The Environmental Impact of Shrimp Aquaculture: Causes, Effects, and Mitigating Alternatives

Attracted by the demand for shrimp in the developed countries, shrimp aquaculture has expanded rapidly, mainly in the subtropical and tropical lowlands of America and Asia. This work provides a global review and viewpoint on the environmental impacts of shrimp aquaculture, considering the causes and effects of the siting and operation of shrimp ponds and abandonment of farm facilities. Additionally, mitigating alternatives are discussed. To date, approximately 1–1.5 million ha of coastal lowlands have been converted into shrimp ponds, comprising mainly salt flats, mangrove areas, marshes, and agricultural lands. The impact of shrimp farming of most concern is the destruction of mangroves and salt marshes for pond construction. Compatibility with other users, the presence of buffer zones, maintaining an acceptable balance between mangroves and shrimp pond area, improved pond design, reduction of water exchange, and an improved residence time of water, size and capacity to assimilate effluents of the water body, are examples of ways to mitigate the adverse effects. The use of mangroves and halophytes as biofilters of shrimp pond effluents offers an attractive tool for reducing the impact in those regions where mangrove wetlands and appropriate conditions for halophyte plantations exist. Healthy seed supply, good feed with the use of prophylactic agents (including probiotics), good water quality, and lower stocking densities are examples of actions suggested to control disease in shrimp farming. Finally, in the context of integrated management, research priorities are suggested.     

Consensus on Criteria for Potential Areas for Wolf Reintroduction in Mexico

Abstract: Given the conflict with human interests that in many cases results in the extirpation of large carnivores, acceptance of their reintroduction is a considerable challenge. By the 1980s Mexican wolves (Canis lupus) were extinct in the wild. In 1998 a population was reintroduced in the Blue Range Mountains of New Mexico (U.S.A.). Efforts to reintroduce the species in Mexico have been ongoing since the late 1980s. Four teams working independently identified 6 areas in northern Mexico in the historic range of Mexican wolves, where reintroductions could potentially be successful. Each team used different methods and criteria to identify the areas, which makes it difficult to prioritize among these areas. Therefore, members of the different teams worked together to devise criteria for use in identifying priority areas. They identified areas with high, intermediate, and low potential levels of conflict between wolves and humans. Areas with low potential conflict had larger buffers (i.e., distance from human settlement to areas suitable for wolves) around human settlements than high‐ and intermediate‐conflict areas and thus were thought most appropriate for the first reintroduction. High‐conflict areas contained habitat associated with wolf presence, but were closer to human activity. The first reintroduction of Mexican wolves to Mexico occurred in October 2011 in one of the identified low‐conflict areas. The identification of suitable areas for reintroduction represents a crucial step in the process toward the restoration of large carnivores. Choice of the first reintroduction area can determine whether the reintroduction is successful or fails. A failure may preclude future reintroduction efforts in a region or country.     

Electrowinning studies for metallic zinc production from double leached Waelz oxide

Waelz oxide is a zinc and lead concentrate pyrometallurgically derived from electric arc furnace dust. There are clear incentives to leaching and purify this oxide to produce liquors that can be electrowinned to obtain recycled metallic zinc. This study is focused on this electrolytic zinc production from previously obtained sulphuric liquor. This liquor was obtained from double leached Waelz oxide (DLWO) throughout a hydrometallurgical process. The electrolytic liquor, after the corresponding leaching and purification stages, contains around 49 kg/m³. This liquor was fed to an electrowinning process where platinum or lead anodes and aluminium cathodes were used. After optimizing the different electrowinning critical parameters, and working at these optimal conditions, almost 88 secondary zinc kg were precipitated per each initial DLWO tonne in one-through process. The zinc purity was higher than 99.5%. After some mass balance calculations, it can be concluded that, optimizing the process configuration through internal recycling, around 210 Zn kg/DLWO t with purity near to 100% could be achieved.     

Novel synthetic approach to the potent germination stimulant strigol and its analogues

Abstract

Strigol (1) is a natural product that triggers suicidal germination of parasitic Striga species. Here we present an improved annulation sequence for the synthesis of the tricyclic moieties of strigol and its analogues. Our approach makes use of the one‐pot cyclization of 5‐nitro‐2‐pentanone and cyclopent‐2‐enone diesters to afford 7‐methyl‐4‐nitro‐l‐oxo‐hydrindene derivatives. Functional group elaboration of these intermediates leads to a series of hydrindene‐2‐acetic and propionic acids.     

Rendering Bio-inert Low-Density Polyethylene Amenable for Biodegradation via Fast High Throughput Reactive Extrusion Assisted Oxidation

Journal of Polymers and the Environment - An energy-efficient high throughput pre-treatment of low-density polyethylene (LDPE) using a fast, reactive extrusion (REX) assisted oxidation technique...     

Importance of the polarity on nanostructured silica materials to optimize the hydrolytic condensation with molecules related to CO2 adsorption

Environmental Science and Pollution Research - The present work reports the changes for the mesoporous materials SBA-15 and KIT-6 associated with the structural, textural, and chemical properties...     

Batch and continuous adsorption of Cu(II) and Zn(II) ions from aqueous solution on bi-functionalized sugarcane-based biosorbent

Environmental Science and Pollution Research - A new one-pot synthesis method optimized by a 23 experimental design was developed to prepare a biosorbent, sugarcane bagasse cellulose succinate...