Serviços dos ecossistemas prestados pelos estuários : especiação e capacidade de retenção do fósforo

O fator nutricional presente nos sapais não é só importante para os organismos que nele habitam como também apresenta uma importância ecológica a uma maior escala. Exemplifica-se este fato com a capacidade de retenção do Fósforo (P) por parte das plantas podendo estas competir como produto químicos para sua imobilização através da incorporação da sua fração biodisponível para cumprimento dos mecanismos básicos de sobrevivência. O rizosedimento dessas plantas é uma importante fonte de nutrientes necessários para garantia básica da perpetuação de todos os serviços (regulação, provisão, cultural) gerados pelo ambiente. A perda de áreas de sapal foi o motivo principal para a elaboração desta tese visto a preocupação em relação aos impactes que a perda de serviços associados à área de estudo escolhida, o sistema lagunar da Ria de Aveiro, poderá vir sofrer caso aconteçam alterações hídricas (naturais ou antrópicas) mais acentuadas no futuro. Essa tese assume como compromisso chamar a atenção para essa questão como também investigar os mecanismos do ciclo do P este importante nutriente considerado essencial para a manutenção da vida em nosso planeta. Para este estudo foram escolhidas 3 espécies de plantas halófitas representantes do sapal amostral, são elas: Bolbochenous maritimus, Spartina maritima e de Juncus maritimus. As questões levantadas buscam compreender o papel do P nas transformações que ocorrem no rizosedimento das halófitas em 3 diferentes contextos: (i) quando comparados os valores da biomassa de P associado às halófitas estudadas (estudo realizado nos sapais povoados por Spartina maritima e Juncus maritimus) em toda extensão da Ria de Aveiro (ii) quando da disponibilidade de P perante a presença de poluentes inorgânicos no Largo do Laranjo, que corresponde a uma zona historicamente contaminada por metais (estudo realizado no rizosedimento das espécies Bolbochenous maritimus e Juncus maritimus) e (iii) quanto à intrusão superficial da água salgada da laguna (estudo focado na avaliação da perda do P próximo às raízes das halófitas que habitam a zona externa do dique do Baixo Vouga Lagunar (BVL) que corresponde à zona de confluência do Rio Vouga com a Ria de Aveiro). Por meio da análise do rizosedimento e da biomassa das diferentes halófitas predominantes do sapal foi possível verificar que, em relação à carga nutritiva fosfática, de Norte (Canal de São Jacinto/Ovar) a Sul (Canal de Mira) da Ria de Aveiro, a cota do sapal é mais importante do que a natureza espacial do sistema. Esta informação é primordial para a assertividade de futuras medidas de criação e reabilitação das áreas de sapal na Ria de Aveiro. Os estudos realizados nas áreas impactadas (Largo do Laranjo e BVL) incidiram na análise do perfil vertical rizosedimentar das halófitas pertencentes ao sapal médio-alto. Estes estudos revelaram que o rizosedimento dessas halófitas possui características peculiares que definem a dinâmica do ciclo do P de forma bastante característica. O rizosedimento das halófitas presentes no Largo do Laranjo apresentaram teores biodisponíveis de P equivalentes àqueles presentes no rizosedimento de área mais afastada da fonte pontual de contaminação para as mesmas espécies. Numa visão otimista, os resultados revelam que ambos sapais, Largo de Laranjo e Cais do Bico, apresentam condições equiparável para perpetuação dos serviços por eles gerados, que nesse caso se tornam ainda mais valiosos devido a garantia da fitoestabilização dos contaminantes (prevenção da entrada de contaminantes na coluna d’água e na cadeia alimentar). No Baixo Vouga Lagunar a análise espacial do sapal na zona exterior ao dique revelou a perda da diversidade das espécies bem como o aumento da área de vasa e consequentemente a perda dos teores de P associados ao rizosedimento das halófitas mais expostas aos efeitos da compressão costeira intensificados pelas ações naturais e antrópicas a que a Ria está sujeita. Em geral, a degradação dessa área de sapal devido aos fenômenos de assoreamento ou de erosão não pode ser separada dos processos sedimentares na área envolvente, principalmente no caso da Ria de Aveiro que tem sofrido constantes mudanças para atender às necessidades das atividades humanas. Essa tendência provavelmente não mudará no futuro próximo. Consequentemente, a evolução da laguna será principalmente dependente do resultado direto das ações humanas que deverão sempre encontrar formas de compensar os danos causados no âmbito de intervenções de reabilitação do sistema hídrico. A recriação de áreas de sapal pode ter lugar como medida mitigadora no âmbito de intervenções de reabilitação de áreas degradadas e ainda poderá servir como forma de captura de P para programas de utilização de fertilizantes naturais (componente desejável para a agricultura moderna o que é particularmente importante para as regiões altamente dependentes do mercado de importação). Deste modo, recomenda-se que a recuperação das áreas de sapal seja enquadrada no âmbito de intervenções mais amplas de valorização dos sistemas estuarinos e lagunares.

