The object of research is a soil cover of the territory located outside the right of way in the area of the possible impact of onshore infrastructure.
The cause of possible impact on soil cover during the operation of the Sakhalin-2 onshore infrastructure can be:
· performance of works on engineering, maintenance and repair of the pipelines;
· change of inter-flow and disturbance of surface-flow as a result of pipeline laying and road construction;
· development of erosion processes due to natural soil contraction in the reclamation strip, as well as due to slow reclamation of vegetation in the reclamation strip;
· more active recreational use of territory;
· aerogenic pollution of the territory with the OPF, BS 2 and LNG plant air emissions;
· motor transport air emissions in the impact area of roads of federal and regional significance;
· active recreational use of the territory;
· anthropogenic impact as a result of gardening and farming activities.
Soil monitoring programme in the area of impact of the Sakhalin-2 onshore infrastructure includes:
· identification, mapping and assessment of soil degradation processes, such as:
· identification, mapping and assessing of soil pollution.
o mechanical disturbance, compaction and littering of soil;
o soil erosion;
Soil monitoring operations are carried out in accordance with Methodological recommendations on the identification of degraded and polluted lands (Letter of Ministry of Nature No. 25/8-34 of 9 March, 1995).
Ecological soil survey within the area of possible impact of the LNG plant and OET is carried out at 12 local soil monitoring sites located in three directions (rhumbs) at distances of 0.5, 1, 2, and 4 kilometres fr om the border of the LNG production site in places with the most characteristic landscape conditions, as well as on two conditionally baseline sites. The organic matter content of soils varies considerably: from elevated (lowland bog soils) to relatively low (high bog soils) and low (brown forest soils).
No disturbance of soil cover and degradation phenomena have been registered at all monitoring sites associated with the activity of the Prigorodnoye production complex. The levels of petroleum hydrocarbons and benzo(a)pyrene in the soils of all monitoring sites are within background values for the entire profile and do not exceed the standard values.
No contamination by the considered ecotoxicants has been detected: average TPH content levels (total petroleum hydrocarbons) in the layer 0−25 cm varied between 32−235 mg/kg, which is also well below the permissible level (1000 mg/kg); average benzo(a)pyrene content levels in a layer 0−25 cm were below the detection lim it.
Monitoring of soil and soil cover along the onshore pipeline route is carried out at 24 permanent sampling areas, located at the right of way, with different landscape and orographic conditions and technogenic soils, as well as at 24 areas considered as conditionally baseline, with undisturbed natural soils. A pronounced vegetation with 75–100% projective cover has formed on almost all monitoring sites, which causes the formation of a good sod horizon.
Content of TPH and main controlled ecotoxicants in soils (layer 0−25 cm) varied between 15–289 mg/kg, which is well below the permissible level (1000 mg/kg).
Soils around the BS 2 are acidic and contain little nitrogen, little phosphorus. The high potassium content may be due to the close location of the Sea of Okhotsk, the salts of which are brought by the wind and come to the soil from the atmosphere (salt impulverisation phenomenon). Content of petroleum hydrocarbons as main ecotoxicants in soils (horizon 0−25 cm) averaged 380 mg/kg, which is well below the permissible level (1000 mg/kg). Benz(a)pyrene − a key indicator of possible contamination − was not detected in soil layers 0−25 cm.
Content of hydrocarbons, heavy metals, ethylene glycol, mobile forms of nitrogen (NO3, NO2 -, NH4+) in the OPF soils is within background values, considerably lower than the maximum permissible concentrations and sometimes cannot be detected by standard methods. Average petroleum hydrocarbon content (layer 0−25 cm) was 523 mg/kg, given the permissible level 1000 mg/kg. Average petroleum hydrocarbon content in bog soils (layer 0−25 cm) was 558 mg/kg, in mineral soils − 274 mg/kg.
No lands contaminated by oil and petroleum products as a result of the operation of infrastructure and activities in the territories of the company’s facilities has been identified.