Eutrophication of Tamar Lakes (1975–2003): a case study of land-use impacts, potential solutions and fundamental issues for the Water Framework Directive

Tamar Lakes is comprised of two reservoirs, which are located in South West England and in the headwaters of River Tamar at approximately 135 m above ordnance datum. Upper Tamar Lake (UTL) is a direct feed source reservoir of potable water in North Cornwall. Immediately following completion in 1975, UTL was subject to intense blue‐green algal blooms that continue to the present. These blooms create operational problems for water treatment, especially in hot‐dry years. Lower Tamar Lake (LTL) was constructed as a water supply reservoir in 1819 and became obsolete following UTL coming on‐line. Detailed water quality investigations over a period of some 28 years have confirmed the source of nutrient enrichment that fuels the algal blooms to be agriculturally derived, corresponding with a substantial increase in livestock farming. Associated poor land management practices, such as extensive field drainage and inappropriate slurry disposal to land, are linked with substantial elevations in organic contaminants such as ammonia, biochemical oxygen demand (BOD) and suspended solids (SS) during rainfall events. Evidence demonstrates that both reservoirs act as primary treatment lagoons, substantially reducing the worst of these pollutants and providing significant environmental gain. The implications of the Common Agricultural Policy (CAP), the Water Framework Directive (WFD) and regulatory monitoring are discussed in relation to resource management.     

The effects of water management on annual maximum floods of Lake Como and River Adda at Lecco (Italy)

This paper presents the results of an analysis aimed to assess the impact exerted on the flood regime of Lake Como and its emissary by different kinds of waterworks in the Adda basin (Italy). This includes construction of reservoirs in the Alps, increase in flow capacity of the exutory and regulation of Lake Como. The assessment of the management effect on peak floods is of particular interest as flood damages could be particularly heavy in densely populated areas along the lake banks and in the river flood plain downstream of the lake. The analysis is carried out by comparing the annual maxima of Lake Como levels and the river Adda discharges at Lecco, at the lake exutory, in different real and hypothetical situations. Both the construction of alpine reservoirs and the improvement of flow capacity of the exutory decrease lake levels and flood discharges, while lake regulation (for irrigation and power production) increases them. The overall effect is a generalised reduction of the flood levels and a slight increase in the discharges with return periods lower than 10 years. The discharges with higher return periods, instead, remain unchanged. The difference between peak and mean daily discharges negligible in all cases disappears altogether for return periods higher than 10 years.     

Impacts of climate and land‐cover changes on water resources in a humid subtropical watershed: a case study from East Texas,USA

This study investigates the response of water resources regarding the climate and land‐cover changes in a humid subtropical watershed during the period 1970–2009. A 0.7°C increase in temperature and a 16.3% increase in precipitation were observed. Temperature had a lower increase trend, and precipitation showed definite increasing trend compared to previous studies. The main trend of land‐cover change was conversion of vegetation and barren lands to developed and crop lands affected by human intervention, and forest and grass to bush/shrub which considered to be caused by natural climate system. Hydrologic responses to climate and land‐cover changes resulted in increases of surface run‐off (15.0%), soil water content (2.7%), evapotranspiration (20.1%) and a decrease in groundwater discharge (9.2%). We found that surface run‐off is relatively stable with precipitation, whereas groundwater discharge and soil water content are sensitive to changes in land cover, especially land cover brought about by human intervention.     

The Environmental Impact of a Chemical Spill from a Timber-Treatment Works on a Lowland River System

A major timber-preservative spillage, resulting from a fire at a timber yard, released substantial quantities of tributyltin and lindane (g hexachlorocyclohexane) into the River Bourne - a tributary of the River Thames. This paper describes the chemical and biological effects resulting from the incident. Water-column concentrations in the River Bourne South ranged from below detection limits to 5200 μg/l and 3700 μg/l for tributyltin and lindane respectively, with contamination extending 80 km into the Thames estuary. The high concentration of pollutants caused extensive fish mortality and virtually eradicated the invertebrate population in the immediate vicinity of the spill. Although sediment monitoring revealed initially high surficial sediment concentrations of tributyltin (3300 ng/g) and lindane (490 ng/g), loadings declined over a period of time, but it is perceived that contaminated sediments may pose a longer-term threat to benthic communities, particularly in the proximity of the spill site.     

