Extraction of aquatic plants based on continuous removal method and analysis of its temporal and spatial changes—A case study of Guanting Reservoir

光谱特征变量的筛选作为水生植物识别的重要手段之一, 在水生植物种类识别研究中应用广泛。该研究将实测光谱特征提取与多时相Landsat 8 OLI影像数据分析相结合, 找到一种有效识别不同种类水生植物的特征变量。在水生植物反射光谱特征分析中引入矿质分析中普遍使用的连续统去除法, 对光谱重采样结果作连续统去除处理后提取光谱吸收深度特征。采用单因素方差分析法对比7个光谱重采样波段和3个连续统去除吸收深度敏感波段, 发现经连续统去除处理的短波红外1波段(SWIR1CR)对于不同类型的水生植物区分效果最佳。将连续统去除法应用到遥感影像处理上, 发现SWIR1CR波段能较好区分沉水植物和挺水植物; 结合影像归一化植被指数和SWIR1CR波段可较好区分三类水生植物。结合特征波段筛选结果采用支持向量机分类方法, 得到水生植物的分类结果精度为86.33%, 对比全生长期12期影像提取的水生植物分布图, 发现水生植物主要分布于官厅水库库区南北岸浅水区, 水生植物面积最大时约占库区总面积的35.13%; 其中沉水植物年内生长分布变化幅度较大, 6月上旬开始迅速生长; 10月份水生植物开始衰减; 11月份水生植物占库区面积的20%, 沉水、浮水植物大幅衰减消失。     

Adaptation of fatty acid compositions to temperature—a study on planktonic crustaceans

• 1.1. Fats of freshwater crustaceans overwintering in an active form are richer in long chain polyunsaturated fatty acids (50%) than of those spending the winter in form of resting eggs (10%).
• 2.2. The former species (Cyclops vicinus, Eudiaptomus gracilis) increase the level of docosahexaenoic acid from about 10 to 25% in their phospholipids with decreasing environmental temperature.
• 3.3. Exposing warm-adapted Cyclops vicinus and Eudiaptomus gracilis to 5°C in laboratory brought about an increase in the phospholipid docosahexaenoic acid level from 10 to 24%.
• 4.4. Ability to adapt membrane fluidity to the temperature might be important for survival at low temperatures.

     

Impact of the Gabcíkovo hydropower plant operation on planktonic copepods assemblages in the River Danube and its floodplain downstream of Bratislava

The structure of planktonic copepod assemblages in a by-passedDanube section, and in the adjacent floodplain water bodies,haschanged since the Gabcíkovo hydropower plant was putintooperation. The greatest change occurred in a former side arm(upstream of the village of Dobrohosí), which driedout.Changes were observed in the parapotamon-type side armssituatedbetween river km 1840 and 1820, fed artificially with waterfromthe head-race canal. The abundance of euplanktonic copepodspeciesdecreased, while that of tychoplanktonic species increased.Summerzooplankton biomass decreased. Definitive, but less extreme,changes occurred in the copepod assemblage in the open-waterareasof the former main channel of the Danube, and in theplesiopotamon-type side arms in the affected river section.These results suggest that the water supply provided to theby-passed floodplain is unable to maintain the previoushabitatdiversity, nor its planktonic assemblages speciesdiversity.     

Impact of fluorination on proteolytic stability of peptides: a case study with α-chymotrypsin and pepsin

Protease stability is a key consideration in the development of peptide-based drugs. A major approach to increase the bioavailability of pharmacologically active peptides is the incorporation of non-natural amino acids. Due to the unique properties of fluorine, fluorinated organic molecules have proven useful in the development of therapeutically active small molecules as well as in materials and crop science. This study presents data on the ability of fluorinated amino acids to influence proteolytic stability when present in peptide sequences that are based on ideal protease substrates. Different model peptides containing fluorinated amino acids or ethylglycine in the P2, P1′or P2′ positions were designed according to the specificities of the serine protease, α-chymotrypsin (EC 3.4.21.1) or the aspartic protease, pepsin (EC 3.4.23.1). The proteolytic stability of the peptides toward these enzymes was determined by an analytical RP-HPLC assay with fluorescence detection and compared to a control sequence. Molecular modeling was used to support the interpretation of the structure–activity relationship based on the analysis of potential ligand-enzyme interactions. Surprisingly, an increase in proteolytic stability was observed only in a few cases. Thus, this systematic study shows that the proteolytic stability of fluorinated peptides is not predictable, but rather is a very complex phenomenon that depends on the particular enzyme, the position of the substitution relative to the cleavage site and the fluorine content of the side chain.     

