Группа авторов "Remote Detection and Maritime Pollution"

French Directorate of Water and Biodiversity

Ministry of the Environment, Energy and the Sea

Oil production at sea is one of the major uses of the ocean. To meet the technical challenges of this industry, it is our duty to preserve what is one of humanity’s key resources. Total, as a leading light in responsible energy, examines and tests the latest advances geared towards minimizing the impact of its activities on the natural environment.

To maintain sufficient safety levels so as to prevent accidental releases, to determine the response actions to be rapidly implemented in the event of an incident and to more fully understand the behavior of oil at sea, Total depends on the research teams liable to support the scientific and technical developments identified so as to preserve the ocean and its ecosystems.

In order to maintain its remote sensing capabilities, Total deploys a research program that encompasses recent developments and promotes exchanges between the different players in the field.

True to its commitment towards meeting the environmental challenges and preserving the environment wherever the Group operates, Total implements anticipatory measures and environmental protection actions against oil pollution. This commitment is illustrated by the support it provides to the activities conducted by CEDRE, with which the Group enjoys close collaboration.

CEDRE’s portfolio of activities clearly positions it at the crossroads of the needs expressed by the different stakeholders and of the proposed solutions promoted by research players.

The CEDRE Information Days, from which this book developed, are a chance to share, discuss and challenge these approaches, in order to pinpoint progress opportunities or even new research projects. Naturally, as an industrial player, Total both benefits from and greatly contributes to these debates.

Frédéric PÉRIÉ

President of CEDRE’s Strategy Committee

Why was remote sensing chosen as the topic of this book? Such systems have been frequently used by CEDRE, in particular during the Prestige oil spill in 2002. Over and above operational aspects, it is also extremely useful for detecting deliberate discharge. In this context, strictly speaking, CEDRE does not conduct remote sensing, but rather works as a partner, in particular alongside the French Navy or within the framework of projects funded by the European Union. We are involved in equipment trials and tests, as well as in analyzing POLREPs, and we have been organizing aerial observation and remote sensing training courses for over 20 years. We also provide advice to the French and foreign authorities in charge of directing operations and of post-response legal aspects. The aim of this book is to offer as broad a vision as possible of remote sensing in the field of marine spills.

StГ©phane DOLL

Director of CEDRE

PART 1 Remote Sensing Means

1

POLLUPROOF Project

1.1. Introduction

In cases of maritime pollution by HNS (Hazardous and Noxious Substances), specific methods of identification and characterization are needed. The project POLLUPROOF (which started in January 2014 and ended in mid-2017) aims to test and validate the use of optical sensing methods, including hyperspectral and radar sensors, in order to detect, locate and classify six HNS. In this chapter, the experimental approach followed during the project is detailed: the calibration of optical sensors in mesoscale experiments and the validation of optical and radar sensors in a realistic experiment at sea. The promising results obtained are specifically explained in the other chapters.

Maritime shipping activities are responsible for about 20% of the pollution at sea. Pollutants discharged accidentally or deliberately can endanger the biodiversity and eco-balance of our oceans. Exhaust emissions and cargo mishaps associated with an increase in vessel traffic are sources of pollution that affect both the marine environment (acidification, contamination of flora and fauna) and land (acid rain). This issue has become a priority at the national (Grenelle de la Mer) and regional (European – directives 2005/35 and 2005/33) levels, as demonstrated by the implementation of several international conventions (e.g. OPRC-HNS Protocol [OPR 00], MARPOL (completed in 1978) [MAR 73]). Obviously, the removal or drastic reduction of pollution resulting from maritime activities is a desirable objective. The magnitude of the problem is highlighted by the quantity of goods transported by sea: of an estimated 8,000 million tonnes (Mt) of chemicals transported worldwide, 350 Mt are transported via European waterways. It is estimated that there are more than 100 incidents per year involving the illegal discharge of noxious liquid substances in these waters. For over 25 years, French Customs (DGDDI) have deployed aircraft equipped with remote sensing instruments (radar and scanner IR/UV), in order to successfully prosecute ships involved in oil spill incidents. The effectiveness of this policy has been demonstrated through a significant reduction in oil pollution in the waters under French jurisdiction (during the period between 2006 and 2012, the number of ships caught polluting was reduced by threefold).

This chapter presents the POLLUPROOF project through its objectives and the experimental approach used to achieve them. Results from the experimental parts are beyond the scope of this chapter and will be part of other chapters.