The effects of reduction of the deposited waste on short‐term landfill leachate composition of a landfill: a case study in Norway

Municipal solid waste landfill leachate was sampled over from a landfill receiving varying amounts of municipal solid waste. The investigation aimed to provide information on expected leachate changes in the short term, either after closure of an active landfill, or after a strong decline in the amount of waste deposited at smaller landfills. It was found that during a two year period following a sudden decline in the amount of waste deposited, the levels of various chemical and physical parameters all dropped sharply. The reasons for the decline in discharge levels are thought to be aerobic decomposition taking place in the municipal solid waste just after landfilling, and thus the decline in the impact of this process when there were less fresh waste masses available, and formation of preferential flow paths for the leachate as the municipal solid waste stabilized in the landfill.     

The effect of slightly warm temperature on work performance and comfort in open‐plan offices – a laboratory study

The aim of the study was to determine the effect of a temperature of 29°C on performance in tasks involving different cognitive demands and to assess the effect on perceived performance, subjective workload, thermal comfort, perceived working conditions, cognitive fatigue, and somatic symptoms in a laboratory with realistic office environment. A comparison was made with a temperature of 23°C. Performance was measured on the basis of six different tasks that reflect different stages of cognitive performance. Thirty‐three students participated in the experiment. The exposure time was 3.5 h in both thermal conditions. Performance was negatively affected by slightly warm temperature in the N‐back working memory task. Temperature had no effect on performance in other tasks focusing on psychomotor, working memory, attention, or long‐term memory capabilities. Temperature had no effect on perceived performance. However, slightly warm temperature caused concentration difficulties. Throat symptoms were found to increase over time at 29°C, but no temporal change was seen at 23°C. No effect of temperature on other symptoms was found. As expected, the differences in thermal comfort were significant. Women perceived a temperature of 23°C colder than men.     

The IVAIRE project – a randomized controlled study of the impact of ventilation on indoor air quality and the respiratory symptoms of asthmatic children in single family homes

A randomized controlled trial was carried out to measure the impact of an intervention on ventilation, indoor air contaminants, and asthma symptoms of children. Eighty‐three asthmatic children living in low‐ventilated homes were followed over 2 years. Several environmental parameters were measured during the summer, fall, and winter. The children were randomized after Year 1 (43 Intervention; 40 Control). The intervention included the installation of either a Heat Recovery Ventilator (HRV) or Energy Recovery Ventilator (ERV). During the fall and winter seasons, there was a significant increase in the mean ventilation rate in the homes of the intervention group. A statistically significant reduction in mean formaldehyde, airborne mold spores, toluene, styrene, limonene, and α‐pinene concentrations was observed in the intervention group. There was no significant group difference in change in the number of days with symptoms per 14 days. However, there was a significant decrease in the proportion of children who experienced any wheezing (≥1 episode) and those with ≥4 episodes in the 12‐month period in the intervention group. This study indicates that improved ventilation reduces air contaminants and may prevent wheezing. Due to lack of power, a bigger study is needed.     

The effect of a redesigned floor plan, occupant density and the quality of indoor climate on the cost of space, productivity and sick leave in an office building–A case study

The aim of this study was to examine changes in the overall costs of an office when the efficiency of space use is increased. The variable in the examination was a space index, calculated as the floor area per employee. The quality of indoor climate was also a variable in the analysis. The overall cost analysis of a given case building showed that when space use is boosted significantly, measures must be taken to guarantee a sufficient quality of indoor climate. The study indicates that investment in the quality of indoor climate is cost-effective when the economic effect of indoor climate to health and productivity are taken into account in addition to the costs of investment, operation and maintenance. Insufficient ventilation without mechanical cooling may cause a substantial loss of productivity. The importance of good ventilation and air-conditioning increases with a more efficient use of space especially in conjunction with high value of work.