes could significantly influence localized limnology/microenvironments and exacerbate internal P loading in freshwater wetlands; thus, studies in such direction deserve the attention of scientific communities.

This work investigated the impact of a clay mineral on toxic waste. The Ivorian Anti-pollution Center discovered the toxic waste from Probo Koala boat on 21 August 2006. This boat had been used to refine oil named naphtha of cokéfaction by Trafigura firm in the sea. The process of refining consists of caustic sodium carbonate washing and produced toxic waste. These toxic wastes have been unloading in 13 zones of the Abidjan district: Akouédo, Abobo, Abobo Alépé road (Djibi village), civile prison road (MACA), industrial zone of Koumassi, Port-Bouët - Vridi CAP Logistic (Rue Saint-Sylvestre)… This situation caused a socio-political crisis and generated the death of many people. To solve this problem, one first part has been excavated and sent to France to be incinerated. A second part is used to be a biopile for bioremediation. After these two processes, the rest of toxic waste remained in the place where they have been unloaded. The analyses of these toxic wastes show that polycyclic aromatic hydrocarbons (PAHs), oxygenated polycyclic aromatic compounds (O-PACs), volatile aromatic compound (VAC), mercaptan and sulfur molecules, and also heavy metal and organometallic are the principal polluters of these contaminated soils. From a mineralogical viewpoint, the tropical climate soils of Ivory Coast in general and district of Abidjan in particular constituted of about 50% of kaolinite, 30 to 40% of smectite, and 10 to 20% of illite (OSTROM 1993). In this study, we want to show the impact of this local clay on toxic waste.

The Nevado de Toluca Natural Protected Area (Zona de Protección de Flora y Fauna Nevado de Toluca, ZPFFNT), Central Mexico, encompasses one of the four highest (> 4000 m a.s.l.) volcanoes in Mexico, Nevado de Toluca; an extended area of woodland surrounds this volcano. Although identified as a remote area based on its high altitude, the ZPFFNT is not far from the urban and industrial zones of Toluca (~20 km) and Mexico (~72 km) cities, which potentially threatens the environmental health of the ZPFFNT by emitting SO₂ and NOX. Acid precipitation falling on areas with low alkaline reserve leads to environmental acidification and land degradation. To provide reliable data on the air pollution reaching the ZPFFNT and the related potential risks, our study analyzed the bulk atmospheric deposition chemistry and its temporal dynamics throughout an annual cycle. There are two well-defined seasons: (a) cold/dry with SW–NE wind direction and (b) warm/rainy with NE–SW wind direction. The pH, electric conductivity (K₂₅), cations, Cl⁻, and HCO₃⁻ were statistically higher in the cold/dry period. Differently, NO₃⁻ and SO₄²⁻ showed steadier behavior. Bulk deposition pH remained acidic at all times but reached extreme low values from July to September during the warm/rainy season. In the cold/dry season, alkaline cations were important in partially neutralizing the acidic compounds from the urban and industrial zones of Toluca and Mexico cities. Previously assumed to be safe based on its remoteness, the ZPFFNT is threatened by acid precipitation, which demand the implementation of preventative and mitigating actions as part of a management plan to avoid environmental deterioration.

Riparian vegetation has a fundamental role in protecting water bodies due to its ability to retain potential contaminants. Therefore, the objective of this work was to evaluate the quality of water according to the different land uses and state of conservation of forest vegetation in springs of tropical climate basins (Bahia, Brazil). Eighteen points at ten rural communities were selected in the Jacuípe and Joanes river basins. In relation to the degree of conservation, the areas were classified as preserved, disturbed or degraded. All the evaluated parameters presented values above the legal standards defined both by international legislation (USEPA and Decree-Law no 152/2017) and also by Brazilian legislation (CONAMA Resolution 357/05) for “degraded” zones. The aluminum concentration (Al³⁺) presented a variation of 0.01 to 4.20 mg L⁻¹, iron (Fe) of 0.01 to 4.50 mg L⁻¹, nitrogen (N) of 0.00 to 5.20 mg L⁻¹, nitrate (NO₃⁻) of 0.00 to 14.50 mg L⁻¹, nitrite (NO₂⁻) of 0.01 to 2.50 mg L⁻¹, phosphorus (P) of 0.00 to 2.22 mg L⁻¹, orthophosphate (PO₄³⁻) of 0.00 to 6.80 mg L⁻¹ and the pH presented a variation between 4.30 and 6.80. In general, it was observed that the values of water quality parameters are directly related to the state of conservation of the riparian zone. Based on this, it is concluded that the water quality monitoring permits to evaluate the influence of changes in the environment and the role of riparian zones in the protection of those water bodies.