Carbon footprint and embodied energy of a wind turbine blade—a case study

Purpose

The main goal of this work is to evaluate the environmental impact of a 63-m blade for wind generators. The embodied energy and the carbon footprint are used as supporting tools for material selection in the initial project stages.

Methods

Real industrial data regarding the most used materials for wind turbine blade construction are used. Two eco-parameters, embodied energy and carbon footprint, were calculated from each selected material together with values of manufacture, transport, use, and final disposal. The blades must be built to have a mechanical strength high enough to withstand vibrations caused by manufacturing flaws, turbulence, or irregular loading. In this sense, Young’s modulus, yield strength, and density were compared to the environmental footprint data to support the final material choice. This evaluation process of the possible materials to be used in the blade manufacture was carried out in the initial stages of the project.

Results

Composite materials such as glass fiber-reinforced polymer (GFRP) and carbon fiber-reinforced polymer (CFRP), bonded together with an adhesive material, are used to build modern wind turbine blades. Those composites comprise a considerable number of different materials that can be mixed to reach adequate performance. Comparisons were made with 46 pre-selected materials, considering the mechanical behavior and environmental impacts. The final selected materials have better properties than the reference material. Finally, two materials with the desired mechanical properties and with a potential lower negative environmental impact than the reference material were selected.

Conclusions

Replacing the reference resin—epoxy/E-glass fiber—with the epoxy resin with the lowest environmental impact—epoxy/S-glass fiber—will reduce the total value of the environmental load to 102 GJ of energy and 3.4 t of CO₂. As important as the material selection in the early stages of product development is the end of life (EoL) choice. In this case, the glass fiber has an EoL potential of 370 GJ of energy and 460 t of CO₂ in the remanufacturing option, against zero for the landfill. This work shows that carefully selected raw materials and EoL alternatives for WTB can significantly reduce the environmental impact of this component.

     

Comparing direct land use impacts on biodiversity of conventional and organic milk—based on a Swedish case study

Purpose

Halting the loss of biodiversity while providing food security for a growing and prospering world population is a challenge. One possible solution to this dilemma is organic agriculture, which is expected to enhance biodiversity on the farmland. However, organic products often require larger areas. This study demonstrates how we can quantify and compare the direct land use impacts on biodiversity of organic and conventional food products such as milk.

Material and methods

This study assessed direct land use impacts of 1 l of milk leaving the farm gate. Inventory data on land occupation were extracted from a life cycle assessment study of 15 farms in southern Sweden. Direct land use change data were derived from the FAO statistical database. Spatially differentiated characterization factors of occupation (CF_Occ) and transformation (CF_Trans) were calculated based on the relative difference of plant species richness on agricultural land compared to a (semi) natural regional reference. Data on plant species richness and regeneration times of ecosystems (for calculating transformation impacts) were derived from a literature review. To account for differences in biodiversity value between regions, a weighting system based on absolute species richness, vulnerability and irreplaceability was applied.

Results and discussion

Organic milk had a lower direct land use impact than conventional milk, although it required about double the area. Occupation impacts dominated the results and were much smaller for organic than conventional milk, as CF_Occ of organic land uses were considerably smaller. For transformation impacts, differences between the two farming practices were even more pronounced. The highest impacts were caused by soymeal in concentrate feeds (conventional milk) due to large-scale deforestation in its country of cultivation (i.e. Brazil and Argentina). However, lack of reliable data posed a challenge in the assessment of transformation impacts. Overall, results were highly sensitive to differences in land occupation area between farms, the CF_Occ and assumptions concerning transformed area. Sensitivity and robustness of results were tested and are discussed.

Conclusions

Although organic milk required about twice as much land as conventional, it still had lower direct land use impacts on biodiversity. This highlights the importance of assessing land use impacts not only based on area but also considering the actual impacts on biodiversity. The presented approach allows to quantify and compare hot- and coldspots in the agricultural stage of milk production and could potentially also be applied to other agricultural products. However, more research is needed to allow quantification of indirect land use impacts.     

