Offshore hard minerals

Soil science in tropical and temperate regions—Some differences and similarities

Phylogenetic structure of communities between temperate and tropical regions: Exploring patterns through literature datasets

A historical perspective on deep-sea mining for manganese nodules, 1965–2019

BackgroundThe northern part of India harbours a great diversity of medicinal plants due to its distinct geography and ecological marginal conditions. The traditional medical systems of northern India are part of a time tested culture and honored still by people today. These traditional systems have been curing complex disease for more than 3,000 years. With rapidly growing demand for these medicinal plants, most of the plant populations have been depleted, indicating a lack of ecological knowledge among communities using the plants. Thus, an attempt was made in this study to focus on the ecological status of ethnomedicinal plants, to determine their availability in the growing sites, and to inform the communities about the sustainable exploitation of medicinal plants in the wild.MethodsThe ecological information regarding ethnomedicinal plants was collected in three different climatic regions (tropical, sub-tropical and temperate) for species composition in different forest layers. The ecological information was assessed using the quadrate sampling method. A total of 25 quadrats, 10 × 10 m were laid out at random in order to sample trees and shrubs, and 40 quadrats of 1 × 1 m for herbaceous plants. In each climatic region, three vegetation sites were selected for ecological information; the mean values of density, basal cover, and the importance value index from all sites of each region were used to interpret the final data. Ethnomedicinal uses were collected from informants of adjacent villages. About 10% of inhabitants (older, experienced men and women) were interviewed about their use of medicinal plants. A consensus analysis of medicinal plant use between the different populations was conducted.ResultsAcross the different climatic regions a total of 57 species of plants were reported: 14 tree species, 10 shrub species, and 33 herb species. In the tropical and sub-tropical regions, Acacia catechu was the dominant tree while Ougeinia oojeinensis in the tropical region and Terminalia belerica in the sub-tropical region were least dominant reported. In the temperate region, Quercus leucotrichophora was the dominant tree and Pyrus pashia the least dominant tree. A total of 10 shrubs were recorded in all three regions: Adhatoda vasica was common species in the tropical and sub-tropical regions however, Rhus parviflora was common species in the sub-tropical and temperate regions. Among the 33 herbs, Sida cordifolia was dominant in the tropical and sub-tropical regions, while Barleria prionitis the least dominant in tropical and Phyllanthus amarus in the sub-tropical region. In temperate region, Vernonia anthelmintica was dominant and Imperata cylindrica least dominant. The consensus survey indicated that the inhabitants have a high level of agreement regarding the usages of single plant. The index value was high (1.0) for warts, vomiting, carminative, pain, boils and antiseptic uses, and lowest index value (0.33) was found for bronchitis.ConclusionThe medicinal plants treated various ailments. These included diarrhea, dysentery, bronchitis, menstrual disorders, gonorrhea, pulmonary affections, migraines, leprosy. The ecological studies showed that the tree density and total basal cover increased from the tropical region to sub-tropical and temperate regions. The species composition changed with climatic conditions. Among the localities used for data collection in each climatic region, many had very poor vegetation cover. The herbaceous layer decreased with increasing altitude, which might be an indication that communities at higher elevations were harvesting more herbaceous medicinal plants, due to the lack of basic health care facilities. Therefore, special attention needs to be given to the conservation of medicinal plants in order to ensure their long-term availability to the local inhabitants. Data on the use of individual species of medicinal plants is needed to provide an in-depth assessment of the plants availability in order to design conservation strategies to protect individual species.

Restoring forest ecosystems to reverse soil degradation is critical to maintain environmental quality, forest and agricultural productivity, biodiversity conservation, and to provide valuable ecosystem services. Yet the impacts of forest restoration on soil quality remain under‐investigated. Here we aim to address a key knowledge gap: how does forest ecosystem restoration affect the recovery of soil quality in tropical and temperate regions? We conducted a global meta‐analysis to compare soil physical, chemical, and biological properties between restoring forests and reference old‐growth/less‐disturbed forests. We revealed for the first time that differences between restoring and reference forests are lower for physical (12–25%; based on median values of effect size) and chemical (10–74%) properties than for biological (32–90%) properties. More specifically, bulk density (12% of difference), pH (10%), and enzyme activity (32%) had mean values in restoring forests closer to those observed in reference forests. Overall, our results suggest that the restoration of soil properties was greater in tropical regions, after longer periods (>30 years), through passive restoration, and over pasturelands. Our global meta‐analysis helps to fill the soil information gap in forest restoration and increase our understanding of how to improve soil quality through forest restoration and soil monitoring processes in tropical and temperate regions.