1.2. POLLUPROOF project

1.2.1.Objectives

The POLLUPROOF (PROOF improvement of HNS maritime POLLution by airborne radar and optical facilities) project would enhance the capabilities of French Customs to detect, locate and classify pollutants (other than hydrocarbons) originating from ship emissions (including particulates), in order to collect evidence for the prosecution of offenders while ensuring an effective intervention in the case of accidental discharge at sea.

The project is funded by ANR ECO-TECH 2013, and the members of the consortium have a recognized and complementary expertise in the field of aerial detection and marine pollution: ONERA, DGDDI, CEDRE, CEPPOL, Agenium, AVDEF and DRDC. In addition to the consortium, Transport Canada (TC) acts as an end-user and member of the steering committee. The project began in January 2014 and concluded in mid-2017.

The objectives of this project are:

1В 1) to verify the ability to detect, locate and classify at least three of the six most noxious liquid substances transported by sea in Europe;

2В 2) to achieve a reduction of spilled noxious liquid substances equivalent to the level for hydrocarbon emissions;

3В 3) to develop a stronger policy to control the release of noxious gases within the sulfide emission control areas (SECA).

These objectives will be achieved by:

– deployment of radar (SAR/SLAR) and optical sensing (hyperspectral cameras) capabilities for detecting liquid pollutants at sea;

– evaluation of the complementarity of optical and radar information;

– identification of gaseous discharges of engine emissions and liquid pollutants using hyperspectral analysis.

To accomplish these activities, the POLLUPROOF project will analyze the needs of French Customs regarding aerial detection and will proceed with:

– calibration of optical measurements on liquid pollutants in mesoscale (test-tank) experiments located at CEDRE;

– airborne measurements of sea spills using hyperspectral optical and radar sensors, following the test-tank analysis;

– algorithm development for detection, location and classification of pollutants. The consortium will then produce a data gathering evidence methodology. French Customs staff will evaluate the effectiveness and applicability of these advances using a human–machine interface.

1.2.2.Hazardous and noxious substances

Six chemical substances have been chosen to evaluate the capability of remote sensing sensors: rapeseed oil, fatty acid methyl ester (FAME), toluene, heptane, xylene and methanol. These chemicals are among the most transported substances by maritime freight in Europe. Methanol and liquid chemicals represent 46% of the 165 million tonnes annually transported by chemical carriers, while vegetable oil accounts for 29% [OLA 09]. Some of these chemicals are classified as the most noxious substances in the IBC Code (IMO website), which provides an international standard for the safe carriage by sea of HNS in bulk. These chemicals have already been involved in accidents at sea, for example Poona sank in 1971 with 600 T of rapeseed oil, Grape One sank in 1993 with 3,000 T of xylene, Cape Horn carrying a cargo of 14,000 T of methanol was seriously damaged by an explosion in the port of Livorno in 2003 [CED 15, CUN 15]. Rapeseed oil and FAME are part of the vegetable oil family; toluene, heptane and xylene are petrochemical products; methanol is part of the family of alcohols and derivatives. Their main properties are described below.

Rapeseed oil: rapeseed or colza oil is a vegetable oil obtained from crushed colza seeds. At ambient pressure and temperature, rapeseed oil is a viscous liquid with a specific gravity of 0.910. Rapeseed oil is insoluble in water and does not evaporate (vapor pressure below 0.01 kPa at 25В°C); these characteristics classify rapeseed oil as a floater F in the SEBC.

FAME: fatty acid methyl esters are biofuel directly added to conventional fuels such as diesel. At ambient pressure and temperature, they are a liquid with a specific gravity of 0.888. This product is virtually insoluble in water (solubility of 0.023 mg.L

at 20В°C) and has a relatively low evaporative potential (vapor pressure of 0.42 kPa at 25В°C) making it a floater F in the SEBC.

Toluene: toluene, also named methylbenzene or phenylmethane, is an aromatic hydrocarbon that is commonly used as a chemical reagent or solvent, particularly in the industrial sector. Toluene is a liquid at ambient pressure and temperature and has a specific gravity of 0.867. Toluene is nearly insoluble in water (535 mg.L

at 25В°C) and tends to evaporate relatively easily (vapor pressure of 2.91 kPa at 20В°C). Considering the SEBC classification, toluene is a floating and evaporating (FE) substance.

Heptane: heptane is the generic term to identify one of the nine isomers of C

H

, and is a saturated hydrocarbon of the linear alkane family. This is a constituent of fuel and is used as an extraction solvent, a synthesis intermediate in the chemical industry and as a solvent for glues, inks, rubbers and plastics. At ambient pressure and temperature, heptane is a volatile liquid (6–7.7 kPa at 20°C) and nearly insoluble in water (< 2 mg.L

at 20В°C). With a specific gravity of 0.710, heptane is lighter than water and floats. According to the SEBC classification, heptane is considered as an evaporator E.