Effect of competition on the demography of planktonic cladocerans — Daphnia and Diaphanosoma

Summary Isolated and mixed continuous cultures of Daphnia hyalina and Diaphanosoma brachyurum in lake water were maintained under laboratory conditions to elucidate demographic effects of competition. Population dynamics curves were obtained. Interspecific competition was revealed by the decrease in the average density of animals in the mixed versus isolated cultures and by the extinction of one species in the presence of the other. Within the first 50 days either Diaphanosoma (4 cases) or Daphnia (1 case) was the superior competitor, depending on the initial conditions. Further cultivation resulted in the extinction of Diaphanosoma in the mixed cultures. There were no statistically significant differences between the maximum rates of population increase (r _m ) in Daphnia and Diaphanosoma at the concentration of edible algae about 2·10⁵ m³ml^-1(0.293 and 0.286 days^-1, respectively). Time lags for density-dependent parameters of the populations were evaluated by means of rank cross-correlations. Regardless of the species identity the time lags of fecundity, birth rate, and the rate of population growth were significantly higher in the superior competitor. The initial conditions of culturing affected the time lags which in their turn influenced the outcome of the interaction. Enhanced competitive ability due to the maximized time lags in Daphnia was not associated with the loss of population stability. Conversely, it brought about destabilization of Diaphanosoma populations which seemed to be the ultimate cause of its extinction observed in the end of the experiment. Time lag of the population growth rate was well predicted based on the half-sum of time lags in birth and death rates (r²=0.80, P<0.001). Daphnia responded to competition with a sharp shortening of the time lags of fecundity, birth rate, and the population growth rate. It increased clutch size and showed inverse relationship between the fecundity time lag and average fecundity even though it was strongly suppressed by Diaphanosoma. The competitive ability was not related to the percentage of adults in the populations. In contrast to the current belief the major result of interspecific competition in the experiment was not a decrease in the rate of population growth but was a reduction in population time lags.     

Subsite mapping of enzymes: Collecting and processing experimental data—a case study of an amylase-malto-oligosaccharide system

Two research groups have independently developed the theory and experimental methodology for quantitatively assessing substrate monomer-subsite binding-energies for depolymerases. When the two approaches are applied to the same enzyme-substrate system they yield surprisingly divergent results. This paper outlines the application of the two approaches to an amylase-maltooligosaccharide system and points out the more important areas of disagreement. We show that by proper data-management, the conflicts between the two laboratories are basically resolved. The complexities of the subsite model demand extensive data-gathering and exacting data-processing and verification that the computed model-parameters can faithfully reproduce the experimental data.     

The effects of tautomerization and protonation on the adenine–cytosine mismatches: a density functional theory study

In the present work, we demonstrate the results of a theoretical study concerned with the question how tautomerization and protonation of adenine affect the various properties of adenine–cytosine mismatches. The calculations, in gas phase and in water, are performed at B3LYP/6-311++G(d,p) level. In gas phase, it is observed that any tautomeric form of investigated mismatches is more stabilized when adenine is protonated. As for the neutral mismatches, the mismatches containing amino form of cytosine and imino form of protonated adenine are more stable. The role of aromaticity on the stability of tautomeric forms of mismatches is investigated by NICS(1)_ZZ index. The stability of mispairs decreases by going from gas phase to water. It can be explained using dipole moment parameter. The influence of hydrogen bonds on the stability of mismatches is examined by atoms in molecules and natural bond orbital analyses. In addition to geometrical parameters and binding energies, the study of the topological properties of electron charge density aids in better understanding of these mispairs.     

Scrutiny of chain-length and N-terminal effects in α-helix folding: a molecular dynamics study on polyalanine peptides

Protein folding remains an unsolved problem as main-chain, side-chain, and solvent interactions remain entangled and have been hard to resolve. Polyalanines are promising models to analyze protein folding initiation and propagation structurally as well as energetically. In the present work, the effect of chain-length and N-terminal residue stereochemistry in polyalanine peptides are investigated for their role in the nucleation of α-helical conformation. The end-protected polyalanine peptides, tetra-alanine, Ac-^LAla₄-NHMe (Ia) and Ac-^DAla-^LAla₃-NHMe (Ib), hexa-alanine, Ac-^LAla₆-NHMe (IIa) and Ac-^DAla-^LAla₅-NHMe (IIb), and octa-alanine, Ac-^LAla₈-NHMe (IIIa) and Ac-^DAla-^LAla₇-NHMe (IIIb), are assessed as chain-length and stereochemical-structure perturbed models. The appreciable variations in the sampling of α-helical conformation, including a sampling of α-helix folds, due to the cooperative effect of chain-length and N-terminal residue stereochemistry have been noted. The electrostatics of α-helical conformation rather than the conformational entropy of the main-chain appear to be decisive in the initiation of α-helix folding. The results of the present work will enhance our understanding on the nucleation of α-helical conformation in short peptides and aid in the design of novel peptides with α-helical structure that can modulate disease-related protein–protein interactions.     