The impact of climatic variations on peritoneal dialysis (PD)-related peritonitis has not been studied in detail. The aim of the current study was to determine whether various climatic zones influenced the probability of occurrence or the clinical outcomes of peritonitis. Using ANZDATA registry data, the study included all Australian patients receiving PD between 1 October 2003 and 31 December 2008. Climatic regions were defined according to the Köppen classification. The overall peritonitis rate was 0.59 episodes per patient-year. Most of the patients lived in Temperate regions (65%), with others residing in Subtropical (26%), Tropical (6%), and Other climatic regions (Desert, 0.6%; Grassland, 2.3%). Compared with patients in Temperate regions, those in Tropical regions demonstrated significantly higher overall peritonitis rates and a shorter time to a first peritonitis episode [adjusted hazard ratio: 1.15; 95% confidence interval (CI): 1.01 to 1.31]. Culture-negative peritonitis was significantly less likely in Tropical regions [adjusted odds ratio (OR): 0.42; 95% CI: 0.25 to 0.73]; its occurrence in Subtropical and Other regions was comparable to that in Temperate regions. Fungal peritonitis was independently associated with Tropical regions (OR: 2.18; 95% CI: 1.22 to 3.90) and Other regions (OR: 3.46; 95% CI: 1.73 to 6.91), where rates of antifungal prophylaxis were also lower. Outcomes after first peritonitis episodes were comparable in all groups. Tropical regions were associated with a higher overall peritonitis rate (including fungal peritonitis) and a shorter time to a first peritonitis episode. Augmented peritonitis prophylactic measures such as antifungal therapy and exit-site care should be considered in PD patients residing in Tropical climates.

Marine manganese deposits. Elsevier oceanography series 15: G.P. Glasby (editor), 1977. Elsevier, Amsterdam, 523 pp., Dfl. 127.00, U.S. $ 49.00

Climate change is the most far reaching of the great challenges of twenty-first century, particularly it is likely to affect agricultural ecosystems in many ways, but perhaps most notable is that it will affect different regions of the globe differently. Tropical regions—and thus developing countries—will generally be more severely affected than temperate regions, primarily because growing temperature ranges and changes in precipitation regimes will add to water use demand. Also, while moderate warming actually benefits crops in the short term in mid and high latitudes, even slight warming would decrease yields in seasonally dry and low-latitude regions. It affects not only all people on the planet, but also governs the future of the rest of the biosphere. Because so much, and so many, are at stake, the question of how to minimize and deal with climate change remains hugely controversial. Densely populated developing countries in tropical and drought-stressed regions could experience increased food insecurity. While total potential world food production is projected to increase with increases in local average temperatures of 1–3 °C (but to decrease at higher temperatures), world food security is very vulnerable to extreme weather events and socio-economic factors. It should be noted that the Intergovernmental Panel on Climate Change’s dire predictions about agricultural productivity in low-latitude countries are not backed by detailed and country specific studies, nor do they sufficiently factor in potential adaptation measures. However, the implications for food security are very sobering. All four dimensions of food security (food production, trade, stability of food supplies, access to food and food utilization) would be affected. Climate change would add to the burden of developing countries already faced with serious food insecurity problems and it would exacerbate them.

Introduction: Hermetia illucens is a fly found worldwide in tropical and temperate regions that feeds on decaying organic matter in its larval stage, which makes them useful to accelerate composing processes. Bacterial component on the larval guts that helps to degrade organic matter is well studied, however fungal communities information is more scarse, specially in tropical regions. Objective: To determine fungal communities in the gut of H. illucens larvae naturally occurring during urban composting processes in a tropical region. Methods: ITS sequencing was employed to characterize fungal communities present in H. illucens larval gut. Results: The analysis of amplicon sequence variants (ASVs) unveiled a notable dominance of Saccharomycetales, being yeasts of the genus Pichia the most abundant. Other relatively abundant yeasts were Candida and Galactomyces and the genus Archaeospora from Archaeosporales. The last two groups not being reported in H. illucens before. Conclusions: Yeasts of the genus Pichia are the most abundant group, this result is in concordance with previous studies which suggest a stable insect-yeast relation. The description of previously unreported fungal groups highlights the importance of continuing to explore the mycobiome dynamics of this larva. This study offers insight into the mycobiome of naturally occurring H. illucens larvae in a tropical region.