Photographic analysis of natural and impounded salt marsh in the vicinity of Merritt Island, Florida

Qualitative analyses of available photographs and maps of Merritt Island, Florida provide a large-scale, historical perspective of ecological changes of the marshes in the vicinity. Sites that deserve closer scrutiny can be identified. Secondarily, such an analysis provides a geographical orientation essential for communication not only between newcomers and those familiar with the area, but also among those familiar with the area but who refer to sites by differing methods. Photographs and maps from various sources were examined. Below are listed what we consider to be the most useful subset of these for ecological and geographical assessment of salt marsh impoundments on Merritt Island, Florida. (Document has 25 pages.)

Tracking rates of ecotone migration due to salt-water encroachment using fossil mollusks in coastal South Florida

We determined the rate of migration of coastal vegetation zones in response to salt-water encroachment through paleoecological analysis of mollusks in 36 sediment cores taken along transects perpendicular to the coast in a 5.5 km2 band of coastal wetlands in southeast Florida. Five vegetation zones, separated by distinct ecotones, included freshwater swamp forest, freshwater marsh, and dwarf, transitional and fringing mangrove forest. Vegetation composition, soil depth and organic matter content, porewater salinity and the contemporary mollusk community were determined at 226 sites to establish the salinity preferences of the mollusk fauna. Calibration models allowed accurate inference of salinity and vegetation type from fossil mollusk assemblages in chronologically calibrated sediments. Most sediments were shallow (20–130 cm) permitting coarse-scale temporal inferences for three zones: an upper peat layer (zone 1) representing the last 30–70 years, a mixed peat-marl layer (zone 2) representing the previous ca. 150–250 years and a basal section (zone 3) of ranging from 310 to 2990 YBP. Modern peat accretion rates averaged 3.1 mm yr)1 while subsurface marl accreted more slowly at 0.8 mm yr)1. Salinity and vegetation type for zone 1 show a steep gradient with freshwater communities being confined west of a north–south drainage canal constructed in 1960. Inferences for zone 2 (pre-drainage) suggest that freshwater marshes and associated forest units covered 90% of the area, with mangrove forests only present along the peripheral coastline. During the entire pre-drainage history, salinity in the entire area was maintained below a mean of 2 ppt and only small pockets of mangroves were present; currently, salinity averages 13.2 ppt and mangroves occupy 95% of the wetland. Over 3 km2 of freshwater wetland vegetation type have been lost from this basin due to salt-water encroachment, estimated from the mollusk-inferred migration rate of freshwater vegetation of 3.1 m yr)1 for the last 70 years (compared to 0.14 m yr)1 for the pre-drainage period). This rapid rate of encroachment is driven by sea-level rise and freshwater diversion. Plans for rehydrating these basins with freshwater will require high-magnitude re-diversion to counteract locally high rates of sea-level rise.

Effect of height of bridge above water on salt deposition levels

Maintenance of bridge structures is a major issue for the Queensland Department of Main Roads. In the previous phase of this CRC project an initial approach was made towards the development of a program for lifetime prediction of metallic bridge components. This involved the analysis of five representative bridge structures with respect to salt deposition (a major contributor to metallic corrosion) to determine common elements to be used as “cases” - those defined for buildings are not applicable. The five bridges analysed included the Gladstone Port Access Road Overpass, Stewart Road Overpass, South Johnstone River Bridge, Johnson Creek Bridge and the Ward River Bridge.

Report : effect of natural cleaning on salt deposition on Queensland bridges

Maintenance of bridge structures is a major issue for the Queensland Department of Main Roads. In the previous phase of this CRC project an initial approach was made towards the development of a program for lifetime prediction of metallic bridge components. This involved the analysis of five representative bridge structures with respect to salt deposition (a major contributor to metallic corrosion) to determine common elements to be used as “cases” - those defined for buildings are not applicable. The five bridges analysed included the Gladstone Port Access Road Overpass, Stewart Road Overpass, South Johnstone River Bridge, Johnson Creek Bridge and the Ward River Bridge.

The structure of the copper(II) complex with 4,5-dichlorophthalic acid: The 1:1 complex 'adduct' salt trans-tetraaqua(2-carboxy-4,5-dichlorobenzoato)(4,5-dichlorobenzene-1,2-dicarboxylic acid)copper(II) 2-carboxy-4,5-dichlorobenzoate

The unusual (1:1) complex ‘adduct’ salt of copper(II) with 4,5-dichlorophthalic acid (H2DCPA), having formula [Cu(H2O)4(C8H3Cl2O4) (C8H4Cl2O4)] . (C8H3Cl2O4) has been synthesized and characterized using single-crystal X-ray diffraction. Crystals are monoclinic, space group P21/c, with Z = 4 in a cell with dimensions a = 20.1376(7), b =12.8408(4) c = 12.1910(4) Å, β = 105.509(4)o. The complex is based on discrete tetragonally distorted octahedral [CuO6] coordination centres with the four water ligands occupying the square planar sites [Cu-O, 1.962(4)-1.987(4) Å] and the monodentate carboxyl-O donors of two DCPA ligand species in the axial sites. The first of these bonds [Cu-O, 2.341(4) Å] is with an oxygen of a HDCPA monoanion, the second with an oxygen of a H2DCPA acid species [Cu-O, 2.418(4) Å]. The un-coordinated ‘adduct’ molecule is a HDCPA counter anion which is strongly hydrogen-bonded to the coordinated H2DCPA ligand [O… O, 2.503(6) Å] while a number of peripheral intra- and intermolecular hydrogen-bonding interactions give a two-dimensional network structure.