A holomorph approach to xiphosuran evolution—a case study on the ontogeny of Euproops

Specimens of Euproops sp. (Xiphosura, Chelicerata) from the Carboniferous Piesberg quarry near Osnabrück, Germany, represent a relatively complete growth series of 10 stages. Based on this growth sequence, morphological changes throughout the ontogeny can be identified. The major change affects the shape of the epimera of the opisthosoma. In earlier stages, they appear very spine-like, whereas in later stages the bases of these spine-like structures become broader; the broadened bases are then successively drawn out distally. In the most mature stage known, the epimera are of trapezoidal shape and approach each other closely to form a complete flange around the thoracetron (=fused tergites of the opisthosoma). These ontogenetic changes question the taxonomic status of different species of Euproops, as the latter appear to correspond to different stages of the ontogenetic series reconstructed from the Piesberg specimens. This means that supposed separate species could, in fact, represent different growth stages of a single species. It could alternatively indicate that heterochrony (=evolutionary change of developmental timing) plays an important role in the evolution of Xiphosura. We propose a holomorph approach, i.e., reconstructing ontogenetic sequences for fossil and extant species as a sound basis for a taxonomic, phylogenetic, and evolutionary discussion of Xiphosura.     

Hydrophilicity and antigenicity of proteins — A case study of myoglobin and hemoglobin

Hydrophilicity index is used to locate antigenic determinants on two related groups of proteins-myoglobin and hemoglobin. The data on 41 species (including 34 mammals) of myoglobin show that average hydrophilicity for the complete myoglobin molecules as well as the average hydrophilicity for all hydrophilic regions put together seem to remain constant; the variation in the size and location of the antigenic determinants in these species is very small indicating that the antigenic sites are not shifted during evolution. In the case of both the proteins there is a good agreement between the antigenic sites picked up by using hydrophilicity index and the experimentally determined antigenic sites. The data on 56 species of hemoglobin α-chains and 44 species of hemoglobinβ-chains showed that although there are few sites on hemoglobin which have remained invariant during evolution, there is a significant variation in other sites in terms of either a splitting of a site, or a drastic change in the hydrophilicity values and/or a length of the site. Comparison of the hydrophilicity data on these two groups of proteins suggests that hemoglobins which perform a variety of functions as compared to myoglobins are evolving faster than myoglobins supporting the contention of earlier workers.     

Chirality of pollutants—effects on metabolism and fate

In most cases, enantiomers of chiral compounds behave differently in biochemical processes. Therefore, the effects and the environmental fate of the enantiomers of chiral pollutants need to be investigated separately. In this review, the different fates of the enantiomers of chiral phenoxyalkanoic acid herbicides, acetamides, organochlorines, and linear alkylbenzenesulfonates are discussed. The focus lies on biological degradation, which may be enantioselective, in contrast to non-biotic conversions. The data show that it is difficult to predict which enantiomer may be enriched and that accumulation of an enantiomer is dependent on the environmental system, the species, and the organ. Racemization and enantiomerization processes occur and make interpretation of the data even more complex. Enantioselective degradation implies that the enzymes involved in the conversion of such compounds are able to differentiate between the enantiomers. Enzyme pairs have evolved which exhibit almost identical overall folding. Only subtle differences in their active site determine their enantioselectivities. At the other extreme, there are examples of non-homologous enzyme pairs that have developed through convergent evolution to enantioselectively turn over the enantiomers of a chiral compound. For a better understanding of enantioselective reactions, more detailed studies of enzymes involved in enantioselective degradation need to be performed.     

Testing the higher-taxon approach: a case study of aquatic marcophytes in China’s northwest arid zone and its implications for conservation

Assessments of biodiversity are time-consuming and require a high level of expert knowledge. A reduced set of taxonomic ranks other than species has been proved to be useful for rapid and cost-effective assessment of biodiversity. However, few studies have examined how well this method performs for aquatic plant group that of enormous ecological importance. We studied the aquatic plant flora in the arid zone of China and examined whether the distribution of species α- and β-diversity could be predicted well from genus-, and family-levels. Analyses of 3 years field data showed that significant and positive relations exist between α-diversity of species and α-diversity of genera and family in both entire arid zone and five sub-zones. In contrast, β-diversity at species level is difficult to predict from β-diversity indexes at higher taxonomic level. The results indicate that higher-taxon α-diversity, especially at the generic level in our research, can be useful surrogates of species α-diversity for aquatic plants conservation.     

