Monograph is a tribute to Latvia in the hundredth century, which in 800 pages of pages A through Z, in the text, tables, diagrams, maps and images, tells about the geography of Latvia. The book, through the prism of the geological development of the territory, describes a very long period of formation of the territory of Latvia, from the period of Pre-Cambrian to the present. The leading geography, environment and ecology specialists of Latvia are involved in the preparation of the monograph. The collective of authors consists of more than 60 leading scientists in geology, ecology, geography and environmental sciences in Latvia. The content of the book is impressive - in general it covers 10 large sections - "Territory of Latvia", "Geological environment and resources", "Atmosfera", "Surface water", "Sphere of life", "Population and culture", "Geography of the holding and the place of Latvia" World "," Landscape "," Natural diversity and cultural heritage values ​​"and" Sustainable development of Latvia ". The target audience of the monograph is the inhabitants of Latvia, notably teachers, scientists and university lecturers, students and public administration employees. | Monogrāfija ir veltījums Latvijai simtgadē, kas teksta, tabulu, diagrammu, karšu un attēlu 800 lappusēs no A līdz Z stāsta par Latvijas ģeogrāfiju. Grāmatā caur teritorijas ģeoloģiskās attīstības prizmu aprakstīts ļoti garš Latvijas teritorijas veidošanās periods, sākot no Pirmskembrija perioda līdz mūsdienām. Monogrāfijas sagatavošanā piesaistīti Latvijas vadošie ģeogrāfijas, vides un ekoloģijas speciālisti. Autoru kolektīvu veido vairāk nekā 60 Latvijā vadošie zinātnieki ģeoloģijā, ekoloģijā, ģeogrāfijā un vides zinātnē. Grāmatas saturs ir iespaidīgs - kopumā tā aptver 10 lielas nodaļas - "Latvijas teritorija", "Ģeoloģiskā vide un resursi", "Atmosfēra", "Virszemes ūdeņi", "Dzīvības sfēra", "Iedzīvotāji un apdzīvojums", "Saimniecības ģeogrāfija un Latvijas vieta pasaulē", "Ainavas", "Dabas daudzveidības un kultūrvēsturiskās vērtības" un "Latvijas ilgtspējīga attīstība". Monogrāfijas mērķauditorija ir Latvijas iedzīvotāji, sevišķi atzīmējot skolotājus, zinātniekus un augstskolu pasniedzējus, studentus un valsts pārvaldes darbiniekus.

The nitrous oxide accounted for the year 2015 gives 60 % of Latvia`s greenhouse gas emissions from the agricultural sector. Majority of nitrous oxide comes from mineral fertiliser application and manure management. Nitrous oxide emission from soils is strongly correlated with the soil moisture and temperature. Since nitrous oxide has very low concentrations in natural environment, there is a risk to overestimate or underestimate nitrous oxide emission. Automated cavity ring down spectroscopy for nitrous oxide emission measurements is a relatively new technology and there is a need for development of proper methodology. The aim of this study is to identify proper measurement time for nitrous oxide emission from soil by using automated cavity ring down spectroscopy with recirculation system. The automated cavity ring down spectroscopy, namely Picarro G2508, was connected in a closed recirculation system with the chamber of total volume 2 litres. Dray soil samples were weighted in containers and different amounts of water and ammonium nitrate were added. Totally 36 samples were used in the experiment. Each sample was measured 10 minutes and the nitrous oxide concentration was recorded for each second. For each sample measurements were repeated three times. The linear regression method was used to calculate the emission amount for different time periods from 30 seconds till 600 seconds. The results of the research show quite high variation of nitrous oxide emission from the soil samples. Data analysis showed that the minimal measurement time has to be at least 250 seconds.