This paper proposes an ecological development efficiency index (EDEI) based on comprehensive metrics to measure the ecological efficiency and human development of the tropics and subtropics in China for the 2005–2016 period. In particular, the proposed index integrates the ecological footprint into the input metrics considering resource exploitation, carbon emission, and energy infrastructures. The traditional output factor, i.e., GDP, is substituted with the human development index to evaluate the local development quality on the basis of health, education, and income. It is observed that the EDEI of the tropics and subtropics in China grew slowly before stabilizing at approximately 0.92. Moreover, as shown in the Theil index analysis, the spatial heterogeneity of the EDEI in tropics and subtropics of China is increasing significantly. The EDEI of the eastern region of China is higher than that of the central region, and the EDEI of the western region is the lowest. Finally, based on the Tobit factor model, research density and urbanization are observed to be the keys to improving the EDEI for achieving sustainable growth.

The present study was conducted to assess the impact of elevated levels of O₃ and shifting of crop calendar practice, singly, and in combination on Triticum aestivum cv. HD 2967 on its growth, gas exchange parameters, and yield attributes in open-top chambers (OTCs). Two sowing dates were considered: timely sown and late sown. Late sowing was delayed by 20 days from the timely sowing date. The result revealed that wheat plants under elevated O₃ and timely sown conditions (ET) showed reductions in growth parameters, while such effects were synergistic when plants were exposed to elevated O₃ under late sown conditions (EL). Photosynthetic rate, stomatal conductance, and water use efficiency reduced significantly under EL followed by ET and AL as compared with AT (ambient O₃ + timely sown) whereas transpiration rate showed maximum increment under EL. Grain yield reduced by 45.3% in EL as compared with AT and 16.2% in ET as compared with AT. The growth parameters and yield attributes obtained from the present experiment revealed that (i) O₃ is affecting the growth and productivity of the wheat and (ii) late sowing practice has not proved to be a feasible adaptation strategy for the wheat cultivation against O₃-induced production losses under the prevailing conditions of Indo-Gangetic Plain. This is the first report documenting the shifting of crop calendar practice at the present and future scenario of O₃ concentration under agro-ecological conditions in the tropical region of India.

For several years, Landsat imageries have been used for land cover mapping analysis. However, cloud cover constitutes a major obstacle to land cover classification in coastal tropical regions including Lagos State. In this work, a land cover appearance for Lagos State is examined using Sentinel-1 synthetic aperture radar (SAR) and Land Satellite 8 (Landsat 8) imageries. To this aim, a Sentinel-1 SAR dual-pol (VV+VH) Interferometric Wide swath mode (IW) data orbit for 2017 and a Landsat 8 Operational Land Imager (OLI) for 2017 over Lagos State were acquired and analysed. The Sentinel-1 imagery was calibrated and terrain corrected using a SRTM 3Sec DEM. Maximum likelihood classification algorithm was performed. A supervised pixel-based imagery classification to classify the dataset using training points selected from RGB combination of VV and VH polarizations was applied. Accuracy assessment was performed using test data collected from high-resolution imagery of Google Earth to determine the overall classification accuracy and Kappa coefficient. The Landsat 8 was orthorectified and maximum likelihood classification algorithm also performed. The results for Sentinel-1 include an RGB composite of the imagery, classified imagery, with overall accuracy calculated as 0.757, while the kappa value was evaluated to be about 0.719. Also, the Landsat 8 includes a RBG composite of the imagery, classified imagery, but an overall accuracy of 0.908 and a kappa value of 0.876. It is concluded that Sentinel 1 SAR result has been effectively exploited for producing acceptable accurate land cover map of Lagos State with relevant advantages for areas with cloud cover. In addition, the Landsat 8 result reported a high accuracy assessment values with finer visual land cover map appearance.

Chloroplasts have luminescent metabolites—chlorophyll being the most known one—whose fluorescence emission may be a useful tool to assess the physiological status of the plant. Some antioxidants (flavonoids and carotenoids), and byproducts of membrane rupture (lipofuscins) and chlorophyll degradation (pheophytins), are chloroplasts’ fluorescent metabolites directly involved in plant response to environmental stressors and pollutants and may act as a biomarker of stress. Here we hypothesized that climatic variations and air pollutants induce alterations in the emission profile of chloroplasts’ fluorescent metabolites in Tillandsia usneoides (Bromeliaceae). To test this hypothesis, an active biomonitoring study was performed during 2 years in five polluted sites located at the Metropolitan Region of Campinas (São Paulo State, Brazil), aiming to identify target chloroplasts’ fluorescent metabolites acting as biomarkers of environmental stress. In situ identification and quantification of the intensity of the fluorescence emission from target metabolites (flavonoids, carotenoids, lipofuscins, and pheophytins) were performed by the observation of fresh leaf sections under confocal laser scanning microscopy. Changes in the profile of fluorescence emission were correlated with local climate and air pollution data. The fluorescence emissions of flavonoids and carotenoids varied seasonally, with significant influence of rainfall and NO₂. Our results expand the use of T. usneoides as a bioindicator by using alterations in the fluorescence emission profile of chloroplast metabolites. This application may be especially interesting for NO₂ biomonitoring.