Phenyl-ring disorder in the two-dimensional hydrogen-bonded structure of the 1:1 proton-transfer salt of the diazo-dye precursor 4-(phenyldiazenyl)aniline (aniline yellow) with L-tartaric acid

The structure of the 1:1 proton-transfer compound from the reaction of L-tartaric acid with the azo-dye precursor aniline yellow [4-(phenylazo)aniline], 4-(phenyldiazenyl)anilinium hydrogen 2R,3R-tartrate C12H12N3+ . C4H6O6- has been determined at 200 K. The asymmetric unit of the compound contains two independent phenylazoanilinium cations and two hydrogen L-tartrate anions. The structure is unusual in that all four phenyl rings of both cations have identical 50% rotational disorder. The two hydrogen L-tartrate anions form independent but similar chains through head-to-tail carboxylic O--H...O~carboxyl~ hydrogen bonds [graph set C7] which are then extended into a two-dimensional hydrogen-bonded sheet structure through hydroxyl O--H...O hydrogen-bonding links. The anilinium groups of the phenyldiazenyl cations are incorporated into the sheets and also provide internal hydrogen-bonding extensions while their aromatic tails layer in the structure without significant interaction except for weak \p--\p interactions [minimum ring centroid separation, 3.844(3) \%A]. The hydrogen L-tartrate residues of both anions have the common short intramolecular hydroxyl O--H...O~carboxyl~ hydogen bonds. This work has provided a solution to the unusual disorder problem inherent in the structure of this salt as well as giving another example of the utility of the hydrogen tartrate in the generation of sheet substructures in molecular assembly processes.

2,3-Dimethoxy-10-oxostrychnidinium 2-(2,4,6-trinitroanilino)benzoate monohydrate : a 1:1 proton-transfer salt of brucine with o-picraminobenzoic acid

In the structure of the 1:1 proton-transfer compound of brucine with 2-(2,4,6-trinitroanilino)benzoic acid C23H27N2O4+ . C13H7N4O8- . H~2~O, the brucinium cations form the classic undulating ribbon substructures through overlapping head-to-tail interactions while the anions and the three related partial water molecules of solvation (having occupancies of 0.73, 0.17 and 0.10) occupy the interstitial regions of the structure. The cations are linked to the anions directly through N-H...O(carboxyl) hydrogen bonds and indirectly by the three water molecules which form similar conjoint cyclic bridging units [graph set R2/4(8)] through O-H...O(carbonyl) and O(carboxyl) hydrogen bonds, giving a two-dimensional layered structure. Within the anion, intramolecular N-H...O(carboxyl) and N H...O(nitro) hydrogen bonds result in the benzoate and picrate rings being rotated slightly out of coplanarity inter-ring dihedral angle 32.50(14)\%]. This work provides another example of the molecular selectivity of brucine in forming stable crystal structures and also represents the first reported structure of any form of the guest compound 2-(2,4,6-trinitroanilino)benzoic acid.

Resolution of the chiral (1R,2S) enantiomer of cis-cyclohexane-1,2-dicarboxylic acid in the brucinium salt 2,3-dimethoxy-10-oxostrychnidinium (1R,2S)-2-carboxycyclohexane-1-carboxylate dihydrate

The structure of the 1:1 brucinium salt of cis-cyclohexane-1,2-dicarboxylic acid, 2,3-dimethoxy-10-oxostrychnidinium (1R,2S)-2-carboxycyclohexane-1-carboxylate dihydrate, has revealed the resolved (1R,2S) enantiomer of the acid. Crystals of the compound are orthorhombic, space group P212121, with unit cell dimensions a = 8.1955(3), b = 12.4034(3), c = 29.9073(9)Å, and Z = 4. The asymmetric unit comprises the brucinium cation, the hydrogen cis-cyclohexane-1,2-dicarboxylate cation, in which the carboxylate group is disordered over two sites (58, 42%), and two water molecules of solvation, one of which is occupies two 50% occupancy sites. The classic undulating brucinium cation substructures are present with the anion and the water molecules occupying the interstitial cavities and are hydrogen-bonded to them in a two-dimensional network structure.

Ion transport in small-molecule electrolytes based on LiI/3-hydroxypropionitrile with high salt contents

Abnormal “polymer-in-salt” conduction behavior is observed in a solid electrolyte composed of lithium iodide (LiI) and 3-hydroxypropionitrile (HPN). Based on comprehensive investigations by X-ray diffraction (XRD) and Raman and infrared spectroscopy, this abnormal conduction behavior is attributed to the formation of new ionic associates [Lim +In−]· · ·N C (m> n) and the reinforced hydrogen bonding of I· · ·HO in the electrolyte at high LiI concentrations.