Xylene: xylene or dimethylbenzene is a group of aromatic hydrocarbons with one methyl derivative on benzene. It is naturally present in oil and can be observed in (diesel) engine exhaust gases, either as a residual oil chemical or formed during incomplete combustion. Xylene is also produced from oil in the petrochemical industry and is one of the 30 most produced chemicals in the USA. It is used in the printing, rubber and leather industries mainly as a solvent. Xylene is an inflammable liquid with a pleasant fragrance. Chemical properties are similar from one isomer to another. Its specific gravity of 0.87 makes it float on water. Xylene is slightly soluble in water (solubility below 20 mg.L

at 20В°C) and is not likely to evaporate (vapor pressure of 0.89 kPa at 20В°C). Due to these characteristics, xylene is considered as an FE (floater and evaporator) in the SEBC classification.

Methanol: methyl alcohol or methanol is the simplest alcohol with the chemical formula CH

OH. At ambient temperature, this polar liquid is used as antifreeze (for coolant, for example), solvent or fuel (in aeromodeling, for example). Methanol is not present in large amounts in nature and is industrially produced. It is mainly used as the basic material for chemical synthesis of more complex chemical products. Nearly 40% of methanol is converted into formaldehyde, which is then transformed into plastics, synthetic resins, paints, explosives or fabrics. Methanol is a light liquid (specific gravity of 0.791), volatile (vapor pressure of 12.3 kPa at 20В°C), miscible in water, inflammable and toxic with a characteristic odor. These properties enable the classification of methanol as a DE (Dissolving and Evaporating) substance.

1.3. Experimental approach

The experimental approach is divided into two parts: first, the calibration of optical sensors on liquid pollutants in mesoscale experiments; second, airborne measurements of sea spills using hyperspectral optical and radar sensors.

1.3.1.Calibration of optical sensors

The calibration of optical measurements on liquid pollutants was realized in mesoscale (test-tank) experiments located at CEDRE (Brest) in October 2014. Three configurations were tested, with each one having specific objectives:

– vertical configuration: comparison between clean water and water covered by a chemical;

– horizontal configuration: detection of the gas cloud produced by the evaporation of the chemical;

– tank: evaluation of the influence of the slick thickness.

1.3.1.1. Vertical configuration

Eight different HNS (benzene, toluene, xylene, diethyl ether (DEE), rapeseed oil, propanol, methanol and heptane) were released into seawater inside a floating aluminum frame that was installed in the CEDRE pool, as presented in Figure 1.1. For each product, different spill volumes were used from 60 mL up to 5 L, and the seawater was thoroughly cleaned after each spill.

Figure 1.1.(a) Aluminum frame installed in the CEDRE pool. (b) Aerial lift with the three hyperspectral cameras

Three different hyperspectral imaging systems from 0.4 to 12 Ојm were used during this campaign: two reflective sensors (NEO HySpex cameras) from 0.4 to 1 Ојm (VNIR) and from 1 to 2.5 Ојm (SWIR) and a thermal longwave (LWIR) sensor from 8 to 12 Ојm (Telops Hypercam). Hyperspectral imaging cameras were deployed inside an aerial lift at a height of 12 m above the pool with a nadir-looking geometry and a Bomem MR300 spectroradiometer was placed next to the edge of the pool. The three sensors were pointed towards the expected center of the slick.

The aim was to evaluate how hyperspectral sensors can contribute to the detection of pollutants in a nadir-looking geometry.

1.3.1.2. Horizontal configuration

The sensors used for this configuration were as follows: two reflective sensors (NEO HySpex cameras) from 0.4 to 1 Ојm (VNIR) and from 1 to 2.5 Ојm (SWIR), an ASD Fieldspec camera from 0.4 to 2.5 Вµm, a thermal longwave (LWIR) sensor from 8 to 12 Ојm (Telops Hypercam), a Bomem MR300 spectroradiometer and a P-iCATSI (Polarized Improved Compact ATmospheric Sounding Interferometer).

Heptane, toluene, xylene, methanol, rapeseed oil, diethyl ether, silicone oil, unleaded gasoline and oil were released (volumes from 2 to 10 L). Diethyl ether and methanol were discharged directly in the basin, whereas the other products were released inside the floating aluminum frame.