The influence of substratum age on patterns of protozoan assemblages in freshwater Aufwuchs — a case study

The sulfate reduction rate was measured for almost four years in the profundal sediments of Lake Kizaki, a mesotrophic lake in central Japan. The rate was generally highest in the surface layer and decreased with depth. Seasonally, sulfate reduction tended to be high in spring and summer, and then to decrease until the end of stratification (December) in spite of a constant in situ temperature of around 6 °C, although fluctuations were found in every year. The rate also fluctuated greatly according to year. The maximum rate of sulfate reduction was 0.33 mmol m⁻² d⁻¹ in May, 1990, and the minimum was 0.004 mmol m⁻² d⁻¹ in March, 1993. These relatively low rates, compared with those reported for freshwater sediments, seem to be due to low concentrations of sulfate in the sediments (5–23 μmol l⁻¹ in the surface layer). The rate was highly correlated with the concentration of sulfate in the sediments. The addition of sulfate stimulated sulfate reduction in all sediment samples tested, but adding lactate did not. Therefore, sulfate reduction should be limited mainly by the supply of sulfate. Measurements of sulfate reduction rates at different concentrations of added sulfate revealed a low concentration of half-saturation constant as low as 12 μmol l⁻¹.     

Amiodarone — an inhibitor of phospholipase activity: a comparative study of the inhibitory effects of amiodarone,chloroquine and chlorpromazine

Amiodarone, an antiarrhythmic drug, like chloroquine and chlorpromazine, is a tertiary amine with amphiphilic properties. Chloroquine and chlorpromazine are known inhibitors of phospholipases. All three drugs produce characteristic microcorneal deposits consistent with lysosomal accumulations of phospholipid. Similar lysosomal bodies were found in leukocytes of 15 patients on chronic amiodarone treatment as well as 3 patients each on chloroquine and chlorpromazine, suggestive of widespread systemic inhibition of lysosomal phospholipases. These lysosomal inclusions were similar in morphology, irrespective of the drug given, and were of four types: multilamellar, amorphous dense, amorphous light, or a combination of 2 or more of the preceding types. There was no simple relationship between the number of inclusion bodies per cell and the cumulative dose of amiodarone (r=0.02) or amiodarone serum levels (r=0.11). An in vitro assay was used to compare the effects of the three drugs on Ca²⁺-dependent phospholipase A and C activities. Phospholipase A₂ activity was inhibited in a dose-dependent fashion (1–8 mg/assay) by all three drugs in the order: chlorpromazine > amiodarone > chloroquine. The inhibitory effect on phospholipase C was more pronounced with all three drugs, producing almost total inhibition at 8 mg/assay. In a Ca²⁺-independent lysosomal phospholipase A system, amiodarone had a greater effect, producing 85% inhibition at 1.2 mg/assay. These observations suggest that amiodarone, like other cationic amphiphiles, induces a generalized phospholipidosis by inhibiting phospholipid catabolism. Its therapeutic and toxic effects may be due to its ability to modulate both Ca²⁺-dependent membrane phospholipases and Ca²⁺-independent acid phospholipases.     

Lysyl oxidase polymorphisms and ischemic stroke—a case control study

Ischemic stroke is a common neurological disease and causes severe disability and death worldwide. Lysyl oxidase (LOX) plays a crucial role in the maintenance of extracellular matrix stability and may participate in vascular remodeling in the development of ischemic stroke. The objective of this study is to identify polymorphisms in LOX genes and investigate the association between LOX polymorphisms and the susceptibility to ischemic stroke in the Chinese population. Genomic DNA sequencing analysis was performed on all 7 exons and all exon/intron splice sites of lysyl oxidase and 850?bp upstream, including the predicted promoter region in 25 control subjects. The identified polymorphisms were then detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 702 ischemic stroke cases and 733 age-matched controls. Data were analyzed using the Chi-square test. Two polymorphisms in the LOX gene, 473G/A (rs1800449) and rs2278226, were observed in the Chinese population. Frequencies of LOX 473AA genotype and A allele were significantly higher in ischemic stroke patients than in controls (odds ration (OR)?=?1.76, 95?% confidence interval (CI) 1.16-2.67, P?=?0.007; and OR?=?1.33, 95?% CI 1.10-1.60, P?=?0.003). Also, the prevalence of AC haplotype was significantly increased in ischemic stroke cases (OR?=?1.32, 95?% CI 1.10-1.60, P?=?0.004). Our data suggest that the G473A polymorphism of LOX gene could be a new risk factor for ischemic stroke.     

