Water environment

About: Water environment is a research topic. Over the lifetime, 13384 publications have been published within this topic receiving 125138 citations.

Superhydrophilicity and spontaneous spreading on zwitterionic surfaces: carboxybetaine and sulfobetaine

Abstract: Zwitterionic surfaces are fabricated by grafting sulfobetaine silane (SBSi) and carboxybetaine silane (CBSi) on glass slides. Their wetting behaviors are investigated using water, polar organic liquids, and hexadecane as test liquids. For the CBSi surface, partial wetting is observed, and contact angles of water and hexadecane are lower than 10°, revealing super-amphiphilicity. For the SBSi surface, all test liquids spread spontaneously and contact angles are absent, corresponding to total wetting. The time evolution of the wetting area of a liquid drop can be divided into three types: spread-withdrawal for water, spread-pin for polar organic liquids, and continuous spread for hexadecane. The spontaneous spreading on SBSi surfaces is driven by the high solid–gas interfacial tension and can be characterized by the power law. Although zwitterionic surfaces like both water and hexadecane in ambient air, their preference for water over hexadecane is typically demonstrated by a hexadecane drop in a water environment. Nonetheless, the contact angle of the hexadecane drop is 120° on the CBSi surface, but becomes 180° on the SBSi surface. As the zwitterionic surfaces are immersed in all test liquids, bubbles generally adhere to the CBSi surface but freely move beneath the SBSi surface. Our experimental results clearly show the wettability difference between the CBSi and SBSi surfaces. The former is superhydrophilic, while the latter is total wetting.

Complex Satellite Monitoring of Coastal Water Areas

Abstract: Possibilities of applying satellite means for monitoring of sea and ocean water areas are considered. Significant parameters of water environment registered by modern advanced space means and problems than can be solved using these means are analyzed. Some results obtained during complex satellite monitoring of anthropogenic influences on Mamala Bay water area (Honolulu, Hawaii) in 2002-2004 are given in this paper. Based on analysis results for optical (panchromatic, multispectral, hyperspectral) and radar satellite image processing, manifestations of anthropogenic influence on water environment were studied. These manifestations are related to changes in hydrodynamic parameters, hydro- optical and hydro-biological characteristics of near- surface ocean layer. Effects of generation of "quasimonochromatic" spectral harmonics of sea waves (Λ~10...150 m) due to ultrahigh frequency internal wave manifestations caused by a deep outfall are detected. Parameters of harmonics revealed in satellite imagery coincide with parameters of internal waves obtained from the results of sea truth measurements. Based on the results of satellite monitoring we have worked out recommendations on nature-conservative measures in the studied recreational area that can be realized also for other coastal water areas.

Spatially significant effects of selective tropical forestry on water, nutrient and sediment flows: a modelling-supported review.

Abstract: INTRODUCTION Selective forestry is a set of commercial forestry practices that involves the selective removal of particular trees within an ‘annual logging coupe’ of forest (Conway, 1982). Selective harvesting within ‘natural forests’ (i.e. those forests that have not been clearfelled for non-forest uses or converted to plantation or agroforestry) covers a very wide range of practices, including highlead and tractor yarding, harvesting of only large, commercial trees, protection of riparian vegetation along rivers and protection of forest on very steep hills. As a consequence, the intensities of the impacts on the water environment (i.e. water, nutrient and sediment systems) are expected to be very varied. Some of these impacts can be profound. One of the most significant environmental impacts of all types of forestry operations within the humid tropics is accelerated soil erosion (Bruijnzeel, 1992). The resultant input of sediments into rivers leads to damage to fish populations (Martin-Smith, 1998), reduced quality of water supplies, reductions in channel capacity which affects flood risk and boat traffic (Sheffield et al. , 1995), and the inundation of offshore corals (MacDonald et al. , 2001). Development of selective harvesting techniques when applied to natural forests in the tropics are currently being focused on so-called ‘Reduced-Impact-Logging’ (RIL) or ‘closely supervised’ methods which aim to improve the ‘sustainability’ of timber production and reduce wider environmental damage.