Slurry pumps in deep-sea mining: A review of numerical and experimental studies

The increasing demand on precious metals has motivated the development of a promising industry, deep sea mining. Currently major technical challenges exist in the development of this new industry, such as the vertical transportation, the seabed excavation process and the stability of the riser system. This paper will focus on the excavation process on the seabed. Considering the fact that the deep sea mining excavation process may occur at 3000∼6000 meters water depth, the hyperbaric pressure applied by the sea water will greatly influence the cutting process. Especially when the cutting speed of the cutter is very high, the so called “dilatancy hardening effect” (Brace and Martin, 1968) may make the seabed rock very difficult to excavate. These factors will make the rock excavation in deep sea much different from shallow water, which is the case in a normal dredging project. In this paper, the physics of the hyperbaric excavation process will first be described into detail. Because the hyperbaric rock cutting experiments are expensive, it is more feasible to make a numerical model to simulate the process, which eventually can replace the experiments. The main difficulties are to model the failure of rock and the interaction between the rock and the pore water. Considering the scale of the problem and the characteristics of the material, it is concluded that the discrete element method (DEM) will be the best tool to simulate the rock behavior. On the other hand, to describe the influence from the hyperbaric pressure which is induced by the sea water, governing equations for the fluid phase are derived and the finite volume method (FVM) is chosen to solve the equations. This paper will give a detailed description about the numerical methods and their interactions regarding this specific problem and show some preliminary tests on clay-like material cutting process.

Bentonite, Kaolin, Calcium carbonate easily obtained in nature as mineral products are widely used in plastics industry for additive materials. In this study, Bentonite, Kaolin, and Calcium carbonate minerals were compounded with polyethylene matrix used in specific rates. Prepared compounds melted in sheet metal molds and cooled down under appropriate conditions. Thus, production of composite material was achieved. Hardness, water absorption, and physical properties of manufactured composite test specimens were investigated accurately.

CDEM, a group of four Dutch paper mills, joined forces to develop a proprietary (patented) process that allows the production of a new type of admixture for use as building material. The process consists of a controlled thermal conversion of de-inking paper residue in a fluidized-bed combustor. The resulting mineral product has both hydraulic and pozzolanic properties. The mineral product is mainly composed of metakaolin and calcium compounds. The mineral product composition depends upon the chemistry of the starting paper residue and the thermal conditions applied. When the raw paper residue is rich in kaolin and the thermal conversion preserves calcium carbonate, a very reactive pozzolan is obtained. When the calcium content increases and decomposition of calcium carbonate occurs, a self-cementing material appears which can replace normal cement in several applications like: masonry blocks, autoclaved products, and backfilling mortars.

In this study different experimental designs for monitoring of sediment plumes produced by deep-sea mining are presented. Plumes of sediment stirred up from the seabed by mining machines are considered to represent a major environmental pressure which may extend far beyond the actual mining area. Two industry field tests with the scaled mining vehicle Apollo II of Royal IHC conducted in a relatively shallow setting offshore southern Spain provided valuable insights for anticipated monitoring of nodule mining activities in the deep Pacific. Although the tests were performed in only 300 m water depth, much less than the depth where future deep-sea mining will take place, the weakly stratified bottom water, tide-dominated near-bed currents with mean magnitude of around 5–10 cm s−1, and gently sloping seabed covered with fine muddy sediment provide a good analogue to operational conditions in the deep sea. The plume of suspended sediment mobilised by the mining vehicle was monitored with turbidity sensors deployed on a ship-operated CTD system and on a static array of moored sensors and monitored visually using a ship-operated ROV. It was found that the generated sediment plume extended no >2 m above the seabed close to the source (<100 m) but increased in height at greater distance. Furthermore, turbidity values decreased rapidly with increasing distance to the source. Even though plume monitoring suffered interference from bottom trawling activities in neighbouring areas, a distinct turbidity signal generated by the mining equipment could still be distinguished above background turbidity at 350 m away from the source. From the experience gained in shallow water, recommendations are made on how a combination of sensors operated from moving and moored platforms may be a suitable and successful strategy for monitoring man-made sediment plumes in the deep sea.

The main cadmium exposure pathway for humans is through diet. A database on Cd concentration in soils and accumulation in edible vegetables from tropical and temperate regions was organized, soil–plant relationships were derived, and then critical soil Cd concentrations were calculated based on human exposure parameters for the State of São Paulo, Brazil. Cadmium accumulation in leafy and root vegetables could be predicted by multiple regression analysis and most of the variance was explained when total Cd concentration and pH in soil were included as predictors. The calculated Cd bioconcentration factors (BCFs) for the tropical dataset were higher as compared to the temperate dataset. Consequently, critical soil Cd concentrations were from 1.7- to 3.2-fold lower for tropical conditions. Higher humidity and temperature at the tropics, as well as more weathered soils with lower retention capacity of Cd, may explain the higher Cd uptake and accumulation in tropical than in temperate regions. To protect human health, exclusive data regarding Cd in soils and edible vegetables from tropical regions should be used for the State of São Paulo to derive critical soil Cd concentrations, instead of (additional) data from temperate regions.