Blueberry cultivation is becoming more and more popular in Latvia, and several commercial plantations have been established recently. Highbush blueberries (Vaccinium corymbosum L.) are perennial and can grow without replanting for 50 years; therefore a choice of soil and its preparation have a great role. This article summarizes results of research carried out in commercial blueberry plantation established in 2004 on loamy Haplic Cambisol. Soil properties, especially reaction and organic matter content, initially were not suitable for blueberry cultivation, therefore deep tillage and application of soil conditioner (acid sphagnum peat) were done before planting and similar peat mulch was applied every second year. Berry yield of 4 blueberry cultivars, soil properties and the nitrogen, phosphorous and potassium content in growing plant leaves were determined. The obtained results showed that sphagnum peat is an effective material for lowering of soil pH in plant root layer (0 – 40 cm). Data about plant nutrient content in topsoil and subsoil as well as in growing plant leaves will help to develop criteria for soil fertility assessment and diagnosis of plant nutrition.

Development of micellar structures in solutions of surfactants may increase the apparent aqueous solubility of polycyclic aromatic hydrocarbons (PAHs). In this study, we tested the effect of the structures of humic acids and their derivates on the enhancement of solubility of six polycyclic aromatic hydrocarbons. Solubility of PAHs in presence of humic acids increased with increasing number of aromatic rings. Similar results demonstrated anionic surfactants with and without aromatic rings. The modified humic substances demonstrated more significant solubilizing effect of PAHs.

In Latvia grey heron (Ardea cinerea) and great cormorant (Phalacrocorax carbo) are nesting in colonies in trees next to water bodies. According to the literature grey heron has nested in the territory of present-day Latvia since the 18th century, whereas great cormorant as invasive and very aggressive species have emerged here only about 30 years ago. The colonies of grey heron and great cormorant are frequent on the islands of Latvia’s lakes. Because of the small size of lake islands and sensitive ecosystems found there, the impact of these birds is fairly strong. The given study summarizes the data how the presence of grey heron and great cormorant has affected the vegetation and soil chemical composition on two lake islands in Latgale (eastern Latvia): the Pildas Island in Lake Pilda and the Siena Island in Lake Ežezers. Hypotheses for the future development of woodlands affected by the studied bird species are advanced. For the study carried out in 2006-2007 on each island two observation plots (each 400 m2) were set up, one representing a natural habitat (background), the other – a site with trees comprising more than 10 nests (contaminated site). For the observation plots the occurrence of plant species for each layer was determined visually. Soil acidity (pHKCl), hydrolytic soil acidity, exchange base, humus content, and total nitrogen content were determined for the topsoil (2-7 cm deep). The amount of chemical elements (Ca, Mg, K, Na, Fe, Mn, Ni, Zn, Cu, Cd, Pb) was determined by using the atomic absorption spectrometer Aanalyst 200, but P – by colorimetricy. Prolonged supply of bird droppings on the soil surface increases substrate acidity and reduces the amount of exchange cations. Normally in broadleaved forests the ground cover is slightly acidic (pH 5.8-6.1) while under the trees with nests it is acidic (pH 3.6-4.0). The difference between the exchange base for a background and a bird contaminated substrate is 4.0-4.7 times, but the difference for the total nitrogen content is 1.4-2.0 times. There are also various results between the content of some chemical elements in the ground cover of the background and contaminated sites. Compared to the background site (Pildas Island), the amount of P in the contaminated site is even 48 times higher, Zn 6.4 and K 2.9 times higher. For Mg and Mn this difference is less: 2.8 and 1.8 times, respectively. The islands of Pildas and Siena are covered by broadleaved forests of lime (Tilia cordata) and oak (Quercus robur) with a slight admixture of spruce (Picea abies) and pine (Pinus sylvestris). Because of bird droppings the ground right under the trees with nests is completely stripped of vegetation. On less impacted places there are clumps of monodominant nitrophilous plants as Urtica dioica, Anthryscus sylvestris, Aegopodium podagraria, Sambucus racemosa. Substrate acidification, disproportions of N and especially of P under the trees with nests affect over a wider area the forest stand composition and the transformation of plant communities. Colonizing an island both grey heron and great cormorant make nests first of all in pines and spruces, and to a lesser extent in lime trees and oaks. Due to changes in substrate chemical properties spruce trees decay at first, while pines and broadleaves are more resistant against the excessive amount of bird droppings. The birds nesting in colonies in trees is an extreme natural disturbance in woodlands, which promotes formation of glades taken over by high-growing herbaceous (Urtica dioica, Rubus idaeus, Pteridium aquilinum et al.). Later the glades may overgrow by trees tolerant to acid soils as birch (Betula pendula) and oak (Quercus robur). Nowadays the migration of great cormorant, similarly to grey heron in the 19th and 20th centuries, occurs along the Baltic coast and the Baltic Ridge, rich with lakes. The migration habits of the both species are associated not only by biological factors (overpopulation, feed availability) but also by the climate changes during the 19th and 20th century.