The effects of α-synuclein on phospholipid vesicle integrity: a study using 31P NMR and electron microscopy

Associations between the 140 amino acid protein α-synuclein (asyn) and presynaptic vesicles may play a role in maintaining synaptic plasticity and neurotransmitter release. These physiological processes may involve disruption and fusion of vesicles, arising from interactions between specific regions of asyn, including the highly basic N-terminal domain, and the surface of vesicles. This work investigates whether asyn affects the integrity of model unilamellar vesicles of varying size and phospholipid composition, by monitoring paramagnetic Mn²⁺-induced broadening of peaks in the ³¹P nuclear magnetic resonance spectrum of the lipid head groups. It is shown that asyn increases the permeability to Mn²⁺ of both large (200nm diameter) and small (50nm diameter) vesicles composed of zwitterionic phosphatidylcholine and anionic phosphatidylglycerol at protein/lipid molar ratios as low as 1:2000. Further experiments on peptides corresponding to sequences in the N-terminal (10–48), C-terminal (120–140) and central hydrophobic (71–82) regions of asyn suggest that single regions of the protein are capable of permeabilizing the vesicles to varying extents. Electron micrographs of the vesicles after addition of asyn indicate that the enhanced permeability is coupled to large-scale disruption or fusion of the vesicles. These results indicate that asyn is able to permeabilize phospholipid vesicles at low relative concentrations, dependent upon the properties of the vesicles. This could have implications for asyn playing a role in vesicle synthesis, maintenance and fusion within synapses.     

Environmental risk assessment of heavy metals pollution in aquatic ecosystem—A case study: Sediment of Kor River,Iran

A comprehensive investigation of fractionation and environmental risk of nine heavy metals is carried out for 12 sediment samples collected from Kor River, Iran. For this purpose, the 5-stage sequential extraction method, along with individual contamination factor, global contamination factor, and Environmental Risk Index (ERI), is used. Total concentrations of Cr, Hg, Ni, and Zn were found to be beyond the threshold effect level. The results of fractionation patterns indicate that As, Cr, Ni, Pb, and Zn are mostly associated with Fe-Mn oxide fraction, organic fraction, and residual fraction, while Cd and Mo are predominantly associated with carbonate fraction. Cu and Hg are mostly associated with organic and exchangeable fractions. The results of ERI revealed High to Dangerous risks in 40% of Kor River stations. The applied approach in this study is beneficial to other environmental studies that require analysis of complex data.     

LCA and LCC of the world’s longest pier: a case study on nickel-containing stainless steel rebar

Purpose

Built in 1941, the Progreso Pier was the first concrete structure in the world built with nickel-containing stainless steel reinforcement. The Pier has been in service for over 70 years without any significant repair or maintenance activities. The aim of this study was to understand the environmental and economic implications of selecting nickel-containing stainless steel reinforcement using the Progreso Pier as the case study.

Methods

A combined environmental life cycle assessment (LCA) and life cycle costing (LCC) study was conducted. The analysis considered the potential environmental impacts and the net present cost of the stainless steel reinforced structure from cradle to grave and compared it to the same structure using conventional carbon steel.

Results and discussion

The results indicated that while using stainless steel reinforcement resulted in a marginally higher environmental impact after initial construction, this is offset by the increased service life and, hence, less frequent maintenance and reconstruction activities. Relative to the as-built stainless steel reinforcement design, the environmental impacts of the carbon steel reinforced design are between 69 and 79 % higher over the analysis period. Similar observations were made for the other investigated impact categories. The cost implications of using stainless steel reinforcement show economic benefits that are complementary to the environmental benefits. Similar to the LCA, the service life benefits outweigh the higher unit costs for stainless steel, assuming a discount rate of 0.01 % as the baseline scenario. The carbon steel reinforced design has a net present cost that is 44 % higher than the as-built stainless steel reinforcement design. The crossover point for the two designs occurs at year 50, which corresponds to the reconstruction activity. A sensitivity analysis shows that the results and conclusions are sensitive to the choice in discount rate: Rates 3 % and lower produce net present costs that are lower for the as-built design; rates 4 % and higher produce net present costs that are lower for the alternative design.

Conclusions

The study demonstrates how LCA and LCC are complementary tools that can be used in decision-making for sustainable construction. The Progreso Pier exemplifies the importance of considering the entire life cycle with service life and recycling as well as long-term life cycle impacts of infrastructure projects from an environmental and economic perspective.