The study was conducted to determine concentrations of sodium and chlorine in snow, soil, and plants of street greenery in the central part of Riga (2004-2005), in relation to the toxic effect on street trees (tilia x vulgaris). Snow, soil, and leaf samples were collected from eight study sites (27 trees) in the central part of Riga with intense traffic and from a control site (three trees) located in a park area. Significantly increased levels of Na**+ and Cl**- in urban snow, soil, and leaf samples were found in comparison with the background values. There was close correlation between the Na**+, Cl**- concentration in the leaves, and the extent of leaf necrosis. The concentrations of Cl**- and Na**+ in damaged leaf samples were at least 6.6 times and 4.7 times higher in comparison with healthy tree leaves in the park.

Nitrogen fertiliser use is important factor for increase of crop yield and its quality parameters. However, environmental consequences, especially leaching of mineral forms of nitrogen in post-harvest period, should be taken into account. One of the risk areas is usage of equal fertiliser norms for fields where some areas are covered by mineral, but some – with organic soils. Therefore, field experiment was carried out in such situation where mineral nitrogen content in soil was monitored during vegetation separately for three layers: 0 – 30, 30 – 60 and 60 – 90 cm. Nitrogen off-take by crops’ yield and balance were calculated. Pattern of mineral nitrogen content in both soils was similar – rapid increase after the use of fertiliser, than decrease during vegetation due to its consumption and then increase again after harvesting. Amount of soil nitrogen pool for organic soil was significantly higher if compared with mineral one. Finally, the non-used nitrogen in organic soil after harvesting was also high, that might cause environmental risk due to its leaching. Therefore, differentiation of nitrogen norms is necessary measure to apply for fields where mineral soils alternates with organic ones.

The objective of this study was to evaluate the main plant nutrient: mineral nitrogen (NH4 + -N and NO3 -N) dynamic in soil under fertilizing for obtaining high grain yields of winter wheat (Triticum aestivum L.) and to determine relationships between nutrient uptake and winter wheat productivity. The field study was carried out at the Research and Study farm ‘Vecauce’ of the Latvia University of Agriculture for two years 2012/2013 and 2013/2014 with winter wheat variety ‘Kranich’. Different nitrogen application rates (0, 85, 153, 150, 175, 180 and 187 kg haE-1) and timing were used for winter wheat. The content of nitrates NO3 -N and ammonium nitrogen NH4 -N was determined in the soil layers 0-0.20 m, 0.20-0.40 m, 0.40-0.60 m. Nitrogen management strategy during the plant growth period based on soil Nmin evaluating can improve N use efficiency and reduce environmental contamination. The maximum of mineral nitrogen content in soil in the vegetation period was observed at the beginning of stem elongation with a tendency to decrease. A significant impact (p is less than 0.05) of nitrogen fertilizer application was noted on the mineral nitrogen content in soil layer 0-0.20 m deep in both trial years. The increasing doses of nitrogen fertilizer raised the amount of mineral N in the soil profile. The significant impact (p is less than 0.001) of nitrogen application and year conditions was observed on grain yield. Close positive correlation significant at 99% probability level was observed between the grain protein content and nitrogen concentration mostly in all soil layers, but it was not found between the grain yield and nitrogen content.

In Latvia, Devonian and Permian sediments such as dolomite and limestone are widely used for the manufacturing of building materials. Unfortunately, the manufacturing processes used involve excessive emissions of calcium, magnesium and other compounds into the atmosphere, resulting in changes in the species composition of flora and fauna. The impact of the Saulkalne lime processing facilities on the surrounding pine forest is described. Intensive synantrophication and eutrophication occurs in the immediate area.